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09-20-2014, 05:20 AM   #1
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Fed up. Ready to give Pentax the flick!

I purchased the K-5. I recently purchased the sigma 70-200mm because I want to get into pet photography. I am at a very expensive 3 day animal photography course and the results I am getting are terrible. The 7 other photographers here are Canon users and are all getting clear photos without a problem. I am using the same techniques etc, but my photos are not in focus. I am so frustrated that I just spent a fortune on a 70-200mm lens, and now just want to quit photography as I am so disillusioned. I should have made the switch before I bought the k-5 last year

I took 300 odd photos today. I am using back button focus (ie shutter button doesn't focus). I am very careful to make sure I focus right between the dog's eyes, yet in almost every photo a different part of the photo is in focus and the dog's face is blurry. I switched to my 50mm prime and had a fairly similar issue. Slightly better results with my Pentax 12-24, I think about 20% of them were in focus.

So frustrated!!!!!

Here is an example - ISO 400, 120mm, f2.8, 1/250

Any suggestions?

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09-20-2014, 05:28 AM   #2
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It suffers from back focus. You need to calibrate your sigma. The dog's ass is in focus but it's head is not. https://www.pentaxforums.com/forums/53-pentax-dslr-camera-articles/61385-auto...ent-hints.html
09-20-2014, 05:33 AM - 1 Like   #3
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I concur - this is definitelly a severe case of back - focusing problem. You are lucky having a K-5 and TONS of advice online - back in 2008 I had no idea what back focus was and yet my poor K10D was bacfocusing for like 4 years before I finally knew what to do , how to enter the dreadful Debug mode, etc..

You are in an easy position - simple calibrate the lens and it will take nice shots. Another thing is that expecting a tack sharp from f2.8 aperture with zoom lens is probably not a good idea. What I would do is (apart from going for a prime lens :P ) go to 135mm focal length ( or even more ) and put like F3.5 or F4 aperture. That will give you pleasant bokeh and great sharpness. ( You might need to go back a little , in order to get the whole subject in frame though ).

And last but not least - your shot is overexposed - at least 1/3rd of a stop ( more like 1/2 ) - that is further reducing clarity and sharpness and emphasizing the halos around all highlights . So my another advice is to dial in some exposure compensation and then adjust all nicely in PP.
EDIT: So just to put it simply - do not get angry with your gear, but embrace it's strenghts and weaknesses and do the following :

1) adjust your front / back focusing correction for your lens
2) dial in some compensation ( -1/3 or -1/2 of stop will do )
3) go for 135mm + and dial in something like f3.5 - f4 - to get sharpest results.
4) shutter speed around 1/200th of a sec should be doable with steady hands easily
5) do minor tweaks in PP

and finally 6) - enjoy tack and amazing shots ( remember to share some too :P )
Good luck !
09-20-2014, 05:37 AM   #4
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Looks like back focus to me as well. Looks sharp otherwise. I use this technique to calibrate auto focus: AF microadjustment for the 1Ds mark III, 1D Mk3, 5D Mk2, 7D, 1D X and it seems to work well.

Good luck!

09-20-2014, 05:55 AM   #5
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I think your lens is more of a problem than the camera, and in any case you can manually focus if you can visually see if your camera isn't focusing correctly ( sometimes I have to do this on my Canon and Nikon cameras when using sigma lenses) And in any case you colleagues will be using brand name lenses - brand name lenses when used on the cameras they are designed for will have an inherent advantage. The proprietary focusing protocols will be designed to work with the manufacturers cameras and lenses - but with third party makers things go pear shaped and protocols don't work as they are expected to.

QuoteOriginally posted by allie181 Quote
am very careful to make sure I focus right between the dog's eyes
Personally, I would have focused on the dogs collar because it is a high contrast target that is close to the plane of the dogs eyes and let the DOF at f/2.8 do the rest of the work.

Last edited by Digitalis; 09-20-2014 at 06:05 AM.
09-20-2014, 06:00 AM   #6
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Keep in mind the AF points are much larger than the little red overlays in the OVF.

One other thing you can try is using live view. Live view is slower, but it never suffers from back or front focus. It merely maximizes contrast.
09-20-2014, 06:02 AM   #7
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Thanks all. I will try and fix the back focus problem.

Manntax - thanks for the tips re the photo. I know it was all wrong. This was my first time going fully manual (rather than aperture or shutter priority), and I'd just been taught back button focusing and continuous autofocus, so trying all of that at once, while it was raining didn't make for the best conditions I'm preoccupied with the focusing problem at the moment. Once I have that fixed I can start concentrating more on settings etc.

