Soviet Lens Focusing: It ain't Voigtlander's

[john_van_v]

Hello all,

Shooting w/ a Jupiter-8 screwed to my Bessa R has worked really well for me.

thinman -> poughkeepsie














This one is on picasa web:




Note the last picture, the one of the "spiked" seeds. The "spikes" are slightly out of focus.

Now the Jup 8 ain't no macro lens, and if macro is your thing -- you need to post on an SLR site.

But, still, I felt frustrated that the focus on the seeds' spikes was off, when the leaves were dead on.

So, for the first time, I checked the focus scale on the Jupiter against the Bessa R's rangefinder, and it's off. Off by a lot. And the problem increased proportionately with the focal distance: a "ratio" problem.

I then checked it on a FED 5 and on the Zorki 4K it came to me on. More or less on, at least within what we would expect from the "high-functioning" Soviets.

I also checked my Leica (WWII vintage) 35 mm lens on the Bessa: that was more or less on within, say, "high-functioning" Nazi standards.

 

[Spyderman]

You have just discovered what many photogs before you: that the FSU lenses were probably built to a slightly different standard - the Contax standard focal length of 52.3mm instead of Leica standard focal length 51.6mm.

This is a widely known problem that majority of FSU lenses backfocus by 5 to 10 cm on Leica standard body at 1m.

 

[patrickhh]

strange ... my J-8 always focuses perfectly both on my Bessa-R and on my Fed-2

BTW I like the picture with the birds.

 

[minoltist7]

I read it many times on Russian photog forums, that this is very common thing with FSU lenses, and it is a matter of luck. Some FSU lenses are off on M-bodies, but right to the spot on Zorkiy/FED.
I'll get J-8 for my Bessa soon - and will prove it in practice.

 

[Spyderman]

strange ... my J-8 always focuses perfectly both on my Bessa-R and on my Fed-2

That's why I wrote majority of FSU lenses. Some people report they have lenses that work just fine though.

 

[Sonnar Brian]

The FSU lenses in Thread Mount are built to the Contax standard. The data sheets that come with the lenses list their focal length; I have a couple of them that came with "new-old-stock" J-3's. The problem is most pronounced when the lens is used wide-open and close-up. If the rear group is moved in "ever so slightly", the effective focal length is reduced to the Leica standard. If you shim the lens to be accurate wide-open and close-up, focus at infinity will be good stopped down slightly. The "Sonnar" focus shift helps you out.

 

[payasam]

My Industar 61 L/D and Jupiter 12 are fine on an M2 and a Zorki 1C; and were fine on a IIIc. A rather battered Jupiter 3, however, was giving focus trouble. It is currently being Kimmed. Apparently the focussing block was re-assembled incorrectly. There may be other problems too, I wouldn't know.

 

[john_van_v]

My industar is at my cabin, so it will be a few days before I can test that on the Bessa, but already think that it will have the same "ratio" problem that the Jupiter is having. The reason I believe this is that the Jupiter is working correctly on two Soviet bodies, a FED and a Zorki.

I am planning to take my Bessa R to photovillage. There I hope to test out a Voigtlander SM 50mm lens on the Bessa to make sure that it focuses correctly, or at least correctly enough.

So, in case any one missed my hypothesis, it is that there is a "ratio" problem that has to do with the mechanics of the focusing. I believe this because if there only a purely focal length problem the focal inaccuracy would be the same across the entire focal scale.

'Just so happens I bought a Voit Vito B on ebay specifically because of something I saw that was funny about the ad; it said that there was an "adjustable thing" on top. Turned out to be a Ziess rangefinder -- which I am going to start using.

In fact, if the test proves my idea, that there is a mechanical difference between the Soviet and Leica-based lenses, or perhaps that Soviet lenses were simply matched with cameras with a complete disregard for standards -- which seems to be the Soviet M-O -- then I may just use my Bessa L with an ajustable viewfinder sitting next to the rangefinder, as I have not really gotten used to a hand-held light meter yet.

I will be in the market for a double shoe thingy.

 

[Santafecino]

My advice--have the Jupiter checked and shimmed for the Bessa; keep the Industar for the Fed. It will be easier than using an uncoupled rangefinder, which would drive me nuts.

Your pictures are great; keep posting them.
--Lindsay

 

[john_van_v]

"have the Jupiter checked..."

I can chuck it myself.. oh, checked, sorry, maybe.

I want to give the Vito B a chance, I hear those little Voits are as good as a Leica for street purposes. Unfortunately the top speed is only 1/300, so I will be required more depth of field than I used to w/ the Bessa R and the Jupiter.

Your pictures are great; keep posting them. --Lindsay

Thanks Lindsay, I post the most at my thinman.com/photography, though the page takes forever to load.

More than anything, I would like to build a PHP gallery web site that photogs like us to exibit using a simple format. I would also like to find artists using other media that have the same frame of mind that we street and nature photogs have.

 

[Sonnar Brian]

The focal length can be different, and you can pick one distance to shim the lens so that the RF designed for 51.6mm and actual focus of a 52.3mm lens agree. On most lenses, this "sweet-spot" is at infinity. That always seemed like a bad place too me, so I started adjusting my lenses so that the "sweet-Spot" would be at 8ft. The residual error when used close-up and wide-open is covered by the DOF. Stopping down to F2.8~F4 allows use at infinity. The Sonnar focus shift works in your favor, shifts the actual focus closer to infinity.

That's my story, I'm sticking to it...

 

[john_van_v]

That's my story, I'm sticking to it...

Ok, I will bite. I just got a-hold of my industar, and I an thinking that the focus is better with the Bessa R than the Jupiter, but I tried infinity at twilight.

My latest idea is to test the lens focusing in real-time with a focusing screen from an SLR taped to the focal plane of the Bessa. When I first got started I tested all my lenses at about 8 feet and all looked good; it was only in my very last roll that I detected a problem. The Bessa has a great feel, and I seem to coordinate the shutter release with the action better with it than any other camera I have used.

I cannot imagine trying to comprehend how specific lens geometry affects the "sweet spot," which btw is one of my favorite phrases.

Thanks Brian

 

[Spyderman]

When I first got started I tested all my lenses at about 8 feet and all looked good

Better approach is to test lenses at infinity by "two cameras" method (google for "rick oleson bring infinity indoors") and then at 1m with the focussing screen from a SLR. If both are good, you know it will be good throughout the range.

I just got a-hold of my industar, and I an thinking that the focus is better with the Bessa R than the Jupiter, but I tried infinity at twilight.

IMO the Industar seems better to you on Bessa because of its inherent larger DOF which covers some slight focussing error.

In fact, if the test proves my idea, that there is a mechanical difference between the Soviet and Leica-based lenses, or perhaps that Soviet lenses were simply matched with cameras with a complete disregard for standards -- which seems to be the Soviet M-O -- then I may just use my Bessa L with an ajustable viewfinder sitting next to the rangefinder, as I have not really gotten used to a hand-held light meter yet.

The fact that the lenses don't focus correctly on Bessa does not imply that the FSU lenses weren't built to a standard. It's just that the standard was different. This is like saying that Nikon RFs were "built with a complete disregard of standards" because they use the Leica standard focal length in a Contax bayonet mount.