Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-03-2008, 05:38 AM   #1
New Member




Join Date: Apr 2008
Location: Melbourne, Australia
Posts: 9
K200D and Sigma 24-60 horrible front focusing

I know there's threads on this already but I'm still a bit confused with how it all goes horribly wrong.

I just received a Sigma 24-60 f/2.8 EX yesterday. I purchased it off eBay.com from an American store and I live in Australia. It front focusses like there's no tomorrow at large aperture. In bright sunlight stopped down a fair bit it seemed to be of less concern. Plainly put though... I want to use my large-constant-maximum-aperture lens indoors in low light.

I was trying to shoot at a fashion show tonight and everything was out of focus. I'm fair raged about the whole deal.

I don't think I can claim it under warranty here in Australia. I don't even know if it's the fault of the body of the lens (my other 4 lenses focus fine all the time).

Please would anyone have advice on how to go about correcting this issue?

Thanks much,
Mike

09-03-2008, 05:55 AM   #2
Pentaxian
Clicker's Avatar

Join Date: May 2008
Photos: Gallery
Posts: 3,241
Have you tried different meter-modes? I find when i shoot auto defaults, not every scene is metered well, so i fine tune it thru the metered mode as per scene.
09-03-2008, 08:14 AM   #3
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by Clicker Quote
Have you tried different meter-modes?
he has an issue w/ AF, not w/ metering.
09-03-2008, 08:20 AM   #4
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by mikey55 Quote
I know there's threads on this already but I'm still a bit confused with how it all goes horribly wrong.

I just received a Sigma 24-60 f/2.8 EX yesterday. I purchased it off eBay.com from an American store and I live in Australia. It front focusses like there's no tomorrow at large aperture. In bright sunlight stopped down a fair bit it seemed to be of less concern. Plainly put though... I want to use my large-constant-maximum-aperture lens indoors in low light.

I was trying to shoot at a fashion show tonight and everything was out of focus. I'm fair raged about the whole deal.

I don't think I can claim it under warranty here in Australia. I don't even know if it's the fault of the body of the lens (my other 4 lenses focus fine all the time).

Please would anyone have advice on how to go about correcting this issue?

Thanks much,
Mike
Mike,

you have several options

1) sell the lens - but another one, no guarantee though that the issue
will be resolved...

2) send the body (and lens) to Pentax (not sure if they will agree to tune AF for Sigma lens) to adjust AF

3) sell K200D and buy either K20D or K10D (there you can try to correct
AF yourself)

PS: or wait until somebody will crack the access to K200D AF adjustment

09-03-2008, 09:08 AM   #5
Veteran Member
Denis's Avatar

Join Date: Jan 2007
Location: St-Albert, Alberta, Canada
Posts: 333
Make sure all contacts are clean.

First thing I would do is to try in manual mode and see the results. If all appear satifactory, try focus using AF "C" mode making sure the focus ring is in auto. Test focus by moving from infinity to a close objects, take a photo on both a few times. See if that focuses properly. If it works, try with the next focus mode "S".

If the lens fails to focus properly, it needs to be repaired.
09-03-2008, 09:17 AM   #6
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
What I would do:

First, download a good focus test chart like the one at focustestchart.com. Do a controlled test of each lens you have at its maximum aperture, using good (eg, outdoor) lighting. For a zoom lens, do it at several different focal lengths.

Then post the results here. My assumption is usually that any such problems are the fault of the camera - a misaligned AF sensor. The problem would only be visible at large apertures, as smaller apertures would create enough DOF to mask the problem. Which could be why some lenses don't appear to be affected. An AF-sensor-alignment problem would also probably manifest itself different at different focal lengths, which could also create variation between lenses.

Only after ruling out the body as the cause of the problem would I start thinking it was the lens, and even then I'd want to test it on another body to be sure.

If the problem is the body, it would normally be covered under warranty (all K200D's would pretty much have to be under warranty still, I would imagine), but I don't know how overseas transactions affect that. If the lens is new, then hopefully it will also be fixable under warranty, but obviously, same potential issue due to the overseas transaction.
09-03-2008, 09:21 AM   #7
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by Marc Sabatella Quote
My assumption is usually that any such problems are the fault of the camera - a misaligned AF sensor.
yeah, right... typically it is so magically misaligned that it manages to focus properly under the daylight and not under the tungsten light or vice versa...
09-03-2008, 07:00 PM   #8
New Member




Join Date: Apr 2008
Location: Melbourne, Australia
Posts: 9
Original Poster
I think I've done this right. I don't have a tripod. Not the best output for showing the fine details. Looks fairly front focusing to me though. I e-mail the vendor yesterday and they've promptly told me I can ship the lens back for an exchange. I would of course like to avoid this due to additional shipping costs. There is also the concern the body is making the error - so not much point in an exchange there. Anyways, here is what I came up with.

