Mamiya TLR Lens Test Results

The following is a test of the lenses for the Mamiya TLR system.

They are all "black" lenses, including the 55, 80, 105D, 135 and 180 Super.

I didn't have room indoors for the 250. Maybe I'll do that later. It goes

without saying that this was really a test of the lens, camera, film and my

technique and ability to discern viewfinder focus, so this test represents

the kind of results I can get when I am most carefull.

 

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I used the "chimney" waist level finder with a Beattie Intenscreen. For the

wide open shots I did refocusing (focus, shoot, refocus, reshoot) and focus

bracketing. I found that shifting the focus a barely discernable amount in

the viewfinder made a drastic difference in the numbers. I found that my

105 lens focusing is slightly off. The numbers in the table represent the

best trials. I didn't test every f-stop becausee I wanted some film left to

take real photos.

 

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The film used was Delta 100, the developer was Xtol diluted 1+3, lighting

was with strobes. Magnification was 1:38 for the 180 lens, 1:54 for all the

others. The test target was the venerable USAF 1951. The edge targets were

23mm down and 23mm over from center. Without further ado, my numbers:

 

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55mm

f-stop center edge (lp/mm)

4.5 45 22

8 50 28

16 64 32

 

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80mm

2.8 40 22

5.6 40 32

11 50 50

22 45 45

 

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105mm

3.5 36 25

5.6 64 36

11 56 45

22 45 45

 

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135mm

4.5 36 28

8 45 32

16 45 32

32 36 28

 

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180mm

4.5 50 40

8 64 50

16 64 50

32 40 35

I don't understand the two numbers referred to as 'centre' and 'edge'. If you don't mind me asking, what do they mean?

The tabulation was lost on the web conversion. (Note: this could be tiresome!)

 

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If you look at the numbers as 3 columns headed 'f, centre, edge', it should make sense.

Center refers to image sharpness at the center of the image.

 

Edge refers to the image sharpness at the outer edge of the image.

Thanks Tim, we all appreciate these types of efforts.

This is an older test. There is a better one at http://www.photo.net/bboard/q-and-a-fetch-msg.tcl?msg_id=0005l3&topic_id=Medium%20Format%20Digest&topic=

I have the latest numbers nicely formatted <a href="http://www.aseonline.net/~brownt/lenstest.htm">here.</a>

for the more ignorant...(or just me) if anyone has the inclination could they breifly explain how to read these tests?

 

does this compare well with modern lenses?