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01-08-2007, 01:18 AM   #1
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black sweater looks purple.....Hot Mirror Filter???

I took a few pics the other day where the subject had a black sweater on but in the pics the sweater looked purple... this was under indoor lighting but its not a yellowish light like most bulbs.. its brighter and whiter but ither way i set the white balance manualy...

i remember reading on here somewhere i think that a hot mirror filter would fix this issue.....

from what i've read hot mirror filters block out infrered light which can cause decrease in IQ..... but i also read that most DSLR cameras have a built in filter that fixes this issue.... but im not sure if my pentax k100d does making it pointless to get a filter for it...

so is this problem easily fixed with a hot mirror filter?? and if so does anyone know where i can get a 52mm???

01-08-2007, 08:54 AM   #2
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2filter.com.
01-11-2007, 09:15 AM   #3
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Increative,

Sorry, I don't know about hot mirror filters, never tried them yet.

As for the WB thread tips, I think this is what you are looking for.

https://www.pentaxforums.com/forums/pentax-dslr-discussion/1844-manual-white-balance.html

Cheers!
01-13-2007, 12:40 AM   #4
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Original Poster
^ no im fine with the white balance... the white balence isn't the problem... the problem is that everything else in the picture looked great except for a black sweater that turned out looking purple.

01-13-2007, 07:18 AM   #5
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UV Filter

Purple to me sounds like some UV light, not IR
Some lights give off UV in thier atempt to add blue, to emulate daylight more closely, and certain fabrics and surfaces are uv reflective

I keep a UV filter on all my lenses perminently, both to protect them (its cheep to replace a filter) and to block the exact problem you have

My sleeping bag and tent both look purple if i dont have the filter on

Hope this helps :P
01-15-2007, 08:56 PM   #6
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Most wedding contracts specifically have a clause that says that the colors in the photographs may or may not match the perceived colors of the clothing the party is wearing. This goes all the way back to the film days.

Film (or sensors) don't respond to colors exactly as the human eye. Plus factor in the effect of ultraviolet light, and you have metamerisim. A well known and documented problem in photography, printing, paint formulations, dyes, and other color applications. Google it.
02-02-2007, 10:31 PM   #7
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The K100D has a weak IR filter, similar to the Nikon D70. I own both and they both have a tendancy to turn black fabrics reddish or purple. While this is annoying in color, it makes for some unbelievable BW conversions because the blacks will have much more texture. The K100, when fitted with the appropriate filter, would probably make a good IR camera.

I haven't tried a hot mirror filter because the problem doesn't really bug me but I've heard it works on the D70 so it would probably work on my Pentax as well.
02-07-2007, 01:10 PM   #8
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I used to get this problem with film images from time to time and I've seen this problem in a few of my digital images as well.

The reason that many black fabrics can sometimes show up purple, or red, or sometimes even green is that virtually all black dye is not "true" black ... it's actually just VERY dark purple, red, blue, or green.

It's easier to end up with black fabrics looking purple or another color if the light reflecting off the fabric is strong ... and depending on the wavelength of the light being reflected you can end up with some funky colors.

I did a shoot of Cheer detergent a year or two ago where I had to photograph a little black dress and the first few attempts came out with the black dress looking radioactive purple. I changed the lighting and I might have also made some adjustments in Photoshop if I recall correctly ... but the end result was a black dress.

05-07-2007, 07:20 AM   #9
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As an owner of the K100D I've noticed this problem myself. Seems like even Leica has issues with this. Anyway, is it an UV/IR-filter that one should invest in to correct these problems? Maybe from Hoya?
05-07-2007, 09:07 AM   #10
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QuoteOriginally posted by JJJPhoto Quote
I used to get this problem with film images from time to time and I've seen this problem in a few of my digital images as well.

The reason that many black fabrics can sometimes show up purple, or red, or sometimes even green is that virtually all black dye is not "true" black ... it's actually just VERY dark purple, red, blue, or green.

It's easier to end up with black fabrics looking purple or another color if the light reflecting off the fabric is strong ... and depending on the wavelength of the light being reflected you can end up with some funky colors.

I did a shoot of Cheer detergent a year or two ago where I had to photograph a little black dress and the first few attempts came out with the black dress looking radioactive purple. I changed the lighting and I might have also made some adjustments in Photoshop if I recall correctly ... but the end result was a black dress.
This is an excelent post. A lot of the modern synthetic fabrics will look funny in digital images because of this. Black polar fleece for example will have a reddish sheen due to the way the fibers trap and reflect light.

A really good exercise is to biew a bunch of black objects under direct light and note the variations in color between them. They will all look 'black individually but together they will exhibit all sorts of color variations.

As a painter as well as a photographer one of my maxims is "black is never black"
05-11-2007, 11:34 AM   #11
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At last - An affordable M8! (sorry, couldn't resist)
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