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M42 Mount Question
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PostPosted: Thu Jun 06, 2019 7:07 pm    Post subject: M42 Mount Question Reply with quote

I have an old ISCO lens that fits my M42 adapter perfectly and hits infinity perfectly, but when it's screwed in all the way the lens is upside-down; in other words, the focus and aperture numbers and hash-marks are on the bottom (toward the tripod mount), and the "Made In Germany" text it on top (toward the hot shoe). Needless to say, this is a bit inconvenient.

It really doesn't bother me that much, but it always makes me wonder which camera or cameras the lens was made for. I assume there must be some old cameras with M42 mounts rotated 180 degrees, and I figured I would ask here since I don't know. I'm also wondering whether or not there are special adapters for mounts like this. If not I might just make one myself.

Thanks.


PostPosted: Thu Jun 06, 2019 7:32 pm    Post subject: Reply with quote

Look at your m42 adapter to see if it is adjustable. My fotasy m42 adapters are. There are three very tiny hex screws that you loosen to turn the lens to the proper position. I ordered this hex set Wiha 35392 5 Piece Mini L-Key Short Hex Metric Set. The one I needed was the 1.3.
I used my lenses for a while before I stumbled upon this answer.

Brian


PostPosted: Thu Jun 06, 2019 7:34 pm    Post subject: Reply with quote

bkwphoto wrote:
Look at your m42 adapter to see if it is adjustable. My fotasy m42 adapters are. There are three very tiny hex screws that you loosen to turn the lens to the proper position. I ordered this hex set Wiha 35392 5 Piece Mini L-Key Short Hex Metric Set. The one I needed was the 1.3.
I used my lenses for a while before I stumbled upon this answer.

Brian


Thanks, Brian. I will do that.


PostPosted: Thu Jun 06, 2019 8:53 pm    Post subject: Reply with quote

Assuming other M42 lenses mount on the adapter with correct orientation, perhaps lens has been put back together with mount upside down. I've never heard of native upside-down M42 mounting camera.


PostPosted: Thu Jun 06, 2019 9:18 pm    Post subject: Reply with quote

Edixa had a unique version of the M42 mount.
I think the thread was deliberately slightly skewed.
And the pin was in a different orientation from standard M42.
Not so much as to mount it upside down though.


PostPosted: Thu Jun 06, 2019 9:25 pm    Post subject: Reply with quote

visualopsins wrote:
Assuming other M42 lenses mount on the adapter with correct orientation, perhaps lens has been put back together with mount upside down. I've never heard of native upside-down M42 mounting camera.


All the M42 lenses I've mounted on M42 cameras have always been correctly oriented but many (all?) of them are wrong on (many?) adapters. I think less than half my M42 adapters have any facility for correcting the alignment Sad

If the cameras are all made the same using 1960s machining tools why can't adapters be done right with today's higher quality tools?


PostPosted: Thu Jun 06, 2019 9:40 pm    Post subject: Reply with quote

bkwphoto wrote:
Look at your m42 adapter to see if it is adjustable. My fotasy m42 adapters are. There are three very tiny hex screws that you loosen to turn the lens to the proper position. I ordered this hex set Wiha 35392 5 Piece Mini L-Key Short Hex Metric Set. The one I needed was the 1.3.
I used my lenses for a while before I stumbled upon this answer.

Brian


+1 with K&F adapters.


PostPosted: Thu Jun 06, 2019 10:08 pm    Post subject: Reply with quote

DConvert wrote:
visualopsins wrote:
Assuming other M42 lenses mount on the adapter with correct orientation, perhaps lens has been put back together with mount upside down. I've never heard of native upside-down M42 mounting camera.


All the M42 lenses I've mounted on M42 cameras have always been correctly oriented but many (all?) of them are wrong on (many?) adapters. I think less than half my M42 adapters have any facility for correcting the alignment Sad

If the cameras are all made the same using 1960s machining tools why can't adapters be done right with today's higher quality tools?


Yes wrong on many adapters in my experience also, with no adjustments, except if lens turns past top orientation, a shim between adapter and lens can correct that, without effect on infinity capability if lens typically focuses past infinity.

Critical is thread-cutting starting point in relation to camera side orientation. Seems like that would be easy today's tools.

Anybody know where to find adjustable M42 adapters?


PostPosted: Fri Jun 07, 2019 7:27 am    Post subject: Reply with quote

Lens skewing can be an annoyance.

On my Pentax DSLRs I've found only a Pentax original M42-PK adaptor will reliably mount any M42 lens (and I've got quite a drawer-full) in more-or-less the "proper" orientation. Unfortunately these adaptors appear to be no longer available from the manufacturers and they demand a premium price on the second-hand market. They are, however, very well made!

Lenses that were originally designed to lock onto their respective bodies, Fujinons for instance, will usually screw in just a little bit further than one might like, as the lock is no longer there to restrict the travel.

The only lens I've got where it's at all important is my early Sigma 21-35mm with it's built-in "petal" lens hood. Fortunately it's a well-made lens and sits perfectly with a Pentax adaptor Smile

For my Samsung NX the M42 adaptor has the little screws to allow perfect alignment, if so desired.


