Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-18-2014, 04:08 PM   #1
Site Supporter
Site Supporter




Join Date: May 2014
Location: Minnesota
Photos: Gallery
Posts: 1,638
Pentax 20-40 f2.8-f4

Does anybody know at what focal lengths does the maximum aperture change on this lens.

08-18-2014, 04:50 PM   #2
Loyal Site Supporter
Loyal Site Supporter
imtheguy's Avatar

Join Date: Mar 2009
Location: Virginia Beach
Photos: Gallery | Albums
Posts: 2,950
QuoteOriginally posted by hjoseph7 Quote
Does anybody know at what focal lengths does the maximum aperture change on this lens.
On my K-5 it jumps from 2.8 to 3.5 at 24mm.
08-18-2014, 05:00 PM   #3
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 49,685
F3.5 is the maximum at 30mm- it seems to scale linearly.

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

08-18-2014, 05:08 PM   #4
Loyal Site Supporter
Loyal Site Supporter
imtheguy's Avatar

Join Date: Mar 2009
Location: Virginia Beach
Photos: Gallery | Albums
Posts: 2,950
QuoteOriginally posted by Adam Quote
F3.5 is the maximum at 30mm- it seems to scale linearly.
I forgot to add that it goes from 3.5 to 4.0 at 34mm. So there you have it;
20-23mm is f2.8
24-33mm is f3.5
34-40mm is f4

If thats what Adam meant by linear scaling then i now understand.

08-18-2014, 05:15 PM   #5
Site Supporter
Site Supporter




Join Date: May 2014
Location: Minnesota
Photos: Gallery
Posts: 1,638
Original Poster
Thanks !
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, 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: HD Pentax 20-40 mm F2.8-4 WR & 50-200 mm F4-5.6 WR lenses Vantage-Point Sold Items 6 09-12-2014 06:02 AM
Cock-eyed Sigma 20-40 f2.8 Wyzard Pentax DSLR Discussion 3 04-11-2008 02:56 AM
sigma 20-40 f2.8? OniFactor Pentax SLR Lens Discussion 3 03-25-2008 06:28 AM



All times are GMT -7. The time now is 04:22 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