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Thread: Anders Uschold Q&A

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    Default Re: Anders Uschold Q&A

    Quote Originally Posted by jebir
    Hi Anders,

    thanks for joining us and share your expertise. I understand that your time is precious so I will only ask one thing that I have had a hard time understanding for a while. Although it has nothing to do with Olympus in particular, it is interesting for the understanding of digital imaging.

    I have seen stated numerous times by several respected authors that a digital sensor without the R, G, and B, filters would provide a B&W image with 3-4 times higher resolution than the same sensor with the Bayer filters.

    I can't understand this since the Bayer interpolation uses all information of the nearest neighbours for its retrieval of the unknown colour values at each pixel. Considering that there are twice as many G and R or B photosites, the resolution (thinking line pairs/mm) loss shouldn't be 'smeared' to more than about 1.5 times from the theoretical value based on photosite pitch of the sensor. This 1.5x is also what one usually see when looking at line resolution tests of digital cameras when good lenses are used. It also seems to fit with what the Foveon chips delivers.

    I would be happy if I you can help me understand how some (quite highly respected) authors can claim that the resolution of a B&W sensor would be 3-4 times higher than a corresponding Bayer-patterned sensor.

    With best regards, Jens Birch.
    Hello Jens,

    thanks for your question.

    First, what does it mean, a reduction of resolution by 3-4. In most cases we talk about linear resolution, that means lines or pixel per length unit.

    Some use a square resolution unit, that means pixel per area unit. That's why many many people think that 4 Megapixel are twice the resolution as 2 Megapixel - in fact it is 1.4 times more resolution :-).

    So, regarding the sensor only, a linear factor of 3-4 would be equivalent to a reduction of 9-16 of the pixel number. That is not applicable from my experience. That's why those experts who speak of 3-4 must think of the square unit.

    Your approach is not that bad, but it misses the influence of the demosaicing / color interpolation procedure. Some cameras do an excellent job and demosaice with high efficiency, other produce low resolution or high resolution with high error information / artefacts.

    The next aspect is - and here you are right - , that a Bayer pattern does produce higher resolution in the green channel, than in red or blue. Respecting, that green has highest influence on our perceptual resolution, a loss of linear resolution from 1:1.5 to 1:2 takes place, according to how well demosaicing performs. But that is not too bad, as if resolution is too high, aliasing and artefacts may spoil fine structures' natural look.

    My opinion is: Too much resolution is bad in the digital world.

    And regarding digital B/W photography one thing is as important than this monochrome sensor discussion: Use optical filters in front of the lens, as you always did with film, and do not try to imitate them later on the computer :-)!

    Anders

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    Default Reality vs. EXIF

    Hi Anders,

    As everybody knows, EXIF contains the exposure fields -- Exposure Time, F-Number, and Exposure Bias Value. The photographers believe these values are real values.

    Nevertheless, perhaps, these numbers are calculated instead of real values.

    Can you confirm a possibility of that in some DSLRs ?

    BR
    Alex

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    Default Re: Reality vs. EXIF

    Quote Originally Posted by Alex31415
    Hi Anders,

    As everybody knows, EXIF contains the exposure fields -- Exposure Time, F-Number, and Exposure Bias Value. The photographers believe these values are real values.

    Nevertheless, perhaps, these numbers are calculated instead of real values.

    Can you confirm a possibility of that in some DSLRs ?

    BR
    Alex
    Hello Alex,

    I know many bad implementation of EXIF data in cheap compact cameras.

    The problem with dSLR's is, that exposure measurement for digital sensors is not calcualated above the noise level of the density/OECF function, that means the lowest light you just get information and the usual approach with film, but below the top of the OECF function, that means little bit under saturation of the sensor. That represents the highest amount of light, the picture just doesn't clip in maximum white and detail burnout.

    Therefore some dSLR's results do not match correctly to those of external light meters. This affects the EXIF data too, even if these are real values and not calculated ones. They are not 100% transferable to what you get with external equipment, that was calibrated on film.

    I have not reliable information, if EXIF data in dSLR's is partly fictious or just calculated.

    As far as I know, EXIF f-stop often shows the real f-stop, selected for that shot. If there is 5.7 instead of 5.6 for example, it indicates an individual correction of the lens mechanics deviation. This is necessary, as no lens mechanism is exactly like another and good lenses get an indivifual calibration in their CPU.

    Best regards,

    Anders

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    Default Re: Reality vs. EXIF

    Quote Originally Posted by Anders Uschold
    I have not reliable information, if EXIF data in dSLR's is partly fictious or just calculated.
    If I understand right, it is possible that a camera shoots at 1/500 and at the same time writes to EXIF 1/1000.

    Clear, that is the simplest way to make so-called “high ISO capability.”

    Thank you very much.

    BR
    Alex

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    Default Re: Reality vs. EXIF

    Quote Originally Posted by Alex31415
    If I understand right, it is possible that a camera shoots at 1/500 and at the same time writes to EXIF 1/1000.

    Clear, that is the simplest way to make so-called “high ISO capability.”

    Thank you very much.

    BR
    Alex
    No, I explained it wrong. If a camera notes 1/1000 it should be 1/1000.

