Agfa 80mm F4: Process Lens

I received the F4.5. It is very much like the F4. My guess is the F4 is the later version as the 4.5 does not have a 4.5 marking on the aperture ring. Only the the first stop( 5.6) is marked. I don't have the time to do the measurements... but it may well be exactly the same lens.... and the 4.5 rating was incorrect. This lens would have been used at a very small aperture so the manufacturer may not have been that concerned with decribing the maximum aperture accurately

One annoying thing with the latest example is that it had been installed in a home made Linhof board for a view camera. I knew this when I purchased it. I had to cut off the board and that's when I had discovered Some idiot had epoxied a locking ring to the lens mount( the board had been glued to that locking ring.
I suspect the locking ring, that is now fixed permanently, to the lens mount wasn't the right size.

It worked out as I discovered I could attach the camera mount end of an old Minolta extension ring set( the same type some use to adapt Printing nikkors) by friction fitting it. The funny thing is that camera mount section actually came with an ebay purchase minus the rest of the extension ring set.I am so glad I didn't throw it way.

I had the resolution test rig set up and it is, at 5.6, just a smidgen better than the F4.


The Extension ring mount looks like it was made for the lens and attached locking ring so I won't be doing any more testing until my application of epoxy resin has cured.
In my research I had read that large format photographers adapt this particular lens because it is sharp and has an image circle that easily covers large format film. My experience should be a warning for any one looking at getting an example that has been adapted for fitting to a view camera( you will at least know what to ask a seller)

I received my AGFA 80/4 Repromaster today and took an aperture sweep of the 1949-S Cent I used for my 100mm shootout. The lens had some issues at f4 but was really good at f5.6 and f8 at 0.7:1 magnification (f9.5 and f13.6 effective). See the f5.6 shot below. You can download the full size original at:

http://s943.photobucket.com/user/rp...?sort=3&o=0.

The lens is extremely sharp and shows no discernible long-CA at f5.6 and beyond. I will be including it in my 80mm shootout and expect it will do very well.

As you probably picked from my earlier posts I was unsure how to measure the mounting thread. How do you measure the pitch of the thread I would not know how to assess .7 from ,5 ( is it the angle of the thread or the number of threads per mm?).

To day while doing some thing complteely different I realized how I might adjust my system of testing resolution so I could measure cnr to cnr. To night I tried it out. It was a case of so close but so far... I need one more focusing rail to sort it. My idea involved changing how the two bellows are mounted .. One is now mounted turned on its vertical axis 90 degrees . This made tuning the whole set up much simpler and now I can bring the 10X objective into play.

At 1-1 the F4 variant. ( picture is very noisy)





I also realized I must be way beyond the DLA for the camera with this set up, so Diffraction is also having its effect. All that said the lens is resolving at group 7 element 2 comfortably. That is 143 cycles per mm. This is well beyond the resolution ability of the sensor.

It looks like Thorlabs has some M34x0.5 adapters, with external or internal threads.

You'd have to go from M34 to SM1 and then from SM1 to T-mount or M42, etc. (I've used SM2-sized adapters with Thorlabs SM2 tubes holding the tube lens for infinity-corrected microscope objectives.)


Just out of curiosity, I wonder what the thread pitch of the usual 34mm filter threads is, used in various step-up or step-down rings?

I have emailed Raf camera asking for two M34 X 0.5 to M39 adapters. From past experience he will have them made in about 2-3 weeks

Today I received proper adapters from RAF Camera. M34X.5( as correctly identified by rmpsrmps) to M39(my preferred mount) the adapters fitted the 80mm and the Staeble 105mm perfectly. Previously with the 80 mm I had to use an extension tube to fit the lens to my bellows as the lens barrel protruded too far out of the M39 mount. The RAF adapter fortuitously provided enough extension to fit the lens to the bellows without an extension ring. I see Raf Camera has a M34X .5 -M42 version so I am guessing rmpsrmps has one on the way to him.