Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-28-2012, 12:38 PM   #1
Site Supporter




Join Date: Feb 2008
Location: Boston MA
Photos: Gallery | Albums
Posts: 273
Tungsten Front Focus - Possible Solution

I know this subject has been beaten to death, but I would like to share my experience on this.

My K-5 is clearly having the front focus issue under tungsten light, which is unfortunate. I happen to have a infrared cut filter (Hot Mirror like this one Hot Mirror Filters Press Release ) and put that on the lens to see what happens.
basically three things happen.

1 Its low tungsten light front focus issue is pretty much gone
2 Its low light focusing capability is significantly reduced (minimum light required to be able to focus is increased)
3 Lot more hunting as if it was much darker in the room under dimmed conditions

It was tricky to set the minimum amount of light that the camera would still focus with a IR cut filter on the lens while showing the front focus without the IR cut filter. I simply use the dimmer on my tungsten ceiling light to dim the room and then I shoot various subjects.

I have a feeling the issue is related to the IR sensitivity, however, my K10D does not show this problem, which is interesting.

From my IR photography I do, using a modified K10D, I know there is a focus shift when shooting IR, which is how I came up with the idea.

I just thought this is interesting, and hope the future K-5 replacement will not have this problem.

Eric

04-28-2012, 12:45 PM   #2
Pentaxian




Join Date: Jan 2012
Location: Slovenia
Posts: 2,141
Well, that's interesting. You listening Pentax?

Mental note: try out when camera received.
04-28-2012, 01:03 PM   #3
Inactive Account




Join Date: Mar 2012
Photos: Albums
Posts: 100
Eric, did you happen to notice if the IR cut filter also helped reds and oranges from becoming oversaturated?
04-28-2012, 01:34 PM   #4
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
Old news, ricehigh i believe already did this test.

found it with the Kr but that one uses the same AF.
http://ricehigh.blogspot.com/2011/12/deeper-technical-investigation-into-k_16.html


Last edited by Anvh; 04-28-2012 at 01:43 PM.
04-28-2012, 02:40 PM   #5
Site Supporter
Jean Poitiers's Avatar

Join Date: Apr 2011
Location: Lost in translation ...
Photos: Gallery | Albums
Posts: 16,376
Merci ...

Thanks for your post ... always good to see solutions!

Salut, John le Frog
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!
camera, dslr, filter, focus, k-5, k-5 ii, k-5 iis, k10d, k5, lens, light, pentax k-5, tungsten
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K-5 low/tungsten light front focus issue with latest firmware, send to CRIS? jeffshaddix Pentax K-5 37 11-06-2012 03:28 PM
Incadescent and tungsten front focus: how much autofocus fine adjustment? Eruditass Pentax K-r 7 10-20-2011 09:46 AM
A-lens front focus but kit lens ok - Why and solution? LIJ Pentax K-r 7 05-25-2011 06:25 AM
Proposed solution to Tungsten Front Focus laissezfaire Pentax DSLR Discussion 6 01-20-2010 10:59 AM
Front Focus and tungsten light question Big G Pentax DSLR Discussion 8 01-18-2010 12:25 PM



All times are GMT -7. The time now is 01:03 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