PostPosted: Fri Jun 07, 2019 7:40 am    Post subject: Reply with quote

bkwphoto wrote:
Look at your m42 adapter to see if it is adjustable. My fotasy m42 adapters are. There are three very tiny hex screws that you loosen to turn the lens to the proper position. I ordered this hex set Wiha 35392 5 Piece Mini L-Key Short Hex Metric Set. The one I needed was the 1.3.
I used my lenses for a while before I stumbled upon this answer.

Brian


Exactly.
I have a K&F Concept adapter and it is adjustable in exactly the same way.
A simple fix really
Tom

PS I notice that Sciolist has already mentioned this.
Whoops
Smile


PostPosted: Fri Jun 07, 2019 8:33 am    Post subject: Reply with quote

Oldhand wrote:
bkwphoto wrote:
Look at your m42 adapter to see if it is adjustable. My fotasy m42 adapters are. There are three very tiny hex screws that you loosen to turn the lens to the proper position. I ordered this hex set Wiha 35392 5 Piece Mini L-Key Short Hex Metric Set. The one I needed was the 1.3.
I used my lenses for a while before I stumbled upon this answer.

Brian


Exactly.
I have a K&F Concept adapter and it is adjustable in exactly the same way.
A simple fix really
Tom

PS I notice that Sciolist has already mentioned this.
Whoops
Smile


Yes, whoops! Thanks Sciolist & Oldhand!


PostPosted: Fri Jun 07, 2019 10:04 pm    Post subject: Reply with quote

Thanks for all the information, guys!

The (M42-FX) adapter I'm using in this case is a Fotasy with a macro helicoid. I use lots of other lenses with it with no problem.

The problem only seems to occur when I mount my Isco 100mm Isconar 4.5. It's a fantastic lens, but it has a number of oddities. The filter thread is an unusual 41mm (iirc) and the ergonomics are unusual too: a big aperture ring behind a very small focus ring near the front. It feels very backwards and requires some getting used to.

I don't think it's been reassembled incorrectly. It's such an incredibly simple triplet design I believe I'd be able to tell, as would anyone else. Old silver Isco lenses are probably the most mechanically simple designs I've seen. The body and the mount are one single piece of tube-shaped metal.

That's why I'm wondering if the upside-down mounting was made for a specific camera line. I will keep researching.


PostPosted: Fri Jun 07, 2019 10:10 pm    Post subject: Reply with quote

There are of course also T2 lenses which can have M42 adapters fitted. These adapters are usually adjustable for orientation. Is that the case for your Isco?


PostPosted: Fri Jun 07, 2019 10:46 pm    Post subject: Reply with quote

Search Google images for that lens. Look for one showing it mounted on a camera. Compare how yours looks... Smile


PostPosted: Mon Jun 10, 2019 4:43 pm    Post subject: Reply with quote

One of my very first mfl was an aluminum isconar 100mm 4.5. Mine was exakta mount though. Delightful little thing. Do you get ghosting with the fotasy helical? I have some pixco adapters that are seriously problematic with certain lenses.


PostPosted: Mon Jun 10, 2019 5:52 pm    Post subject: Reply with quote

KEO wrote:
...

I don't think it's been reassembled incorrectly. It's such an incredibly simple triplet design I believe I'd be able to tell, as would anyone else. Old silver Isco lenses are probably the most mechanically simple designs I've seen. The body and the mount are one single piece of tube-shaped metal.

That's why I'm wondering if the upside-down mounting was made for a specific camera line. I will keep researching.


Ahem, there are here, elsewhere, and have been, many, who are able to take apart that lens completely and put it back together so well nobody could ever discern it has been worked upon, yes?


PostPosted: Mon Jun 10, 2019 8:13 pm    Post subject: Reply with quote

Thanks for the responses.

DConvert wrote:
There are of course also T2 lenses which can have M42 adapters fitted. These adapters are usually adjustable for orientation. Is that the case for your Isco?


No, it's definitely M42. It mounts perfectly except for finishing upside down. Smile

visualopsins wrote:
Search Google images for that lens. Look for one showing it mounted on a camera. Compare how yours looks... Smile


That's an excellent idea and I tried it, but there aren't many images of this lens to begin with, and the only images of it adapted seem to be Exakta mount...

visualopsins wrote:
Ahem, there are here, elsewhere, and have been, many, who are able to take apart that lens completely and put it back together so well nobody could ever discern it has been worked upon, yes?


No doubt, but I believe the mount and the body are a single piece of metal. There's nothing to disassemble. It's an incredibly simple mechanical design.

Nonetheless, I'm going to give it a close inspection again just to be absolutely sure. I've been too busy for the past few days.


PostPosted: Mon Jun 10, 2019 11:21 pm    Post subject: Reply with quote

https://spiral-m42.blogspot.com/2010/02/isco-gottingen-isconar-100mmf45.html


https://www.pentaxforums.com/forums/14-general-talk/99051-your-latest-acquisition-839.html


PostPosted: Tue Jun 11, 2019 12:01 am    Post subject: Reply with quote

Laugh 1

I'd guess the lens is pk-mount because many pk to canon adapters mount the lens upside down so protruding parts back of lens don't foul camera mirror.

