Different lenses give different RF readings on FED-2

[02Pilot]

I've got a late FED-2 that originally wore an Industar-26. That had some internal issues (the long screw that runs into the shim bent; I'm in the process of trying to fix that now) so I replaced it with a Jupiter-8. I've only done a couple of rolls with that lens, but focus seemed fine without any adjustment to the RF.

Now I've gotten a Jupiter-12 and I'm noticing that the RF is a little off with this lens. It seems that the I-26 and the J-8 both have a minimum distance on their scales of something less than 1m, while the J-12 stops precisely at 1m. It appears that what's happening is that with the collars fully retracted (minimum focusing distance), and thus the RF cam in the same position, the J-8 is at less than 1m and the J-12 is at 1m. The RF is therefore going to be incorrect for one lens or the other, depending on how it is adjusted.

I checked the focus on both lenses and it seems to be correct at 1m. My question is, short of opening up one of the lenses, is there any way to correct this discrepancy? If not, I may just choose to live with it; I'm not afraid to open up a lens if need be, but if there's an easier way I'd opt for that first.

Thanks for any help you might be able to provide.

 

[Ron (Netherlands)]

J-12's normally do not work correctly on a FED 2. You have to adjust the rangefinder arm to get it working properly. However in doing that you might disturb correct working for other lenses. So some choices have to be made. I guess that they will all work great for long distances. On short distances, you have to test which lens works best for you

 

[02Pilot]

I did make a very slight adjustment in the position of the rangefinder arm to get the J-12 to fit without rubbing, but I checked the RF adjustment afterwards and it was not changed. Right now I've got the RF set for the J-8, which is my primary lens, so it may be that I simply won't be able to use the J-12 up close and wide open, which doesn't really seem like much of a problem.

 

[wolves3012]

Have you actually checked focus at exactly 1m with both lenses, to see if the RF is actually different? You may find it's not. For the I-26 and J-8, the lens focus can be turned slightly beyond 1m but it's probably not accurate doing so. It is normal to find slight variation between lenses, more noticeable at infinity but it's rarely a problem in actual use. Depth-of-field on the J-12, even close-up and wide-open is probably enough to cover errors anyway. I would check all of this before making any adjustments.

 

[02Pilot]

Yes, I checked the focus on both lenses at precisely 1m (tripod mounted, shutter open, scotch tape faux ground glass) and they are correct. By my measurement, the collar on the J-8 is roughly 0.25mm beyond the base of the threads at 1m, while on the J-12 it is approximately 0.10mm. If I could figure out an easy way to shim the J-12 the necessary 0.15mm that would probably be the simplest fix.

 

[David Hughes]

Hi,

If you were shooting with any other lens and IR film you'd probably have an IR mark or use the f/6.3 marker as it, or similar.

So what's wanted is a 0.15mm mark that you turn to after focussing with the RF. Does that make sense? The number of degrees you need to turn it could be sorted out with a piece of anything that thickness and comparing the infinity mark's position with the packing and without...

NB I don't mean unscrewing the lens but moving the focus tab, simples?

Regards, David

 

[SimonK]

J-12's normally do not work correctly on a FED 2. You have to adjust the rangefinder arm to get it working properly. However in doing that you might disturb correct working for other lenses. So some choices have to be made. I guess that they will all work great for long distances. On short distances, you have to test which lens works best for you

If a Jupiter 12 does not correctly with a FED 2, what 35mm lens would you recommend?
Also, is the problem just with the FED 2 or the entire range - will a Jupiter 12 work with a FED 5 for example?

 

[wolves3012]

If a Jupiter 12 does not correctly with a FED 2, what 35mm lens would you recommend?
Also, is the problem just with the FED 2 or the entire range - will a Jupiter 12 work with a FED 5 for example?

The usual issue with a J-12 on a FED 2 (if there is an issue) is that the RF sensor tip is a bit low and scrapes on the rear element of the lens or just doesn't run properly on the lens-cam. Taking the camera back off and mounting the lens whilst holding the shutter open allows you to see if there is a problem. If there is, you just need to bend the RF arm upwards (CAREFULLY) until it stops fouling.

 

[SimonK]

OK, many thanks. It seems surprising that among the range of FSU lenses available, there is not really any choice at 35 or 28mm.

 

[02Pilot]

Thanks for all the feedback and suggestions. I spent a considerable amount of time today checking and tweaking the RF adjustment; it was perfectly serviceable as it was, but a little subtle adjustment made it a bit more accurate. Is now as close to perfect at 1m and infinity as I can get it with the J-8. With the J-12, there is a slight imperfection at 1m and a tiny bit more at infinity (both have the RF image too far to the left, beyond the point it should be at those ranges). I'm hoping this will not prove much of an issue. If it does, I'll either have to come up with some sort of alternate marking scheme as suggested, or dig into the lens and see if I can fix it outright.

 

[SimonK]

I was thinking about the issue you raised, and it seems to me that one solution, given that FED bodies are cheap as chips, is to buy a FED 2 or 3 body and adjust it specifically for use with a J12.

 

[02Pilot]

Yes, one could certainly do that. In my case, however, I purchased the J-12 to go along with the J-8 on a trip overseas this summer, so space is at a premium; carrying two FED bodies would be a bit more than I'd prefer to add to my luggage.

 

[julio1fer]

The extreme solution would be getting a different body. A good FED-3 should work well with no adjustments. Of course Zorki-4 or -6 would also do the job.

 

[wolves3012]

The extreme solution would be getting a different body. A good FED-3 should work well with no adjustments. Of course Zorki-4 or -6 would also do the job.

Since the two lenses he has give different results, that won't provide a solution. Clearly, one of the two lenses is the cause.