July 2020 Part 2 — This Month Through Your Adapted Lens

Started 3 months ago | Discussions thread
fferreres Veteran Member • Posts: 5,415
Re: July 2020 Part 2 — This Month Through Your Adapted Lens
4

This lens I believe is from mid 1950s. It gives a 6x6 image, but I am using it in FF. Primotar's are four elements...is this not a Tessars?

Meyer Primotar V 80/3.5 - Raw Therapee defaults

As Tessar, it has good performance from infinity to closer focusing distances, and is quite high resolution stopped down a bit. Even at f3.5 resolution is high although contrast drops.

More information about the Practisix lenses can be found here. This was originally the only normal lens for the system. It covers at least 6x6, but I use on FF. .

http://www.pentaconsix.com/lenspub.htm

I initially stated it is over corrected, but at narrower apertures the background felt smoother. I had also read this post from another forum:

http://forum.mflenses.com/meyer-optik-grlitz-primotar-80mm-f-35-t57121.html

After inspecting the lens render a bit more, I recognized I was wrong in thinking it's overcorrected. Indeed, it seems undercorrected by all means. Wide open, due to aging and maybe a very faint separation in the outer region of the cemented read doublet, in slightly OOF and wide, there is outlining, as well as a strong center bright spot. This makes slightly OOF features a little glowy or ghostly, as you can see in the hair above. This reduces the DOF behind a bit at f3.5. But otherwise, it's mostly an undercorrected optic. Towards the foreground it has all the typical outlining. However, I can't understand why, but foreground bokeh still looks smoother than with other lenses.

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Anecdote from the cleaning process: it was quite challenging to even understand how the lens was constructed, and I had to think a lot on disassembly, and a huge lot more on reassembly. Mechanisms are unlike others I knew, even from Meyer itself. But that's another story...I almost gave up. Actually, I had earmarked the lens to be sold, and opened in an impulse late Friday, since one open I almost never leave a job unfinished. But I could not figure out how to reassemble as many mechanisms must be loosened while still masked from view, and are quite precise (eg. to separate focusing part and aperture and front, one needs to do the equivalent of a combination safe...I really had to play with the lens maybe 1 full hour to find out the unlocking of these parts, and it involved twists, pull of focusing while expanding the preset, and rotating counter clockwise, then changing the aperture until the pin that prevents opening it finds an narrow 2mm gate that allows it to get out.

Of course, all this is hidden from view, so when I unlocked after an hour, I had not seen exactly how it worked, and on trying to assemble it back, even looking at the thing, it was quite cryptic to notice that unless this is done, the aperture pin will not be able to be put back, and the present aperture marker in the barrel will be 180 degrees from the correct place.Really, really, I tried to avoid this lens, since from day one it puzzled me as the front ring would not bulge no matter what torque I applied. Still, the reason I could clean it is it has two front rings, one for the optic, and the outer one is for the preset aperture. And from the back, focusing and rear elements and aperture mechanism can be accessed.

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