Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
02-14-2010, 01:59 PM   #1
Forum Member

Join Date: Nov 2009
Location: Idaho
Posts: 95
Green Button Metering with Manual Lens

I'm in the process of trying to figure out the metering on my manual 50 f/1.7. I'm using the M mode on my K20D and using the green button to set the initial shutter speed. I saw a post the other day that mentioned the "Sunny 16" rule so I thought I'd try it out. Using f/16 at ISO 200, this guideline should put me at a speed of 1/250 (closest to 1/200). I found that's a bit underexposed, and that 1/180 seems to be the proper shutter speed with this lens. I hit the green button to see if it would set it to 1/180 rather than 1/250, and to my surprise, it set the shutter to 1/20. I tried various compositions, and the green button takes me to the 1/15-1/30 range. I stopped down to f/8 and found similar results. Here are a few examples (taken in full sun at round 1:00pm):

f/16, ISO200, 1/20 second (this is the speed the green button set)

f/16, ISO200, 1/180

f/8, ISO200, 1/30 second (this is the speed the green button set)

f/8, ISO200, 1/125

Why would my K20D's green button be setting the shutter so low? There's no exposure compensation, and I tried center-weighted and spot focusing, both of which had similar results.



02-14-2010, 07:21 PM   #2
Veteran Member
indytax's Avatar

Join Date: Jan 2009
Location: Indianapolis, Indiana, USA
Photos: Gallery
Posts: 312
No one definitively knows why some cameras meter inconsistently with pre-A manual lenses, but it's a well documented fact here in the Forums and elsewhere. The consensus is that the focusing screen causes a metering error with these legacy lenses. Some people have changed their screen to the one found in the *istD series cameras and found the metering to be improved. Do a search of the Forums and you will find many threads on the subject. My solution is to learn how your manual lenses meter and dial in EV comp (or adjusting shutter speed/ISO if in M mode on by K10D) as appropriate for the aperture.
02-14-2010, 11:15 PM   #3
Senior Member

Join Date: Jul 2008
Location: Sammamish, WA
Photos: Gallery
Posts: 161
Same with my K200D, I just shoot a few to get an Idea of what the proper speed should be looking at the Pic & Histogram....I shoot a ton with old manual lenses....
02-15-2010, 12:42 AM   #4
Forum Member

Join Date: Nov 2009
Location: Idaho
Posts: 95
Original Poster
Thanks for the replies indytax and JETninja. I should have been more diligent in using the search function. I think dialing in EV is the best solution. I'll put the lens to work to figure out what compensation for a given scenario. Thanks again.

02-15-2010, 06:07 AM   #5
Site Supporter
Site Supporter
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 17,144
the K10D and K10D have very poor metering with manual lenses.

I made the following using my *istD, K10D and K7D. It seems to be highy related to the focusing screen on the K10D and K20D (they are the same)


  • 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!
button, camera, dslr, f/16, f/8, iso200, lens, photography, results, shutter
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
Stop Down Metering With The Green Button: Wrong Exposure Recomendations Obs Troubleshooting and Beginner Help 55 03-27-2015 09:39 AM
Green Button Stop-Down Metering Acting Differently woefulwabbit Pentax DSLR Discussion 22 03-29-2011 09:56 PM
k10D metering with M lenses in M mode - K200D doing a better job w/ Green button mrpackerguy Pentax DSLR Discussion 8 10-03-2008 11:53 AM
K10D and Green Button Manual Lens Shutter Speed David Pentax DSLR Discussion 4 10-15-2007 12:41 AM
K/M Lenses, Manual Mode and the Green Button Sailor Pentax DSLR Discussion 14 02-15-2007 10:48 AM

All times are GMT -7. The time now is 01:01 PM. | 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]