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06-07-2011, 11:57 PM   #16
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QuoteOriginally posted by mikknu Quote
I would blame the lens, was it not because I have had these same problems with the Pentax DA* 16-50 and the Tamron Dii 17-50. Also, last weekend, my Sigma 70-200 HSM II seemed to struggle.
If you have focusing issues with multiple different lenses then surely something's wrong with your camera or you're doing something wrong. Maybe you just need to calibrate your lenses.

QuoteOriginally posted by mikknu Quote
Also, I'm uploading a picture of the CA in the sigma 30 mm below:
That doesn't look sharp, I guess focus is off. Maybe try a shot in LV mode with contrast AF, that surely rules out FF/BF.

I'll try to find a backlit photo shot wide open (or snap one on the balcony) when I get home.

06-08-2011, 12:01 AM   #17
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QuoteOriginally posted by Sekul Quote
Wow, now im scared to recieve my 30mm, its almost 50% chance to get dud.
Come on, get real. Just because you read one problem (which may be user error or camera issue at this point), suddenly you have 50% chance to get dud? Pff... by that logic you have 90% chance to get a dud SDM lens and 50% to get a dud any FA/DA lens if you read this forum lol
06-08-2011, 10:53 AM   #18
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A small update, I handed in my K-5 and the sigma 30mm, so that the shop could send in both for calibration/repair, if they find anything wrong with it, that is. So hopefully it will reveal somthing.
06-08-2011, 12:43 PM   #19
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QuoteOriginally posted by mikknu Quote
A small update, I handed in my K-5 and the sigma 30mm, so that the shop could send in both for calibration/repair, if they find anything wrong with it, that is. So hopefully it will reveal somthing.
Hopefully.

Autofocus systems don't seem to do that well with fast lenses, and Pentax does not even have an exemplary autofocus system. It's not uncommon to be a little out of focus, and see a little CA because of that. Do you shoot RAW? RAW allows you to get out little imperfections like that much more simply than with JPEGs.

06-08-2011, 01:09 PM   #20
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QuoteOriginally posted by paperbag846 Quote
Hopefully.

Autofocus systems don't seem to do that well with fast lenses, and Pentax does not even have an exemplary autofocus system. It's not uncommon to be a little out of focus, and see a little CA because of that. Do you shoot RAW? RAW allows you to get out little imperfections like that much more simply than with JPEGs.
I don't in general shoot raws, though I know it is the better choice for the photoshop aftermath. But I guess I should start doing so.

Really, Pentax has a inferior Af system? That seems a pretty hideous flaw for a modern camera. I mean, AF seems quite essential, how else will you cap a sudden moment, where MF is not an option.

Do you know if Canon and Nikon fare any better with their AF systems here? I really thought cameras today acted quite similar.
06-08-2011, 01:21 PM   #21
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QuoteOriginally posted by mikknu Quote
Do you know if Canon and Nikon fare any better with their AF systems here? I really thought cameras today acted quite similar.
Nikon is generally thought to have the best AF system. The K5 is a big step up, but things like back-focus are still a problem. My FA 50 was *always* out of focus until I went and calibrated it.

This only applies to fast lenses. AF cameras have no problems with lenses in the f2.8 range and slower.
06-08-2011, 02:30 PM   #22
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QuoteOriginally posted by simico Quote
Come on, get real. Just because you read one problem (which may be user error or camera issue at this point), suddenly you have 50% chance to get dud? Pff... by that logic you have 90% chance to get a dud SDM lens and 50% to get a dud any FA/DA lens if you read this forum lol
Well, now I'm scared of never receiving the lens, has been a month since I ordered from B & H, lol.
07-06-2011, 09:12 PM   #23
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Update:
Got my K-5 and the Sigma 30mm 1.4 back yesterday and was only able to do little testing, but so far, there doesn't seem to be that much of a difference. At one point it did seem to focus correctly with F2.8, but then it went back to FB'ing again. Tried the lens on my K-x and even tho that did get some out of focus shots too, it generally seemed to nail the focus better than the K-5. I wonder if it could be because the K-x and Sigma 30mm don't have as big an age gap between them as with the K-5, I read somewhere that new cameras and old lenses, can cause problems, but not necessarily.

Anyway, will do some more testing today under more normal circumstances.

Edit: Should probably just mention that they found nothing wrong with the K-5 in the shop and there is no mention of how they tested it.


Last edited by mikknu; 07-07-2011 at 12:34 AM.
07-07-2011, 10:28 AM   #24
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Went out and shot some pictures in shade and in sunlight. It seems if I focus in any sort of shadow area, even if it is just a mild one, the AF gets it wrong. If I focus on an area in direct sunlight, it can uptain correct focus, but even then, it still back focuses. I forgot to bring my Pentax Kit lens to compare shots, but after I got home I did some tests with F4 stop and the Sigma focus failed pretty much all shots where the pentax kit lens set to 30mm F4 got it right.
To my horror I tested my sigma 70-200, which I have percieved to have done right by me on my K-x, had similar issues. So did my Sigma 105mm when I tried that on aswell. After constantly focusing and re-focusing, the Sigma 105mm suddenly started to get it right, which was kind of odd.

