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05-24-2011, 06:15 AM   #1
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Backwards lens non-compatibility

I keep hearing about "any k-mount lens" fitting the newer DSLR's but I've struck 3 incompatibilities that deal with the best part of my old gear (not much I can salvage from it).

First is an issue with the flange on 2 old Sigma lenses mentioned here: Old manual Sigma lens "for K mount" won't fit on K100d - Photo.net Pentax Forum that effects 2 old Sigma Lenses I have (the only two) - a 28mm Macro and a 70-210 Zoom. Seems the flange has to be ground back for it them fit my k-r. Not sure it is worth it for the 70-210 (new lens on the way) but am a bit disappointed about the 28mm. Has anyone done the grind/trim?
What I'm worried about is:
"I saw that your flange may have been grind down too much as the flange is meant to protect the shutter blade actuation lever (stop down) from hitting by K lens body upon lens mount"
but then another post says
"Don't worry, I've seen plenty of older, 3rd party lenses that don't have a flange at all, so you shouldn't have any problems."
Not sure if I'll grind the 28 flange yet but if I do should I watch how much I take off or not? Last thing I want is to cause camera damage.

Other issue is with a set of King Auto Extension tubes. These weren't cheap when I bought them but would sell cheap now. They fit the body of the k-r but the kit 18-55 lens won't fit them. That's a shame because they are auto and have a full series of contact pins.

Consolation is that the 28 mm fits the tubes which fit the body bit it's all manual and I don't think I'd be able to focus with that combo (I think the focal plane might be out of reach). They'll work with an old Pentax 50mm F2 but that's about it.

05-24-2011, 06:57 AM   #2
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Bill

while it is true that the phrase "ANY K mount lens will fit" is somewhat generalized, you need to consider the following:
- for the ricoh pin issue, the Ricoh lens mount KR is not a recognized K mount lens by pentax.
- the "protective shield" on the aperture activation lever only occurrs on third party lenses, not pentax ones, and when pentax designed the KAF2 mount in the early 1990's for the PZ series of cameras, they did what any manufacturer would do, look at their own specification for the lens, and not the interpretation by third party licensee's of their mounts

As for the tight mount on the extension tubes, this would be interesting to look at the real cause of the failure to mount, because again, I am quite certain if you sent these to pentax they would tell you that they are not responsible for aftermarket lenses and accessories.

The truth is, these tubes are probably a very poor interpretaion of the K mount by the maker, Your issue is with them, not pentax or the claim that any K moutn lens will fit. ANy lens made to the pentax K mount lisence definitions or specifications WILL fit your camera, ones that are reverse engineered, may not, and that is true of any camera maker.
05-24-2011, 07:03 AM   #3
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QuoteOriginally posted by Lowell Goudge Quote
Bill

while it is true that the phrase "ANY K mount lens will fit" is somewhat generalized, you need to consider the following:
- for the ricoh pin issue, the Ricoh lens mount KR is not a recognized K mount lens by pentax.
- the "protective shield" on the aperture activation lever only occurrs on third party lenses, not pentax ones, and when pentax designed the KAF2 mount in the early 1990's for the PZ series of cameras, they did what any manufacturer would do, look at their own specification for the lens, and not the interpretation by third party licensee's of their mounts

As for the tight mount on the extension tubes, this would be interesting to look at the real cause of the failure to mount, because again, I am quite certain if you sent these to pentax they would tell you that they are not responsible for aftermarket lenses and accessories.

The truth is, these tubes are probably a very poor interpretaion of the K mount by the maker, Your issue is with them, not pentax or the claim that any K moutn lens will fit. ANy lens made to the pentax K mount lisence definitions or specifications WILL fit your camera, ones that are reverse engineered, may not, and that is true of any camera maker.
Will I appreciate your reply and defense the statement is made generally here and often generalised to include 3rd party k-mount lenses or accessories or without an exclusion.

The lesson is that there are exceptions and there needs to be some caution. Worse case scenario is that the generalisation that is often used here results in someone "forcing" a lens on and results in damage. I've posted this thread primarily for that reason and to see if anyone has used the mod.
05-24-2011, 07:34 AM   #4
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QuoteOriginally posted by Bill_R Quote
Will I appreciate your reply and defense the statement is made generally here and often generalised to include 3rd party k-mount lenses or accessories or without an exclusion.

The lesson is that there are exceptions and there needs to be some caution. Worse case scenario is that the generalisation that is often used here results in someone "forcing" a lens on and results in damage. I've posted this thread primarily for that reason and to see if anyone has used the mod.
Bill

I can't personally comment on the ricoh pin mod, but I know that it will work. THe issue there was the pin would stick into the screw drive for AF due to its placement.

as for the flange on the aperture activation lever, that works just fine., I have an old Series 1 70-210 F3.5 (first version) that needed this flange cut back to allow the lens to mount.

