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10-28-2010, 05:52 AM   #1
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Jupiter 37A M42 + K100DS, no antishake, why?

Hello everyone.

I've just acquired a new lens, a Jupiter 37A 135mm f3.5 lens straight out of soviet russia... and as per all the online reviews, it seems very well made. I took the first test shots this morning.

Its m42, mounted via the pentax-branded adapter to my K100D Super.

Problem is that the antishake is disabled when this lens is mounted, and I'm not certain as to why. Also disabled is autofocus (yes its a MF lens but trap focusing should still work, but doesn't). Also, the images seem under-exposed when previewed on the camera display, and the camera is correspondingly using longer exposures than I would have expected (don't think it's my imagination...). There may be one or two other features similarly disabled that I haven't noticed yet.

Google isn't finding much, but I did find mention of funny things happening with exposure when M42 lenses don't touch the contacts around the lens mount... which this doesn't seem to.

Can anyone offer or confirm any explanation as to what's going on, or even better suggest possible solutions? I mean, there are a lot of contacts around the mount, if they're to blame, am wondering which one to press, or shortcircuit, or what...

Thanks

A.

10-28-2010, 05:58 AM   #2
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What shooting mode are you using? If using self-timer - switch to normal mode. Timer disables SR (not sure how override it).
10-28-2010, 06:01 AM   #3
MrA
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Not using self timer. Currently set to auto-pict(ure), but tried P and M as well.
10-28-2010, 06:03 AM   #4
Ira
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Is this your first M42, and do you have it set for "Use Aperture Ring--Permitted"?

When you power up the camera, it should give you the menu to select the focal lens to properly set Shake Reduction. If it doesn't, something in the base of the camera is improperly shorting out the body contacts and making it think that lens is something it isn't. Also, does your menu show SR crossed out, and if so, can't you simply turn it on?

Putting catch focus/trap focus aside, put some plain scotch tape on the base of the lens and see what happens. You SHOULD now get the FL menu for SR when you power up.

For catch focus/trap focus to work properly, you have to use aluminum tape on the base of the lens to short ALL of the contacts on the body.

10-28-2010, 06:05 AM   #5
Ira
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Also, AF has nothing to do with trap focus, so that SHOULDN'T be on for a manual lens anyway.
10-28-2010, 06:07 AM   #6
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QuoteOriginally posted by MrA Quote
Not using self timer. Currently set to auto-pict(ure), but tried P and M as well.
Auto and P won't work with a manual lens. Only M and Av, and for M, you have to use the Green Button.
10-28-2010, 06:20 AM   #7
MrA
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QuoteOriginally posted by Ira Quote
Is this your first M42
No, but my other m42 was just a junk lens I picked up, haven't used it in an age.

QuoteQuote:
do you have it set for "Use Aperture Ring--Permitted"?
yes

QuoteQuote:
When you power up the camera, it should give you the menu to select the focal lens to properly set Shake Reduction. If it doesn't, something in the base of the camera is improperly shorting out the body contacts and making it think that lens is something it isn't.
It doesn't give me this. It usually does when I mount MF K mount lenses, but not for this one.

QuoteQuote:
Also, does your menu show SR crossed out
Yes
QuoteQuote:
and if so, can't you simply turn it on?
switch is in on position already.

QuoteQuote:
Putting catch focus/trap focus aside, put some plain scotch tape on the base of the lens and see what happens. You SHOULD now get the FL menu for SR when you power up.
Did this, no change. Also as a test tried detaching lens, leaving just adapter mounted, holding lens 1mm in front (ie so no contact at all). Still no antishake.

QuoteQuote:
For catch focus/trap focus to work properly, you have to use aluminum tape on the base of the lens to short ALL of the contacts on the body.
Presumably aluminium kitchen foil would work. Will try once I'm at home tonight (in the office now!).

QuoteQuote:
Also, AF has nothing to do with trap focus, so that SHOULDN'T be on for a manual lens anyway.
The AF/MF switch on the camera usually turns trap focusing on/off with an MF K-mount lens - but isn't doing so with this m42 lens. Appologies for being unclear. Perhaps this is normal though.

QuoteQuote:
Auto and P won't work with a manual lens. Only M and Av, and for M, you have to use the Green Button.
Never found them "not working" with manual K mounts, presume for M42 it's different though hence underexposure. I don't seem to have a "green button" on this camera body though.



EDIT

QuoteQuote:
If it doesn't, something in the base of the camera is improperly shorting out the body contacts and making it think that lens is something it isn't.
QuoteQuote:
For catch focus/trap focus to work properly, you have to use aluminum tape on the base of the lens to short ALL of the contacts on the body.
I suppose my question then, is how to distinguish between improper and proper shorting out of contacts...

Last edited by MrA; 10-28-2010 at 06:26 AM.
10-28-2010, 06:27 AM   #8
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How can Program and Auto modes work when the body has no way to either read the aperture settings, nor change the aperture? What's happening is your camera was defaulting to Av mode, because they're certainly not operating in true P and Auto-pict modes.

