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FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
Thread started 04 Mar 2018 (Sunday) 15:24
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Using a manual focus - manual exposure lens

 
RPCrowe
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Post edited 3 months ago by RPCrowe.
     
Mar 04, 2018 15:24 |  #1

I learned something today about using a manual focus / manual exposure lens on my Canon DSLR camera.

I have an 8mm Vivitar f/3.5 fish-eye (sold under many brand names), of course this lens has no electronic connection with my camera.

In the past, I used a hand held light meter and the camera on manual exposure, stopping the lens down before I shoot. This works great and will probably be my method of choice.

However, I learned that if I have my camera on AV mode and stop down the lens to the shooting aperture, the camera will give me an in-the-ballpark exposure which using the histogram, I can tweak with the camera's + and - exposure compensation...

The camera's info screen will read 00 for the f/stop but will be able to calculate close to the correct exposure for the ISO that I have chosen...

I can extrapolate this to using a manual exposure/focus lens on a bellows. Using a hand held light meter to determine exposure is not as easy as with the fish-eye, since there will be light losss due to the length of the bellows...


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Bassat
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Mar 04, 2018 15:50 |  #2

You can make the entire process less cumbersome by purchasing a manual exposure camera. No light meter required. Well, besides the one in the camera.


Tom

  
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Wilt
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Post edited 3 months ago by Wilt. (4 edits in all)
     
Mar 04, 2018 19:41 |  #3

RPCrowe wrote in post #18577520 (external link)
However, I learned that if I have my camera on AV mode and stop down the lens to the shooting aperture, the camera will give me an in-the-ballpark exposure which using the histogram, I can tweak with the camera's + and - exposure compensation...

The camera's info screen will read 00 for the f/stop but will be able to calculate close to the correct exposure for the ISO that I have chosen...

I can extrapolate this to using a manual exposure/focus lens on a bellows. Using a hand held light meter to determine exposure is not as easy as with the fish-eye, since there will be light losss due to the length of the bellows...

The problem is that exposures are NOT metered correctly at all stopped-down /fstops! This is very easily proven to yourself.

This is not the test itself, but it a comparison of a number of lenses shot with camera in manual at identical shutter speed and aperture (f/16). Next to each manual shot is the same lens with camera in Av mode set to f/16, and the camera was allowed to set the shutter speed. Notice that the recorded densities while in Av mode were all over the place, in spite of f/16 being chosen for every one!

IMAGE: http://i69.photobucket.com/albums/i63/wiltonw/POTN%202013%20Post%20Mar1/testseries_zps0e472812.jpg

If you mount ONE LENS, if the meter is linear across the full range of f/stops (e.g. f/2 thru f/22), the camera in Av mode SHOULD choose a shutter speed resulting in IDENTICAL TONALITY for all shots. If the tonality is not very close to the same for all shots, you have evidence of meter error. I have done this test with five different models of Canon (20D, 30D, 40D, 5D, 7DII) with a wide variety of lenses (6 lenses in the above test) and all have failed, with the sole exception being a Tamron-to-EOS chipped adapter with Tamron manual lenses.

Here is the result of testing a 40D with an Olympus OM 50mm f/1.8 thru its range of apertures with an unchipped adapter to EOS mount. What should have been was about same tonality on all frames...that did not happen

IMAGE: http://i69.photobucket.com/albums/i63/wiltonw/40DunchippedOM50_18.jpg

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Using a manual focus - manual exposure lens
FORUMS Canon Cameras, Lenses & Accessories Canon EF and EF-S Lenses 
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