Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-24-2008, 11:38 AM   #1
Forum Member




Join Date: Dec 2006
Location: Bloomington Ca.
Posts: 84
How do you know if your lens is focusing right?

I bought a 17-70 Sigma DC lens awhile ago. It takes very good pictures up close but anything longer just isn't as sharp to me. It's not bad but It seems to me it should be better. I use it on a K200. Is there a card that I can shoot to see how the focus is or are there other ways? How long does Sigma warranty the lens and will they recalibrate it if it needs it?

I'm still a bit of a newbie with slr's and need help at times.

Thanks

04-24-2008, 11:57 AM   #2
Veteran Member
247nino's Avatar

Join Date: Sep 2007
Location: Sunnyvale, CA
Photos: Gallery
Posts: 302
try this
test chart

http://www.focustestchart.com/focus21.pdf
04-24-2008, 12:11 PM   #3
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,400
QuoteOriginally posted by hmcfly Quote
I bought a 17-70 Sigma DC lens awhile ago. It takes very good pictures up close but anything longer just isn't as sharp to me. It's not bad but It seems to me it should be better. I use it on a K200. Is there a card that I can shoot to see how the focus is or are there other ways? How long does Sigma warranty the lens and will they recalibrate it if it needs it?

I'm still a bit of a newbie with slr's and need help at times.

Thanks
I would post a sample of your photos, including the EXIF data (i.e. shutter speed and fstop etc)

I guess the question is, if it takes good photos up close, will testing using a focusing chart actually help.

SHow us what is wrong in a photo.
04-29-2008, 04:24 PM   #4
Forum Member




Join Date: Dec 2006
Location: Bloomington Ca.
Posts: 84
Original Poster
Here are two I took on Vacation The first one is focused on the men in the dock.
The second one is focused on thatched hut. It may just be me but they don't looked real focused or it's the way I'm taking them. I use Point and shoot most times on the P mode. The last one looks better in focus than the others but it's lots closer

Attached Images
     
04-29-2008, 10:03 PM   #5
Veteran Member
wlachan's Avatar

Join Date: Sep 2006
Location: Canada
Photos: Albums
Posts: 2,626
Can't help you much w/o checking the gears in person but there are 2 possible reasons that any lens might not AF as expected. 1) Each AF sensor of any Pentax DSLRs covers quite a large area and is attracted to higher contrast (and often the background), 2) the AF sensor might not be centred perfectly. What these mean is that the camera might AF properly but not seeing what you think it is seeing.
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!
k-mount, lens, pentax lens, sigma, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Focusing manual lens with OEM focusing screen, is a split screen really needed? skid2964 Pentax Camera and Field Accessories 16 09-17-2010 02:54 PM
Trouble focusing with M lens garfield160 Pentax SLR Lens Discussion 13 06-22-2009 09:00 PM
Lens Focusing Problems craig1024 Pentax SLR Lens Discussion 9 11-14-2008 05:05 PM
Focusing and manual lens... schmikey Pentax DSLR Discussion 22 08-24-2007 06:13 AM
Lens not focusing apete12 Pentax DSLR Discussion 9 08-11-2007 09:02 PM



All times are GMT -7. The time now is 04:46 AM. | 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