Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-11-2015, 02:28 AM   #1
Pentaxian
Paul the Sunman's Avatar

Join Date: Aug 2011
Location: Melbourne
Photos: Gallery
Posts: 1,268
Great Sigma 35mm Exposure Mystery Solved! Auto EV Compensation on the K3

I have mentioned several times in these forums that my Sigma 35mm f1.4 Art habitually overexposes by between 0.7ev and 1.7ev on my K3, especially outdoors in natural light. It's been driving me crazy. None of my other lenses do this (6 Pentax and 1 Tamron).

Well, I think I've solved it (sort of). There is a basically undocumented setting in the C1 menu page: "Auto EV Compensation". All the K3 manual says is "Sets whether to automatically compensate when the proper exposure cannot be determined".... whatever that means. For some reason, I had this turned on. I don't know why, in fact I didn't even know it was there. Testing in both dull and bright natural light since turning it off sees the Sigma 35mm exposing pretty much the same as my other lenses, i.e., correctly.

But that still begs a couple of questions:
  1. What is this "Auto EV Compensation" setting supposed to do?
  2. Why did it screw up the Sigma but leave all other lenses untouched?
Any theories?

01-11-2015, 03:20 AM   #2
Forum Member




Join Date: Jan 2014
Posts: 98
C6 is the setting specially designed to confuse us to death!

No seriously, I've read the manual and looked in the menu and I can't make head nor tail of it either! I get the impression that neither did the author, he just translated it! Best leave it off! Perhaps someone who has the read the manual in Japanese might have a more appropriate translation!

Last edited by Dave's clichés; 01-11-2015 at 03:25 AM.
01-11-2015, 05:07 AM   #3
Pentaxian
Fogel70's Avatar

Join Date: Sep 2009
Location: Stockholm, Sweden
Photos: Albums
Posts: 1,748
"Auto EV Compensation" is used to let the camera compensate exposure if the available exposure will give an over/under exposure.

FI if shooting with a fast lens wide open in very bright light using AV-mode, then the camera might not have fast enough shutter speed to avoid over exposure. With "Auto EV Compensation" on, then the camera will stop down the lens enough to be able to capture the shot with correct exposure.

Last edited by Fogel70; 01-11-2015 at 05:25 AM.
01-11-2015, 07:50 AM   #4
Forum Member




Join Date: Jan 2014
Posts: 98
QuoteOriginally posted by Fogel70 Quote
"Auto EV Compensation" is used to let the camera compensate exposure if the available exposure will give an over/under exposure.

FI if shooting with a fast lens wide open in very bright light using AV-mode, then the camera might not have fast enough shutter speed to avoid over exposure. With "Auto EV Compensation" on, then the camera will stop down the lens enough to be able to capture the shot with correct exposure.
Well done Fogal70!

01-11-2015, 09:12 AM   #5
Pentaxian
Digitalis's Avatar

Join Date: Mar 2009
Location: Adelaide.
Posts: 8,795
I don't know why Pentax chose to hide an automatic exposure setting in the custom functions menu. I have always turned this "feature" off.

QuoteOriginally posted by Paul the Sunman Quote
Why did it screw up the Sigma but leave all other lenses untouched?
Because the transmission at each aperture setting is inaccurate. With pentax lenses, even old ones without lens/camera communication the aperture behaves in a certain way.
01-11-2015, 04:37 PM   #6
Pentaxian
Paul the Sunman's Avatar

Join Date: Aug 2011
Location: Melbourne
Photos: Gallery
Posts: 1,268
Original Poster
QuoteOriginally posted by Fogel70 Quote
"Auto EV Compensation" is used to let the camera compensate exposure if the available exposure will give an over/under exposure.

FI if shooting with a fast lens wide open in very bright light using AV-mode, then the camera might not have fast enough shutter speed to avoid over exposure. With "Auto EV Compensation" on, then the camera will stop down the lens enough to be able to capture the shot with correct exposure.
I don't believe that's what was happening in my case. The worst behaviour was in uniformly overcast conditions where the shutter speed was actually quite low. Nevertheless, clearly there is a mis-communication of some sort between the Sigma lens and the K3, and the camera for some reason decides to take a longer exposure than required if "Auto EV Compensation" is On.
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!
35mm, 35mm exposure mystery, dslr, ev, ev compensation, exposure, k-3, k3, lenses, light, pentax k-3, sigma, sigma 35mm art, sigma 35mm exposure
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
The 540 Flash with the k-3 Mystery....SOLVED! CeciProAm Pentax Price Watch 3 11-26-2014 02:50 PM
K3 Exposure Compensation Setting Bigdomino Pentax K-3 5 04-22-2014 06:15 AM
Exposure compensation with auto iso Big Bob Pentax K-01 2 05-07-2013 01:38 PM
Auto EV Compensation Billgscott Pentax DSLR Discussion 7 10-26-2011 11:07 AM
Auto EV Compensation Workingdog Pentax DSLR Discussion 18 09-17-2008 08:25 PM



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