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04-09-2009, 04:44 PM   #1
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Trouble with screw Mount lenses

I need help with a Pentax brand screw mount adapter for my k10d. In the 70"s I had a
Fujica st701with a vivitar 35mm 28 Auto Wide Angle that had switch for A&M. It seemed to fit flush but I can not focus past a few feet. I also have a Fujinon 50mm 1.4 that I would like to try but I can not get to fit flush. It has a smsll flange on the back. Both lenses have 1 pin on the back.I have set aperture ring to permitted and tried every possible setting I could think of to try. I have read a lot of posts on differnt blogs about the m42 adapter situation but can not figure out the answer. I bought this from the PENTAX WEB STORE. Maybe I wasted my momey? I hope somebody has an answer. I have found two links to my lenses. I will try and link them.

http://whitemetal.com/pentax/viv_35_28-infohtm

http://m42.artlimited.net/site_lens.php

Thanks anybody

04-09-2009, 05:42 PM   #2
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Hi,
Two questions:
  1. When the adapter alone is mounted to the camera, is the adapter flange flush with the k-mount flange? The official Pentax version should be.
  2. Does the adapter screw all the way onto your M-42 lens? The adapter flange should be tight against the lens back flange when properly attached.
All of the above must be true to attain infinity focus. There are issues with some Fujinons, but your Vivitar should work fine.

I assume the back of your Fujinon looks something like this:


Image found at http://m42.artlimited.net/img/lens/486-3.jpg

That little nubbin at 4:00 o'clock on the lens back is probably the cause of your problem.

I generally attach the adapter to the lens and then mount the lens on the camera. If there are any physical obstruction issues, they are generally apparent at either step.

Steve

Last edited by stevebrot; 04-09-2009 at 06:07 PM.
04-09-2009, 05:53 PM   #3
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BTW...Welcome to the forum!

Steve
04-09-2009, 09:39 PM   #4
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The adapter fits just a hair below flush on the K10d.It The vivitar fits snug and screws onto the adapter well.On the Fujinon to make it fit snug I must almost force it. Then I can not turn the aperture ring. I put both Lenses on the old slr and they will focus. What doe the pin do?

Robert

04-09-2009, 09:53 PM   #5
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QuoteOriginally posted by golfing rob Quote
The adapter fits just a hair below flush on the K10d.It The vivitar fits snug and screws onto the adapter well.On the Fujinon to make it fit snug I must almost force it. Then I can not turn the aperture ring. I put both Lenses on the old slr and they will focus. What doe the pin do?

Robert
The pin is the auto-aperture activator, but is only useful on screw-mount bodies (like the Spotmatics). If the lens has an A/M switch near the aperture ring, set it to M so you can use stop-down metering on a DSLR. If there is no switch, you'll only be able to use the lens wide open unless you find a way to keep the pin depressed.
04-09-2009, 09:54 PM   #6
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Oh I forgot . That is what the lens looks like. I thinking that little nubbin may be part of the problem on that one.
Robert
04-09-2009, 10:19 PM   #7
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QuoteOriginally posted by golfing rob Quote
Oh I forgot . That is what the lens looks like. I thinking that little nubbin may be part of the problem on that one.
Robert
That nubbin is probably why you can't turn the aperture ring when you have the lens snugged down. My understanding is that it is the coupling mechanism for the Fujica open-aperture metering system. I believe that it moves with the aperture ring and normally engages a "follower" on the Fujica camera body. The nubbin is a potential problem with non-Fuji cameras. According to some sources I read on the Web, it affects the ability to attain infinity focus on some cameras and may even result in the lens becoming stuck on the body. (This may be a risk as well with the K-mount adapter. Consider too that the body may be damaged in the process.)

I would suggest that you screw the adapter onto the lens FIRST and they try mounting the assembly onto the camera. I suspect that it will fail to mount due to the nubbin. Options? Grind the nubbin off (or remove by some other method) or find another lens.

Steve

Last edited by stevebrot; 04-09-2009 at 10:24 PM.
04-11-2009, 12:20 PM   #8
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I ground the nubbin off. It improved but i still can not focus to infinity. I will try the vivitar next. If I can not get them to go, perhaps I can use the adapter on other screw mounts out there if I find a good buy on some. Can you tell me why my gear does not show up on my post. Are you entering that info by hand every time you post?

Also I have heard about reversing the lens and putting it on front of another lense for macro? Just thinking about uses

04-11-2009, 12:32 PM   #9
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QuoteOriginally posted by golfing rob Quote
Can you tell me why my gear does not show up on my post. Are you entering that info by hand every time you post?
Go to Quicklinks in the Forum Menu Bar. Select Edit Signature. Enter your gear there and it will appear every time you post. I entered part of a poem by Kipling in my signature file. The Option is also available from the User Control Panel
04-12-2009, 01:22 PM   #10
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QuoteOriginally posted by OregonJim Quote
The pin is the auto-aperture activator, but is only useful on screw-mount bodies (like the Spotmatics). If the lens has an A/M switch near the aperture ring, set it to M so you can use stop-down metering on a DSLR. If there is no switch, you'll only be able to use the lens wide open unless you find a way to keep the pin depressed.
You are so right!
04-12-2009, 07:57 PM   #11
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Thank you for this info. I don't know how I missed it.
04-12-2009, 08:03 PM   #12
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Thanks for the info on this. I had to back off on this for awhile till i can get back to it. By the way took a lot of shots in oregon this fall from Bend across Mackenzie Pass to the coast in Yachats. We make it
up there every so often. Beautiful coastline and mountains.
04-13-2009, 11:13 AM   #13
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QuoteOriginally posted by golfing rob Quote
Thanks for the info on this. I had to back off on this for awhile till i can get back to it. By the way took a lot of shots in oregon this fall from Bend across Mackenzie Pass to the coast in Yachats. We make it
up there every so often. Beautiful coastline and mountains.
I love the Bend area - high-desert beauty in the summer & a snow paradise in the winter. Newport, Lincoln City, & Depoe Bay are all great coastal destinations in addition to Yachats.
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