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06-19-2017, 11:54 AM   #1
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Adjusting Infinity On a SMC Tak f1.4. Clarification needed!

Hello folks, I hope you are well!

My name is John and I am a keen photographer who has to work on a budget. After searching around for a new lens I stumbled on to how I could use vintage lenses on my nikon. From there I picked up a SMC Takumar 1.4 after doing a lot of research which included this forum (so thank you!). So far am chuffed with it, the lens seems sharper and with nice bokeh then my nikkor 35mm 1.8g.

However, am trying to adjust the helicoid so I can hopefully get infinity focus back or somewhere close. Am using the guide linked on the forum (This one http://k10dpentax.blogspot.co.uk/2009/03/fixing-infinity-focus-on-takumar-lenses.html)

My understanding is that you remove the filter ring, loosen the barrel, twist the focus away from infinity, re tighten the screw for the barrel, then twist the lens back to infinity. That causes the helicoid's position to move closer to the camera, regaining some of the lost focus. This worked fine on my Super Tak 135mm, but the helicod refuses to budge on my 50mm.

What am I missing folks?

Any help would be much appreciated

Attached is what am looking at (the lens has a knurled focus grip rather than a shape metal one featured in the guide)

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NIKON D90  Photo 
06-19-2017, 01:08 PM   #2
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What do you mean it refuses to budge? Can you not turn the focus at all?

If that is not the case there is a stop on the focus barrel to keep from turning past infinity or minimum focus. Sometimes it is easier to remove the focus barrel.

Mount the lens on your camera. Set the lens to the infinity mark. Removing the three screws should allow you to remove the focus barrel from the helicoid. Turn the helicoid and focus on some object distant enough to be at infinity. Slip on the focus barrel with the infinity marked lined up. Without the screws you should be able to turn the focus ring without moving the helicoid for fine alignment adjustment. Replace the screws but tighten only one down. Check focus from infinity to minimum. Loosen the one screw and adjust as needed or tighten down all the screws if ok.
06-19-2017, 01:29 PM   #3
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The Helicoid refuses to move past the infinity setting its current at, it just won't move. it'll only rotate to focus on close objects. When I loosen the helicoid's screws, twist the focus barrel then retighten the helicoid and attempt to rotate back to infinity the barrel won't move. If I am more aggressive the focus barrel just twist back to it's infinity mark without rotating the helicoid.

When I've removed the focus barrel I just can't rotate it past infinity
06-19-2017, 04:56 PM - 1 Like   #4
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Welcome to the Pentax Forums!

QuoteOriginally posted by BootleBlue Quote
When I've removed the focus barrel I just can't rotate it past infinity
I read the linked instructions and am not surprised you are having problems. The instructions are not very precise. With any luck user @dcshooter will check in on this thread. He knows the insides of many Takumar lenses and can probably shed light as to which screws should be loosened and as to whether there is a hard stop on the helicoid itself that is impeding your efforts.


Steve

06-20-2017, 12:33 PM   #5
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Fingers crossed it is a screw and not a hard stop!
06-22-2017, 02:31 PM   #6
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Right! Update time.

First of all, thank you very much @dcshooter for your detailed response, it's really appreciated.

Secondly, I've been able to utilise the info from A) to gain about 2 ft of focus, so infinity is around 6ft right now. The rear of helical had a bit of a bit of give so I tightened that. I then spent an hour twisting the front and back of the helical to try get more of my focus back. However, the helical is limited to how far it can move backwards as it touches the aperture mechanism.

I couldn't see any of the other issues you mentioned dc.

John
06-22-2017, 03:23 PM   #7
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QuoteOriginally posted by BootleBlue Quote
Right! Update time.

First of all, thank you very much @dcshooter for your detailed response, it's really appreciated.

Secondly, I've been able to utilise the info from A) to gain about 2 ft of focus, so infinity is around 6ft right now. The rear of helical had a bit of a bit of give so I tightened that. I then spent an hour twisting the front and back of the helical to try get more of my focus back. However, the helical is limited to how far it can move backwards as it touches the aperture mechanism.

I couldn't see any of the other issues you mentioned dc.

John
you need to dis assemble as per instructions provided by dcshooter and completely rebuild the helical. As he said maybe someone rebuilt it wrong ,by not screwing the primary helical in far enough. also check your adapter. Nikon and Pentax have similar focal distance from the sensor. You should be able to do it other wise mail it off to dcshooter ps again check your adapter isn't too thick.

06-22-2017, 05:26 PM - 1 Like   #8
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I recall having the same problem with a SMC M. What was happening was that the front assembly was too far out, and when you focused to infinity, the aperture arm would fall off the rail, and hangs. Then the front assembly wouldnt turn back cuase the arm was jamming it..it would best to always check that the aperture arm stays on rail at all times, then adjust the front assembly very slightly until where the arm fits in the rail..
06-22-2017, 06:12 PM   #9
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QuoteOriginally posted by niceshot Quote
you need to dis assemble as per instructions provided by dcshooter and completely rebuild the helical. As he said maybe someone rebuilt it wrong ,by not screwing the primary helical in far enough. also check your adapter. Nikon and Pentax have similar focal distance from the sensor. You should be able to do it other wise mail it off to dcshooter ps again check your adapter isn't too thick.
As far I am aware I've followed Dc's instructions exactly.

If I fully twist the brass lower section of the helical until it's locked then refit the upper section it pinches down on the aperture mechanism preventing it from rotating. So I've given the brass helical a few twists and rehoused the upper helical as low as it will go without pinching the aperture mechanism. I literally spent an hour repeating that progress to get the best I can out of it but 6 foot was the best I could do.

Attached is my adaptor. Seems pretty typical

---------- Post added 06-22-17 at 06:24 PM ----------

QuoteOriginally posted by Jeff Lopez Quote
I recall having the same problem with a SMC M. What was happening was that the front assembly was too far out, and when you focused to infinity, the aperture arm would fall off the rail, and hangs. Then the front assembly wouldnt turn back cuase the arm was jamming it..it would best to always check that the aperture arm stays on rail at all times, then adjust the front assembly very slightly until where the arm fits in the rail..
Am gunna have another look tomorrow Jeff just to make sure am doing everything right
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06-22-2017, 06:57 PM   #10
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ok here is the monkey wrench check to see if the optics are in the right order
06-22-2017, 11:30 PM   #11
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QuoteOriginally posted by BootleBlue Quote
After searching around for a new lens I stumbled on to how I could use vintage lenses on my nikon.
The OP is using a Nikon body. I don't think you can get flangless M42 adapters for Nikon. I think all the infinity focus ones have an optical element.

It is possible that there is not enough "play" in the focus helicoid to achieve infinity focus with the adapter.

Last edited by Not a Number; 06-22-2017 at 11:35 PM.
06-23-2017, 01:50 AM   #12
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QuoteOriginally posted by Not a Number Quote
The OP is using a Nikon body. I don't think you can get flangless M42 adapters for Nikon. I think all the infinity focus ones have an optical element.

It is possible that there is not enough "play" in the focus helicoid to achieve infinity focus with the adapter.
He should be able to by way of rebuilding it achieve the little bit of distance. the registration difference is almost identical. However it could be the adapter is causing it to sit out too far away from the sensor. Or lens groups were reassembled wrong
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