Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-02-2016, 02:39 PM   #1
Forum Member




Join Date: Apr 2010
Location: Las Vegas
Photos: Gallery
Posts: 62
Sigma 28-105 Image Distortion

Greetings. I recently purchased a Sigma 28-105 3.8-5.8 UC-III. I have very bad image distortion at the long end. Straight edges come out jaggy. Anyone have any ideas why this is? I’ve never experienced this in a lens.

Attached Images
 
05-02-2016, 03:23 PM   #2
Veteran Member
RollsUp's Avatar

Join Date: Apr 2008
Location: AK USA
Photos: Gallery
Posts: 1,766
Looks like an effect from heat to me. What was the temperature at the time you took this?
05-02-2016, 04:15 PM   #3
Site Supporter
Site Supporter




Join Date: Sep 2010
Location: Blue Hill, Nebraska
Photos: Gallery
Posts: 494
I agree. Looks like atmospheric distortion (heat waves).
05-02-2016, 04:25 PM   #4
Forum Member




Join Date: Apr 2010
Location: Las Vegas
Photos: Gallery
Posts: 62
Original Poster
QuoteOriginally posted by RollsUp Quote
Looks like an effect from heat to me. What was the temperature at the time you took this?
Never thought of that. The temp was only around 78 deg., however. I’ve taken many images with other lenses in 100+ deg. here in the desert and have never had this issue. I’ll keep playing with the lens. The aperature value didn’t seem to help either. Thanks for your reply.

05-02-2016, 04:29 PM   #5
Senior Member




Join Date: Oct 2007
Posts: 145
QuoteOriginally posted by iClick Quote
Never thought of that. The temp was only around 78 deg., however. I’ve taken many images with other lenses in 100+ deg. here in the desert and have never had this issue. I’ll keep playing with the lens. The aperature value didn’t seem to help either. Thanks for your reply.
Probably a lot asphalt between you and the store, radiating heat.
05-03-2016, 12:47 AM   #6
New Member




Join Date: Dec 2009
Location: Atlanta, Georgia
Posts: 24
The greater the distance, the greater the thermal "heatwave" effect will be. And you note the effect is greatest at the long end of the lens, which is when the distances tend to be the greatest as well.
05-03-2016, 09:13 AM   #7
Forum Member




Join Date: Apr 2010
Location: Las Vegas
Photos: Gallery
Posts: 62
Original Poster
QuoteOriginally posted by gavinhw Quote
Probably a lot asphalt between you and the store, radiating heat.
Actually everyone’s suggestion that it is a result of heatwave makes a lot of sense now. I was waiting in a drive thru at a bank and I snapped a few quick shots straight through the windshield. I bet the “heatwave” was coming from the hood of the car. I’ll have to go back out there and try again...this time not shooting over the car. If this turns out to be the case, I will be very pleased that it’s not a defective lens.


Last edited by iClick; 05-03-2016 at 09:21 AM.
05-03-2016, 02:21 PM   #8
Forum Member




Join Date: Apr 2010
Location: Las Vegas
Photos: Gallery
Posts: 62
Original Poster
QuoteOriginally posted by iClick Quote
Actually everyone’s suggestion that it is a result of heatwave makes a lot of sense now. I was waiting in a drive thru at a bank and I snapped a few quick shots straight through the windshield. I bet the “heatwave” was coming from the hood of the car. I’ll have to go back out there and try again...this time not shooting over the car. If this turns out to be the case, I will be very pleased that it’s not a defective lens.
Tested the lens again. This time not over the car hood. That appears to have been the problem. The lens is actually pretty decent for the price I paid. Thanks everyone for your input.
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!
28-105mm f/3.8-5.6 uc-iii, distortion, image, k-mount, pentax lens, sigma, sigma 28-105 image, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K20D + Sigma 28-105 alexvaras Pentax DSLR Discussion 2 09-23-2008 11:41 PM
For Sale - Sold: Tamron 28-70, Sigma 28-105, Pentax 80-200 khardur Sold Items 2 09-25-2007 08:14 PM
Sigma 28-105 for K10D Kemal Pentax SLR Lens Discussion 2 02-16-2007 08:49 AM



All times are GMT -7. The time now is 02:23 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