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02-25-2009, 09:04 AM   #1
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M42 converter... does it matter which one?

I'd like to get the M42 converter for my K20D. I see there are a number of generics. Is there any specific one I need in order to retain and capabilities of the lenses? Or are M42 lenses purely manual?

Thanks,

Ken

02-25-2009, 09:15 AM   #2
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it does matter, but not to maintain manual functions.

I know of 3 types of M42 to K mount adaptors.

Real pentax adaptors. These have no flange and when installed correctly the lens is correctly alligned with the apature and focus indications vertical. Note real pentax adaptors do not have a flange, and allow the screw mount lens to thread fully on. Some (many?) M42 thread mount lenses do not make contact with the data pins on the cvamera body causing the focus indication to not function. These adaptors have an internal spring that locks them onto the body. It requires a little patience to release the spring and remove the adaptor, but removing the spring can lead to lensers falling off. This has been reported here on the forum

imitation pentax adaptors, which are identical to the real pentax ones except that the lens does not allign vertically. This is really only important if you intend to use a petal or square hood and could lead to vignetting (especially on film bodies)

third party "Flanged" adaptors. These adaptors have a 0.5-1mm flange, which causes many lenses (especially true pentax ones) to fail to reach infinity focus. The flange , however covers the camera body contacts, and as a result, AF indications may work. It should also be noted that the flanged adaptors usually have a locking pin slot, as opposed to a spring. These adaptors, if a lens can focus past infinity, are best left on the lens and then use the lens as a K mount.
02-25-2009, 09:27 AM   #3
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I can't seem to find the genuine Pentax converter on the the Pentax website. Can someone please provide me a link to where I can buy one?

Thanks,

Ken
02-25-2009, 09:46 AM   #4
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QuoteQuote:
Real pentax adaptors. These have no flange and when installed correctly the lens is correctly alligned with the apature and focus indications vertical. Note real pentax adaptors do not have a flange, and allow the screw mount lens to thread fully on. Some (many?) M42 thread mount lenses do not make contact with the data pins on the cvamera body causing the focus indication to not function. These adaptors have an internal spring that locks them onto the body. It requires a little patience to release the spring and remove the adaptor, but removing the spring can lead to lensers falling off. This has been reported here on the forum
not completely true.... the genuine pentax adapter may or may not align the lens completely vertical. I own two genuine adapters both an old 'Asahi Pentax' and a newer 'Pentax' adapter and neither lines up any Takumar lens I own completely vertical. however, they do come closer than any known 3rd party adapter. and this is also dependent on the lens as it seems to vary in how close it comes based on who you ask and what lens they used. the spring lock on the genuine adapter is actually very easily to remove and requires no tools. you can purchase it here: http://www.pentaxwebstore.com/detail/PTX+30120

here are a few crappy photos to illustrate. took just now, sorry about the flash glare and sensor dust and what not. dont use my K110D much anymore.



as you can see by the orane colored index diamond it is not vertical
super-takumar 35 3.5 on Pentax adapter


here is the adapter locked into place. notice it sits flush with no flange


grip the adapter and depress the locking spring tab with thumb and pointer finger. rotate counter clockwise to unlock and pull out. takes a matter of seconds


adapter in the unlocked position




02-25-2009, 10:18 AM   #5
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For the extra few dollars ... get the genuine one ... no tools required.
As Seamuis has shown ... just use a fingrenail and spin it and out of place .... easy.
02-25-2009, 12:23 PM   #6
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QuoteOriginally posted by Lowell Goudge Quote
Some (many?) M42 thread mount lenses do not make contact with the data pins on the cvamera body causing the focus indication to not function.
This is not the case. The focus indicator in the viewfinder still functions, no matter whether the data pins are shorted.

What needs the data pins to be shorted to work is the "focus trap" feature.

This is how the "focus trap" feature works: with camera body in AF-S mode, you hold down the shutter release and change the focus, either by rotating the focus ring on the lens, or by moving the camera back and forth. When the image is in focus, the shutter will be released. This is very helpful in macro photography.

Some of the M42 lenses touch the contacts on the camera body's lens mount, but the flange of the lens is painted, so the contacts do not short. In this case, you can use a piece of aluminum foil between the lens and the body to short the contacts, or you can scrape off the paint from the lens flange.

I happen to have the K10D with me now, but I don't have an M42 lens here to test. So I "simulated" and verified the above with a piece of Scotch tape covering the contacts on the lens mount.
02-25-2009, 12:32 PM   #7
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For the extra few bucks the Pentax original is the best. It's just better machined. I have 2 and also a Bower. As séamuis says, none of them line the lens up perfectly but that really doesn't matter. They are all close enough to vertical to be easily readable.