Normally, this second issue is not a real risk, because the lens simply won't mount on any camera with a KAF2 mount, because the flange hits the block supporting the power contacts of the lens mount in the camera.

If you want to get into warnings about 3rd party things, you also need to add to the list all the issues with third party (non pentax that is) M42 to K mount adaptors, because there are all sorts of incompatibilities there.

In a nutshell, the issues are not aall that bad, and they ahve been covered here in the forum because pentax users have the tendancy to attach the weirdest things to their cameras, including several who consider a nikon lens mount to be close enough to fit.

05-24-2011, 07:50 AM   #5
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QuoteOriginally posted by Lowell Goudge Quote
Bill

I can't personally comment on the ricoh pin mod, but I know that it will work. THe issue there was the pin would stick into the screw drive for AF due to its placement.

as for the flange on the aperture activation lever, that works just fine., I have an old Series 1 70-210 F3.5 (first version) that needed this flange cut back to allow the lens to mount.

Normally, this second issue is not a real risk, because the lens simply won't mount on any camera with a KAF2 mount, because the flange hits the block supporting the power contacts of the lens mount in the camera.

If you want to get into warnings about 3rd party things, you also need to add to the list all the issues with third party (non pentax that is) M42 to K mount adaptors, because there are all sorts of incompatibilities there.

In a nutshell, the issues are not aall that bad, and they ahve been covered here in the forum because pentax users have the tendancy to attach the weirdest things to their cameras, including several who consider a nikon lens mount to be close enough to fit.
Thanks Lowell. I did get the 28 to fit without any mod a few days ago but it was very tight and I think I'd need slight mod/grind to be on the safe side. The 70-210 I won't worry about.

I tried the extension tubes again and the kit lens does fit but just needed a bit more force than I was initially comfortable with after experiencing the interference with the 2 lenses. So, am happy I'll get to used these tubes as auto tubes (if I want to do auto) since they were only used a few times and are in as new condition and heaps sturdier than a lot of the real cheapies I see on ebay. Whether that makes them "better" will be something to see.

I'd done a search on Google and here and the only real hit I had was the link I posted in the initial post. My search terms might have been out but with this thread Googlised and some good advice the slight caution with some lenses might come to the front again for a while.
05-24-2011, 10:40 AM   #6
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One reason that you see the sweeping generalizations: some people just haven't had a problem with their old lenses. There aren't that many problem lenses to begin with, and with luck and/or less LBA, someone might never see one. Everyone's advice tends to come from their own experience. Yours might help someone with a Sigma lens.

When I have to remove parts of a light shield flange, I first remove it from the lens and second, make it look like the flange on the kit lens. That's worked so far.

The only Ricoh pins I have seen are on Sigma and Vivitar lenses and have not caused the lens to be stuck on the mount. They are rounded enough and spring loaded. However, I did notice that some of them don't work as well as others, and my older DSLR has some wear on the mount because of this. I ended up removing two pins on older lenses.

If you end up with an old K-mount film camera, it can be a useful test for suspicious lenses.
05-24-2011, 11:05 AM   #7
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dave

just to clarify one point for a lot of people on the ricoh pin, there seem to be two different pin dimensions. some lenses I have seen photos of, use a pin that is quite small (about 0.5mm) which is small enough to get stuck in the slots of the screw drive, if by chance, the drive is in the right orientation. Others have a pin about 1.0mm in diameter, which is big enough to float over the screw drive and cause no problem.
05-24-2011, 12:09 PM - 1 Like   #8
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For what its worth, PENTAX never said that any k-mount lens would fit. Pentax said that any PENTAX k-mount lens would fit. They never claimed that a Sigma or Vivitar lens would fit.

As others have pointed out, Pentax can not be held responsible for other companies misinterpretation of the specs, or their poor quality control, or, in the case of Ricoh, extending the specs in an incompatible way, even if those incompatibilities worked in the past.

Nor can Pentax be held responsible for forum posters making erroneous statements.

As Lowell said, most third-party k-mount lenses work just fine. There are a few that are incompatible, but it is the fault of the third-party, not Pentax. Plus, there are known workarounds for the problems.

All in all, even with the few incompatible lenses, Pentax still enjoys the best compatibility of any dslr maker. Any Pentax-made 35mm SLR lens ever made will mount and function on a Pentax dslr, although the M42 and M37 screw mount lenses require an inexpensive adapter. Neither Nikon or Canon can say that.

