Replacing a missing T / T2 mount on vintage manual telephoto lens

[dorcasmallorcus]

What type of fitting do l need to replace what has obviously been removed?

I'm sure the mount is meant to be a T mount. Instead all l have is a smooth ring.

The outer diameter is 48mm, BUT there is no thead. The scrape / scratch marks on the outer surface indicate that some sort of manually-tightened ring used to be there, and that ring offered a T mount. I can imagine such a flimsy fitting would nonetheless have been strong enough to hold an SLR camera.

BUT ... l can find no such parts on eBay. All l'm seeing is M48 ---> M42 / T mount converters .... for telescopes.

IMPORTANT NOTE: The internal thread that is focused in on, in the 2nd attached image, appears to be a 46mm thread, but it's fairly far down the barrel, surely there's no such converter that would attach to that and give me T mount?

 

[Box Brownie]

No idea from such small (unenlargeable thumbnails)......so apart from bigger full size images how about some others of the details on the rest of the lens so that TP'ers can id the lens as well to guide you?

 

[dorcasmallorcus]

The thumbnails enlarge just fine for me :-S

It's the rear of a Palar 500mm f8

 

[Box Brownie]

The thumbnails enlarge just fine for me :-S

It's the rear of a Palar 500mm f8

Ah! they do now......no idea why all i could see were thumbnail!

 

[dorcasmallorcus]

It's a common issue with old manual telephoto lenses, seen it with one or two other brands. I'm interested in where to buy the fitting from, l can check whatever the recommended vendor is offering to get the specific part.

Right now though, l just don't know what to even call the part. That's what l'm really after l guess - a name for that part.

 

[Phil-D]

I have no idea if this link is of any use, they sell many different types of adaptors

I bought from them a couple of years ago when I was looking for an adaptor to mount me camera to a spotting scope

https://www.srb-photographic.co.uk/adaptors-649-c.asp

 

[Nod]

Saved me digging out an SRB link!

On a side issue, if that lens is a mirror telephoto, the internal thread might be for a "filter" that could be an essential part of the light path.

 

[dorcasmallorcus]

Hi there, thanks for the tip about the filter, l didn't realise they were essential for mirror telephoto lenses - any idea why?

Btw it's just a normal tele lens.

 

[Nod]

No idea why, I'm afraid.

 

[dorcasmallorcus]

https://www.srb-photographic.co.uk/adaptors-649-c.asp

Thank you, but l see no way of attaching any of the T mount adapters to the pictured rear of the lens. I think l need something with a tightening screw perpendicular to the ring?

 

[Box Brownie]

I wonder if:-

The ring shown is actually a flange that had been screwed to an external thread?

Subject to the above being "so", if removed will that allow for a T mount to be attached?

If not removable, has it been modified for some attachment not related to a conventional camera usage?

PS some searching does throw up ref to a non mirror type Palar 500mm f8 but cannot yet see any pictures of an example with a bright metal outer case finish??

 

[AndrewFlannigan]

I wonder if:- The ring shown is actually a flange that had been screwed to an external thread?

I think Laurence may be on to something here. You might want to check for any small screws that might be locking the flange to the lens.

 

[dorcasmallorcus]

I wonder if:-

The ring shown is actually a flange that had been screwed to an external thread?

Subject to the above being "so", if removed will that allow for a T mount to be attached?

If not removable, has it been modified for some attachment not related to a conventional camera usage?

PS some searching does throw up ref to a non mirror type Palar 500mm f8 but cannot yet see any pictures of an example with a bright metal outer case finish??

I think Laurence may be on to something here. You might want to check for any small screws that might be locking the flange to the lens.

I tried to remove the ring just now, using pliers. This could actually be the reason for the pre-existing scuff marks around the ring, maybe somebody else had the same idea.

Nope, l don't think that ring will shift. It may actually be metal and part of the body - specifically, part of the rear end of the lens from the blades down (it unscrews at around the point of the blades, as you may expect from vintage long manual lenses).

 

[dorcasmallorcus]

Btw: If the ring does somehow shift, what would it have been doing there to begin with?

 

[AndrewFlannigan]

Nope, l don't think that ring will shift. It may actually be metal and part of the body

The second picture suggests a join between the flange and the ribbed lens tube. If you've checked for locking screws the next step might be some penetrating oil and then large clamps to give you leverage. Pliers aren't usually big enough to break the friction between light alloys, which I suspect that is.

Btw: If the ring does somehow shift, what would it have been doing there to begin with?

Could be part of an adapter to a medium format camera. Long focus lenses often covered bigger formats than 35mm as well.

