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View Poll Results: Should I adjust front focus under tungsten light. (for the poster's situation)
yes, I agree with your solution 1242.86%
no, I disagree with your solution 725.00%
I have no idea what you're talking about! 932.14%
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12-20-2008, 07:42 AM   #1
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Proposed solution to Tungsten Front Focus

Having just discovered the (already) forum documented front focus issue under tungsten lighting, I would like your thoughts on the following:

If I shoot a high % of shots under tungsten:

a) and my use of wide open apertures (f/1.4-2.8) is most likely under tungsten....

b) and if front/back focus is not a real world issue when shooting at f/5.6+ in natural light.....

Then, adjusting under tungsten, makes the most sense to me.

If I'm in a situation when I need to shoot wide open under natural light, then I could easily go to the custom menu and turn off the focus adjustment.

Do you agree?

here's my original thread:
https://www.pentaxforums.com/forums/pentax-dslr-discussion/44459-front-focus-could-bad.html

12-20-2008, 12:15 PM   #2
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I see I'm good company .

You can guess my answer from this response.
12-20-2008, 12:42 PM   #3
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QuoteOriginally posted by laissezfaire Quote
Having just discovered the (already) forum documented front focus issue under tungsten lighting, I would like your thoughts on the following:

If I shoot a high % of shots under tungsten:

a) and my use of wide open apertures (f/1.4-2.8) is most likely under tungsten....

b) and if front/back focus is not a real world issue when shooting at f/5.6+ in natural light.....

Then, adjusting under tungsten, makes the most sense to me.

If I'm in a situation when I need to shoot wide open under natural light, then I could easily go to the custom menu and turn off the focus adjustment.

Do you agree?

here's my original thread:
https://www.pentaxforums.com/forums/pentax-dslr-discussion/44459-front-focus-could-bad.html
Too complicated. Try a hot mirror filter (and step rings)
I'd like to track this thread's findings down a bit but don't have the time. This statement is interesting:
Makes sense, there is more IR in the sunny conditions reported as causing the prob on RG. The Pentax boys found that a hot mirror cured their tungsten lighting focus problems with the K100D. The filter is not sharpening the photo, it's changing the wavelength of the light hitting the AF sensors and according the OP, providing accurate focus.
Hot Mirror fixes 1D-III softness - FM Forums

BTW: I went fishing to see what I could catch..
http://forums.dpreview.com/forums/read.asp?forum=1018&message=30417808

Last edited by jeffkrol; 12-20-2008 at 12:56 PM.
12-20-2008, 01:00 PM   #4
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If someone would direct me to where to get up to speed on this, (Is the above-referenced thread enough preluse?) it's of significant interest to me, and I have a K20 and a 1.4 right here, and knowing about pushing the available-light AF could be my friend.

Only, I guess I need some tungstenish light bulbs. When we moved in here we filled the place with CF's.

06-17-2009, 11:47 PM   #5
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Did anyone try a blue colored filter (tungsten to daylight)?
01-18-2010, 03:22 PM   #6
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QuoteOriginally posted by asdf Quote
Did anyone try a blue colored filter (tungsten to daylight)?
Adjust your focus at daylight setting

Use an 80a filter to correct tungsten light (3200K) to daylight (5500K) - solves your problem.

Filter Wratten Number
01-20-2010, 10:59 AM   #7
Dom
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Probably not very helpful

Have you tried changing your light bulbs.
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