    But if you measure with your external light meter an aperture - speed - combination for ISO 100 and set it to your film camera holding an ISO 100 film, you expect a well exposed image. If you set the measured result to a dSLR set on ISO 100, it is possible, that you get a differently exposed image and nobody did something wrong, not even the manufacturer. It is just another technical approach to calculate a sensor's speed.

    Anders

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    Default Re: Reality vs. EXIF

    Quote Originally Posted by Anders Uschold
    No, I explained it wrong. If a camera notes 1/1000 it should be 1/1000.
    Anders,

    Can you tell about your real shutter speed tests? What kinds of objects were shot during these tests?

    BR
    Alex

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    Default Re: Reality vs. EXIF

    Alex,

    we do not do shutter tests with digital cameras. With analogue ones it was possible and very precise, but due to the more difficult battery handling of digitals, it refrained from it.

    We started a new shutter delay and AF.speed test. The first results will be available soon.

    Anders

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    Default Re: Anders Uschold Q&A

    Quote Originally Posted by Anders Uschold
    What do you mean saying micro contrast? Please explain.

    Anders
    Micro contrast.

    Microcontrast refers to the relative luminances of two adjacent very small subject areas. It has special relevance to very fine textural details. If some object detail is just recorded, but the contrast is below the visual threshold, we are not able to see it. What we will see however is a kind of image noise, that reduces the clarity of the picture. It will be appreciated that good microcontrast is needed when the higher spatial frequencies must be clearly separated. Flare eradicates marginally resolved textural details.

    Link is here: http://www.imx.nl/photosite/leica/ms...tm/M10-50.html

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    Default Re: Anders Uschold Q&A

    Thanks Anders, for some very interesting and highlighting points.

    So, given that the linear resolution of the E-1 is reported to be about 650-700 line pairs/image height which is just a factor of ~1.5x from what a B&W version of the same chip ever can resolve (based on the Nyquist criterion: 960 lp/ih), I conclude that the E-1 is doing very well in converting its RAW file into an RGB image (resolutionwise).

    In other words, if a 5 MP B&W Fourthirds sensor ever was made, its ultimate resolution would 'only' correspond to an ~11 MP RGB sensor based on the E-1 technology (which is only a factor of 2.2=1.5² gain).


    Cheers, Jens
    Motto: Wildlife won't come to me unless I go to it.
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    My Wildlife Photos: jensbirch.smugmug.com

    E-5, E-3, E-510, IR-E-1 ,E-P2
    ZD: 7-14, 14-54, 50, 50-200 SWD, 90-250/2.8, 300/2.8, EC-14, EC-20
    Peleng 8mm fisheye, shift Tamron SP 17/3.5, Tokina AT-X 300/2.8
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    Default Re: Anders Uschold Q&A

    Hi again Anders,

    since this thread still is open, I venture one more question for you:

    There have been (and still is) a huge controversy about if the Zuiko Digital lenses are worth the money or not.

    Some, and I am one of those, claim that lenses for the Fourthirds sensors, with only about half the linear dimension of a 35 mm film frame, needs to be manufactured with twice the resolving powers and that makes them more expensive for a given focal length.

    Also, it is debated wether lenses should be compared based on focal length or angle of view. Personally I am a believer of the latter since that gives the possibility to factor-in the mentioned better resolving power. IMO it is also better suited for comparing what end result (image) you get for the money.

    Then we have the near telecentricity that very few of us understands the implications of for the future. Some claim that it is nothing but "marketing drivel" while others tend to believe in Olympus' designed ground-up for digital philiosophy as an insurance for use with future higher speced bodies.

    As a professional reviewer with much experience with theses lenses as well as high end designed-for-film lenses, I'd like to ask you about your oppinion:

    Are the Zuiko Digital lenses special in the above mentioned respects?

    Are they worth the money?

    With best regards, Jens.

    PS. That was actually 2 questions... sorry about that.
    Motto: Wildlife won't come to me unless I go to it.
    --------------------------------------------------------
    My Wildlife Photos: jensbirch.smugmug.com

    E-5, E-3, E-510, IR-E-1 ,E-P2
    ZD: 7-14, 14-54, 50, 50-200 SWD, 90-250/2.8, 300/2.8, EC-14, EC-20
    Peleng 8mm fisheye, shift Tamron SP 17/3.5, Tokina AT-X 300/2.8
    FL-50R, FL-40, FL-20, HLD-2, HLD-4, cleaved ZD EX-25 w. electric bypass, 250D, 500D, KatzEye Plus OptiBrite
    Feisol CT-3472LV and CM-1471

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    Default Re: Anders Uschold Q&A

    Quote Originally Posted by Hacker
    Micro contrast.

    Microcontrast refers to the relative luminances of two adjacent very small subject areas. It has special relevance to very fine textural details. If some object detail is just recorded, but the contrast is below the visual threshold, we are not able to see it. What we will see however is a kind of image noise, that reduces the clarity of the picture. It will be appreciated that good microcontrast is needed when the higher spatial frequencies must be clearly separated. Flare eradicates marginally resolved textural details.