 

[dorcasmallorcus]

It truly does look like it's a ring that's been placed around a nice long flanged screw thread doesn't it

 

[dorcasmallorcus]

Hahah snap, l just typed the above message

One thing l could really do with is a proper bench with vice. That'd settle the matter one way or the other with minimal damage. I was using a type of plier with serrated grips on both sides. Very surprised if it still turns out to be a ring that wouldn't shift.

Any idea what that ring could be, if it can be shifted? I've seen this more than once with long lenses, different models.

 

[Box Brownie]

Sometimes rather than pliers (a pipe wrench would grip more but the damage could be significant ) I would use a pair of washing up gloves.....................I learnt this a long while ago that the grip they achieve is widespread and effective, though does if tried need a lot of strength ~ if the threaded item is going to "give".

Can you show a couple more pictures of the whole lens to illustrate what it looks like overall?

 

[Petrochemist]

Hi there, thanks for the tip about the filter, l didn't realise they were essential for mirror telephoto lenses - any idea why?

Btw it's just a normal tele lens.

Mirror lenses & some other long lenses, have such a large front end that filters there are excessively expensive, so they are designed to take much smaller ones at the back as well. If you remove the clear filter that's usually in place you have altered the effective distance behind the lens that the light travels. Light sees glass as around 1.5x as long as the equivalent length of air. Some fish eye lenses which have too large a FOV for a front filter will employ a similar approach, but many just leave you unable to fit filters.

WRT to your original question, many T2-camera adapters are made in two parts:
a screw threaded part (with 42x0.75 female thread) which has a V groove around the outside &
the camera mount part, which secures to the first part with small grub screws that fit into the groove.

The idea is you can adjust the mount to get the lens the right way up. FWIW the OD of this threaded part varies from adapter to adapter (a real shame) but 48mm is roughly what I've measured many of mine at.
I think your lens might have the threaded part left on, and from the sound of things its either glued or thoroughly seized. If you can gently heat the mount without getting the rest of the lens hot it might help free it up.

 

[dorcasmallorcus]

I would use a pair of washing up gloves..................

Just tried now, with cargo gloves, it's inert. I believe it was superglued on.

Mirror lenses & some other long lenses, have such a large front end that filters there are excessively expensive, so they are designed to take much smaller ones at the back as well. If you remove the clear filter that's usually in place you have altered the effective distance behind the lens that the light travels. Light sees glass as around 1.5x as long as the equivalent length of air. Some fish eye lenses which have too large a FOV for a front filter will employ a similar approach, but many just leave you unable to fit filters.

Thanks! That was very informative.

Could be part of an adapter to a medium format camera. Long focus lenses often covered bigger formats than 35mm as well.

WRT to your original question, many T2-camera adapters are made in two parts:
a screw threaded part (with 42x0.75 female thread) which has a V groove around the outside &
the camera mount part, which secures to the first part with small grub screws that fit into the groove.

The idea is you can adjust the mount to get the lens the right way up. FWIW the OD of this threaded part varies from adapter to adapter (a real shame) but 48mm is roughly what I've measured many of mine at.
I think your lens might have the threaded part left on, and from the sound of things its either glued or thoroughly seized. If you can gently heat the mount without getting the rest of the lens hot it might help free it up.

OK l think we've solved it.

Some people perhaps use long full frame lenses for medium format. In doing so, l'm guessing they reduce the focal length, so it's always a super-telephoto they'd use to compensate for lost focal length - or would they lose infinity? Maybe they were prepared to lose infinity, just to save money because medium format is so pricey whereas vintage manual is quite cheap.

So, l'm guessing not very long ago, somebody picked up this lens relatively cheap as it was already vintage, and incorporated it into their medium format system.

That'd also explain why the superfluous ring won't budge - it's superglued on, for convenience to then adapt it to medium format and also because medium format cameras would be heavy, and also because the lens being relatively cheap, is relatively expendable, so superglue would be in okay.

That'd also explain why only on very few occasions l also see this with other models too. It must be a known trick but not that well known.

That'd also explain why l think there was a sticker saying "Ex 66" on the barrel, which l peeled off and threw away!



I think the only avenues open to me are:
- Heat
- Hacksaw

I'll dabble more next week, after all, what could possibly go wrong.

 

[Canon Bob]

OK l think we've solved it.

Some people perhaps use long full frame lenses for medium format. In doing so, l'm guessing they reduce the focal length, so it's always a super-telephoto they'd use to compensate for lost focal length - or would they lose infinity? Maybe they were prepared to lose infinity, just to save money because medium format is so pricey whereas vintage manual is quite cheap.

So, l'm guessing not very long ago, somebody picked up this lens relatively cheap as it was already vintage, and incorporated it into their medium format system.

That'd also explain why the superfluous ring won't budge - it's superglued on, for convenience to then adapt it to medium format and also because medium format cameras would be heavy, and also because the lens being relatively cheap, is relatively expendable, so superglue would be in okay.

