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04-30-2016, 01:15 PM   #1
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Pentax 67 165mm Leaf Shutter doesn't always fire in Auto Aperture

I have the following issue:

Manual Aperture - leaf shutter works perfectly and fires each time.
Auto Aperture - works intermittently - sometimes LS doesn't fire. The aperture closes, but it is like the mechanism to fire the leaf shutter isn't triggered. The LS stays cocked open and the flash isn't triggered.

Has anybody had this issue, or know what the problem can be?

Thanks.


Last edited by glass; 04-30-2016 at 01:58 PM.
04-30-2016, 04:04 PM   #2
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QuoteOriginally posted by glass Quote
I have the following issue:

Manual Aperture - leaf shutter works perfectly and fires each time.
Auto Aperture - works intermittently - sometimes LS doesn't fire. The aperture closes, but it is like the mechanism to fire the leaf shutter isn't triggered. The LS stays cocked open and the flash isn't triggered.

Has anybody had this issue, or know what the problem can be?

Thanks.
You can't use the 67II in aperture priority with the 165/4 LS in leaf shutter mode.

You need to set the 67ii shutter speed to 1/8 second and then use one of the LS speeds on the lens.

Phil.
04-30-2016, 04:39 PM   #3
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Thanks, but I don't mean aperture priorty mode (which is an in-camera metering mode).
I mean the big toggle switch on the lens that says MANUAL and AUTO. When set to MANUAL the LS fires, when set to AUTO it only intermittently fires.
04-30-2016, 07:28 PM   #4
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Are you cocking the LS lens — the shutter, in auto as well as in manual (stop-down)? And why are you using stop-down mode on a lens with an auto-aperture?
When the LS shutter is cocked there is no viewfinder, and this is what it should be in manual or auto mode. The cocking is not automatic; that is to say, you must cock the shutter before firing the camera shutter, which by association will then fire the leaf shutter. Very, very few things can go wrong when the correct and methodical process is followed.

04-30-2016, 10:58 PM   #5
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Silent is right. The shutter on 645 LS lenses stays closed until the lens is cocked so you can't make that mistake.
05-01-2016, 12:50 AM   #6
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I have a number of other LS lenses. As you say, operation is quite straightforward. I can replicate the problem off-camera by sliding the aperture tab on the back of the lens mount - in MANUAL mode the cocked shutter fires as expected, in AUTO mode the cocked shutter only fires intermittently. The aperture slide tab feels a bit stiffer and the trigger point is further around when in AUTO mode.

So my question isn't about technique or operation, but rather if the problem I am experiencing with my lens anybody else has had, or may know what the problem is.

I bought the lens on eBay and got a good price, optically and cosmetically the lens is really nice, but if it is going to be expensive or impossible to fix the LS firing in AUTO mode issue, I'll send the lens back.

Last edited by glass; 05-01-2016 at 02:26 AM.
05-01-2016, 09:59 AM   #7
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QuoteOriginally posted by glass Quote
I have a number of other LS lenses. As you say, operation is quite straightforward. I can replicate the problem off-camera by sliding the aperture tab on the back of the lens mount - in MANUAL mode the cocked shutter fires as expected, in AUTO mode the cocked shutter only fires intermittently. The aperture slide tab feels a bit stiffer and the trigger point is further around when in AUTO mode.

So my question isn't about technique or operation, but rather if the problem I am experiencing with my lens anybody else has had, or may know what the problem is.

I bought the lens on eBay and got a good price, optically and cosmetically the lens is really nice, but if it is going to be expensive or impossible to fix the LS firing in AUTO mode issue, I'll send the lens back.
OK sorry I see what issue you are having. The answer is the LS should work in either mode AUTO/MAN.

I would email Eric and see if he has the answer as to what might be causing the problem.

Also PM me if if you want a scanned copy of the 165/4 LS manual.

Phil.
05-01-2016, 10:50 AM   #8
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QuoteOriginally posted by gofour3 Quote

I would email Eric and see if he has the answer as to what might be causing the problem.
Thanks. Apologies, I'm new here - who is Eric and where do I find his email address?

05-01-2016, 12:53 PM   #9
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That lever at the rear of the lens activates both the diaphragm and leaf shutter when in auto mode. It should stop down the diaphragm, then a fraction of a second later, activate the leaf. Yours has some sort of internal problem.
05-01-2016, 04:51 PM   #10
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QuoteOriginally posted by glass Quote
Thanks. Apologies, I'm new here - who is Eric and where do I find his email address?
He is our go to guy for Pentax camera repairs:

Pentax Camera Repairs

He may be able to help, send him an email.

Phil.
05-03-2016, 06:02 PM   #11
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i just bought the 165 LS lens and it has the same issue. first roll LS lens did not fire at all. next 3 rolls fired 3 frames only. i have fired the camera with backing paper only and it seems to fire every other frame. so is it the camera body or the lens?
05-03-2016, 11:29 PM   #12
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Assuming that all users are following the modus operandi of the LS lens (1/8 second or slower, LS engaged, LS shutter cocked and no MLU activated on the P67 body [NB: MLU must not be used with the 165LS lens). The possibility must be considered that the lens has at some stage been improperly used, sufficiently so or often enough that the mechanism interfacing with the body jams or does not work to its intended process, irrespective of following the correct operational procedure. That, or there is a sticking or broken mechanism within the LS lens. I would hold my bets and take the lens and the camera to a service centre and get the speculation over and done with.
05-20-2016, 04:42 AM   #13
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I should have added that this problem only occurs on a 645z. I'm pleased to announce I've found a solution to this problem.

I purchased a number of 67 LS lenses as at first I thought it was a problem with my particular lens. But on my 645z they all exhibited problems with the LS not firing reliably.

It turns out that the aperture tab on the back of the lens mount needs to fall back to the home position exactly, or the leaf shutter mechanism won't completely reset. The 67 to 645 adapter has a hard stop which prevents the lens' tab from completely returning far enough to the home position. For aperture control only, this is no problem as this would simply cause the aperture to be ever so slightly closed instead of wide open, but not enough to be noticeable. But it does cause a problem with the Leaf Shutter mechanism; without returning to the full open position it causes the Leaf Shutter to fail on the next shot.

I tried multiple 67 to 645 adapters, including genuine Pentax and Fotodiox, and had the same problem on all.

The solution was to file away part of the metal hard return stop on a Fotodiox adatper, allowing the lens' aperture tab to completely return to the correct home position. Now all my 67 LS lenses fire accurately, 100% of the time. Very happy with this and hope it helps other users with a similar problem. The 67 LS lenses on a 645z are very beautiful.

The other benefit of 67 LS lenses vs the 645 LS lenses is the 67 lenses have auto aperture, the 645 lenses are stop-down only.
05-20-2016, 07:37 AM   #14
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QuoteOriginally posted by glass Quote
I should have added that this problem only occurs on a 645z. I'm pleased to announce I've found a solution to this problem.
Yeah that would have helped, as you had us assuming you were using a Pentax 6x7 body!

The 67 165/4LS can only be used in the focal plane mode with the 6x7 to 645 adapter, so there is no surprise the leaf shutter does not fire. (This also applies to rear converters and extension tubes.)

Glad you found a solution for using the 165/4LS on your 645z.

Phil.
05-20-2016, 08:26 AM   #15
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QuoteOriginally posted by gofour3 Quote
Yeah that would have helped, as you had us assuming you were using a Pentax 6x7 body!


QuoteOriginally posted by gofour3 Quote
The 67 165/4LS can only be used in the focal plane mode with the 6x7 to 645 adapter
I didn't realise this was the official line. Where is this documented?
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