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08-18-2011, 09:17 AM   #1
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what do people use non infinity m42 adapters for?

I'm just curious why someone would use a not infinity focusing m42-pk adapter. Is it just that they are easier to use if you don't need infinity focus? Reason I ask is that I got a non infinity focus one to use as a lens mount thinking it would be thicker but it was in fact thinner and not usable for that. Its this one
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The outer rim is .050 thick but it fits outside the face on the camera. The inner ring that mates up with the camera is about .030" (can not get an exact measurement with a dial caliper and the kids got at my depth gauge and broke it). All the other ones that don't have the ridge that I have gotten have been .040". So since I already have an infinity adapter, and a regular non infinity one, Is there any advantage to having this one that brings it a little closer (since I'm stuck with it). I'm still not sure why someone would use one over an infinity focusing one anyway.

08-18-2011, 09:40 AM   #2
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Macro, portraits, any shot that do not require you to point at distant objects. Realistically, the wide flange m42 adapters are most suited for a dedicated macro set up or studio portrait where you know you won't be shooting at infinity ever. If mounted on a general purpose lens, it can be a pita if you try to take a shot of distant object and forget the wide flange adapter was on the lens.

Thanks,
08-18-2011, 09:54 AM   #3
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QuoteOriginally posted by ripit Quote
I'm just curious why someone would use a not infinity focusing m42-pk adapter. Is it just that they are easier to use if you don't need infinity focus? Reason I ask is that I got a non infinity focus one to use as a lens mount thinking it would be thicker but it was in fact thinner and not usable for that. Its this one
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The outer rim is .050 thick but it fits outside the face on the camera. The inner ring that mates up with the camera is about .030" (can not get an exact measurement with a dial caliper and the kids got at my depth gauge and broke it). All the other ones that don't have the ridge that I have gotten have been .040". So since I already have an infinity adapter, and a regular non infinity one, Is there any advantage to having this one that brings it a little closer (since I'm stuck with it). I'm still not sure why someone would use one over an infinity focusing one anyway.
Thanks for the heads up question!

First to answer your question: I use flange type adapters when exact distance doesn't matte - with extension tubes, bellows, etc. I also use them for DIY projects like changing a Nikon base lens into a PK based lens. Others use then with a regular m42 lens and re-adjust infinity focus on the lens.

The particular item you showed is very thin where it matters so could well be useful with m42 lenses in general because only a small adjustment to infinity focus (if any) would be required.
08-18-2011, 09:58 AM - 1 Like   #4
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What I use NIF (non-infinity-focus) M42-PK adapters for:

* As mentioned, for macro and closeup and portrait shooting. I use NIFs with tubes and bellows, or just situations where infinity is not an issue.

* Similarly, with longer teles for subjects closer than infinity. A NIF on a 200-300mm lens may drop the near focus from 2m to 1m, and far focus down to ~75m (YMMV).

* Some cheap old long lenses and mirrors normally focus *past* infinity, so using a NIF just brings them down to nominal focus.

* To mount a thin-body lens whose base is too narrow to cover the electric contacts. This is for when I *must* use CIF when shooting.

* As replacement bases for some modded lenses -- at least, that is the plan! With Petri bayonets, I pry off the base and glue on an infinity adapter; with some Nikons, I should be able to replace the base with a NIF. But that may require grinding down the NIF's perimeter. I'll get to that someday...

08-18-2011, 10:09 AM   #5
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I figure it might be useful for people that actually use it for m42 lenses. I assume the thicker outer ring makes it stiff enough despite the thin inner part. I wanted it to replace the mount on a lens so Its worse for what I wanted it for (thicker is stronger and better). I'm still hunting for a good source for cheap donor lenses (the last I used was about .070" thick and it worked great). Trying to counter sink for a screw head one a .040 or even worse a .030 flange has its issues (even if you bend it in instead of cutting). I need something for a few heavy lenses. The back ring on some Chinese macro tube will be my next thing to try.

@RioRico, I know you have done some mount modding. Do you own macro extension tubes and if so, does the back look like it might be adapted to a lens mount? In theory my mount needs to be .190" or a little under 5mm including spacers if necessary. I shouldn't have too much issue with a spacer.

