Mount a LTM lens on a Pentax body?

V

vdonovan

Vince Donovan
Local time
5:23 AM
Joined
Aug 23, 2007
Messages
477
Screwball idea of the day: I would like to mount my Leica thread Summitar on my Pentax *istDL. Why? Why not. So what if none of the automatic stuff works. Anyone have a clue what adapter or combination of adapters would get me there?

I see there are K mount to M42 Universal Screw Mount adapters but I don't think this is the same as Leica Thread Mount.

Any ideas?
 
vdonovan said:
Screwball idea of the day: I would like to mount my Leica thread Summitar on my Pentax *istDL. Why? Why not.
Click to expand...
With an SLR the flange of the bayonet is more distant to the film plane than on a rangefinder. Using the right adapters, which exists, you will be able to mount the Summitar on your Pentax but the lens will be to far away from the filmplane/sensor. This way your Summitar becomes an odd macro-lens which ,as I suppose, is not exactly what you want.

best

Stefan
 
As mentioned above, the LTM lenses are designed to sit closer to the film plane, so if mounted on an SLR will not be able to focus to infinity, in fact nowhere near it!. Nice for close macros. You need an M39 > M42 adapter and a M42 > K adapter, used together.

Here's a Canon 50/1.8 mounted on my *istDS.

attachment.php
 
Chris: how far can you focus when the lens is set to infinity? I have a set of LTM lenses I'd love to play with on my DSLR.
 
cmedin said:
Chris: how far can you focus when the lens is set to infinity? I have a set of LTM lenses I'd love to play with on my DSLR.
Click to expand...
Think of it this way... a 50mm LTM lens fitted onto most SLR bodies will pretty much be focused somewhat to lifesize macro.

Just like if you put a 20mm or so extension tube on a lens designed for the camera.
 
Summitar on Pentax

Summitar on Pentax

Something that has not been mentioned is that the Summitar is a collapseble mount and will fit further into the bodyand therefore the focussing range will be extended, though not quite infinity .

One thing to be very careful of is that you do not recess the lens that far that it will touch the mirror.

Have fun.
 
Interesting thought - I was just playing with my Summitar.

Infinity focusing is at about 8 inches or 200mm. I posted some shots once before in another thread (http://www.rangefinderforum.com/forums/showthread.php?t=25535), but here's another plus a shot of the Summitar mounted. I won't try collapsing it!
 

Attachments

  • IMGP9671.jpg
    IMGP9671.jpg
    47.9 KB · Views: 0
  • IMGP0035.jpg
    IMGP0035.jpg
    21.7 KB · Views: 0
Last edited:
1948nikon said:
Something that has not been mentioned is that the Summitar is a collapseble mount and will fit further into the bodyand therefore the focussing range will be extended, though not quite infinity .

One thing to be very careful of is that you do not recess the lens that far that it will touch the mirror.

Have fun.
Click to expand...
Funny enough though, I've tried this on an olympus PenF using a collapsible industar-10 50/3.5, basically by utilizing a T-mount adapter then to a LTM adapter, I was able to collapse the lens back down to a proper registration distance though would need a shim or two to make it perfect lol.

But the reason that would work is because the PenF and Leica registration distance are very close to each other, where as on an 35mm SLR typically you're talking distances that would smack the barrel of that lens into the mirror before you hit infinity, or would cause the mirror to clip the lens when you fired the shutter. (But you did say 'extended' so would be better than what you'd normally get).
 
50mm is my longest LTM. :)

I think the register distance for LTM is supposed to be 28.8mm, and the M42 is 45.46, so I'd have to collapse the Summitar 16.66mm, which would certainly bring it into contact with the mirror. I suppose you could always hacksaw off the back of the tube. :eek:
 
ChrisN said:
50mm is my longest LTM. :)

I think the register distance for LTM is supposed to be 28.8mm, and the M42 is 45.46, so I'd have to collapse the Summitar 16.66mm, which would certainly bring it into contact with the mirror. I suppose you could always hacksaw off the back of the tube. :eek:
Click to expand...

Would probably do that to a hazy I-10... to anything else you'd have bystanders gasp in horror. I noticed on the longer lens lens though while the focusing range is still pretty close it makes it almost like a telephoto macro. You won't have to stand as close to the item.
 
Likely a J-12 would be a bad idea as well; I tried my ltm lenses on my dad's K10d this way but was not brave enough to mount the J-12.
I think you might be able to get bigger than 1:1 with some extension tubes?
Or does that put the plane of focus somewhere inside the lens?
Rob
 
rbiemer said:
Likely a J-12 would be a bad idea as well; I tried my ltm lenses on my dad's K10d this way but was not brave enough to mount the J-12.
I think you might be able to get bigger than 1:1 with some extension tubes?
Or does that put the plane of focus somewhere inside the lens?
Rob
Click to expand...

I wouldn't just for the simple fact of the way the J-12's back element is designed.
 
You must log in or register to reply here.
Back
Top Bottom