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03-26-2011, 01:47 PM   #1
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Auto extension tubes not working on K-5??

Just today, I bought a set of kenko auto extension tubes on a sale. The tubes looked fine and in working order, and I have tried them on the K200. Worked like a charm.

When I tried them on the K-5, however, the K-5 simply does not stop down the lens. I do not have an idea why this happens. I tried an another set of tubes - again the same behavior - the k200 stops down the lens with no problem, the K-5 won't budge.

When I mount the lens with the tubes, the aperture is cocked normally into fully open position, but it won't stop down on preview or when a picture is taken. There is no sound, as if it does not try to actuate the stop down lever at all. Furthermore, why would everything work normally on the k200?

I think it is needless to point out the fact that the K-5 functions flawlessly with the lens attached directly to the body.

03-26-2011, 02:26 PM   #2
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QuoteOriginally posted by Mirek Quote
Just today, I bought a set of kenko auto extension tubes on a sale. The tubes looked fine and in working order, and I have tried them on the K200. Worked like a charm.

When I tried them on the K-5, however, the K-5 simply does not stop down the lens. I do not have an idea why this happens. I tried an another set of tubes - again the same behavior - the k200 stops down the lens with no problem, the K-5 won't budge.

When I mount the lens with the tubes, the aperture is cocked normally into fully open position, but it won't stop down on preview or when a picture is taken. There is no sound, as if it does not try to actuate the stop down lever at all. Furthermore, why would everything work normally on the k200?

I think it is needless to point out the fact that the K-5 functions flawlessly with the lens attached directly to the body.
Make sure the body is set up to permit the use of manual aperture rings
03-26-2011, 02:30 PM   #3
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QuoteOriginally posted by enoeske Quote
Make sure the body is set up to permit the use of manual aperture rings
It is. Probably the first thing I enabled.
03-26-2011, 05:34 PM   #4
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QuoteOriginally posted by Mirek Quote
It is. Probably the first thing I enabled.
Actually you may want to disable the use of lens aperture. As you're looking for the camera to drive the aperture anyway.

It almost sounds that there's a contact failure with the "A" pin in one of the tubes, and the camera thinks you've manually set the lens off auto. Or does the K5 fail with each individual tube? I would check the springing of the contact.

PS. you got me concerned so I tested mine with the K5 and they operated correctly... so its not the camera model.

03-26-2011, 09:52 PM   #5
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Do these Tubes have the Aperture 'A' through electroical contacts? if so you need to ensure the body of the tubes provides a conductive circuit as well. Otherwise itr won't work. I bought some tubes and the mounts were anodised and indulted the nmount ring, thus the camera didn't recognise the aperture.. I rubbed off some of the anodising with emery paper and tey worked
03-26-2011, 10:28 PM   #6
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I just received my set of Kenko Auto Aperture tubes today. I found on the K-5 (as well as the K20D) that with all 3 sections mounted there seem to be so many electrical contacts that it was very iffy to keep it working. Was not a cleaning problem, just the slight pull of a lens broke contact and either gave me a blinking "F--" or shutter speed bouncing around until I pushed the lens to the camera a little. I found that just using the first extension gave me no problems and proved that everything works as long as there is contact.

So my first thought for you is to try just the primary extention (that normally connects to the camera) and see if that handles the aperture. Also if you normally mount the extention on the camera first, try mounting it on the lens first. I am sure there is a recommended way to do that but i am just doing what works. Good luck. If we have the same tubes I'd be happy to try any settings or combinations and provide results.
03-27-2011, 10:35 AM   #7
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The camera does not work with any of the individual tubes, or any combination of tubes.

Another thing is:
The inscription on the tube reads: "APK KENKO AUTO EXTENSION TUBE".

However, these tubes are not electrical, they do not conduct aperture information pins, and there are no contacts on the tubes. Purely mechanical.

Second: these tubes operate normally on the K200D, on the mz-5n, and the Super Program. Not on the K-5.

Also, I've tried with an another set of tubes, not made by kenko. Identical behavior.
03-27-2011, 10:50 AM   #8
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Hi,
I have a Kenko AF tube too(25mm), i use them with a K200d & a K5 without any problem on both systems.