    Link is here: http://www.imx.nl/photosite/leica/ms...tm/M10-50.html
    Thanks Hacker,

    well, that is a new word for long existing and well known aspect - the MTF. The modulation tranfer function decribes the relation between spatial frequency of structures and the contrast the have. If a structure is crude, of low spatial frequency, contrast is usually high. If a structure is fine, high spatial frequency, contrast goes down. The character of structures of very low frequency = edges we call sharpness. The character of structures with high spatial frequency, we call resolution. Both are important but different aspects.

    We do test both, therefore we also check what you call micro contrast. This represents our resolution mark. We define a minimum contrast equivalent and determine the corresponding frequency = resolution.

    Best regards,

    Anders

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    Default Re: Anders Uschold Q&A

    >Hi again Anders,
    >
    >since this thread still is open, I venture one more question for you:
    >
    >There have been (and still is) a huge controversy about if the Zuiko Digital lenses are worth the money or not.
    >
    >Some, and I am one of those, claim that lenses for the Fourthirds sensors, >with only about half the linear dimension of a 35 mm film frame, needs to >be manufactured with twice the resolving powers and that makes them >more expensive for a given focal length.
    >

    The relation of production costs to resolution doesn't only relate to spatial frequency. The smaller lens diameter results in more precise production, less costs for material (optical glass is very expensive especially in times heavy metal fabrics are publicly banned), easier to handle mounts, lower sensitivity for temperature changes and therefore less efforts on lens mount thickness, and what you stated correctly: - given focal length - ! The reduction of focal length allows to gain every fast maximum apertures without the tremendous increase of costs and loss of quality.

    At all the smaller sensor size has been THE PRECONDITION to design lenses on high optical level on an affordable budget. A re-design has been necessary anyway more later.

    >Also, it is debated wether lenses should be compared based on focal >length or angle of view. Personally I am a believer of the latter since that >gives the possibility to factor-in the mentioned better resolving power. >IMO it is also better suited for comparing what end result (image) you get >for the money.

    IMO the choice for focal length as the unit to describe the field of view has been the most stupid and short sighted off-the-need-of-the-nonscientist-user-decision during the last 150 years. To give the angle of view would have been the perfect unit, I agree. But here the technicians decided and obviously they had not a clue what photography means to the user.

    >Then we have the near telecentricity that very few of us understands the >implications of for the future. Some claim that it is nothing but "marketing >drivel" while others tend to believe in Olympus' designed ground-up for >digital philiosophy as an insurance for use with future higher speced >bodies.

    No, it is an essential aspect. Background:
    - Film doesn't care of the angle of incidence of light, it absorbs it quite efficiently.
    - The beampencils of light show a 90° incidence only in the image center and only at infinite small aperture. If you integrate a beampencil of light, the mean angle of incidence is a mean of all angles of the beampencil of light. It must be below 90° and is the samller the more aperture is open.
    - Out of image center, the whole beampencil of light will be slanted additionally. this additional angles, that reduce the mean angle of a beampencil are the bigger the short the exit pupil is.
    - All center beams or the axis' of the beampenicils of light come out of a fixed / theoretical point somehwere on the lens' optocal axis. This point is called exit pupil. The distance from this point to the focal plane can be determined in mm. It is not the focal length, but often relates to it!
    - Silicon is different from silver. A digital sensor absorbs the inciding photo, but separates the energy in the sine (0°) and cosine (90°) fraction / vector. Only the cosine part can be transformed to electric energy. The sne part is lost. That means, that a slanted beam of light cause less exposure on silicon than on silver halide. The loss raises the more the mean angle differs from 90°. THAT IS THE MOST ESSENTIAL PROBLEM! It is called the cosin condition and it adds to the well known cosine^4 condition of wide angle lenses.

    Consequences:

    - The more beampencils are slanted, the more light / exposure you loose
    -> stronger corner shading

    - The wider aperture is, the more light gets lost
    -> An aperture of 1:1.4 will lead to 1:1.4 exposure in analogue, but only to 1:1.42 in digital image center and to 1:81 once the beampencil is slanted only 30° additionally. That adds to the cosine^4 condition

    This alone wouldn't be too bad. But another problem is, manufacturers put microlenses on the individual pixels to raise sensor's input aperture and efficiency.
    - These micro lenses show additionally reduced aperture, when they absorb slanted light. That can't be solved and is another additional restriction not known in film use.
    - If the microlenses-pixelcenter-axis of off the center axis of the beampencil of light, a mismatch of light spot and sensitive area happens and leads to additional loss, flare, spectral artefacts etc. This can be solved by slanting the microlenses-pixelcenter-axis to the EXPECTED beampencil axis. THAT'S MY FAVOURITE :-)))))) because:

    Film designed lenses have a variable exit pupil, that means the angle of beampenicals of light may vary widely. Different from broadcast lenses, it was never necessary to define the exit pupil position. So what is the EXPECTED angle you correct your micro lens shifting for? You can optimise for long exit pupils, Canon 60D, and get good telephoto and poor wide angle results, or change to short exit pupils, good wide angle and bad telephoto results. But as we say in German: There will be always one death you die.

    Going back to Olympus:
    - The definition of a new and standardised exit pupil over the full lens range is the precondition to constant optical performance over the full lens line up.
    - To set the exit pupil on a long mark, = near telecentric, will reduce the loss by additional drop of angle of incidence in the image corner. This is well suited to keep constant performance from image center to corner.

