Enlarger Lens Comparison

Would be interesting to see how the 50/2 performs at the corners (or at least at center top/bottom, most appropriate for coins) and also for loNGCA.

What do all the blurry images mean - in non-technical terms?

heres another way of understanding those blury lines

Here is a full photograph(compressed for viewing here) of the resolution test target with a lens set to 0.4X ( 40% of life sized. the sensor is 36mm X 24mm. Look at the pattern square with 4 and 5 that square in real life is 4 millimetres on a side. Look in side it and the square with 6 and 7 is a millimeter each side(according to my calipers and old eyes)






By zooming in we get to see how small the lens can actually "see"





If this was using life size magnification we would say the lens is resolving ("seeing") to group five element six which equates to 57 cycles per mm or the lens can see 57 lines inside a single millimetre. However this lens was reducing the image it is less than half size . If it were at half size we would know from this test the lens was actually resolving 114 lines per mm. but the lens was at .4 magnification which means it is resolving better than that probably it is able to see 143 lines inside a millimetre..... give the magnifications involved I think you understand why the pictures are so blurry.... most of them are zoomed in around 300% ( this last picture was only zoomed in 67%)

The test tell me the lens has very good resolution..... and it was not at is optimal magnification( around .25 to .3X)

the lens is the Schneider Kreuznach APO 45mm F4 HM( high modulation) What the test tells me is in real life stick this lens on a MFT camera and take a picture of an ASE and you are going to see incredible detail ( assuming you do everything else right) the test also tells me it won't perform so well on an APSc or full Frame sensor

On the Oly 50mm F2, I did some research and discovered it is supposed to have an extremely flat field... its gone past the 80mm ( which was on my nice to have list and jumped on to my must get list) There was also a 90mm macro produced I had never heard of it!

Well, 0.3mm is a fairly big number.

The method I use is qualitative. I simply focus high, center, and low to see what the effect is on hue. Comparing these tells me what effect the CA will have on the final image, given single images rather than stacks. This is not so different from the "tilted ruler" technique used by Mark Goodman in his lens reviews. Un-toned silver coins are the most telling, since they show the shift from the normally grey-ish color often very dramatically. Also, since the effect of the loNGCA depends on aperture (DOF) it's often necessary to shoot wide open as well as stopped down to normal shooting aperture. Shooting wide open has of course the strongest presentation of the loNGCA effects.

Note that while Mark does not mention it (that I can find), in the various photos he takes using each lens, the ones of the un-toned ASE are excellent for showing the loNGCA effects in real-world shots. In many of the reviews, for lenses with large-ish loNGCA, the ASE has tone shifts from high points to low points.


Edited to add:

I don't know why the forum software changes "long CA to "loNG CA".

Is this without a filter? If so this seems like very severe longitudinal / axial CA.

Note this is a completely reedited post. After rmpsrmps post( below this one) I disassembled the rig with the two two bellows on it. I then used a micrometer, set square and electronic calipers to reassemble it. I then took three different test shots for each lens. The final shots posted here are repeatable shots. Unlike my first post the Schneider Kreuznach APO 40/2.8 HM performed impressively well( at F 4)
As I noted originally my testing rig just isn't as good as pepactonius's the issue may be skill but also the microscope objective is a real weak point. Both final test shots were taken at 1-1 magnification through a five times objective. With this more rigorous test the Agfa 80mm F4.5(@5.6) is performing at about the same level as the SK. I am sure with a better set up Both lenses would be showing better resolution



This is the Agfa ( F4.5 @5.6) Note this was not the F4 lens




This is the SK APO 40/2.8 @ F4

Comparing the two I think the SK would with a better test rig be resolving very close to group 7 element 5 where are the Agfa might only make it to group seven element 4.

given the differences in prices( second hand on ebay) the Agfa is a winner.






Note While the rig is tuned I will add a test shot from the AGFA F4.

Here is that shot from the Agfa 80/4 also at 5.6.

I recall pepactonius mentioning the oly 80mm bellows lens could out resolve other lenses at 1-1. I tried it just now. it resolves to about the same level as the Agfa and SK perhaps a little more. but what was really noticeable was the Chromatic aberration, just moving the focus too far one way would see the image turn red, and the other direction it would go green. This final shot has a purplish tinge which shows how different it is to the APO lenses( I am assuming the Agfa is APO). I know the other shots I have posted seem to have a slight red tinge but the Agfa 80mm process lenses and SK 40mm and 45 mm lenses are far better than the oly as far as CA goes. ( of course the PN 105mm beats them all)

Oly 80mm at 5.6