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Spotmatic's Exakta-PK adapter
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PostPosted: Fri Jan 01, 2010 8:01 pm    Post subject: Spotmatic's Exakta-PK adapter Reply with quote
Since I sold my EOS 5D I had no means to mount my Exakta lenses to any of the Pentax DSLR's I have. As far as I know adapters from Exakta mount to Pentax K mount do not exist, so I decided to make my own (with all limitations, such as the fact that only close-ups can be made).

My own solution consists of a combination of a genuine Asahi M42 to PK adapter (50 eurocents), and the Exakta bayonet mount part of an original Exakta extension tube set (bought for 2 euros). That mount screws off easily, but the screw mount part is smaller than the M42-mount part of the M42-PK adapter. To mount the two parts together a friend of mine made a very small aluminium ring that was glued (with Araldite) between the two parts. The glue is so strong that the two parts will never separate again.













What I like about my adapter is that ANY Exakta lens can be mounted normally (except for the large ones which use the outer Exakta bayonet, my solution does not have such an outer bayonet). Also, the lens locks securely in place (was never so with my Exakta to EF adapter).

The drawback is that I can only use the lenses for close-ups. In the case of the 75mm f/1.5 Biotar (on APS-C) I have barely enough room for portraits (see below). The longer the lens gets, the bigger the usable focusing range. though. Of course I could recalibrate the lenses to get a little bit closer to infinity, but I prefer not to alter my lenses.

Two not so interesting samples made with the 75mm f/1.5 Biotar wide open (the first one shows some movement blur):





PostPosted: Fri Jan 01, 2010 8:10 pm    Post subject: Reply with quote
A neat trick!


PostPosted: Sat Jan 02, 2010 11:13 am    Post subject: Reply with quote
Some more samples!

With the pre-war Schneider-Kreuznach 15cm f/5.5 wide open:




With the pre-war Meyer Görlitz Primoplan 7,5cm f/1.9 wide open and f/2.8. To me there's no doubt that the Primoplan is one heck of a sharp lens, even wide open.







PostPosted: Sat Jan 02, 2010 2:03 pm    Post subject: Reply with quote
Great idea Peter, I did teh same for my Nikon cameras!!
"Great souls think alike" Wink Wink


PostPosted: Sat Jan 02, 2010 3:34 pm    Post subject: Reply with quote
Nice solution!
It should have been possible to gain around 0,5 to 0,7mm when making the base of the Exakta mount (I meant the extension ring's base, not the lens!) a bit thinner on a lathe.

Klaus

Last edited by exaklaus on Sun Jan 03, 2010 2:25 pm; edited 1 time in total


PostPosted: Sat Jan 02, 2010 4:58 pm    Post subject: Reply with quote
Nice ! I did make same with Nikon adapter , but I wasn't to lucky after a couple of usage "super glue" divided and my lens felt down to floor Twisted Evil
so be a bit careful for a while keep lens always in your hand.


PostPosted: Sat Jan 02, 2010 8:24 pm    Post subject: Reply with quote
Attila wrote:
Nice ! I did make same with Nikon adapter , but I wasn't to lucky after a couple of usage "super glue" divided and my lens felt down to floor Twisted Evil
so be a bit careful for a while keep lens always in your hand.


I will do that of course, but my friend is working in the Aviation/Space/Defense industry and I think he does know the materials he's using Wink


PostPosted: Sat Jan 02, 2010 9:12 pm    Post subject: Reply with quote
Spotmatic wrote:
Attila wrote:
Nice ! I did make same with Nikon adapter , but I wasn't to lucky after a couple of usage "super glue" divided and my lens felt down to floor Twisted Evil
so be a bit careful for a while keep lens always in your hand.


I will do that of course, but my friend is working in the Aviation/Space/Defense industry and I think he does know the materials he's using Wink


There exists a high strength, two-part epoxy from Bison especially for metal-to-metal bonding, I have used that one in many mount adaptations involving rather long and heavy lenses without problems to date.