    All these decisision and aspects do affect corner shading, sharpness, resolution and cromatic aberration.


    >As a professional reviewer with much experience with theses lenses as >well as high end designed-for-film lenses, I'd like to ask you about your >oppinion:

    >Are the Zuiko Digital lenses special in the above mentioned respects?

    Yes, they are. Regarding the complete lens line up they are even unique at this point of time, because they don't give the user the chance to use a film-based lens. Beside some restricted OM adaptions via the adator :-).


    >Are they worth the money?

    This I cannot answer. It depends on your individual preferences and will to spend money. To give you some examples:

    - The 14-45 is a budget lens not more or less than budget lenses of other brands. Regarding the slow maximum aperture, it suffers from a relevant restriction. With 4/3 you need fast lenses.
    - The 150 2 costs around 2/5 of the competitors' 200 2 and provides outstanding performance. I would call that price-worthy :-)
    too.

    The 7-14 4 is the most expensive ultra wide zoom lens. But it is the only, that handles corner shading in a very good way against the partly dramatic results of the other 10-22 or 12-24 lenses. Optical distortion is excellent. So if you are highly into landscape and architecture - it is the choice. If you're not, it is an expensive toy.

    >With best regards, Jens.

    >PS. That was actually 2 questions... sorry about that.


    Pooh, and that was a lot of typing to me.

    Anders

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    Default Re: Anders Uschold Q&A

    Wow, very interesting and useful stuff... Thank Anders for taking the time to enlighten us.

    Excuse me for not able to express this in a scientific manner...

    I've read some ZD lens reviews and the resolution doesn't seem that high. Why are ZD lenses, when tested at the lab, have lower resolution figures? Is this a sensor restraint?

    Resolution is measured in lines/mm. Say a camera sensor has resolution of 1000 lines/mm. What will be the difference of using a lens that has resolution of 1200 lines/mm and a lens that can resolve 1500 lines/mm? Will the resolution be better by using lens with a higher resolving power? As far as I know, almost all lens on the market have resolution exceeding that of the sensors (is this really true?). Why the final image resolution(maybe I should say sharpness?) are so different with different lenses? Even very slight change in lens resolution(say from ZD50-200 to ZD40-150) will result in a huge drop in final image sharpness?


    Thanks!

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    Thumbs up Re: Anders Uschold Q&A

    Quote Originally Posted by Anders Uschold
    >PS. That was actually 2 questions... sorry about that.


    Pooh, and that was a lot of typing to me.

    Anders
    :up:

    Anders,

    Thanks a LOT for the exhuastive answer - it all makes sense to me.

    Being a physicist myself (although not much involved in optics/imaging), it also means a lot to hear (read) these things from a guy with your scientific, academic and professional background!

    I'll spare you from more of my questions - for now .

    Once again - Thanks!

    Jens.
    Motto: Wildlife won't come to me unless I go to it.
    --------------------------------------------------------
    My Wildlife Photos: jensbirch.smugmug.com

    E-5, E-3, E-510, IR-E-1 ,E-P2
    ZD: 7-14, 14-54, 50, 50-200 SWD, 90-250/2.8, 300/2.8, EC-14, EC-20
    Peleng 8mm fisheye, shift Tamron SP 17/3.5, Tokina AT-X 300/2.8
    FL-50R, FL-40, FL-20, HLD-2, HLD-4, cleaved ZD EX-25 w. electric bypass, 250D, 500D, KatzEye Plus OptiBrite
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    Default Re: Anders Uschold Q&A

    Wow, Anders. Thanks so much for taking the time to share your great insight.

    Greatly appreciated.

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    Default Re: Anders Uschold Q&A

    About that sine/cosine thing as far as sensor energy being accepted, do you have a link to a reference that explains this phenomenon of dgital sensors? I have never heard of this.

    I find it interesting, that in Olympus's marketing materila regarding the new LiveMos sensor, they say that the new sensor does not require the same degree of telecentricty for good performance.

    Quote Originally Posted by Anders Uschold
    >Hi again Anders,
    >
    >since this thread still is open, I venture one more question for you:
    >
    >There have been (and still is) a huge controversy about if the Zuiko Digital lenses are worth the money or not.
    >
    >Some, and I am one of those, claim that lenses for the Fourthirds sensors, >with only about half the linear dimension of a 35 mm film frame, needs to >be manufactured with twice the resolving powers and that makes them >more expensive for a given focal length.
    >

    The relation of production costs to resolution doesn't only relate to spatial frequency. The smaller lens diameter results in more precise production, less costs for material (optical glass is very expensive especially in times heavy metal fabrics are publicly banned), easier to handle mounts, lower sensitivity for temperature changes and therefore less efforts on lens mount thickness, and what you stated correctly: - given focal length - ! The reduction of focal length allows to gain every fast maximum apertures without the tremendous increase of costs and loss of quality.

    At all the smaller sensor size has been THE PRECONDITION to design lenses on high optical level on an affordable budget. A re-design has been necessary anyway more later.

    >Also, it is debated wether lenses should be compared based on focal >length or angle of view. Personally I am a believer of the latter since that >gives the possibility to factor-in the mentioned better resolving power. >IMO it is also better suited for comparing what end result (image) you get >for the money.