24mm f/2.8



39mm f/2.8



60mm f/2.8




Thanks for all the help thus far,
Mike

09-03-2008, 07:16 PM   #9
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by deejjjaaaa Quote
yeah, right... typically it is so magically misaligned that it manages to focus properly under the daylight and not under the tungsten light or vice versa...
I assume you're being sarcastic, but yes, different wavelengths of light are refracted differently, and hence differences in light color do affect what the AF sensor "sees" - *especially* if the sensor is misaligned.
09-03-2008, 07:19 PM   #10
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
Looks to me like there is a problem at the wide end especially. The long end looks much better, the middle somewhere between. But really, only the widest angle has the focus point really *out* of focus. Sure would be nice if you had another "fast" wide angle lens to compare with to be sure it isn't the body...
09-03-2008, 08:09 PM   #11
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by Marc Sabatella Quote
I assume you're being sarcastic, but yes, different wavelengths of light are refracted differently, and hence differences in light color do affect what the AF sensor "sees" - *especially* if the sensor is misaligned.
yeas, I was sarcastic - they do affect what the AF "sees" regardless of AF sensor alignment...
09-03-2008, 08:42 PM   #12
Veteran Member
deejjjaaaa's Avatar

Join Date: May 2007
Location: steel city / rust belt
Posts: 2,046
QuoteOriginally posted by mikey55 Quote
...
I had a chance to test that lens too (but on K20D) - here is what I have under
the daylight, see my posting in another thread

https://www.pentaxforums.com/forums/329300-post25.html

I checked 24mm->28mm->35mm->40mm->50mm->55mm->60mm
09-03-2008, 11:43 PM   #13
New Member




Join Date: Apr 2008
Location: Melbourne, Australia
Posts: 9
Original Poster
QuoteOriginally posted by deejjjaaaa Quote
I had a chance to test that lens too (but on K20D) - here is what I have under
the daylight, see my posting in another thread

https://www.pentaxforums.com/forums/329300-post25.html

I checked 24mm->28mm->35mm->40mm->50mm->55mm->60mm

Yes thank you. I read that thread over twice lol. I still didn't quite get from it what i needed i think. But it was most helpful nonetheless. I called my local service centre today and they were very understanding and suggested I bring it in to look at.

Even though it's a grey import they took the lens for calibration and have held on to the body just to double check. They're also going to clean my sensor it appears. All under warranty! I can't believe it. Absolutely amazing service here in Australia.

We'll see how it comes back in a couple of days...

Mike

Last edited by mikey55; 09-04-2008 at 12:57 AM.
09-04-2008, 07:54 AM   #14
Site Supporter
maxwell1295's Avatar

Join Date: Jan 2008
Location: Long Island, New York
Photos: Gallery
Posts: 2,704
That's a pretty bad front focus problem...

I have the exact lens with the same body (K200D) and it is the best camera/lens combo I have. Sharp as a tack. Of course, I have another K200D body that has a FF issue with anything wider than F2.8, so the Sigma works with that one too. I never mount my FA50 on that body though because the FF will rear its ugly head when I open it up.

If you have a problem with just that one lens, I think it's the lens' fault and not the body. Take your fastest (widest aperture) lens and open it up using the same chart. I'm curious as to how that tests out. At least you'll find out for sure where the problem lies.
09-04-2008, 10:58 AM   #15
Inactive Account




Join Date: Nov 2007
Location: US
Posts: 41
I'm just about to send back my third Tamron 28-75mm, two had FF one had BF, along with some other issues. I've got a K200D, I tested a 77mm ltd and that was spot on, so it must be the Tamrons. The focus charts are similar to yours.

Interestingly BH have refused to pay for return postage as they say they tested the previous two I returned and found nothing wrong with them.

I have the pictures and charts I took as a record of those lenses. But I don't like to feel like I'm being made out to be a bad customer because I was supplied with what to me were deficient lenses.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
australia, bit, camera, dslr, focus, front, lens, photography, sigma
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
My new K-x is front focusing, now what? skid2964 Pentax DSLR Discussion 19 11-01-2009 11:16 AM
K200D Focusing (Sigma 24-60 EX/DG) jk333 Pentax DSLR Discussion 14 03-21-2009 11:45 PM
Front Focusing Done to Death NorrisTudor Pentax DSLR Discussion 42 12-08-2008 04:22 PM
Front Focusing - K200D + Tamron 28-75 - Who do I contact? cputeq Pentax DSLR Discussion 13 06-19-2008 09:48 PM
Front Focusing Mark Castleman Pentax DSLR Discussion 23 01-27-2007 06:24 PM



All times are GMT -7. The time now is 02:07 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top