However it does look like m42 lens adapter on the Canon, one with defective orientation. Then the m42 to pk adapter for the k-x mounts the lens correct orientation.


PostPosted: Tue Jun 11, 2019 1:02 am    Post subject: Reply with quote

Hey, just slightly OT. I have one of those Isconar 100mm 4.5 lenses but it came to me full of light fungus. How can I get this one apart easily for cleaning? I could resell it, but don't have any other 100s.

Steve


KEO wrote:
Thanks for all the information, guys!

The (M42-FX) adapter I'm using in this case is a Fotasy with a macro helicoid. I use lots of other lenses with it with no problem.

The problem only seems to occur when I mount my Isco 100mm Isconar 4.5. It's a fantastic lens, but it has a number of oddities. The filter thread is an unusual 41mm (iirc) and the ergonomics are unusual too: a big aperture ring behind a very small focus ring near the front. It feels very backwards and requires some getting used to.

I don't think it's been reassembled incorrectly. It's such an incredibly simple triplet design I believe I'd be able to tell, as would anyone else. Old silver Isco lenses are probably the most mechanically simple designs I've seen. The body and the mount are one single piece of tube-shaped metal.

That's why I'm wondering if the upside-down mounting was made for a specific camera line. I will keep researching.


PostPosted: Tue Jun 11, 2019 9:05 am    Post subject: Reply with quote

KEO wrote:
Thanks for the responses.

DConvert wrote:
There are of course also T2 lenses which can have M42 adapters fitted. These adapters are usually adjustable for orientation. Is that the case for your Isco?


No, it's definitely M42. It mounts perfectly except for finishing upside down. Smile



I meant a T2 lens with a M42 adapter already fitted - I've brought lenses like that assuming they were in the visible mount then found the T2 thread later allowing correction of orientation or simple change of mount.


PostPosted: Tue Jun 11, 2019 8:34 pm    Post subject: Reply with quote

Lightshow wrote:
https://spiral-m42.blogspot.com/2010/02/isco-gottingen-isconar-100mmf45.html


The mount-end of mine looks exactly like the mount-end of the lens on this page. Smile
You can see the screw mount is not separate from the body.

Taken apart and reassembled upside-down seems like the most likely cause. I can't discount it anyway.

It's hard to wrap my mind around how it could have happened though, especially considering the lens functions perfectly. It looks like it would require the aperture to be disassembled and removed, because taking off the front optical group wouldn't change the orientation of the aperture and focus scale.


secludedsea wrote:
Hey, just slightly OT. I have one of those Isconar 100mm 4.5 lenses but it came to me full of light fungus. How can I get this one apart easily for cleaning? I could resell it, but don't have any other 100s.


Mine had some fungus too. Luckily this is a pretty easy lens to clean since it only has three elements and its construction is so simple. If you open it up you'll be amazed how simple it is. I would -not- sell it without giving it a try; it's a real gem IMO.

The main thing to be extra-careful about is noting exactly how the focusing helicoid fits together so you can put it back the way it was. If you don't know how to do that you should make sure you at least read up on it before you begin.

There are three tiny screws around the focus ring that hold the front group in place. Make sure to note the position of the screws so you can put them back in the right place. If you remove them you can unscrew the front group, which will give you access to the first two elements, and access to the third element through the body as well. You can open up the front group if you need access to the inner faces of the first two elements.

When you're done cleaning all you have to do is make sure you mate the pats of the helicoid correctly, put the focus ring back on, and return the screws to the right place. There will be little dents in the brass where the sharp ends of the screws grab the front optical group, so you can use those as a guide. Hopefully you will have left marks with tape or something so you won't even need a guide.


DConvert wrote:
I meant a T2 lens with a M42 adapter already fitted - I've brought lenses like that assuming they were in the visible mount then found the T2 thread later allowing correction of orientation or simple change of mount.


I don't think that's the case, but I'm willing to explore any possibility. Smile


PostPosted: Tue Jun 11, 2019 8:54 pm    Post subject: Reply with quote

Like 1 +1 for whomever wrote
Quote:
The main thing to be extra-careful about is noting exactly how the focusing helicoid fits together so you can put it back the way it was. If you don't know how to do that you should make sure you at least read up on it before you begin.

There are three tiny screws around the focus ring that hold the front group in place. Make sure to note the position of the screws so you can put them back in the right place. If you remove them you can unscrew the front group, which will give you access to the first two elements, and access to the third element through the body as well. You can open up the front group if you need access to the inner faces of the first two elements.

When you're done cleaning all you have to do is make sure you mate the pats of the helicoid correctly, put the focus ring back on, and return the screws to the right place. There will be little dents in the brass where the sharp ends of the screws grab the front optical group, so you can use those as a guide. Hopefully you will have left marks with tape or something so you won't even need a guide.