    IMO the choice for focal length as the unit to describe the field of view has been the most stupid and short sighted off-the-need-of-the-nonscientist-user-decision during the last 150 years. To give the angle of view would have been the perfect unit, I agree. But here the technicians decided and obviously they had not a clue what photography means to the user.

    >Then we have the near telecentricity that very few of us understands the >implications of for the future. Some claim that it is nothing but "marketing >drivel" while others tend to believe in Olympus' designed ground-up for >digital philiosophy as an insurance for use with future higher speced >bodies.

    No, it is an essential aspect. Background:
    - Film doesn't care of the angle of incidence of light, it absorbs it quite efficiently.
    - The beampencils of light show a 90° incidence only in the image center and only at infinite small aperture. If you integrate a beampencil of light, the mean angle of incidence is a mean of all angles of the beampencil of light. It must be below 90° and is the samller the more aperture is open.
    - Out of image center, the whole beampencil of light will be slanted additionally. this additional angles, that reduce the mean angle of a beampencil are the bigger the short the exit pupil is.
    - All center beams or the axis' of the beampenicils of light come out of a fixed / theoretical point somehwere on the lens' optocal axis. This point is called exit pupil. The distance from this point to the focal plane can be determined in mm. It is not the focal length, but often relates to it!
    - Silicon is different from silver. A digital sensor absorbs the inciding photo, but separates the energy in the sine (0°) and cosine (90°) fraction / vector. Only the cosine part can be transformed to electric energy. The sne part is lost. That means, that a slanted beam of light cause less exposure on silicon than on silver halide. The loss raises the more the mean angle differs from 90°. THAT IS THE MOST ESSENTIAL PROBLEM! It is called the cosin condition and it adds to the well known cosine^4 condition of wide angle lenses.

    Consequences:

    - The more beampencils are slanted, the more light / exposure you loose
    -> stronger corner shading

    - The wider aperture is, the more light gets lost
    -> An aperture of 1:1.4 will lead to 1:1.4 exposure in analogue, but only to 1:1.42 in digital image center and to 1:81 once the beampencil is slanted only 30° additionally. That adds to the cosine^4 condition

    This alone wouldn't be too bad. But another problem is, manufacturers put microlenses on the individual pixels to raise sensor's input aperture and efficiency.
    - These micro lenses show additionally reduced aperture, when they absorb slanted light. That can't be solved and is another additional restriction not known in film use.
    - If the microlenses-pixelcenter-axis of off the center axis of the beampencil of light, a mismatch of light spot and sensitive area happens and leads to additional loss, flare, spectral artefacts etc. This can be solved by slanting the microlenses-pixelcenter-axis to the EXPECTED beampencil axis. THAT'S MY FAVOURITE :-)))))) because:

    Film designed lenses have a variable exit pupil, that means the angle of beampenicals of light may vary widely. Different from broadcast lenses, it was never necessary to define the exit pupil position. So what is the EXPECTED angle you correct your micro lens shifting for? You can optimise for long exit pupils, Canon 60D, and get good telephoto and poor wide angle results, or change to short exit pupils, good wide angle and bad telephoto results. But as we say in German: There will be always one death you die.

    Going back to Olympus:
    - The definition of a new and standardised exit pupil over the full lens range is the precondition to constant optical performance over the full lens line up.
    - To set the exit pupil on a long mark, = near telecentric, will reduce the loss by additional drop of angle of incidence in the image corner. This is well suited to keep constant performance from image center to corner.

    All these decisision and aspects do affect corner shading, sharpness, resolution and cromatic aberration.


    >As a professional reviewer with much experience with theses lenses as >well as high end designed-for-film lenses, I'd like to ask you about your >oppinion:

    >Are the Zuiko Digital lenses special in the above mentioned respects?

    Yes, they are. Regarding the complete lens line up they are even unique at this point of time, because they don't give the user the chance to use a film-based lens. Beside some restricted OM adaptions via the adator :-).


    >Are they worth the money?

    This I cannot answer. It depends on your individual preferences and will to spend money. To give you some examples:

    - The 14-45 is a budget lens not more or less than budget lenses of other brands. Regarding the slow maximum aperture, it suffers from a relevant restriction. With 4/3 you need fast lenses.
    - The 150 2 costs around 2/5 of the competitors' 200 2 and provides outstanding performance. I would call that price-worthy :-)
    too.

    The 7-14 4 is the most expensive ultra wide zoom lens. But it is the only, that handles corner shading in a very good way against the partly dramatic results of the other 10-22 or 12-24 lenses. Optical distortion is excellent. So if you are highly into landscape and architecture - it is the choice. If you're not, it is an expensive toy.

    >With best regards, Jens.

    >PS. That was actually 2 questions... sorry about that.


    Pooh, and that was a lot of typing to me.

    Anders

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    Default Re: Anders Uschold Q&A

    Quote Originally Posted by david_e1
    Wow, very interesting and useful stuff... Thank Anders for taking the time to enlighten us.

    Excuse me for not able to express this in a scientific manner...

    I've read some ZD lens reviews and the resolution doesn't seem that high. Why are ZD lenses, when tested at the lab, have lower resolution figures? Is this a sensor restraint?

