400mm Spiratone - Is it t-mt or m42?

Foto Ludens · May 12, 2006

Hey folks

I just bought a 400/6.3 Spiratone from KEH, and a t-mt to FD adapter, and it seems that the threads don't quite match.

So, does anyone know if the spiratone was an t, t2, or m42 mount? That way I can go and buy the correct adapter...

Thanks,

André

glennfromwy · May 13, 2006

Well, they do require a T mount adapter but I can't say which "T" they use. I just sold one of these lenses to Donald Qualls, so maybe he can give you some insight. I know the two lenses I had were close to, but definitely not, M42 without the adapter. Pretty sharp lens, by the way.

David H. Bebbington · May 13, 2006

Measure the thread across - is it 42 mm? The end of a T-mount lens will measure 49 mm and will not be threaded - it will have a flange which inserts into the mount and is held by three pinch screws.

Incidentally, a T-mount as supplied has a keeper ring in the middle - this has an inside diameter of about 42 mm and some ribbing on the exposed inner face (don't think it's actually a thread). The function of the keeper ring is to provide something for the pinch screws to be tightened against - the ring is laid aside when the mount is actually fitted to a lens.

Regards,

David

Foto Ludens · May 13, 2006

Thanks for the quick replies,

Both the lens and the adapter measure 42mm across, but it seems that the thread pitch is slightly different (the lens begins to screw in, but doesn't go all the way, and I can't get infinity focus).

Any other thoughts?

Foto Ludens · May 13, 2006

Ok, Glenn, I just re-read your post (I must be really tired). So it's definately NOT m42... cool, that gives a start.

David H. Bebbington · May 13, 2006

Does the adapter have the 3 pinch screws (visible in the outside edge at intervals of 120°)? Does it look as if it has a ring in the middle which could be removed?

Foto Ludens · May 13, 2006

Yes, it does have 3 screws on the outside. Actually, both the lens and the adapter have 3 screws on the outside...

Hmm, perhaps the lens has come with a m42 adapter fitted on it, and I've been trying to screw that into the keeper ring of the adapter I've bought? Well, I'll have to take a look at that tomorrow, when I'm less tired.

Thanks, David.

André

David H. Bebbington · May 13, 2006

Andre R. de Avillez said:
Hmm, perhaps the lens has come with a m42 adapter fitted on it, and I've been trying to screw that into the keeper ring of the adapter I've bought? Well, I'll have to take a look at that tomorrow, when I'm less tired.

Thanks, David.

André

This is highly plausible. Make sure you have a smallish jeweller's screwdriver handy, und loosen the screws just enough to release the ring (finding and refitting the little screws if you unscrew them all the way and allow them to fall on the floor is a total PIA).

Regards,

David

Dan Fromm · May 13, 2006

David H. Bebbington said:
Measure the thread across - is it 42 mm? The end of a T-mount lens will measure 49 mm and will not be threaded - it will have a flange which inserts into the mount and is held by three pinch screws.

Incidentally, a T-mount as supplied has a keeper ring in the middle - this has an inside diameter of about 42 mm and some ribbing on the exposed inner face (don't think it's actually a thread). The function of the keeper ring is to provide something for the pinch screws to be tightened against - the ring is laid aside when the mount is actually fitted to a lens.

Regards,

David

David, have you lost your mind? T-mount is M42x0.75 with 55 mm register. T-mount adapters are female M42x0.75 in front, male target camera -- I was going to write SLR but I have a couple of T-mount to LTM adapters -- at the rear, and with thickness = 55 mm - target camera register.

T-mount adapters are solid. T-2 mount adapters are much like T-mount adapters but are in two parts, an internal ring threaded M42x0.75 at the front and an external ring with male target camera mount at the rear. The internal ring fits in the external ring, is held in place by three set screws. This allows the camera and lens' tripod mount to be aligned.

Andre, the lenses were sold in T-mount and in M42x1. You could have one in native Pentax thread mount, in which case I'm sorry but you're SOL.

Cheers,

Dan

David H. Bebbington · May 13, 2006

Dan Fromm said:
David, have you lost your mind? T-mount is M42x0.75 with 55 mm register. T-mount adapters are female M42x0.75 in front, male target camera -- I was going to write SLR but I have a couple of T-mount to LTM adapters -- at the rear, and with thickness = 55 mm - target camera register.