Rarely, AF don't works, so I remove and reattache the lens, and it works fine.
It'ssurely a question of tube to lens contacts. Does it append with all your lenses ?

03-27-2011, 11:13 AM   #9
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I tried with three separate lenses, the FA35, K24 and a Chinon 50/1.7.

And I repeat again, there are no electrical contacts whatsoever on the tubes, or autofocus contacts, for that matter.

They are purely mechanical.

They work well with K200D, MZ-5n, and Super Program. Not with the K-5.
03-27-2011, 06:15 PM   #10
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QuoteOriginally posted by imtheguy Quote
I just received my set of Kenko Auto Aperture tubes today. I found on the K-5 (as well as the K20D) that with all 3 sections mounted there seem to be so many electrical contacts that it was very iffy to keep it working. Was not a cleaning problem, just the slight pull of a lens broke contact and either gave me a blinking "F--" or shutter speed bouncing around until I pushed the lens to the camera a little. I found that just using the first extension gave me no problems and proved that everything works as long as there is contact.
Then you have the PKA Mount version. The design of the PKA Mount uses the body of the lens and camera as a'contact'

Some companies like Jessops have made or sourced exteneions tubes that have been designed without knowing that the body of the lens needs electrical contact with the body of the camera.

My Jessops PKA mount tubes came with anodised bodies. I had to rub off this coating so there was an electrical contact between bodies.

I suspect this is your problem? Is the mount ring on the tubes black by any chance?
03-27-2011, 07:04 PM   #11
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You must be a mind reader. Yes, only the mount ring for the body is anodized black (except for the contacts of course) and the rest or the mount rings are chromed, I guess, shiney anyway.
03-28-2011, 12:57 AM   #12
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QuoteOriginally posted by Smeggypants Quote
My Jessops PKA mount tubes came with anodised bodies. I had to rub off this coating so there was an electrical contact between bodies.
Hmm. My tubes are apparently PK, though they are marked as "APK KENKO AUTO EXTENSION TUBE". They carry only the mechanical aperture coupling and the stop down lever.

The mount area, however, is anodized black. I have no electrical contacts.
Still this does not explain to me how the tubes work OK on the K200D, or the film bodies.
03-28-2011, 03:45 PM   #13
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Ok, I did a simple test.
I took both the K-5 and K200D, removed the lens, and pulled the DoF preview.

The K200D promptly pulled the lever even if there was no lens attached.
The K-5 wouldn't budge, unless a lens is mounted.

It appears that, the K-5 behaves differently from the older bodies and somehow detects if a lens is attached, most likely through electrical contacts.

I am puzzled why Pentax would change this behavior from earlier K-mount cameras.
Nevertheless, I will try scrubbing off the black paint to see if it helps.
03-28-2011, 03:53 PM   #14
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just a simple guess here, but I am willing to bet the lens mount is either painted black or black anodizing.

Some bodies, the K7 being the one I own that does this, need the pin furthest away from the lens locking pin shorted to the lens mount to permit aperture activation.

I have a set of Vivitar Automatic extension tubes, and note these are old and the term "automatic" means simply they control aperture by stopping the lens down to the aperture ring setting, as well as having the aperture coupling to the body for TTL metering. It has nothing to do with the PKA mount and the electrical transfer of aperture information to the body, or body controlled aperture.

if you clean the paint off the mount in the area of the contact pins it will work
03-28-2011, 04:47 PM   #15
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QuoteOriginally posted by Lowell Goudge Quote
just a simple guess here, but I am willing to bet the lens mount is either painted black or black anodizing.

Some bodies, the K7 being the one I own that does this, need the pin furthest away from the lens locking pin shorted to the lens mount to permit aperture activation.

I have a set of Vivitar Automatic extension tubes, and note these are old and the term "automatic" means simply they control aperture by stopping the lens down to the aperture ring setting, as well as having the aperture coupling to the body for TTL metering. It has nothing to do with the PKA mount and the electrical transfer of aperture information to the body, or body controlled aperture.

if you clean the paint off the mount in the area of the contact pins it will work
Fair enough. They appear the same as I have, and mine are black anodized at the mounts.
So, scraping off paint it is.

Still, why does it work normally on older bodies, and why the need for suddenly putting this "feature" into effect? That's what generally puzzles me.

In any case, thank you, everyone, for your replies.
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