    Resolution is measured in lines/mm. Say a camera sensor has resolution of 1000 lines/mm. What will be the difference of using a lens that has resolution of 1200 lines/mm and a lens that can resolve 1500 lines/mm? Will the resolution be better by using lens with a higher resolving power? As far as I know, almost all lens on the market have resolution exceeding that of the sensors (is this really true?). Why the final image resolution(maybe I should say sharpness?) are so different with different lenses? Even very slight change in lens resolution(say from ZD50-200 to ZD40-150) will result in a huge drop in final image sharpness?


    Thanks!
    Resolution is, as I mentioned yet, not a fixed but a multi dimensional unit.

    Usually sepcialist reduce resolution to two dimensions or aspects: discrimination of structures or spatial frequency, like lp/mm, and contrast at this spatial frequency. A lens that resolves 200 lp/mm with 70% contrast may resolve 300lp/mm with 40% contrast. The first question is: how can your sensor handle this reduced contrast?

    The next is, that resolution is affected by many more aspects like just spatial freqency and contrast. How about resolution space - the change of resolution, once you slightly shift focal plane. Only from the theoretical point of view, a simplification, depth of focus is symmetrical :-).

    What about chromatic aberration. If the width of the misplacement of the chromatical channels is that wide, that it interferes with pixel pitch, artefacts may result.



    Usually a change of 20% lens resolution will not affect the image quality significantly. It affects the presence of artefacts and that is kind of lens-camera-interaction. If you have a camera, that tries to squeeze out the last per cent of resolution at the cost of high artefact presence, then a high resolving lens will provide you with a higher resolution mark in your magazine's test review and with significant artefacts at fine structures. Here, a lower resolving lens will give you better results , as it will smooth the interference necessary for artefact's. In short words: the more aggressive your camera is, the more benefits you get from a low resolving lens .

    Finally, if your camera's fine detail reproduction is not aggressive, the best is a lens, which's "resolution" exceeds the sensor's pixel pitch by at least 1.4 times. Or a sensor's pixel number, that exceeds the maximum pixel number you need by 2 times.

    I hope I did not cause more irritation than information.

    Anders

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    Default Re: Anders Uschold Q&A

    Quote Originally Posted by ActionMike
    About that sine/cosine thing as far as sensor energy being accepted, do you have a link to a reference that explains this phenomenon of dgital sensors? I have never heard of this.

    I find it interesting, that in Olympus's marketing materila regarding the new LiveMos sensor, they say that the new sensor does not require the same degree of telecentricty for good performance.
    The sine/cosine condition is elementary know-how of every opto-semiconductor or photovoltaic specialist. I know this from internal discussion with specialists like this. A reasonable part of knowledge is based on specialist talk - as we do here :-).

    I do not know this specific marketing detail you mentioned. Would you send me a link? A assume the MOS sensor to be more light sensitive or to posses a larger sensitive area. Therefore it shows less need to collect light by micro-lenses. If micro-lenses are not needed that much and are less intensive implemented, the sensor is less critical against different angle of incidence. Not by the cosine condition, but by the best-match-condition of the microlens-pixel-axis to the center axis of the beampencil of light.

    To get more detailed information on the MOS technology, I must await the next specialist meeting. The last time, MOS was so new, that many aspects were still highly confidential. It took me a resonable amount of red wine and Sake to loose my japaneses collegue's tongue just that little bit .


    Anders

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    Default Re: Anders Uschold Q&A

    Anders, or anyone;
    Thank you for your insight and input to this forum. It is informative and helpful. This may be too much to ask, but here is my question. Olympus seems to be the only camera manufacture who offers this unique feature. [Lens data to camera, or post processing corrections] I'm very curious in that I have not read in other reviews of E1, E300, E500, or E330 the real effect the camera processing or post processing of lens data has on the true quality of prints (or optical test) ( except for shading) Is this hype from Olympus or is there real scientific data that supports this function? Will lens data help image quality? for example: ["Imatest" data? or prints] of 18-180mm, 14-45mm, 40-150mm, 14-54mm, 11-22mm etc. etc. pre and post correction! Do you know of anyone who has done this? This type of information would be on the forefront to me. I have seen at other web site(s) the testing of :14-45mm, 40-150mm, 14-54mm, 11-22mm, 50mm, 50-200mmOlympus len(s) but not after processing.[ http://www.photozone.de/8Reviews/index.html and http://www.imaging-resource.com/PRODS/EV500/EV500A6.HTM ] Could you shed some light in this field?

    Thank for reading this long post. I am a technical and data type of guy, and I appreciate your input. Thanks again.








