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03-12-2013, 05:54 AM   #1
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Catch in Focus and Lens Resolution [k-x]

Hey Everyone!

I have a few questions..
I've been shooting wildlife (mostly birds) for a few years now..
I've been using a 200mm f4 SMC Tak.
The issue is that I cannot seem to ever get a perfectly sharp photo...
I know right away its all about practice.. But i feel as if the lens may not be entirely sharp for whatever reason.
I find myself zooming in with Lightroom and not feeling like its sharp then upping the clarity to make it seem sharper.. (something I would rather not have to do....)

I went to a talk wildlife photography talk hosted by Christopher Dodds last Friday and he recommended that I try and do a lens resolution test..
Seems like there are all sorts of complicated jigs on the internet to do this type of thing..

Does anyone know a simple way to test this sort of thing?

Also,
I was hoping to enable the catch in focus function using my manual lenses hoping that may help me with my focusing issues...

I've set the auto focus to AF.S, Manual, Catch in focus on (2), Using aperture ring on (2)...
The shutter will fire despite the image not being in focus..


Thank you very much,
Some pictures below to illustrate my problems..

Alec

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03-12-2013, 05:57 AM   #2
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That robin looks quite a bit sharper on my screen but still evidently nowhere near really sharp.
The loon got a thorough dosage of clarity adjustment in Lightroom..
03-12-2013, 06:42 AM   #3
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I also struggle to get good bird photos, but I am getting better. My photos started to improve after I switched from a Sigma 70-300mm to an old Bushnell 400mm screw mount. That seems counter intuitive unless either there is something wrong with my Sigma or my technique finally started to improve around the time I switched lenses, or both. One thing I do is take tons of shots and discard the rejects, which are not always due to the same reason. Sometimes camera shake and sometimes poor focus. It helped me a lot to start using a monopod. You should be able to use a 200mm hand-held, but you could always try using a support to see if that helps. Your photo of a Robin was at 1/100s, and that might be too slow. The others were faster. If focus is your issue then there might be something else nearby with good focus. Even though I am using an old manual focus lens, I still get a focus indicator dot in the frame (K10D). In your last photo it seems the base of the trunk has better focus than the bird, but it is hard for me to tell. Are any of these photos focused at infinity? Is it possible that your screw mount adapter is impacting your ability to focus at infinity? How is your aperture set? I will be watching this thread for useful tips including any lens resolution hints. It would also be nice to have more tips for distinguishing causes for unsharp photos.
03-12-2013, 07:20 AM   #4
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QuoteOriginally posted by Alec [k-x:
;2309859]I've been using a 200mm f4 SMC Tak.
You cannot have CIF with a takumar (42mm screw thread) lens because there is nothing to shorten the electrical contacts on your camera body. CIF will only work with lenses that have a K-mount and the base has to be clean (not anodized) metallic.

03-12-2013, 07:31 AM   #5
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QuoteOriginally posted by Stone G. Quote
You cannot have CIF with a takumar (42mm screw thread) lens because there is nothing to shorten the electrical contacts on your camera body. CIF will only work with lenses that have a K-mount and the base has to be clean (not anodized) metallic.
Sorry, I beg to differ. I've been using various M42 lenses, including a Takumar 55 1.8 and a 105 2.8 preset, you just have to short the contacts on the camera by using some tin foil or various other methods that have been discussed in previous threads. I always use CIF with all my manual lenses, K and M42 mount.



I personally use a shim cut out of a soft drink can

EDIT: No problem with infinity, the shim is very thin.

Last edited by altopiet; 03-12-2013 at 07:36 AM.
03-12-2013, 07:32 AM   #6
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QuoteOriginally posted by Stone G. Quote
You cannot have CIF with a takumar (42mm screw thread) lens because there is nothing to shorten the electrical contacts on your camera body. CIF will only work with lenses that have a K-mount and the base has to be clean (not anodized) metallic.
Ya, you can. If you are using the flange'd adapters this will effectively short the contacts and allow for CIF, however, infinity focus will be off. If you are using the standard m42 adapter, using a piece of foil will short the contacts and allow for the use of CIF.

QuoteOriginally posted by Alec [k-x:
;2309859]Also,
I was hoping to enable the catch in focus function using my manual lenses hoping that may help me with my focusing issues...

I've set the auto focus to AF.S, Manual, Catch in focus on (2), Using aperture ring on (2)...
The shutter will fire despite the image not being in focus..
See response above. Sounds like you are using the normal adapter, place a piece of foil on the contacts while screwing in the lens...
03-12-2013, 10:12 AM   #7
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QuoteOriginally posted by altopiet Quote
I personally use a shim cut out of a soft drink can EDIT: No problem with infinity, the shim is very thin
That's interesting. I tried a similar trick sometime ago on my S-M-C 135mm f/3.5 with common household alufoil glued on paper. I did get CIF but lost infinity focus. Did you sand or otherwise make the shim (much) thinner?
03-12-2013, 10:15 AM   #8
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Alec - why not test the lens on a non-moving subject?

