Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
11-02-2010, 05:23 AM   #1
Junior Member

Join Date: Oct 2009
Location: Chaska, Minnesota
Posts: 43
"A" MF Lenses

I've picked up three A lenses to complement the two kit AF lenses I carried over from my film SLR. The question is; what are the orange colored buttons on the A lenses? They seem to not have any purpose and are not on my AF lenses.

11-02-2010, 05:28 AM   #2
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 16,528
what lenses are they.

Lenses with an A in the aperture ring are for automatic exposure modes. When in the A position the camera controls the aperture setting. and this allows matrix metering, P-TTL flash and auto exposure modes.

when the aperture ring is out of the A position, you need to have the function "Use Aperture Ring" enabled, and then the lenses can only meter in manual mode with the green button or equivelent
11-02-2010, 05:31 AM   #3
Loyal Site Supporter
Loyal Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: North Syracuse, NY
Photos: Gallery
Posts: 15,672
They are just to provide a little extra grip when you are mounting/unmounting the lens.
11-02-2010, 05:33 AM   #4
drougge's Avatar

Join Date: Jan 2010
Location: Malmö
Photos: Gallery
Posts: 787
You press it to make it possible to move the aperture ring on or off the A setting. Your AF-lenses probably have the same button (unless they're FAJ or DA lenses), but without the colour.

This is of course assuming you're actually talking about a button, and not the index bump as boriscleto thinks.

11-02-2010, 05:46 AM   #5
Junior Member

Join Date: Oct 2009
Location: Chaska, Minnesota
Posts: 43
Original Poster
Boriscleto got it...I'm refering to the Orange button not the one to release the aperture ring. Thanks
11-02-2010, 06:12 AM   #6
Senior Member
sajah's Avatar

Join Date: Mar 2009
Location: South Korea
Photos: Gallery
Posts: 275
It's there to help you aligning the lens when you're going to mount it. So its purpose is similar to the red dot on the lens mount and the red dot on the mount plate (of camera body). But of course you don't align it directly to red dot on the camera mount plate. I don't have my lenses at the moment but you can try yourself and once you did you'll know where to align it in order to mount the lens, without looking at or trying to find the red dot. Useful when it's dark so you can't easily see the red dot.
11-02-2010, 06:29 AM   #7
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 16,528
If he is referring to pentax A lenses or any pentax K mount lens, and the orange/yellow/white Bump on the lens,. it is alligned to the lens release lever when the lens is in the position to insert the bayonet. This is so you can mount the lenses by feel, in the dark.

  • 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!
af, camera, lenses, pentax help, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
Sports "Highside Exit" took 1st Place in DPReview "Missed It by THAT much, Part 1" Challenge MRRiley Post Your Photos! 27 02-21-2010 08:26 PM
For Sale - Sold: 2 18-55mm kit lenses ("L" and "AL II" version) dgaies Sold Items 5 12-28-2009 07:58 AM
K-7 and metering with "K" and "M" lenses NaClH2O Pentax DSLR Discussion 17 07-18-2009 09:00 PM
Original "K" and "M" lenses wlank Pentax SLR Lens Discussion 1 08-31-2008 11:00 AM
"Hunger for a DA*50-135?" or "The DA*50-135 as a bird lens!" or "Iron age birds?" Douglas_of_Sweden Post Your Photos! 4 08-13-2008 06:09 AM

All times are GMT -7. The time now is 08:07 AM. | See also:, 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?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]