09-20-2014, 06:10 AM   #8
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QuoteOriginally posted by allie181 Quote
...just been taught back button focusing and continuous autofocus
Back button focusing is great for moving subjects especially when combined with continuous autofocus - but bear in mind you should never use continuous AF when the subject isn't moving. Canon and Nikon DSLRs have an automatic switch that change between the two modes if motion (or a lack of it) is detected. Pentax only recently developed this protocol for the SAFOX AF system. The K5, being an older camera doesn't have this functionality.
09-20-2014, 06:10 AM   #9
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QuoteOriginally posted by allie181 Quote
Manntax - thanks for the tips re the photo. I know it was all wrong. This was my first time going fully manual (rather than aperture or shutter priority), and I'd just been taught back button focusing and continuous autofocus, so trying all of that at once, while it was raining didn't make for the best conditions I'm preoccupied with the focusing problem at the moment. Once I have that fixed I can start concentrating more on settings etc.
Great ! Let us know how you are getting on - I am sure you will be soon delivering some amazing dogs shots
09-20-2014, 06:14 AM   #10
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I agree, with the above, I recently went through the same thing with a Sigma 18-250. My wife complained the edge were soft. Everything was soft... I put a ruler down on the table and a target, and my camera was focusing 2 inches behind the target. I messed around, ended up setting the camera to +5. That seemed pretty good, although I'm not convinced it's bang on yet, but stopped down my subject is in focus.

K-5 pet image taken with a Tamron 90. A 70-200 is a pretty big lens for pets. I usually use my 18-135 outdoors.


K-3 and 18-135 remember 135 APS-c is 200 FF. Your lens probably should have been the 50-135, and you would shave smoked those dudes.


09-20-2014, 06:24 AM   #11
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can someone explain why it is thought that is the Sigma lens focus issue if he says he is having similar issues with his other lenses?
09-20-2014, 06:30 AM   #12
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All these issues with phase detect make me really appreciate my K01s contrast AF system. Can you switch to cdaf on the k3 or k5?
09-20-2014, 06:48 AM - 1 Like   #13
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Relax! Just a little time in a cool comfortable spot to adjust the back focus and you will be all set to shoot animals to your hearts content! Animals love a Pentax camera, take it from Otis, and we all know Otis is never wrong!
Hopefully you will make it your life's ambition to shoot handsome squirrels?


Regards!
09-20-2014, 06:59 AM   #14
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Goooood daaay Aillie
What are you doing taking portrates with a tele zoom for!!, as one of the other posters said use a short tele prime, the usual rule of thumb is as follows 50-70mm studio full lenght 70-100mm 2 thirds of body (or large dog) and finaly 135 face or head and shoulders, lets talk of Tims rule of depth of field (or front to back focus as our American cousins say), the rule is simple, if you have a 80mm lens shutdown to f8 and your subject is 8 foot away you have double "8" or about 16 inches of depth of field, so even if you fix the back focus problem you will need to adjust your settings/composure to get enough depth of field to cope, most large dogs are longer than 16 inches in body so even if you get the eyes in focus by the time the image hits the rear of the animal you will be out of focus again, so to increase the amount of focus field you have to use a smaller f stop or a shortter lens, most animal snappers shoot a side on shot with the animals head only turned towards the camera, all horse shots are like this if the whole animal is shot, my advice is to use a 90mm lens and shutdown to about f11 if you require a out of focus background buy one! yep use a studio backgound of foliage out of focus,
09-20-2014, 07:04 AM   #15
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QuoteOriginally posted by Rudy Quote
can someone explain why it is thought that is the Sigma lens focus issue if he says he is having similar issues with his other lenses?
I thought back focus issues when I heard it was with the 70-200mm.. then read further and said soft images with other otherwise not so soft lenses and wondered.

Either there is a back/front focus issue with all of your lenses (possible), the photographic technique needs some tweaking, or there is something wrong with the focusing system of that particular K-5 body.

Or a combination of the above.

At this point it is easier to just calibrate the 70-200 and see if that resolves the issue. If not, go from there (checking technique or considering the body has an issue).

That said, this issue can occur on any manufacturer's system. I mean there are hundreds of us on here sharing images and enjoying our Pentax cameras, so obviously we all don't have faulty systems producing soft images that we are living with. If it is a focusing issue it can be rectified one way or another.

On some (such as the Canon 60D) you can't even adjust back/front focus!!! I think you have to send the lens into support for adjustments (or find one that doesn't have the focusing issue). At least with your K-5 you can make those changes.
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