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Does it really worth reversing enlarger lenses ?

 
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Macrero



Joined: 01 Sep 2011
Posts: 823
Location: Valladolid , Spain

PostPosted: Wed Oct 19, 2011 8:17 am    Post subject: Does it really worth reversing enlarger lenses ? Reply with quote

Hello, I wanted to ask you a question related to the enlarger lenses mounted onto bellows, I have a few of them, APO-Componon , APO-Rodagon , El-Nikkor , etc ... and I use them with a Canon (FD) Auto Bellows , I do field macro and basically I work between 0.5 X and 3-4X, I do not stacks , I use all the lenses reversed, but I also tested the lenses mounted normally (without reversing) and I can not see differences in image quality . I think most enlarger lenses have a symmetrical design, so I do not know if really worth reversing them ? And if it's worth from that increase would benefit the quality of the image ? For example, about 1:1 you think is better shoot with the lens reversed or or normally mounted Question Thanks in advance and sorry for my horrible English ...

Kind Regards !
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 20473
Location: Richland, Washington State, USA

PostPosted: Wed Oct 19, 2011 8:54 am    Post subject: Reply with quote

It sounds like you've answered the question for your own purposes -- if you can't see a difference, it doesn't matter.

At 1:1, reversing should not matter much because of symmetry -- not necessarily the lens, but definitely the test setup.

At other magnifications it is different. Some enlarging lenses are obviously asymmetric. For example the 50 mm f/2.8 EL Nikkor has a strongly curved rear surface but only weakly curved on the front. I expect that a careful test of that lens at higher magnification would show a clear difference between normal and reversed. Whether the difference would be enough to matter in practice, I don't know.

But I am curious. Most enlarging lenses are easy to reverse, so why not just use them as designed, short distance to the back?

--Rik
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Macrero



Joined: 01 Sep 2011
Posts: 823
Location: Valladolid , Spain

PostPosted: Thu Oct 20, 2011 1:35 am    Post subject: Reply with quote

You are right Rik , the best way to find the answer is testing , and also depends on the particular lens and optical design, but I wanted to hear more opinions about it because you know we're all a little obsessed with image quality and sharpness ... Rolling Eyes Thanks for your answer !

Cheers !
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Pau
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Joined: 20 Jan 2010
Posts: 4946
Location: Valencia, Spain

PostPosted: Thu Oct 20, 2011 2:14 am    Post subject: Reply with quote

If you want to test the differences, the most probable ones would be in the periphery of the image, and more likely related to the flatness of field. A flat test object like a printed paper can show them better than a real life shot of an insect in the center of the image where the resolution will be about the same and the field curvature doesn't matter.
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mgoodm3



Joined: 08 Sep 2008
Posts: 273
Location: Southern OR

PostPosted: Thu Oct 27, 2011 10:09 am    Post subject: Reply with quote

my own experience with rev vs. normal mounting for enlarging lenses comes down mainly to focal length.

Longer focal length, say 75 mm and above don't work any better reversed, and may work better normally mounted.

50 mm and below tend to work better reversed. The shorter the focal length the more improvement you will see.
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