T-mount adapters are solid. T-2 mount adapters are much like T-mount adapters but are in two parts, an internal ring threaded M42x0.75 at the front and an external ring with male target camera mount at the rear. The internal ring fits in the external ring, is held in place by three set screws. This allows the camera and lens' tripod mount to be aligned.

Andre, the lenses were sold in T-mount and in M42x1. You could have one in native Pentax thread mount, in which case I'm sorry but you're SOL.

Cheers,

Dan

I thought I was pretty sane, Dan, and my invisible friend agrees with me! Seriously, though: I have 3 T-mount devices, two cheapo telephoto lenses and a slide copier. The copier I bought new about 15 years ago, the cheapo lens are probably anything up to 30 years old. I also have a new unused T-mount. These are all the same, as I described in my earlier posting. At the rear is a male fitting to match up with a certain type of camera mount (Nikon F, Pentax K, M42). The T-mounts themselves have no particular register, they simply bring a lens into the required register of the camera model in question.

On the sides of all 4 mounts are 3 set screws. When loosened, these allow the keeper ring in the center of the mount to be removed - in no case have I experienced the need to use this ring to mount lenses. The rear of the T-mountable lenses has a tapered flange which fits inside the T-mount (the inside of which has plain parallel sides with no thread whatsoever), the 3 set screws are then almost fully tightened, the mount is checked for orientation, and the screws are then fully tightened. This as far as I am aware is a T2 mount - it's certainly what I've got whenever I asked for a T2 mount in a British camera store! Are you talking about adapters to fit M42 lenses on various bodies?

Regards,

David

mawz · May 13, 2006

dan, he's not entirely SoL with an M42 lens, Canon made a nice FD-M42 adaptor, The Canon Lens Mount Converter P, which I've got lying around somewhere (Came on the back of an Auto Rikenon 90-190 f5.8 zoom I bought for $10 a couple weeks ago).

mawz · May 13, 2006

David H. Bebbington said:
I thought I was pretty sane, Dan, and my invisible friend agrees with me! Seriously, though: I have 3 T-mount devices, two cheapo telephoto lenses and a slide copier. The copier I bought new about 15 years ago, the cheapo lens are probably anything up to 30 years old. I also have a new unused T-mount. These are all the same, as I described in my earlier posting. At the rear is a male fitting to match up with a certain type of camera mount (Nikon F, Pentax K, M42). The T-mounts themselves have no particular register, they simply bring a lens into the required register of the camera model in question.

On the sides of all 4 mounts are 3 set screws. When loosened, these allow the keeper ring in the center of the mount to be removed - in no case have I experienced the need to use this ring to mount lenses. The rear of the T-mountable lenses has a tapered flange which fits inside the T-mount (the inside of which has plain parallel sides with no thread whatsoever), the 3 set screws are then almost fully tightened, the mount is checked for orientation, and the screws are then fully tightened. This as far as I am aware is a T2 mount - it's certainly what I've got whenever I asked for a T2 mount in a British camera store! Are you talking about adapters to fit M42 lenses on various bodies?

Regards,

David

Hmm, I think you might have an Adaptall rather than T mount. Adaptall uses that sort of setup IIRC.

Dan Fromm · May 13, 2006

David H. Bebbington said:
I thought I was pretty sane, Dan, and my invisible friend agrees with me! Seriously, though: I have 3 T-mount devices, two cheapo telephoto lenses and a slide copier. The copier I bought new about 15 years ago, the cheapo lens are probably anything up to 30 years old. I also have a new unused T-mount. These are all the same, as I described in my earlier posting. At the rear is a male fitting to match up with a certain type of camera mount (Nikon F, Pentax K, M42). The T-mounts themselves have no particular register, they simply bring a lens into the required register of the camera model in question.

On the sides of all 4 mounts are 3 set screws. When loosened, these allow the keeper ring in the center of the mount to be removed - in no case have I experienced the need to use this ring to mount lenses. The rear of the T-mountable lenses has a tapered flange which fits inside the T-mount (the inside of which has plain parallel sides with no thread whatsoever), the 3 set screws are then almost fully tightened, the mount is checked for orientation, and the screws are then fully tightened. This as far as I am aware is a T2 mount - it's certainly what I've got whenever I asked for a T2 mount in a British camera store! Are you talking about adapters to fit M42 lenses on various bodies?