    Mark Morris
    Protein Analysis Core Lab
    Dept. Biochemistry
    WFUBMC
    jmmorris@wfubmc.edu

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    Default Re: Anders Uschold Q&A,on zooms versus single FL lenses

    Anders, can you offer(1) any generalizations about the current crop of Zuiko digital zoom lenses compared to what some people seem to think is lacking in the lens array, which is "fast primes.meaning single FL lenses?" It appears that Olympus has learned how to make very good and very fast zooms,but not at an affordable price by most of we buyers' standards, and certainly not light in weight either--? (2) Is there any technical "impetus" do you think or can guess at,to release more ultra fast fixed focal length lenses-for the general consumer' s real life needs,if there is indeed a real vs imagined need or only a 'system completeness market drive' need.(3) And,lastly, what do you judge to be the practical limits on relatively fast 4/3 zooms from your 4/3 testing so far? (I am thinking that f2.8 and f 3.5 is fast enough for most-well many- applications and beyond that we get into very costly glass and very complex design features,correct? And a bonus question, would it have been difficult for Olympus to make their 50-200 zoom with internal zoom feature,vs extensing lens barrel feature?
    Aloha,Gerry

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    Wink Re: Anders Uschold Q&A

    "Regarding the complete lens line up they are even unique at this point of time, because they don't give the user the chance to use a film-based lens. Beside some restricted OM adaptions via the adator :-)."

    Have you ever used the OM adaptor for any sort of lens test?
    Is it a 'fools paradise' to use such OLD lens designs on Silicon?
    *you can even mount your MD collection on a 4/3 dSLR!

    If a 35mm/APS 'hybrid' body was available to Film test the ZD lenses, how do you think they would rate compared to a normal film lenses?
    *would your company be able to sell such test data to anyone?

    Do you think a concept of a user changable sensor (for better BW/High ISO/WideAngle)will be seen in the next few years?
    *why can't Olympus upgrade an 5Mp E1 to a 8Mps E1n for $$$...

    So i'm a little bit Greedy in asking more than ONE Question.... So shoot me with K64 ;-)

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    Default Re: Anders Uschold Q&A

    Quote Originally Posted by Snoocam
    Anders, or anyone;
    Thank you for your insight and input to this forum. It is informative and helpful. This may be too much to ask, but here is my question. Olympus seems to be the only camera manufacture who offers this unique feature. [Lens data to camera, or post processing corrections] I'm very curious in that I have not read in other reviews of E1, E300, E500, or E330 the real effect the camera processing or post processing of lens data has on the true quality of prints (or optical test) ( except for shading) Is this hype from Olympus or is there real scientific data that supports this function? Will lens data help image quality? for example: ["Imatest" data? or prints] of 18-180mm, 14-45mm, 40-150mm, 14-54mm, 11-22mm etc. etc. pre and post correction! Do you know of anyone who has done this? This type of information would be on the forefront to me. I have seen at other web site(s) the testing of :14-45mm, 40-150mm, 14-54mm, 11-22mm, 50mm, 50-200mmOlympus len(s) but not after processing.[ http://www.photozone.de/8Reviews/index.html and http://www.imaging-resource.com/PRODS/EV500/EV500A6.HTM ] Could you shed some light in this field?

    Thank for reading this long post. I am a technical and data type of guy, and I appreciate your input. Thanks again.




    Mark Morris
    Protein Analysis Core Lab
    Dept. Biochemistry
    WFUBMC
    jmmorris@wfubmc.edu

    Hello Mark,

    first, most manufacturers do store various information in the lens' CPU and hand it over to the body:

    - individual calibration of the diphragm defect. According to mechanical tolerances, the real aperture often deviates from the selected. Then the camera adapts exposure time slightly. This correction table is evaluated for many aperture - zoom position - combinations, if you have a prefessional lens :-). That is one of those aspects you pay for with a good lens - and you never knew.

    - individual loss of contrast from image center to corner. Again, a wide set of aperture - zoom position - combinations are evaluated to get details of the individual degree, the camera's internal contrast enhancement should raise from sensor center to corner.

    - focus offset. As I mentioned yet in this thread, a lens' focal length does vary according to the selected aperture. Therefore the AF must slightly change its focus position according to the aperture you have chosen. This is the aspect, your lenses usually get re-calibrated, if you send your camera-lens-combination to the service, if they suffer from front/back focus. But that usually doesn't occur with ZD lenses.

    We have tested some images, that have passed sophisticated postprocessing, e.g. DxO Optics Pro. And we found, that overall image quality raises, as long as you have a moderate to poor lens. As far as O know, DxO doesn't provide optimisation profiles for ZD lenses. For Canon and Nikon you can get many.

    Finally: Data transfer from lens to body is business as usual with almost all brands. And it is necessary.


    Anders

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    Default Re: Anders Uschold Q&A

    Quote Originally Posted by Anders Uschold

    The E-330 shows better dynamic range, even in vivid mode. Tone reproduction and OECF are almost identical.

    The MOS is better than the CMOS.
    Hi Anders - good to see you here

    It's a while since we bumped into each other; surprised I didn't see you at PMA, though I guess you were there.

    Above, do you mean by the example that MOS is better than CCD? Or are you referring to the general technology step in MOS over CMOS?

