Results 1 to 7 of 7

Thread: knocking at the door

  1. #1
    Join Date
    Jul 2006
    Location
    denmark
    Posts
    78
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Feedback Score
    0

    Default knocking at the door

    I am glad to be here.

    I have for some time been looking at the net for information about the E-system and found your place: complete, clever, friendly and sometimes amusing.

    I am living in Denmark in the countryside in the south. I have had SLR camera since 1967, digital camera since 2003 and E-500 since nov 2005.

    My main interests photographically are travelling, nature, architecture. I think the picture and the photographer is more important than the camera, but I am suffering from a serious disease called equipmentitis and lose a lot of time studying everything written about the cameras and their lenses.
    I hope it will not worsen the pictures but may be sometimes make them better.

    What this equipmentitis can lead to you can see below.

    CHEAP 10 MM SUPER WIDE ANGLE:

    One of the interesting threads I have seen was “Lens Focal Length Confusion” about zoom lenses with inner focusing having smaller focal length when focusing.
    This could be considered a disadvantage in the tele range, but on the other hand it will widen the wide angle.
    So 14 mm could be 10 mm while focused nearby, but it will be very blurred at the distance. The solution is to place a negative (concave) lens in front of the zoom to move the focus farther out.

    My house with Zuiko digital 14-54 at 14 mm:

    Attachment 2185

    Combined with – 10 D: f/8 1/200

    Attachment 2188

    All the aberrations you can think of, but distorsion and vignetting can be corrected:

    Attachment 2186

    cons not for any serious use
    pros very cheap

    Thank you for your patience. Have a nice time.

    Lars





  2. #2
    Join Date
    Sep 2005
    Location
    Knoxville
    Posts
    2,437
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Feedback Score
    6 (100%)

    Default Re: knocking at the door

    Good to have you Lars and Welcome! That is an interesting technique and will have to try it sometime

  3. #3
    Join Date
    Jan 2006
    Location
    In Beautiful So-Cal
    Posts
    6,791
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Feedback Score
    20 (100%)

    Default Re: knocking at the door

    That looks really cool with what you did.... But I don't understand what did you do?
    BTW welcome to the board!

  4. #4
    Join Date
    May 2006
    Posts
    477
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Feedback Score
    6 (100%)

    Default Re: knocking at the door

    That's a great idea!

    It basically comes down to the same issue we saw a few days ago with the 18-180 seemingly having a shorter focal length than the 40-150 when focused close up to a subject.

    It seems that when focused at short range, the 14-54 has a focal length that is less than 14mm. I'm not sure what it is exactly, but it's less than 14mm. So the trick is to use a negative diopter lens to alter the focusing distance of the lens. It's exactly the opposite of a "close-up filter" (Perhaps, a far-out filter!). This will increase the minimum focusing distance quite a bit, but might allow the lens to be internally focused at 1m (where actual focal length could be 11 or 12mm) to achieve effective infinity focus.

    Certainly an interesting way to eke out a few extra mm from a lens!


    Luc
    Thank you Oly, it's been a good 5-year run!

  5. #5
    Join Date
    Jul 2006
    Location
    denmark
    Posts
    78
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Feedback Score
    0

    Default Re: knocking at the door

    Quote Originally Posted by tspore
    That looks really cool with what you did.... But I don't understand what did you do?
    BTW welcome to the board!
    I just place a plain glass element (concave = having a "negative" focal length of 10 cm) in front of the lens.

    Having a look:

    Attachment 2194

    Thank you for your "welcome"

    Lars

  6. #6
    Join Date
    Jul 2006
    Location
    denmark
    Posts
    78
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Feedback Score
    0

    Default Re: knocking at the door

    Quote Originally Posted by RFMan
    It seems that when focused at short range, the 14-54 has a focal length that is less than 14mm. I'm not sure what it is exactly, but it's less than 14mm. So the trick is to use a negative diopter lens to alter the focusing distance of the lens. It's exactly the opposite of a "close-up filter" (Perhaps, a far-out filter!). This will increase the minimum focusing distance quite a bit, but might allow the lens to be internally focused at 1m (where actual focal length could be 11 or 12mm) to achieve effective infinity focus.
    Luc
    Luc!

    The actual focal length is around 10 mm !
    The first picture is 1,5 bigger than the second measured with a ruler.
    If we use 15 mm as a pessimistik value of the 14-54 lens then 15/1.5 makes 10 mm

    lars

  7. #7
    Join Date
    Sep 2005
    Location
    North Carolina, USA
    Posts
    3,686
    Thanks
    1
    Thanked 2 Times in 1 Post
    Feedback Score
    6 (100%)
    Real Name
    Ann

    Default Re: knocking at the door

    Welcome. I have one friend who lives in Denmark.

    Ann
    Appreciate what we have, instead of worrying about what we haven't. Enjoy what is, before it isn't.
    --------
    http://www.scenicphotos4u.smugmug.com
    Moderator/Photo Contests Forum

Similar Threads

  1. Old Door
    By cosmonaut in forum Photos
    Replies: 7
    Last Post: 04-22-2008, 07:12 PM
  2. Keep Door Closed
    By cosmonaut in forum Photos
    Replies: 4
    Last Post: 01-06-2008, 09:26 AM
  3. Grunge Door
    By refiningman in forum Photos
    Replies: 13
    Last Post: 12-16-2007, 08:58 AM
  4. Two windows and a door...
    By tb2 in forum Photos
    Replies: 2
    Last Post: 06-15-2006, 01:34 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •