Setting up a camera/lens test?????

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stradibarrius

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I want to set up a test to see how two MF's compare.

My plan would be have both cameras load with the same film. take a photo with one camera and the immediately take the same shot from the same tripod, to insure framing, with the other camera. I would use the same exposure settings, f/stop and speed based on the same hand held meter. I would shoot some outside and some inside in the "studio". Then develop both rolls in the same developer in the same session but with fresh developer for both rolls.
Of course I would use the same focal length lens too or as close as possible.
One is a 6x6 Hasselblad with 80mm f/2.8 and the other is an RB67 with a 90mm f/3.8 but would use an f/stop around f/8 or f/11 to get into the sweet spot of each lens.

Does this sound like a valid test?
 

Q.G.

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It does, yes.

It doesn't matter too much if the photos aren't taken immediately following each other. And if lighting conditions change while you're changing camera, just change the shutterspeed to make sure that both are exposed correctly.
Framing too doesn't have to be exactly the same. Proper focus is much more important. So take care focussing both cameras as best as you can.

Why not develop both films together? (I don't know what you are using, but i routinely put two 120 films on one Paterson spool, and never a problem.)
 
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stradibarrius

stradibarrius

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I have never tried to load two rolls onto the same reel. Do you just load one and the when it is fully loaded the follow with the second rol of film? Will the second roll push the first in further on the spiral? It seems they may overlap???
But if it works that would be great!!
 

Q.G.

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Yes (using Paterson reels) i just load the first one, push it along the spiral until it hits the end, then proceed to load the second film in the normal manner, as i the first one wasn't there.

At first, i did indeed worry about one film sliding over the other.
So i shuffed the first one along far enough to clear the ball-grippers and i could start the second film, then taped the end of the first roll to the begining of the second and finished loading the second (which pushed the first one along as it went on).

But no more: too much trouble, and, as it turned out, completely unnecessary.
Theoretically, i guess it would be possible that the end of one film would slide over the end of the other. But i have never had that happen.
 
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It does, yes.

It doesn't matter too much if the photos aren't taken immediately following each other. And if lighting conditions change while you're changing camera, just change the shutterspeed to make sure that both are exposed correctly.
QUOTE]

For this I would make certain your outside tests are done on a nice sunny day. This will provide more or less even illumination during the space of changing over where clouds might make for different situations and unneeded calculations. You're going for consistency so this would lend the best for a controlled and repeatable exposure.
 

ic-racer

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I suspect you won't see any difference when stopped down, you would need to test the lenses wide open if you are looking for a difference due to lens design and coating.

Also, those 'normal' lenses will probably be the best performers in the lens lineups. If I were trying to select between two systems I'd check the 40mm Zeiss against the RB equivalent.
 

Q.G.

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I suspect you won't see any difference when stopped down, you would need to test the lenses wide open if you are looking for a difference due to lens design and coating.

There are enough frames on a roll, so test both wide open and closed down to f/8 or so.

(You will not be able to see a difference due to coatings, by the way. Coatings have far too little effect on image quality anyway, and the difference between two 'variants' of multicoating will be nil.)
 

ic-racer

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There are enough frames on a roll, so test both wide open and closed down to f/8 or so.

(You will not be able to see a difference due to coatings, by the way. Coatings have far too little effect on image quality anyway, and the difference between two 'variants' of multicoating will be nil.)

Coating will be the major factor influencing contrast when wide open (assuming similar lens design for each lens).

Evaluation of image contrast is incorporated into MTF testing, but in the old days a separate indicator of contrast was measured, in addition to a lines/mm grading. (Like the old Popular Photography lens tests from the 70s).
 

ic-racer

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In an uncoated vs (multi-) coated lens comparison perhaps.
But not here.

Yes, I agree with you very much. For the two lenses in question they will probably be identical on all accounts within the error of a home test.
 
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