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08-18-2008, 09:31 AM   #1
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Disapointing results with K20D + Infrared

I have made some initial tests with my K20D and an Opteka IR filter. The results are disappointing, mostly due to the very long exposure times.

I've posted the results to smugmug. jfsavage : photos : Infrared- powered by SmugMug

The first image (of a street) was 1/125, f4.0, ISO 100 with visible light, but 30 seconds, f4.0, ISO 800 with IR.

The second image (with water) was 1/30 with visible and 5 minutes with IR (same f-stop and ISO)

Is this typical of what others have seen with an unconverted K20D? I did wonder if the problem was with the cheap Opteka filter.

(Let me know if I should have posted the pictures using a different technique)

I am considering a pure IR camera as well: converted older pentax DSLR, Sony 7x7 with ND filters, Sony H9 with the nightshot switch mod, Fuji IS-1, Converted Canon Gx, etc. Lots of options, none very cheap ;{

Thanks,

Jonathan

08-18-2008, 09:40 AM   #2
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Did you try using the K20D infrared setting w/o the filter?
08-18-2008, 10:01 AM   #3
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If you want a dedicated camera send me a PM, and I'll suggest one to you.
Where you can easily put the filter back anytime you want.
08-18-2008, 10:43 AM   #4
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QuoteOriginally posted by Tom S. Quote
Did you try using the K20D infrared setting w/o the filter?
My K20D is not IR converted, so the hot mirror is still in place. The smugmug should show the visible spectrum pictures along with the IR pictures.

08-18-2008, 12:41 PM   #5
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actually there is a setting in K20D that it will output the picture as infrared picture, but of course it is just a digital filter.
08-18-2008, 04:17 PM   #6
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What he said.

The K20D has a setting for IR. I was wondering if you had tried using it, but obviously not.
08-18-2008, 05:57 PM   #7
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QuoteOriginally posted by vizjerei Quote
actually there is a setting in K20D that it will output the picture as infrared picture, but of course it is just a digital filter.
I shoot raw, but I the same effect is available in PS. The IR filters can be interesting, but they are not what I am looking for.
08-18-2008, 06:25 PM   #8
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QuoteOriginally posted by jfsavage Quote
I have made some initial tests with my K20D and an Opteka IR filter. The results are disappointing, mostly due to the very long exposure times.

I've posted the results to smugmug. jfsavage : photos : Infrared- powered by SmugMug

The first image (of a street) was 1/125, f4.0, ISO 100 with visible light, but 30 seconds, f4.0, ISO 800 with IR.

The second image (with water) was 1/30 with visible and 5 minutes with IR (same f-stop and ISO)

Is this typical of what others have seen with an unconverted K20D? I did wonder if the problem was with the cheap Opteka filter.

(Let me know if I should have posted the pictures using a different technique)

I am considering a pure IR camera as well: converted older pentax DSLR, Sony 7x7 with ND filters, Sony H9 with the nightshot switch mod, Fuji IS-1, Converted Canon Gx, etc. Lots of options, none very cheap ;{

Thanks,

Jonathan
Your results are far from disappointing!

IR photography with a filter is just like that, looooong exposure times, you need a very steady tripod to use ISO 100. Seems to me you're getting good tones and have little visible light creeping in, that's a great start.

The pics are indeed a little soft/hazy, is everything clean, sensor, lens' front and back elements, filter? Maybe it's camera shake, or a light haze that is building up with the long exposures. Opteka is certainly not known for quality, but you might just be lucky

08-19-2008, 04:18 AM   #9
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the results are brilliant IMHO

If you want any better get an old film body and some Rollei IR film!
08-19-2008, 05:31 AM   #10
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They look pretty good for a first try.

Drop the ISO to 100 for less noise.

Test different apertures. I find that my 18-55 kit lens works best at f11-f13 when using infrared.

The focusing will be off a little when shooting IR. Since you have digital, you can try again if it's not sharp, but a small twist of the lens to the left (from the back of the camera) is a good place to start.

Your meter will seriously underexpose. The first shot looks good, but the second one is underexposed. Bright, sunny, daylight works best for IR, since you'll have plenty of IR bouncing around. Shaded scenes like the water can be troublesome.

