Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-26-2012, 06:39 AM   #1
Veteran Member
ihasa's Avatar

Join Date: Jul 2009
Location: West Midlands
Photos: Gallery
Posts: 2,054
FA28-70mm lens flawed?

I picked up a superb condition FA28-70mm f4 last week, and was just trying it out today. There seems to be an issue in that at wider FLs, there is a bleary unclear portion of the image. Not off to one side, or in the corners, like you commonly see, but just below the middle of the shot. Where the telephone cables cross the road in the image below. There does not seem to be anything inside the lens that is causing this - everything looks crystal clear in there.





I have tried several times, adjusting focus, with similar results.

This is only a cheap lens, and I can probably send it back, but I just wondered whether the forum members could shed any light on this.

10-26-2012, 06:51 AM   #2
Site Supporter
victordeamorin's Avatar

Join Date: Sep 2010
Location: Lyon area
Photos: Gallery
Posts: 205
The FA28-70 is known for being prone to element separation in the rear group. I had one like that myself but in my case the whole frame was very soft at all apertures.
Check if you see some white fog or haze when you look through the lens wide open with a light. It should be very easy to see if that causes the problem.
Try another sample, apart from that issue it's a fine little lens!
10-26-2012, 10:26 AM   #3
Site Supporter
JimJohnson's Avatar

Join Date: Jan 2012
Location: Lake Superior - Michigan
Photos: Gallery
Posts: 2,270
Do you use a lens hood or do you use a protective filter? If the issue isn't the above mentioned element separation, I would suspect a flare issue. Flare can best be avoided by using an appropriate lens hood and (with or without a hood) avoiding the use of any extra optical surfaces in front of the lens.
10-26-2012, 10:35 AM   #4
Veteran Member
westmill's Avatar

Join Date: Jan 2012
Location: Stoke on Trent
Photos: Gallery | Albums
Posts: 1,146
It looks like it could possibly be a spot of condensation on the centre of one of the convex lenses. If that was the case, I would expect it to dissapear within a few hours. Otherwise I would say the lens is faulty and I would ask for an exchange unit if possable.

10-26-2012, 03:26 PM   #5
Veteran Member
ihasa's Avatar

Join Date: Jul 2009
Location: West Midlands
Photos: Gallery
Posts: 2,054
Original Poster
Thanks for the responses. No filter (or hood) was used, but I will take more shots and see if it improves.
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!
fa28-70mm, image, k-mount, lens, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale - Sold: MZ-5N Modern Classic Autofocus Film Body, FA28-70mm f/4 violini Sold Items 2 09-21-2011 04:40 PM
For Sale - Sold: Pentax FA28-70mm/4 & Helios 58mm/2 (AUS) ddhytz Sold Items 11 07-06-2009 03:14 PM
flawed lens? rpriedhorsky Pentax SLR Lens Discussion 17 05-11-2009 04:17 PM
For Sale - Sold: A flawed diamond: Pentax SMC-A 50/2.8 Macro..with oil on the blades :-( dumrox Sold Items 5 01-27-2009 03:46 PM



All times are GMT -7. The time now is 08:01 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