The Bower fits on tighter abut I've used it enough that I can now use it just like the Pentax ones, thumbnail removal is possible but that wan't the case at first.
02-25-2009, 12:46 PM   #8
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QuoteOriginally posted by SOldBear Quote
This is not the case. The focus indicator in the viewfinder still functions, no matter whether the data pins are shorted....

Some of the M42 lenses touch the contacts on the camera body's lens mount, but the flange of the lens is painted, so the contacts do not short. In this case, you can use a piece of aluminum foil between the lens and the body to short the contacts, or you can scrape off the paint from the lens flange.....
This is consistent with how the K100D behaves. Here's the pinout of the FA adapter according to Mark Roberts:



My experiments show that grounding the DATA pin enables proper exposure measurement for the K100D. About the Data pin, Wikipedia says "It carries the following information: focal length, distance to the subject, exact absolute f-stop value, and lens size."

I think the state of the data pins shown in the table are used to tell the camera the aperture lever range so the camera can then calculate how far to move the lever during exposure. This implies the state of these pins doesn't matter if the lens in question has no aperture lever and/or is manually stopped down (m42, adapted Nikon, etc.)

About the A pin, Wikipedia says "... is slightly recessed and allows the lens to indicate whether the aperture ring is set at 'A' or not. If it is, a pin on the lens extends slightly and makes contact, while if the lens is at any other setting the pin is retracted and does not make contact."

I'll be pleased to be corrected as I've been unable to document all my guesses thus far; it may differ for K10D etc.

Dave


Last edited by newarts; 02-25-2009 at 09:48 PM.
02-25-2009, 06:11 PM   #9
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I have few blog posts on m42 adapters

Thanks,
Hin
02-25-2009, 06:36 PM   #10
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Stickify?

Hey mods, maybe this thread ought to be made sticky. Just in my short weeks on PentaxForums, the adapter question has been posted perhaps 5 times. This particular incarnation of the answer would be a good one to stickify, as it's got not only the usual Pentax web store link and links to Hin Man's blog, but also the pin-out diagram which I've not seen in other such threads. Come on, someone post the link to Henry's in Toronto(?) and make it complete! --Dave
02-25-2009, 11:13 PM   #11
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I don't have much to add to what has already been posted except that I got a new generic adapter from Adorama (SKU# CZPUPKA). I was expecting a Bower (like the one in the Web site illustration), but instead got a box labeled ProOptic. Oh well, it looked OK and proceeded to mount it on my Ricoh XR-2s.

That was about an hour and a half ago.

Not only does the adapter not fit well (there is about 15 degrees of slop when locked in), but it is apparently permanently attached to my camera. I have tried all sorts of motions, actions, and incantations; all to no avail. I am concerned that I may have to take the Dremel to it or find my micro cross-point screwdriver set and disassemble the mount from the camera.

Not happy.

Steve

(Shoulda bought the Pentax...)

Last edited by stevebrot; 02-25-2009 at 11:56 PM.
02-25-2009, 11:55 PM   #12
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Finally!

A little postscript to the message above...

I finally gave the adapter a little time out and did something else for awhile. I then picked up the camera, gave the spring catch a little twist with my fingernail and tada...off came the ring.

Needless to say, I will not mount it back on again. I think Adorama is going to have to accept this one back as a defective return!

Steve
02-26-2009, 01:48 AM   #13
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QuoteOriginally posted by stevebrot Quote
A little postscript to the message above...

I finally gave the adapter a little time out and did something else for awhile. I then picked up the camera, gave the spring catch a little twist with my fingernail and tada...off came the ring.

Needless to say, I will not mount it back on again. I think Adorama is going to have to accept this one back as a defective return!

Steve
Steve, what a relief. I had few of those moments. That happens with poor quality in 3rd party adapters in the material and construction. Please buy a Pentax Genuine adapter unless you can't find one. I have seen three different copies of genuine adapter and they share different wordings, you can see the wordings in this blog post with pictures:

How to mount and dismount M42 adapter - Hin's Tech Corner

All the best,
Hin
02-26-2009, 09:57 AM   #14
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QuoteOriginally posted by hinman Quote
Steve, what a relief. I had few of those moments. That happens with poor quality in 3rd party adapters in the material and construction. Please buy a Pentax Genuine adapter unless you can't find one. I have seen three different copies of genuine adapter and they share different wordings, you can see the wordings in this blog post with pictures:

How to mount and dismount M42 adapter - Hin's Tech Corner

All the best,
Hin
Fortunately, I already have a Genuine Pentax adapter. I was buying the generic version with the intent of doing a permanent conversion of my Jupiter-9. After this initial experience, I don't want to let the thing near any of my cameras. Even with the spring removed, the fit is substandard.

Steve
02-26-2009, 10:25 AM   #15
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I use the genuine Pentax one. Its only 30 bucks. I don't find it very difficult to take on and off but i'm not changing lenses every other shot.
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