That'd also explain why only on very few occasions l also see this with other models too. It must be a known trick but not that well known.

That'd also explain why l think there was a sticker saying "Ex 66" on the barrel, which l peeled off and threw away!

Just a few observations.......

Your mention of using full frame lenses on a medium format body is very unlikely.......it's easy to do the other way around but the shorter register distance of ff lenses makes them unusable.

You state the outside diameter of the ring as being 48mm......far too small for small for even the reduced mf formats (ie, Pentax 645).

The Ex 66 sticker would hint at it being for Exacta 66 mount.....again, from the points above this is not likely. The mount diameter (body orifice) is near to 60mm

I think Mike (Petrochemist) is on the mark. This looks like an M42 or T-Mount inner sleeve with the outer, adjustable collar missing. The collars have set screws around the rim to allow lens rotation if the screw in action becomes tight before the lens is correctly orientated. If the set screws are removed then the collar can be dismounted. From your photos above, there does appear to be some small indentations behind the flang where the set screws would have landed. Mistaking M42 for T-Mount was not so unusual 40 years ago and I sure many lenses were damaged in this way....screw it on until it gets stuck and then it's nigh on impossible to remove as the set screws in the collar give way before the 42mm gnarled up threads.

Bob

 

[dorcasmallorcus]

Just a few observations.......

Your mention of using full frame lenses on a medium format body is very unlikely.......it's easy to do the other way around but the shorter register distance of ff lenses makes them unusable.

You state the outside diameter of the ring as being 48mm......far too small for small for even the reduced mf formats (ie, Pentax 645).

The Ex 66 sticker would hint at it being for Exacta 66 mount.....again, from the points above this is not likely. The mount diameter (body orifice) is near to 60mm

I think Mike (Petrochemist) is on the mark. This looks like an M42 or T-Mount inner sleeve with the outer, adjustable collar missing. The collars have set screws around the rim to allow lens rotation if the screw in action becomes tight before the lens is correctly orientated. If the set screws are removed then the collar can be dismounted. From your photos above, there does appear to be some small indentations behind the flang where the set screws would have landed. Mistaking M42 for T-Mount was not so unusual 40 years ago and I sure many lenses were damaged in this way....screw it on until it gets stuck and then it's nigh on impossible to remove as the set screws in the collar give way before the 42mm gnarled up threads.

Bob

Hi there Bob, so what would you suggest with this remnant?

I was hoping to repurchase a "collar" to give T mount, because l too originally thought a collar would fit around that (from past experience of disassembling long lenses).

However, l don't know what to call this "collar" in order to search for vendors or in order to browse their shop once l find a vendor.

 

[dorcasmallorcus]

Either way this calls for fire and sword / a lighter and hacksaw

 

[Canon Bob]

Hi there Bob, so what would you suggest with this remnant?

I was hoping to repurchase a "collar" to give T mount, because l too originally thought a collar would fit around that (from past experience of disassembling long lenses).

However, l don't know what to call this "collar" in order to search for vendors or in order to browse their shop once l find a vendor.

I'm a little busy until this evening but I'll put up a few photos that might help you.

Edit....sorry, life has got in the way....I'll try to get the photos sorted soon.

 

[the black fox]

thats definetly a flange for a ? mount more than likely screwed on to a m42 thread which is probable due to age of lens . I would be dubious about using a vice as that could assert to much pressure your best bet is large mouthed mole grips or even a adjustable wrench . a bit of heat or easing oil might also help .. had a similar problem with a mount for a telescope last year took a lot of pressure to actually crack the bond . there has definetly been a outer part T mount fitted as you can see the indent for the grub screw in top pic .. any motor mechanics locally that should have the right grips and strength to unscrew it . BTW I doubt its superglued on just aluminium corrosion. p.s where are you as someone else might be able to help

 

[dorcasmallorcus]

OK here's the latest. I sawed through part of that pesky ring, and you know what? I strongly believe it's part of the body. As l originally suspected, there is meant to be a ring that, in a seemingly flimsy manner, fits over the rear, being held in by screws.

I believe l can still make a rear adapter fit if l had long enough screws as l've made an approx. 2-3mm deep gash in the ring now.

The question is: what do you even call that type of adapter?

 

[ChrisH]

To be fair if its an old 500mm mirror lens I wouldn't waste my time. Ive had a couple and the quality of photographs taken with them is abysmal. I had the Polar and a Sigma.

If you like weird polo mint bokeh and weird reflections then go ahead otherwise just use it as a paperweight.

 

[dorcasmallorcus]

Hi there ChrisH thanks but it's not a mirror lens, and l was really only after an answer to my question ...