There are several photoshop actions available that will make a false color image that isn't all red, and doesn't require converting to B&W. This guy has one: Shawn-Knight.net Blog Archive False Color Infrared Photography How-To. It's basically swapping the red and blue channels in the channel mixer, so it can be done in any graphics program.
08-19-2008, 06:04 AM   #11
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QuoteOriginally posted by alohadave Quote
They look pretty good for a first try.

Drop the ISO to 100 for less noise.

Test different apertures. I find that my 18-55 kit lens works best at f11-f13 when using infrared.

The focusing will be off a little when shooting IR. Since you have digital, you can try again if it's not sharp, but a small twist of the lens to the left (from the back of the camera) is a good place to start.

Your meter will seriously underexpose. The first shot looks good, but the second one is underexposed. Bright, sunny, daylight works best for IR, since you'll have plenty of IR bouncing around. Shaded scenes like the water can be troublesome.

There are several photoshop actions available that will make a false color image that isn't all red, and doesn't require converting to B&W. This guy has one: Shawn-Knight.net Blog Archive False Color Infrared Photography How-To. It's basically swapping the red and blue channels in the channel mixer, so it can be done in any graphics program.
Thank you for the feedback; I will try the photoshop action. Given your experience with IR, I have some questions;

Are you using an unconverted camera?
Which camera do you use?
What IR filter to you use?
What length exposure are you seeing with f11-13 on a bright sunny day?

Many thanks,

Jonathan
08-19-2008, 08:14 AM   #12
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QuoteOriginally posted by jfsavage Quote
Thank you for the feedback; I will try the photoshop action. Given your experience with IR, I have some questions;

Are you using an unconverted camera?
Which camera do you use?
What IR filter to you use?
What length exposure are you seeing with f11-13 on a bright sunny day?

Many thanks,

Jonathan
I'm using the K100D Super (It has a weaker IR cut filter than the K20D from what I've heard)
It's unconverted
I use the Hoya R72
I typically use a 1-3 second exposure, but sometimes up to 10 seconds. It's a lot of trial and error. I shoot RAW, so when you have a good exposure, it will almost look like it's over-exposed on the camera's screen. If you go by the auto-exposure, it will be a couple stops under-exposed and dark looking.
08-19-2008, 08:35 AM   #13
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One other thing to do is to set a custom white balance. As vegetation shows up as white in IR, you can point WB sample point at grass to set the WB with the IR filter on. You'll need to do that in bright light (e.g., the neighborhood shot) rather than in a shady area (the water shot).
FYI, I recently did some custom WB testing with my IR filter (Hoya R72). I set custom WB based on: 1) grass; 2) White card; 3) translucent lens cap pointed at sky. I saw very little difference in color temperature of RAW images so I just set WB based on grass. If I'm not sure where I might be shooting, I'll set it at home before I go shooting so I already have the custom (IR) setting ready to go.
Steve
08-19-2008, 11:44 AM   #14
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QuoteOriginally posted by atnbirdie Quote
One other thing to do is to set a custom white balance. As vegetation shows up as white in IR, you can point WB sample point at grass to set the WB with the IR filter on. You'll need to do that in bright light (e.g., the neighborhood shot) rather than in a shady area (the water shot).
FYI, I recently did some custom WB testing with my IR filter (Hoya R72). I set custom WB based on: 1) grass; 2) White card; 3) translucent lens cap pointed at sky. I saw very little difference in color temperature of RAW images so I just set WB based on grass. If I'm not sure where I might be shooting, I'll set it at home before I go shooting so I already have the custom (IR) setting ready to go.
Steve
I usually set the white point when I'm processing the picture on the computer. Both ways work, it's more of personal style which one you use.
08-19-2008, 03:54 PM   #15
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QuoteOriginally posted by alohadave Quote
I'm using the K100D Super (It has a weaker IR cut filter than the K20D from what I've heard)
It's unconverted
I use the Hoya R72
I typically use a 1-3 second exposure, but sometimes up to 10 seconds. It's a lot of trial and error. I shoot RAW, so when you have a good exposure, it will almost look like it's over-exposed on the camera's screen. If you go by the auto-exposure, it will be a couple stops under-exposed and dark looking.
That's interesting! You're using 1-3 seconds at f11-13, I'm looking at 5 minutes at f4! So either the K20D has a much stronger hot mirror, or the problem is with my cheap Opteka filter.
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