My main concern is the thickness of the rear flange (I can cut off the outer rim). I would like to find some cheap ebay macro rings where the mount screws onto the tube (so its pre drilled and countersunk)and no rim to cut off) but they all seem to be 1pc.

Last edited by ripit; 08-18-2011 at 10:24 AM.
08-18-2011, 10:34 AM   #6
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Over time, I have bought 7 M42 adaptors, 1 origonal, one bower from B&H which has ain internal flange for Auto lenses with no A/M switch, and 5 flanged adaptors (non infinity)

At present, I still have 2 flanged adaptors new in box.

1 I used to modify a miranda 4 prong bayonet to miranda screw adaptpr fpor a bellows to K mount by cutting off the miranda screw thread and epoxying the flanged mount to the adaptor. this let me use a miranda bellows on my pentax cameras.

the other 2 I have used, went to a Kiron (for minolta) 28mmF2 to convert it from minolta to K mount with manual aperture, the other went to a vivitar for nikon 24mmF2 for the same reason.

Flanged adaptors are great for mount conversions.

that's what I use them for
08-18-2011, 10:54 AM   #7
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I have 4 lenses waiting to be modded. one is 19oz(538g), one is 22oz (623g), one is 23oz(652g) and the last is just a small prime (though it got its own issues). I don't have an issue using one with smaller lenses but I just don't trust the thin soft aluminum with the heavy ones. That makes me realize I could use the new one with the 50mm prime (or just keep it and use the regular one I have). I know, primes are cheap (and I have pentax ones already). I just want to see if I can beat the challenge of converting a canon lens (that detentes the aperture ring against the old mount).
I recently did one that was more like 800g with a mount ripped off another lens and it came out beautiful and I have no worries about the strength of the mount.

The one that is 19oz in the only one I really care about right now (it is one I actually want to use and don't have a comparable lens). Maybe if I can find some compatible screws off another lens, I can use several screws (its a vivitar so it has several mounting holes for different mounts.
I'm thinking if I could get 5 or 6 screws in there it would hold.
08-18-2011, 10:59 AM   #8
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QuoteOriginally posted by ripit Quote
I have 4 lenses waiting to be modded. one is 19oz(538g), one is 22oz (623g), one is 23oz(652g) and the last is just a small prime (though it got its own issues). I don't have an issue using one with smaller lenses but I just don't trust the thin soft aluminum with the heavy ones. That makes me realize I could use the new one with the 50mm prime (or just keep it and use the regular one I have). I know, primes are cheap (and I have pentax ones already). I just want to see if I can beat the challenge of converting a canon lens (that detentes the aperture ring against the old mount).
I recently did one that was more like 800g with a mount ripped off another lens and it came out beautiful and I have no worries about the strength of the mount.
not sure what make you have useed, mine are nickle plated brass.

having said that a 24/2 or 28/2 is not very heavy, BUT my K10D is and I put that on the back of the bellows all the time, the difference is that mount is epoxied in place with about 4 square centimeters (1 square inch) of surface area.

the moubts themselvs are pretty strong, and pretty stiff, I would be more concerned about the screw heads and engagement through the flange

08-18-2011, 11:06 AM   #9
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QuoteOriginally posted by Lowell Goudge Quote
not sure what make you have useed, mine are nickle plated brass.

having said that a 24/2 or 28/2 is not very heavy, BUT my K10D is and I put that on the back of the bellows all the time, the difference is that mount is epoxied in place with about 4 square centimeters (1 square inch) of surface area.

the moubts themselvs are pretty strong, and pretty stiff, I would be more concerned about the screw heads and engagement through the flange
So far just cheap ebay ones (unbranded). I am using original screws (plenty of thread engagement and they were designed to support the lens in the first place). I am more worried about the tiny screw heads ripping right through the thin aluminum (the thicker one I have right now is .040" aluminum). That why I was thinking if I could find screws that fit (pilfered off another junk lens maybe), I could use the original screws plus extras. Maybe a brass one would be better (I have heard they are thicker) but I'm thinking that the back section of some extension tubes (just cheap 7$ ebay ones) would be much thicker as it was not designed to be as thin as possible like an m42 adapter is.