05-24-2011, 04:20 PM   #9
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QuoteOriginally posted by noblepa Quote
For what its worth, PENTAX never said that any k-mount lens would fit. Pentax said that any PENTAX k-mount lens would fit. They never claimed that a Sigma or Vivitar lens would fit.
+1 and rep points for that. Pentax has no responsibility for 3rd party lens compatibility. That is so obvious it shouldn't even need to be stated.
05-24-2011, 04:41 PM   #10
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But thankfully, just about any K-mount lens still fits well and is usable on any Pentax dSLR.
I have had innumerable old Chinon, Sigma and Vivitar K-mount lenses that have fit very smoothly I'd be none the wiser that 3rd party K-mount lenses had compatibility issues.
05-24-2011, 08:18 PM   #11
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QuoteOriginally posted by Lowell Goudge Quote
dave

just to clarify one point for a lot of people on the ricoh pin, there seem to be two different pin dimensions. some lenses I have seen photos of, use a pin that is quite small (about 0.5mm) which is small enough to get stuck in the slots of the screw drive, if by chance, the drive is in the right orientation. Others have a pin about 1.0mm in diameter, which is big enough to float over the screw drive and cause no problem.
It looks like Sigma has upgraded their pin over time. The oldest one I have was smaller diameter and pointy. A newer version gets fatter and more rounded. The latest one is still fatter, on a lens made after AF cameras were common. I'm guessing that they were responding to the issue as more customers had AF cameras.
05-24-2011, 11:08 PM   #12
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QuoteOriginally posted by Just1MoreDave Quote
One reason that you see the sweeping generalizations: some people just haven't had a problem with their old lenses. There aren't that many problem lenses to begin with, and with luck and/or less LBA, someone might never see one. Everyone's advice tends to come from their own experience. Yours might help someone with a Sigma lens.

When I have to remove parts of a light shield flange, I first remove it from the lens and second, make it look like the flange on the kit lens. That's worked so far.

The only Ricoh pins I have seen are on Sigma and Vivitar lenses and have not caused the lens to be stuck on the mount. They are rounded enough and spring loaded. However, I did notice that some of them don't work as well as others, and my older DSLR has some wear on the mount because of this. I ended up removing two pins on older lenses.

If you end up with an old K-mount film camera, it can be a useful test for suspicious lenses.
In the link I found and posted in the original post the guy merely cut down the flange on the 70-210 with a pair of tin snips and claims it worked. Then there is a caution post about cutting it too low and another saying it should be ok.
Is this flange meant to fit or make contact with anything? In other words, is cutting it low a problem?
It seems a bit different than the Vivitar that has a flange that wraps around further.
Oddly I have a Ricoh 50 mm F2 (no clue where it came from) with no pin but 2 Sigmas with flanges that are too deep.
05-24-2011, 11:33 PM   #13
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QuoteOriginally posted by Bill_R Quote
Is this flange meant to fit or make contact with anything? In other words, is cutting it low a problem?
The flange is supposed to guard the aperture actuation lever. Most K-mount lenses have a guard of some sort. Others do not. The Tamron Adaptall-2 mounts are a good example of mounts with a "naked" lever.

As for your "too deep" Sigmas...chances are they worked fine with the K-mount Sigma cameras of the day. They probably also worked fine on contemporary Pentax. Ditto for the Rikenon-P lenses with the notorious Ricoh pin. They were perfectly compatible with Pentax and other K-mount cameras of the day, though those other bodies obviously would not have supported the Ricoh program exposure features of the mount.

Short story is:
  • Backwards compatibility to non-Pentax brand lenses is generally excellent with a few exceptions. This is true for both K-mount and M42 screw mount lenses.
  • Any incompatibility is generally the result of Pentax not being particularly concerned about protecting the customer's investment in the competition's product. This is particularly true regarding the Ricoh pin. The stuck lens issue was known to Pentax designers when the AF K-mount was developed.


Steve


(BTW...the only Ricoh lenses that require concern are the Rikenon-P series with the GREEN P on the aperture ring. Other Rikenons are well-worth looking into as vintage lenses.)
05-25-2011, 02:03 AM   #14
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Been looking through the lens database and I can't see any of the lenses I've had the issue with or even much mention of the Ricoh pin problem in lenses in the Ricoh group.
I'm thinking the place to note the possible issue with these few lenses might be the lens database in the lens description with a link on how to "fix" it. Seems to be enough people specifically aware of the lenses with these issues to add them.
I can certainly add the 2 sigma lenses after/if I trim them and try them out.
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