    And to everyone here - I haven't yet seen references to this, but this morning Olympus released some technical details on the LiveMOS sensor - we have reproduced the release here on DPNow:

    http://dpnow.com/2617.html

    Ian

    Digital Photography Now
    http://dpnow.com

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    Default Re: Anders Uschold Q&A,on zooms versus single FL lenses

    Quote Originally Posted by orthogent
    Anders, can you offer(1) any generalizations about the current crop of Zuiko digital zoom lenses compared to what some people seem to think is lacking in the lens array, which is "fast primes.meaning single FL lenses?" It appears that Olympus has learned how to make very good and very fast zooms,but not at an affordable price by most of we buyers' standards, and certainly not light in weight either--? (2) Is there any technical "impetus" do you think or can guess at,to release more ultra fast fixed focal length lenses-for the general consumer' s real life needs,if there is indeed a real vs imagined need or only a 'system completeness market drive' need.(3) And,lastly, what do you judge to be the practical limits on relatively fast 4/3 zooms from your 4/3 testing so far? (I am thinking that f2.8 and f 3.5 is fast enough for most-well many- applications and beyond that we get into very costly glass and very complex design features,correct? And a bonus question, would it have been difficult for Olympus to make their 50-200 zoom with internal zoom feature,vs extensing lens barrel feature?
    Aloha,Gerry

    Hello Gerry,

    ad1):

    Lens quality is always a matter of price. To be honest, lenses and cameras have never been that cheap and mechanically poor, as they were in the end of the last century. One example:

    A Minolta SRT 101 did cost 1000 USD - in 1966! For that amount, man had to safe his money one to two years, respect the average income fourty years ago. All cameras and lenses were on professional level.

    In the 80ies we had a split: Some manufactures started to sell cheap lenses, Ricoh, Fuji, Carena, or lowered their mechanical standard, Minolta MD, Canon FD. Some sold cheap and expensive versions Nikon, Minolta. And some stayed on high standard only, Leica, Contax, Olympus, Alpa.

    With the raise of third party brands, Sigma, Tamron, Cosina, Tokina, a wide range of cheap lenses conquered the market and the masses of people got in contact with photography. Cheap prints were another key feature.

    Well, mechanical quality has never been that baaaaaaad than in the 90ies. Cameras consisted of plastic only, so did lenses - no matter which manufacturer. Except Leica and Contax - one is fighting for survival and one died meanwhile.

    The price of prints dropped dramatically - 2 cents here in Germany - so did pictorial quality. The "photographer" has lost the meaning of photography. It must be a reliable tool - and these are never cheap.

    Now what to do now. the 35mm parties are deeply customed to those cheap lenses, millions exist. To change the system completetely and the loack of compatibility is a great chance to a manufacturer to start - from where? Is it affordable photography to the masses or is it a new implementation of quality, we lost contact and use to?

    We live in a time of heavy consumption. You change your car each two years, you go for dinner twice a week, you don't have one hobby - you have three. You only can afford this variety of luxury goods, if they are cheap. That's what we are used to.

    If you think of the price of a lens, compare it to a Hasselblad or old Nikkor or Zuiko or Leica lens, that is in use for decades. We must get rid to think of photographic equipment of a mean lifetime of two years - a dSLR's mark - and invest our money according to that short time. If we continue like that, we never regard a photographic equpiment as e worthy tool again.

    ad 2.

    Fast prime lenses are a real problem in digital photograhy. a mayor restriction is focus accuracy. Without hurting an NDA, I can tell you, that 1:2.0 is a speed, that makes sense from the technical point of view. Faster lenses are critical. There is only one in the market, Sigma 30mm 1:1.4. And this one shows relevant technical and quality restrictions.


    ad 3.

    I recently tested the 1:2.0 35-100. An amazing lens! This is a competitor to the 70-200 2.8. Regarding the lack of image stabilisation:
    In digital use, we know one stabilised lens only, that doesn't suffer from high restrictions, caused by the loose optical element. The Canon 24-105 4 IS. But that lens is slow and shows bad corner shading.

    Stabilised lenses usually show:
    - higher corner shading
    - more sudden vignetting = limited image circle
    - some lottery capabilities in optical centering reliability :-)
    - shifting unreliable field of view ( but we live in the digital age - a well set frame on the scene is lost knowledge - the slide photographers have died out )

    IMO the best image stabilisation is a durable fixed optical system with fast maximum aperture.


    Regarding the 50-200 zoom design:
    I am not deep enough in the optical design to judge this aspect.


    Anders

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    Default Re: Anders Uschold Q&A

    Quote Originally Posted by dpnow
    Hi Anders - good to see you here

    It's a while since we bumped into each other; surprised I didn't see you at PMA, though I guess you were there.

    Above, do you mean by the example that MOS is better than CCD? Or are you referring to the general technology step in MOS over CMOS?

    And to everyone here - I haven't yet seen references to this, but this morning Olympus released some technical details on the LiveMOS sensor - we have reproduced the release here on DPNow:

    http://dpnow.com/2617.html

    Ian

    Digital Photography Now
    http://dpnow.com
    Hello Ian,

    good to hear from you again!

    To speak frankly: The US border procedure for journalists is an insult to individual rights and a torture I am not willing to pass. Flight on your own costs to an embassy on the other side of the country, waiting for hours in a waiting room, then being interrogated imbecile questions by some embassy people and a secret service employee named Smith or Jones and then have a 50/50 chance to be admitted, sorry no way!

    On the other hand I am also not willing to lie on the immigration form, like almost all international journalists I know do, to enter the country in an acceptaple way by negledging their occupation.

    As soon as the officials have turned back to the real good kernel of the American mentality, open arms and friendliness, it will be a pleasure to me to visit this beautiful country again.

    In short terms:
    I wasn't at PMA.


    From my experince MOS is an improve to CMOD or CCD.

    Best regards,

    Anders

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