Of course I am watching ebay for donor lenses (anything that sells mega cheap for whatever reason including damage).
08-18-2011, 12:09 PM   #10
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QuoteOriginally posted by ripit Quote
I'm just curious why someone would use a not infinity focusing m42-pk adapter. Is it just that they are easier to use if you don't need infinity focus?
I use one when using my Taks for sports shooting when I know infinity focus is not needed. These flanged adapters are extremely useful when you are shooting moving subjects as they will allow you to use catch-in-focus without the need to foil the contacts on the body (as long as the adapter is a non-coated metal one as most are).

QuoteOriginally posted by RioRico Quote
To mount a thin-body lens whose base is too narrow to cover the electric contacts. This is for when I *must* use CIF when shooting.
So, me too as RioRico says




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08-18-2011, 12:16 PM   #11
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QuoteOriginally posted by ripit Quote
@RioRico, I know you have done some mount modding. Do you own macro extension tubes and if so, does the back look like it might be adapted to a lens mount? In theory my mount needs to be .190" or a little under 5mm including spacers if necessary. I shouldn't have too much issue with a spacer.
Yes, I have numerous macro tubes, in both M42 and PK. The PK tubes are all cheap modular sets -- lens and body mount pieces, with extension pieces, all threading together. Thread is about 60mm; ID of extension sections is about 57mm. Yes, the (male) lens mount piece is thick enough to use as a lens base. Counting the thread portion, it's about 5mm thick. But I'm much more likely to glue an extension section around the lens body -- I have more such sections available than I do mount pieces!
08-18-2011, 01:21 PM   #12
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QuoteOriginally posted by RioRico Quote
Yes, I have numerous macro tubes, in both M42 and PK. The PK tubes are all cheap modular sets -- lens and body mount pieces, with extension pieces, all threading together. Thread is about 60mm; ID of extension sections is about 57mm. Yes, the (male) lens mount piece is thick enough to use as a lens base. Counting the thread portion, it's about 5mm thick. But I'm much more likely to glue an extension section around the lens body -- I have more such sections available than I do mount pieces!
When you say you glue an extension section around the lens body, do you remove the aperture ring and just glue the mount with a ring to the lens?
It seems like there are many variations based on the pictures on ebay. Some have a thinner rim on the mount side (and I think they have male threads). I just ordered one that had a thick base and looked to have female threads on the mount portion. I'm hoping the dimensions turn out similar to what you said your are (it might wind up fitting perfectly). I would like to maintain aperture control though so I need to keep the aperture ring.
08-18-2011, 01:28 PM   #13
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I have purchased flanged adapters from J Russel in TX and can recommend dealing with him. They cost about $8 incl shipping. The flange measures 1.0mm thick.

Pentax K to Pentax Screw M42 Lens Adapter PK PX NEW | eBay
08-18-2011, 01:41 PM   #14
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That's about the same thickness as the generic black aluminum ones I have got on ebay. I kind of wonder how the nickel plated brass ones would hold up to having the countersink for the screw head forged into them with a punch? You have to be careful with the aluminum ones (I have drove the punch entirely through the mount before which Is why I'm hesitant to use one on a heavy lens).
08-18-2011, 01:48 PM   #15
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QuoteOriginally posted by ripit Quote
That's about the same thickness as the generic black aluminum ones I have got on ebay. I kind of wonder how the nickel plated brass ones would hold up to having the countersink for the screw head forged into them with a punch? You have to be careful with the aluminum ones (I have drove the punch entirely through the mount before which Is why I'm hesitant to use one on a heavy lens).
I countersunk the holes I drilled with a drill bit; using a punch I'd worry about deformation beneath the ring causing it to seat too high - has this not been a problem in your experience? If not that's nice to know.

Russel's adapters are chrome* plated brass. He delivers fast.

* uhh maybe nickle plated? shiny at least!
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