The short version is I still don't know if there is a problem with the K-5 or not.
I can just see that my K-x seems to focus better than my K-5 with sigma 70-200mm, Sigma 30mm and on the Sigma 105mm. Kit lens seems the same. Perhaps I should drop Sigma lenses and stick with Pentax only, tho I had some problems with the DA* 16-50, then again others have aswell with that.
Would be nice if I had a chance to test my K-5 with a Pentax prime I guess.
Maybe the 1.03 firmware did somthing, since it was only after that I really started to notice BF'ing. Should try and update to 1.1, maybe it will change somthing, eventhough it is not suppose to...
07-08-2011, 12:43 AM   #25
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Sounds like an issue with your K-5 and not the lenses. I have zero focusing issues with my K-5 and Sigma 30, Sigma 50-150 (and Pentax 16-50).

Did you reset the AF micro adjust values after fw update? After the last fw update I had to reset AF adjustments and check&set each lens again because AF was off after the fw update. I saw others reporting the same.
If possible, you should also try another K-5.
07-08-2011, 03:26 AM   #26
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QuoteOriginally posted by simico Quote
Sounds like an issue with your K-5 and not the lenses. I have zero focusing issues with my K-5 and Sigma 30, Sigma 50-150 (and Pentax 16-50).

Did you reset the AF micro adjust values after fw update? After the last fw update I had to reset AF adjustments and check&set each lens again because AF was off after the fw update. I saw others reporting the same.
If possible, you should also try another K-5.
I tired doing micro adjustments, but it didn't yield any benefits of notice. So I reset my adjustments after that, This was before updating to 1.1 firmware.

My K-5 is less than 3 months old and the Sigma 30mm is not even a month old. Gonna try and get my money back on the Sigma 30mm as it didn't do all that well on my K-x either and then see if I can get to try another K-5 model. Hopefully I'm entitled to that.
07-08-2011, 03:58 AM   #27
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Try auto-focus in live view mode, F2 or a bit narrower, with a high shutter speed (1/200 or quicker). Preferably on a tripod, with the 2 second timer.

If it's still blurry, the lens is dodgy.
If it's sharp, then try again with the calibration for "normal" AF and be patient this time.
07-08-2011, 04:48 PM   #28
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A number of comments:
  • The Sigma 30/1.4 is a great lens.
  • You need not make any concessions regarding its price. It just isn't overly expensive, but it is still an excellent lens. Note that the Pentax 50/1.4 was only $199 a few years ago. It was every bit as weak from f/1.4-f/2.2 and fantastic from f/2.8 upwards as it is today with its inflated price.
  • The Sigma lens is not "old" and should work perfectly well with a K-5 that has got a working AF.
  • All fast (f/1.4) lenses will show some CA/PF wide open. All cameras will struggle to AF at f/1.4 to some degree.
  • The test done by your dealer may or may not have any significance. Given that you have so many problems with so many lenses you either have a dud K-5 or have some problem properly using your equipment.
  • The AF points are (rather big) AF areas. It is possible for the camera to pick a place to focus on which you don't expect.
  • Try to systematically fine adjust a number of your lenses. Please see these AF adjustment hints. It is easy to do AF adjustment incorrectly and end up with incorrect settings.
  • The suggestion to try and use Live View (contrast AF) is a good one. It will help you to find out whether your K-5 has a phase AF issue and/or your lenses FF/BF.
While it is possible that your Sigma 30/1.4 has a problem, it does not look like this at the moment.

Note that ditching Sigma and going Pentax will not work if your K-5 has the problem, you use your equipment incorrectly, or you repeatedly get a dud Pentax DA* 55/1.4. A forum user went through five copies of that lens and still didn't get one that worked in terms of AF. He went for an FA 43/1.9 in the end.

Last edited by Class A; 07-08-2011 at 04:58 PM.
07-09-2011, 05:57 AM   #29
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QuoteOriginally posted by Class A Quote
A number of comments:
  • The Sigma 30/1.4 is a great lens.
  • You need not make any concessions regarding its price. It just isn't overly expensive, but it is still an excellent lens. Note that the Pentax 50/1.4 was only $199 a few years ago. It was every bit as weak from f/1.4-f/2.2 and fantastic from f/2.8 upwards as it is today with its inflated price.
  • The Sigma lens is not "old" and should work perfectly well with a K-5 that has got a working AF.
  • All fast (f/1.4) lenses will show some CA/PF wide open. All cameras will struggle to AF at f/1.4 to some degree.
  • The test done by your dealer may or may not have any significance. Given that you have so many problems with so many lenses you either have a dud K-5 or have some problem properly using your equipment.
  • The AF points are (rather big) AF areas. It is possible for the camera to pick a place to focus on which you don't expect.
  • Try to systematically fine adjust a number of your lenses. Please see these AF adjustment hints. It is easy to do AF adjustment incorrectly and end up with incorrect settings.
  • The suggestion to try and use Live View (contrast AF) is a good one. It will help you to find out whether your K-5 has a phase AF issue and/or your lenses FF/BF.
While it is possible that your Sigma 30/1.4 has a problem, it does not look like this at the moment.

Note that ditching Sigma and going Pentax will not work if your K-5 has the problem, you use your equipment incorrectly, or you repeatedly get a dud Pentax DA* 55/1.4. A forum user went through five copies of that lens and still didn't get one that worked in terms of AF. He went for an FA 43/1.9 in the end.
Thank you for that, I can see i have taken many of your points into consideration. I returned the Sigma 30mm becuase I just rather have my money back now instead of keep waiting to find out if the problem is with my K-5, especially when the Lens also seems a bit dodgey nor acts how I was expecting.
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