Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-31-2009, 10:03 AM   #1
Junior Member
switch's Avatar

Join Date: Dec 2008
Location: Hungary
Photos: Gallery
Posts: 26
Pentax DA 100/2.8 macro lens problem

This picture was taken from my new, unused Pentax F/DA 100/2.8 macro lens' aperture blades. Clearly wisible, the a circle is not round, assymetrical instead.
My question is: this is bug, or feature?!
100/2.8 macro owner's answers are welcome.
Thank you.

Attached Images
 
08-31-2009, 10:14 AM   #2
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,678
Usually, aperture openings are designed to be geometrically symmetrical.
AFAIK all my good lenses are quite regular in this regard, and I have a couple of older no-name brand lenses that look similar to your photo above. Though I couldn't tell you if it is a defect in the lens.
Does it affect your photo quality? Can you have it looked at by the vendor you bought it from?
08-31-2009, 10:31 AM   #3
Veteran Member
octavmandru's Avatar

Join Date: Jan 2009
Location: somewhere around
Posts: 615
there was a thread somewhere about this. Seems it is quite common
08-31-2009, 10:45 AM   #4
Veteran Member
Pentaxor's Avatar

Join Date: May 2009
Location: Vancouver, B.C.
Photos: Gallery
Posts: 6,513
it should be symmetrical. I think some of the blades are misaligned. and I do believe it would affect the outcome of your shots. particularly the precise amount of light that goes thru and could even affect bokeh results as well.

the best thing would be to bring the lens to the shop where you bought it and compare it to the other lens they have in stock.

08-31-2009, 10:58 AM   #5
Junior Member
switch's Avatar

Join Date: Dec 2008
Location: Hungary
Photos: Gallery
Posts: 26
Original Poster
QuoteOriginally posted by octavmandru Quote
there was a thread somewhere about this. Seems it is quite common
Hi! Can you help me to search that thread? My english is not so good, and I not properly understand the forum's search engine. Thank you.
08-31-2009, 11:46 AM   #6
Veteran Member
octavmandru's Avatar

Join Date: Jan 2009
Location: somewhere around
Posts: 615
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/41357-cosina-5...2-club-20.html
08-31-2009, 11:50 AM   #7
Pentaxian
8540tomg's Avatar

Join Date: Feb 2008
Location: Waterloo, Ontario
Photos: Gallery
Posts: 4,444
QuoteOriginally posted by switch Quote
This picture was taken from my new, unused Pentax F/DA 100/2.8 macro lens' aperture blades. Clearly wisible, the a circle is not round, assymetrical instead.
My question is: this is bug, or feature?!
100/2.8 macro owner's answers are welcome.
Thank you.
Switch,

I just took a look through my A 100/2.8 macro and the blades are perfectly symetrical. Looks like a flaw to me. If this is a brand new lens I would send it back and ask for another one.

Tom G
08-31-2009, 06:29 PM   #8
Site Supporter




Join Date: Jan 2008
Location: Fly-over, USA
Photos: Gallery
Posts: 1,169
Hmmmmmm...??

Mine appears to be a perfectly balanced opening, when I look straight into the lens. If it's a tiny bit off center, or not square with my eye, it can look distorted.

Also, may I ask what it looks like from about F/4.0 to (say) F/16, the len's sweet-spot range? Is the opening still distorted? If it's balanced, what's the problem?

Cheers...

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, macro, macro lens, pentax, pentax da, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
FA 100 macro problem? Pentaxor Pentax SLR Lens Discussion 15 07-16-2009 05:47 AM
Macro lens for insects (Tamron 90 / Sigma 105 / Pentax 100) ? JeanChris Pentax SLR Lens Discussion 38 05-12-2009 03:51 AM
For Sale - Sold: Pentax SMC-A 100/4 macro lens heatherslightbox Sold Items 14 10-25-2008 07:39 PM



All times are GMT -7. The time now is 03:17 AM. | See also: NikonForums.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