Regards,

David

David, I've always thought you were pretty sane too. My sanity is always in doubt, my invisible friend often tells me I've lost it, but this time I have a little faith in it. My sanity, that is, not my invisible friend. He/she/it speaks with my voice and is wrong a lot.

See Dead Link Removed

Also visit Dead Link Removed , search for 0.75

I have a small pile of "t-mount" adapters including a couple of Vivitar Ser. I adapters, still with their boxes, that I bought new. The Vivitars' boxes are marked "T-mount Adapter" and the adapters are solid, with no set screws and no way of adjusting the camera's orientation on the lens. My other adapters have the three radial setscrews we both have mentioned and their fronts are threaded female M42x0.75.

Every T-mount adapter I've ever seen, with or without setscrews, has been threaded M42x0.75 at the front.

I also have a Vivitar 2x Matched Multiplier for their Ser. I 450/4.5. The SI 450/4.5 is a T-mount lens and its teleconverter is threaded M42x0.75 at both ends, female at the front, male at the rear.

The tapered flanges you've described must have a circumferential groove for the setscrews to engage. Those flanges are the inner parts of T-2 mounts that some barbarian has glued to your lenses' rear mounts. Did you buy your t-mount lenses new?

Best,

Dan

Foto Ludens · May 13, 2006

Dan,

Thanks for posting those links. That seems to explain what's going on here. The lens seems to be an M42 (42 x 1) while the t-2 adapter I've bought is 42 x 0.75.

Well, now to the next phase: Does anyone have an m42 to fd adapter they would be willing to sell? (I'll post this in the classified as well).

Thank you all once again,

André

David H. Bebbington · May 14, 2006

Dan Fromm said:
The tapered flanges you've described must have a circumferential groove for the setscrews to engage. Those flanges are the inner parts of T-2 mounts that some barbarian has glued to your lenses' rear mounts. Did you buy your t-mount lenses new?

Best,

Dan

Dan, one of the great things about photography (and APUG) is that you never stop learning! Having owned 3 T2 devices which all had a preformed flange equivalent to the inner part of the mount, I assumed that all devices were like this (T2 mounts have not featured very prominently in my life anyhow, as of course they have very limited application in normal photography due to the fact that they do not provide any aperture linkage).

I now know that there are other devices (apparently, principally telescopes) in which the inner part of the mount comes into play. Even so, I would not be surprised if Andre finds he can take off the outer part of the M42 mount currently attached to his lens and replace it with the outer part of the extra mount he has bought. I have an f6.3 400 mm Soligor lens which could well be exactly the same as Andre's under a different name to which this principle applies - I also recall owning some Russian mirror lenses which were sold as M42 but in fact had T2 mounts which could be interchanged if necessary.

Best regards,

David

Dan Fromm · May 14, 2006

David you could well be right about Andre's lens. I have a $20 marvel of a 400/6.3 Tele-Astragon that seems to a Nikon T-2 adapter glued to it. I'd like to use my T-mount teleconverter on it, can't get the inner part of the adapter off the lens. Arrgh!

Cheers,

Dan

Foto Ludens · May 14, 2006

David,

You were right about my lens. Half of the adapter is glued on the lens, it attached right into half of the t2 adapter I bought. And infinity focus is right on. thanks, man.

Bottom line: we're all insane, just like my invisible friend's friend told him.

David H. Bebbington · May 14, 2006

Good to hear that, Andre. I think this thread has been a classic case of arriving at the truth gradually through a Platonic dialog! Of course, here at APUG, we're always right (except when we're wrong!).

Best regards,

David

Donald Qualls · May 15, 2006

Woops, read the first page and replied before I got to the second.

I see Andre's got his lens working, and now we have only the great mystery: why would anyone, sane or otherwise, glue a T-ring to a lens? I'm guessing that it's not glued, it's galled -- the aluminum of the lens barrel and mount have "swapped spit" so to speak, and changed from smoothly sliding to interfering rough surfaces, locking in place. It happens with aluminum when it's overtightened, or from friction; it's one of the main reasons it's a bad idea to directly thread aluminum for any load-bearing application.