PostPosted: Sat Jan 02, 2010 10:21 pm    Post subject: Reply with quote
Thank you! I was lazy to take that , I know also that is strong like metal.


PostPosted: Sun Jan 03, 2010 9:54 am    Post subject: Reply with quote
Hello Peter!
He super great idea and I was sure that you will find a good solution to used again your biotar with your pentax body Very Happy ..So now you know what it is to used a MF lens with short focus distance Rolling Eyes .....
Anyway, I'm very happy for you Wink ....


PostPosted: Sun Jan 03, 2010 10:26 am    Post subject: Reply with quote
Indeed Pascal, it's no fun with such a short focus distance (like Nikon with M42 lenses) Smile

Actually I'm thinking about modifying a cheap Pentax DSLR (an *ist DS maybe) by removing the K-mount and put an Exakta mount in there. I'm sure it can be done!


PostPosted: Sun Jan 03, 2010 10:39 am    Post subject: Reply with quote
Yes I know it, 4 meters with a 85mm is sometimes too short Confused ....
Is it not a easier solution to replaced the Exakta mount from the biotar with a M42 mount????


PostPosted: Sun Jan 03, 2010 10:59 am    Post subject: Reply with quote
Yes, a mount conversion is feasible, but I don't want to alter it. I mean --- it's in a near mint condition so why damage it?


PostPosted: Sun Jan 03, 2010 1:53 pm    Post subject: Reply with quote
pich900 wrote:
Yes I know it, 4 meters with a 85mm is sometimes too short Confused ....
Is it not a easier solution to replaced the Exakta mount from the biotar with a M42 mount????


To ruin an old lens just because not much your current camera is a crime. Exakta adapters available for 4/3 and Canon this is the way, not mount conversion.


PostPosted: Sun Jan 03, 2010 2:24 pm    Post subject: Reply with quote
+1

Klaus


PostPosted: Sun Jan 03, 2010 3:46 pm    Post subject: Reply with quote
+2


PostPosted: Sun Jan 03, 2010 5:04 pm    Post subject: Reply with quote
Attila wrote:
pich900 wrote:
Yes I know it, 4 meters with a 85mm is sometimes too short Confused ....
Is it not a easier solution to replaced the Exakta mount from the biotar with a M42 mount????


To ruin an old lens just because not much your current camera is a crime. Exakta adapters available for 4/3 and Canon this is the way, not mount conversion.


I would disagree and agree with some points..

If some lens is meant to be sold again or untouched -- there's not any doubt that conversion is a bad solution..

But I must always say -- it's not a crime -- it's a CHOICE -- and all responsibility is on the owner..

-- Back to the Spotmatic's solution -- I must say it's GREAT and if this works perfectly any conversion is really not good option Smile

Speaking about Canon FD glasses - I must say that the Canon FD 85 f1.2 L was one of my best choices Smile

I have got Angenieux 2.5/35 (Exakta mount) which is A REAL GEM , I must say. There's not possible to reach infinity via my Exakta/EOS adapter (it may be faulty, or so) despite the fact, I AM NOT thinking about ANY conversion to M42 mount.

Therefore, conversion is a choice between real value of the lens and the your results they need to be achieved.

tf


PostPosted: Sun Jan 03, 2010 8:12 pm    Post subject: Reply with quote
Attila wrote:
pich900 wrote:
Yes I know it, 4 meters with a 85mm is sometimes too short Confused ....
Is it not a easier solution to replaced the Exakta mount from the biotar with a M42 mount????


To ruin an old lens just because not much your current camera is a crime. Exakta adapters available for 4/3 and Canon this is the way, not mount conversion.

A crime Shocked .....Well, personally I don't think that the lens is ruin if you change the mount and I’m agree with “Trifox”....but of course, I understand your point of view Wink ...And the biotar is also available with M42 mount (or not?) so is it really a "crime" in this case???
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