No green button? Well, that means Av mode for you--and M42 lenses consistently underexpose like this. Or M mode, using the dial to set your shutter speed.

Try the scotch tape thing, though. But aside from the SR button being on, doesn't SR display in the menu settings? Maybe the button is on, but the display says off.

It sounds like one or two of the contacts are or aren't making contact screwing this up, so try cleaning. The camera should definitely recognize the lens as manual, and immediately give you SR FL selections. They should either all make contact, or NONE should make contact--except for Trap Focus, where you should use the tin foil or aluminum tape.

10-28-2010, 11:02 AM   #9
MrA
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Tin foil does the trick, I get both antishake and trap-focusing back if I cover all the contacts.

Have cleaned the lens-mount where it ought to be making that same contact, so no grime/oil present (there wasn't anyway!), but it still doesn't happen, not certain why, since it's a metal component too.

Might have to get some metal tape and permanently adhere some to that bit of the lens mount, in lieu of tin foil.

QuoteQuote:
But aside from the SR button being on, doesn't SR display in the menu settings? Maybe the button is on, but the display says off.
Exactly so. When I power-on with the lens mounted (minus tin foil), instead of the "confirm focal length" screen, I get one showing all the settings (AV mode, SR crossed out, etc etc) appear briefly. Even when the SR button is "on". It goes so quick though that I hadn't noticed that, as was pointed out, it's defaulting from Auto/P into AV automatically.
10-28-2010, 11:16 AM   #10
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Glad you got it working!

I shoot only manual (see my signature), but I've never cared about catch focus--although I really should. I know it would improve the quality of my focus, which stinks now.

The aluminum tape is the best way to go, but being unemployed, I haven't been able to justify the 12 bucks to buy a roll which would cover 3,000 lenses.

I mean, once I have the tape, what's to stop me from buying more lenses to utilize it all?
10-28-2010, 11:38 AM   #11
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stupid question here, but somewhere, I seem to recall a post where there was mention of an option in one of the cameras for screw mounts.

I do not recall now where I saw that post, but what is curious is the lack of shake reduction if the pin is not shorted. I don't get that on my K10D, and don't recall it with my K7 either, although I lknow the K7 and my *istD want the data pin shorted to lens mount for focus confirmation to work. (K10D seems to give focus confirmation without this being the case.
10-28-2010, 03:25 PM   #12
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QuoteOriginally posted by Lowell Goudge Quote
...what is curious is the lack of shake reduction if the pin is not shorted. I don't get that on my K10D, and don't recall it with my K7 either, although I lknow the K7 and my *istD want the data pin shorted to lens mount for focus confirmation to work. (K10D seems to give focus confirmation without this being the case.
I am with Lowell. While there are several quirks related to the K100x bodies, lack of SR with M42 lenses has not been one that I have heard of. I have been fielding questions on PF for 3 years now and this is the first I have heard of this issue. In general, the only time you should have to be fiddling with or trying to "hack" the "A" contacts on the mount is if you are trying to enable "catch-in-focus" or some other undocumented feature.


Steve
10-28-2010, 03:46 PM   #13
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QuoteOriginally posted by stevebrot Quote
I am with Lowell. While there are several quirks related to the K100x bodies, lack of SR with M42 lenses has not been one that I have heard of. I have been fielding questions on PF for 3 years now and this is the first I have heard of this issue. In general, the only time you should have to be fiddling with or trying to "hack" the "A" contacts on the mount is if you are trying to enable "catch-in-focus" or some other undocumented feature.


Steve
Maybe there's a warp in the base of the lens or SOMETHING that's not touching what it's supposed to.

That's why I originally suggested using scotch tape to eliminate ALL contact, to see if that would at least trigger manual SR selection. (Forget catch-in for this part of it.)

It just doesn't make any sense as is.
10-29-2010, 05:35 AM   #14
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Interesting we're in some sort of agreement that something wierd is going on.

Am going to pick up some conductive tape, or maybe conductive paint (good idea?) from Maplins Electronics tonight.

Here's a question, though. How does the camera know it's got a lens mounted at all (rather than just a big gaping hole)? Is it possible the camera isn't picking up the presence of a lens for ... some reason? Presumably with K mount lens it's those contacts, but if the m42 lens doesn't (normally) interfere with them, then how in that case? I mean, what stops the camera trying to offer antishake when no lens is mounted if you take a shot?
10-29-2010, 05:44 AM   #15
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QuoteOriginally posted by MrA Quote
Interesting we're in some sort of agreement that something wierd is going on.

Am going to pick up some conductive tape, or maybe conductive paint (good idea?) from Maplins Electronics tonight.

Here's a question, though. How does the camera know it's got a lens mounted at all (rather than just a big gaping hole)? Is it possible the camera isn't picking up the presence of a lens for ... some reason? Presumably with K mount lens it's those contacts, but if the m42 lens doesn't (normally) interfere with them, then how in that case? I mean, what stops the camera trying to offer antishake when no lens is mounted if you take a shot?
On my K10D, I get the same SR response at startup, with or without a lens attached. I may enter any Focal Length I like.
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