It's remotely possible penetrating oil (like WD-40 without the spray propellant) would loosen the collar enough to unscrew it, but now that you know what's up, it's not that big a deal, since all T-2 rings are made to the same dimensions (cheaper that way, because the female threaded pieces are then all identical). It's not the way T mounts were intended to be used -- but it'll work as long as you don't need to mount any other T-mount accessories behind the lens.

cdholden · May 15, 2006

some people's kids...

Donald Qualls said:
why would anyone, sane or otherwise, glue a T-ring to a lens?

Here's one better. As part of a LF kit I bought a while back, the seller offered to throw in a "Heliar lens as-is". The lens turned out to be a Technika badged Voigtlander Heliar 210/4.5 in a Compur shutter. The lens was amazing... BUT... some genius decided to superglue a Cokin filter holder to the front of the lens, giving it a cosmetic wart as well as blocking the ability to use normal threaded filters (due to the superglue being in the threads). The Cokin holder had broken off and someone attempted a second superglue job. It looked horrible, but the lens performed like a champ.
I haven't seen the lens since moving. If it wasn't lost in the move, it's in a box that has yet to be opened since moving here in November. I'll take a shot at cleaning it up if I can ever find it!
Chris

David H. Bebbington · May 15, 2006

There does remain the problem of what to do with lenses with non-standard filter threads (or none). I have 2 barrel lenses on Sinar panels where I have superglued a Cokin holder to the rear of the panel, leaving the front free for an add-on shutter, and I did even superglue a stepping ring to the front of a 168 mm Angulon so that I could use standard filters. This particular lens had a front which was too small for my standard oddball filter solution, which is a Cokin filter holder with 3 pinch screws instead of a threaded ring.

I am sure Donald is right in suggesting that T-mount adapters can seize onto lenses. My worst experience of aluminum corrosion of this kind was changing the plug on a lawn mower which had a Briggs & Stratton engine. The plug had been in for about 3 or 4 years, when I unscrewed it the plug came out complete with the plug hole and a disk of surrounding metal 3 or 4 mm thick. This was one of those few occasions when superglue was not able to effect a repair

Regards,

David

Dan Fromm · May 15, 2006

Donald, galling/corrosion is an interesting and scary idea. But all of the T-mount (including T2s and reverse T) adapters I own are hard anodized and so are all of the T-mount devices I own. That's why I suspect glue on my 400/6.3 cheapy.

Cheers,

Dan

Donald Qualls · May 15, 2006

Unfortunately, galling can take place even on hard anodized parts, especially if accelerated by corrosion. Aluminum doesn't "rust" but that's because "rust" refers only to hydrated oxides of iron. The oxide layer that protects aluminum (and which is artificially thickened and often colored in the anodizing process) can be destroyed very quickly by enough pressure to deform the relatively soft metal under the super-hard but brittle oxide (essentially polycrystalling sapphire), which could occur if the adapter were tightened with grit in the threads; moreso, aluminum oxide and then the metal undeneath will literally dissolve in water with significant chloride ion (like sea water, sweat, etc.), causing corrosion pitting, redeposition, and what amounts to welding.

If David has been at your lens and super-glued the ring in place, you might be able to debond it with acetone (I'd suggest standing the lens, big end up, in a tiny cup of the stuff and checking it every few hours for as much as 2-3 days -- but beware of the flammability of acetone vapor!), but if it's galled or corroded in place, the only solution would be to cut most of the way through the ring (very careful application of a hacksaw or rotary tool with cutting wheel), insert a screwdriver in the cut and twist to break the remaining metal in the threads, and then pry the ring open to get it off the lens threads; more or less like splitting a seized nut off the bolt. This will likely work if it's glued, too, but either way there's a very distinct possibility of completely destroying the rear section of the lens (in case you're not aware, the Spiratone 400/6.3 comes apart at the tripod mounting ring).

Meanwhile, I think I'll pull the T-ring off mine and give it a very light coat of the Superlube Teflon grease I keep around for stuff that needs to stay slick...

400mm Spiratone - Is it t-mt or m42?

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