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09-02-2010, 01:19 AM   #1
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Cannot stop down manual lens for some reason

Hi there guys, I'd like to ask for some help. Recently I bought a Hanimex 135mm f/2.8 manual lens. It looks used, but mechanically it works like a charm. The aperture blades aren't stuck, the aperture lever is working as it should. At least in my hands. The problem is when I mount it on my K-x, and try to use it in manual exposure, I can't stop it down using any of the buttons, EV +/-, AF/AE-L, Green Button set to Tv Shift, nothing stops down the lens even though the aperture ring isn't set to 2.8. USING APERTURE RING is set to PERMITTED. And yes, the ring is working while the lens is off camera. It doesn't have an "A" setting. So when I push the Green Button while the ring is set to 11 for example, it does not stop the lens down, instead takes a meter reading at 2.8. When I take the shot, the camera stops down to the ring setting and takes the shot with the shutter setting metered to f/2.8. So shots taken on other aperture value than f/2.8 are always underexposed. But it seems like the aperture lever is operational because at exposure the lever is released. But to take a meter reading I simply cannot stop down.

Do you guys have any ideas what could cause the problem? Thank you for your help.


Last edited by SamWarrick; 09-05-2010 at 11:13 PM.
09-02-2010, 03:09 AM   #2
Ira
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When you turn the aperture ring, does the viewfinder get darker?

In other words, in manual, the lens should ALWAYS be stopped down. All hitting a button does is lock in the shutter speed.

And on on the K-x, yes--you can use the EV button for this with no special set-up required in the menu. (If you use the Green button, it has to be set for Tv Shift.)
09-02-2010, 03:37 AM   #3
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Hi Ira!

Thanks for the reply, I've seen your post about using manual lenses on digital bodies, and I think I've tried all those tips. No, the screen doesn't get darker when I turn the aperture ring, because the aperture lever is locked by the body. It's released only before I fully press the exposure button. Thats why I can't use stop down metering. It meters wide open then at exposure applies the wide-open measured shutter speed to the aperture value set on the ring. And if that's not 2.8, it underexposes. I'm thinking about selling it. I think I've tried everything.
09-02-2010, 05:18 AM   #4
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Last time I've checked, my Kx didn't close the aperture with insulated lenses... So check on yours, if the mount is painted.

A good modification I do to my manual lenses is to drill a second locking hole so they lock halfway into the mount, and behave just like m42. This enables Av metering (but is useful only if you restrict yourself to rather wide apertures, as the viewfinder darkens along your selected aperture).

09-02-2010, 05:54 AM   #5
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It will work only in M mode plus green button or AE lock button (in K100D).
09-02-2010, 06:15 AM   #6
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Is the camera in Manual mode? Manual lenses only work on Pentax DSLRs in M and Av mode...and in Av mode, but only wide open in Av.

Put the camera on Manual, and set the aperture. Then try the green button or twisting the on/off switch to the aperture preview setting (twist it further than "on" in the opposite direction from off) and it should meter for you.

Have other manual lenses worked for you?
09-02-2010, 06:35 AM   #7
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Thanks for the tips, but I've already done those. The camera is set to manual, the Green Button is set to Tv Shift, aperture ring isn't set to 2.8, and yet if I press the Green Button, EV +/-, AE-AF-L buttons, it takes a meter reading at 2.8. Doesn't stop down. And if I set the Green Button to Optical Preview and press it, still nothing happens. The camera does not release the lever in any scenario, only at exposure. I own a Cosinon 50mm f/2 manual lens, I have just tried it to see if the problem occurs, and guess what, it does. Same as the Hanimex. And this one is working off-camera too, blades/lever/ring working properly.

I have no idea what could be the problem. I hope someone does. Thanks in advance.
09-02-2010, 07:05 AM   #8
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Again, can you tell us if the lenses' mounts are painted or if they are metallic?

09-02-2010, 07:41 AM   #9
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The Hanimex is metalic, the Cosinon is painted.
09-02-2010, 08:29 AM   #10
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Are these M42s?

Doesn't make any sense:

If they open and close off the camera, they should open and close ON the camera. It's not like the camera is electronically telling the lens's blades to do anything.

Sounds like the pins aren't engaged when mounted. And do either of the lenses have M/A switches?
09-02-2010, 08:49 AM   #11
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I'm also wondering if these are M42 or K-mount. If K-mount, what you're describing seems right, but do read the sticky thread on using manual lenses at the top of this forum if you have not done so recently to make sure you aren't missing something. With M42, they should be stopping immediately when you turn the ring, uinless they have a switch that prevent this - and in that case, I think you need to disengage that switch (but I have no personal experience with M42 lenses).
09-02-2010, 02:09 PM   #12
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QuoteOriginally posted by Marc Sabatella Quote
I'm also wondering if these are M42 or K-mount. If K-mount, what you're describing seems right, but do read the sticky thread on using manual lenses at the top of this forum if you have not done so recently to make sure you aren't missing something. With M42, they should be stopping immediately when you turn the ring, uinless they have a switch that prevent this - and in that case, I think you need to disengage that switch (but I have no personal experience with M42 lenses).
But what about M42 Auto lenses with no AUto Manual switch. They will always stop down because they need to be on the camera (M42 body) to press the aperture pin and open the aperture.

I have one lens like this. (actually an adaptall II mount)
09-02-2010, 03:11 PM   #13
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QuoteOriginally posted by Lowell Goudge Quote
But what about M42 Auto lenses with no AUto Manual switch. They will always stop down because they need to be on the camera (M42 body) to press the aperture pin and open the aperture.

I have one lens like this. (actually an adaptall II mount)
You lost me:

Because according to what you're saying, his lens(es) should STILL stop down correctly, right?

I asked about the A/M switch above because some people slide the switch in the DIRECTION of M/Manual to get to manual, exposing the AUTO on the lens barrel, and that ain't right.

You have to slide it in the direction of AUTO, hiding the AUTO letters on the lens and showing M/manual, to be in M mode.
09-02-2010, 03:58 PM   #14
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QuoteOriginally posted by Ira Quote
You lost me:

Because according to what you're saying, his lens(es) should STILL stop down correctly, right?
no actually it is fully stopped down all the time, unless you block the mechanism open at which point it behaves like a preset, tracking perfectly the aperture.
QuoteQuote:
I asked about the A/M switch above because some people slide the switch in the DIRECTION of M/Manual to get to manual, exposing the AUTO on the lens barrel, and that ain't right.
yeah that is a little confusing the switch showes where you are not where you are going
I am still not sure what lenses the op is using
09-02-2010, 04:21 PM   #15
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QuoteOriginally posted by Lowell Goudge Quote
But what about M42 Auto lenses with no AUto Manual switch. They will always stop down because they need to be on the camera (M42 body) to press the aperture pin and open the aperture.

I have one lens like this. (actually an adaptall II mount)

M42 lenses are wide open unless the camera pushes the pin. Pushing the pin stops the lens down to the working aperture. This is the opposite of a k-mount lens. A k-mount lens, off camera, will stop down, because the camera is not holding the aperture open. An M42 lens is wide open until the camera stops it down.

This is why M42 lenses without the auto/manual switch are not very useful on a dslr. The camera lacks the ability to push the pin, so the lens can not be stopped down.
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