Take your camera, put it on a tripod, put it in live-view, focus until you are certain it's accurate, and take several pictures of a subject at different apertures. Keep ISO low.

Choose a subject of an appropriate distance for the lens. For your 200, maybe take a picture of a brick house across the street. See if it looks sharp, when accurately focused in live-view. This will tell you what is wrong - the camera, or your technique.

03-12-2013, 01:52 PM   #9
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Hi
You just need a flat chart on the wall at about 30 ft. , first focus with the live view using the zoom so it is perfectly in focus. Shut off the camera without touching
the lens. Look in the viewfinder to see if it is as clear as the live view.
If it is not and can't be adjusted enough with the viewfinder diopter then you will need adjustments there.
Turn the camera back on and out of live view, half press the shutter and if the AF is ok then the Green focus light should come on, if not
the AF needs adjusting.
Any problems send me a message, If you were at the Photo talk then you are not far from me. I could give you a hand.
03-12-2013, 03:49 PM   #10
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QuoteOriginally posted by Gaberlunzi Quote
One thing I do is take tons of shots and discard the rejects, which are not always due to the same reason.
Sometimes camera shake and sometimes poor focus. It helped me a lot to start using a monopod. You should be able to use a 200mm hand-held, but you could always try using a support to see if that helps. Your photo of a Robin was at 1/100s, and that might be too slow. Are any of these photos focused at infinity? Is it possible that your screw mount adapter is impacting your ability to focus at infinity? How is your aperture set? I will be watching this thread for useful tips including any lens resolution hints. It would also be nice to have more tips for distinguishing causes for unsharp photos.
this is what i'm trying to avoid! haha i'd rather be able to comfortably know its focused so i can concentrate on composing,etc.
and yes for the supporting, i'll start being a little more strict using the tripod.. i had slacked since it wasnt a heavy lens but i will get back into that habit.
my birding pictures are rarely focused at infinity but the bird on the trunk may have been.. and i dont think the adapter is affected it..

QuoteOriginally posted by altopiet Quote
you just have to short the contacts on the camera by using some tin foil or various other methods that have been discussed in previous threads. I always use CIF with all my manual lenses, K and M42 mount.
I personally use a shim cut out of a soft drink can
.
i briefly tried this last night but i will retry it.. if the contacts are shorted out, will AF.S work as it is supposed to? (as in not shooting till in focus?)

QuoteOriginally posted by JinDesu Quote
Alec - why not test the lens on a non-moving subject?
Take your camera, put it on a tripod, put it in live-view, focus until you are certain it's accurate, and take several pictures of a subject at different apertures. Keep ISO low.
Choose a subject of an appropriate distance for the lens. For your 200, maybe take a picture of a brick house across the street. See if it looks sharp, when accurately focused in live-view. This will tell you what is wrong - the camera, or your technique.
this is a great idea (and simple.. shouldve thought of that!) thank you.
i will try it out very soon and post the pictures!


thank you everyone!

and really funny that theres a fellow Pentax shooter at the talk, i was figuring it was going to be mostly Canon/Nikon photographers!
03-12-2013, 03:53 PM   #11
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here are the photos of the lens with the adapter.
the third photo is where i am planning on putting the foil.
that looks right, right?
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03-12-2013, 04:51 PM   #12
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QuoteOriginally posted by Alec [k-x:
;2310477]that looks right, right?
No - you only need a small piece of foil, enough to cover the contacts on the camera body - screw in the lens part way (into the adapter that is mounted in the body), put the foil in, screw the lens the rest of the way.
03-12-2013, 05:50 PM   #13
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Btw, don't use "clarity" for sharpness. Go to the sharpness tab and add "detail" and "sharpness". Clarity affects all sorts of things.
And for CiF yes, you need to short the contacts. If your lens covers them but doesn't short them, add foil. Make sure the AF switch on the camera is actually set to AF. Otherwise CiF is disabled. You might also need to set Focus confirm priority over shutter priority. Also, CiF will fire at different moments depending on whether you reach focus going from infinity to close or for close to far. And the lens will appear soft if you are moving the focus while photographing. You can try turning off CiF and going by focus indicators, or focus peaking (if your camera has that). You can even try zone focusing for some subjects, if you have enough available light.
03-12-2013, 06:54 PM   #14
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Get some Aluminum tape that is sold for ductwork, Home depot has some. It is very thin and wont come apart.
Cut a ring that will cover the base of the lens, stick it on and smooth it with a cloth, lasts a long time.

P.S.
This will also take care of the Metering, you will no longer have to dial in a + Ev to compensate.
03-12-2013, 09:46 PM   #15
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QuoteOriginally posted by Stone G. Quote
That's interesting. I tried a similar trick sometime ago on my S-M-C 135mm f/3.5 with common household alufoil glued on paper. I did get CIF but lost infinity focus. Did you sand or otherwise make the shim (much) thinner?
I did sand the outside a bit, but just to ensure proper contact between the lens and body contact points. The lens in the picture is actually a Cunor, and I have to use 2 shims on that one
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