Photographs by Frank

17 August 2013

Experiments in Optics

Filed under: Garden Flowers,The "New" Yard & Environs — Tags: , — Frank @ 6:00 PM

I recently acquired a bunch of lenses from old enlargers… both enlarging lenses and condenser lenses. One of the largest lens in the collection is a 5″ in diameter condensing lens that is mounted in a metal frame. It is probably from a 4″x5″ enlarger. Today, I decided to “play” with this lens in conjunction with a digital camera.

Here are the first results…

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The last photo in this set shows the set up. I mounted the condensing lens on a tripod, added a cardboard lens hood (which you can’t see in this photo) and a dark cloth. Both the hood and the cloth are attached to the lens with masking tape. The first couple of images I tried were low in contrast and had lens flares. Thus, I added the lens hood.

To use this set up, I placed myself and the digital camera under the dark cloth and made photos of the lens.

Clearly the middle of the circular frame is the sharpest, but it will never be “tack sharp”, and that the images goes soft and distorted towards the edges. All of which is really the point in something like this. Isn’t it?

It was interesting to watch how the image made by the lens changed in large ways with small movements of me and the camera. I learned quickly to make an exposure when the composition was good and not try to worry about stuff at the edges of the frame that were going to get cropped out any way.

Post-processing consists basically of cropping to the square format (to eliminate the extraneous part of the frame ) and  adjusting the exposure to make sure that the frame is pure black). A few images got small amounts of other processing (curves adjustments, etc.) but nothing major.

I forgot how hot it gets under a dark cloth in the bright sun… even on a day when the air temperature is in the low 70’s. However,  I think that results were worth the “suffering”! What say you?

1 Comment

  1. Nice effect Frank. I especially like the first image and the one with the black eyed susans with your greenhouse in the background. Great illustration of depth of field.


    Comment by Kevin — 17 August 2013 @ 8:21 PM

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