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06-05-2013, 07:15 PM   #1
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Can't focus on far-away objects, is my lens faulty?

Hi guys,

I want to start doing some street photography and have an old Quantaray manual 28mm lens. I'm trying to zone focus with f/8 and f/16 and at close distances (eg. 1m, 2m) the pictures are sharp. But if I focus to 2m or infinity or anywhere in between, far away objects are blurry.

I even tried using catch-in focus to see whether focus locks when it gets to infinity, but it doesn't. The trigger never fires. I'm doing catch-in focus right, because it works on close objects, the trigger fires when the object is in focus.

Do you think this lens is faulty? It doesn't seem to be able to focus on far-away objects. Even at f/16, with the lens focused at infinity, far-away objects are blurry.

Or (hopefully) I'm doing something wrong and can do something differently to get sharper photos?

Thanks,
Daniel

06-05-2013, 07:16 PM   #2
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Sorry forgot to mention, this is on a K-5 in manual mode with ISO 100.


Cheers,
Daniel
06-05-2013, 07:17 PM   #3
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it is very possible that the focus ring may need to be adjusted to infinity. if for whatever reason it is not calibrated properly, this would result in going past infinity and making everything blurry.
06-05-2013, 07:23 PM   #4
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Is this possible for me to attempt myself? It's only a cheap lens and I have a Pentax-A28 2.8 on the way, but I'd love to give this a go as the lens will be a throw-away if I can't fix it anyway.

Cheers,
Daniel

06-05-2013, 07:38 PM   #5
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QuoteOriginally posted by djmundy Quote
Is this possible for me to attempt myself? It's only a cheap lens and I have a Pentax-A28 2.8 on the way, but I'd love to give this a go as the lens will be a throw-away if I can't fix it anyway.

Cheers,
Daniel
K mount or adapter ?
06-05-2013, 07:41 PM   #6
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K mount
06-05-2013, 07:59 PM - 1 Like   #7
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It should be pretty easy to adjust the infinity focus, the screws are somewhere on the focus ring, they could be under the rubber. It would really help if you have a body with a good split prism focusing screen, but live view will work too.

Setup on a tripod
Find a nice distant object that is easy to focus on
Turn the focus ring until it stops at infinity
Loosen the screws and turn the ring all the way back to minimum focus distance (it should move freely and not change the focus)
Tighten the screws and start going towards infinity while watching for correct focus
When you have achieved infinity focus loosen the screws again, turn the ring until it shows infinity and tighten them again

If it is still way out it may have been repaired at some point and assembled incorrectly, this could be much harder to fix.
06-05-2013, 08:01 PM   #8
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I had a FA28-105 (PZ) lens that was very sharp at close distances, but soft at anything at a distance. It did not matter what the focal length was. I think it just is that way with some older & cheaper lenses.

06-05-2013, 08:54 PM   #9
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Softness at infinity or inability to attain infinity focus is either a matter of adjustment or evidence of damage or botched service. Unless the lens has a floating internal element, the only difference between near and far focus is the physical distance of the lens from the sensor/film. Resolution should be the same for both cases.


Steve

(Is it my imagination or has there been a recent flurry of infinity focus/softness issues with vintage lenses?)
06-05-2013, 10:03 PM   #10
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Thanks heaps Elliott for pointing me in the right direction. My lens now focuses great it was slightly different for my lens, there was a stopper screw which could not be adjusted but the pieces were held in place with tape. I focused on infinity, removed the tape, adjusted the focus until a far-away object was in focus, then replaced the tape.

I only wish I read your post before I tried it myself... I opened up the lens from the back to see whether I could figure it out, and now the aperture ring doesn't "click"... It still works though. Not a huge deal but it was fun seeing how it works lol.

Cheers,
Daniel
06-05-2013, 10:41 PM   #11
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QuoteOriginally posted by djmundy Quote
I only wish I read your post before I tried it myself... I opened up the lens from the back to see whether I could figure it out, and now the aperture ring doesn't "click"... It still works though. Not a huge deal but it was fun seeing how it works lol.
You lost the ball that makes it click, it is a rite of passage, everyone does that at least once. If I have a lens that is a lost cause or just not worth fixing, I always try to save that ball because I'll be sure to lose one on a lens I actually care about.

Since you mentioned tape, I guess that Quantaray lens could really be a Sigma, they did that a lot.

Last edited by elliott; 06-05-2013 at 10:50 PM.
06-05-2013, 11:01 PM   #12
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The funny thing is, I fixed it before coming back here to tell you about it, only to see your last post about the ball .

I did notice when I was pulling it apart that a ball bearing that had fallen out, but i couldn't figure out where it came from. After my last post I had a break and then decided to give it one last look. It took me a while to figure out where it was supposed to go, but I found it, and now my aperture ring clicks again! Thanks heaps again for your help Elliot.

Cheers,
Daniel
06-08-2013, 06:45 PM   #13
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QuoteOriginally posted by stevebrot Quote
(Is it my imagination or has there been a recent flurry of infinity focus/softness issues with vintage lenses?)
My impression, too.

Possible reasons?
06-08-2013, 08:12 PM   #14
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QuoteOriginally posted by RKKS08 Quote
My impression, too.

Possible reasons?
Possible that people are just now noticing, a lot of this stuff has been sitting unused for decades and for the last few years it has been getting more and more common to dig out that stuff and use it.
06-09-2013, 05:49 AM   #15
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One of the greatest things about this forum is the number of examples of what is meant by sharp versus soft, and in-focus versus out of focus. It isn't perfect of course because we have to compress high resolution images down to a fraction of their original size. It has certainly made me critique my own photos that much more. I think others are noticing the same thing.
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