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toplake
07-29-2006, 09:33 AM
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:

2185

Combined with – 10 D: f/8 1/200

2188

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

2186

cons not for any serious use
pros very cheap

Thank you for your patience. Have a nice time.

Lars

llpoolej
07-29-2006, 11:31 AM
Good to have you Lars and Welcome! That is an interesting technique and will have to try it sometime

tspore
07-29-2006, 08:44 PM
That looks really cool with what you did.... But I don't understand what did you do?
BTW welcome to the board!

RFMan
07-29-2006, 10:01 PM
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

toplake
07-30-2006, 03:26 AM
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:

2194

Thank you for your "welcome"

Lars

toplake
07-30-2006, 03:37 AM
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

AnnF
07-31-2006, 06:14 PM
Welcome. I have one friend who lives in Denmark.

Ann