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08-06-2008, 07:53 PM - 1 Like   #1
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Infrared Photography with a non-converted K10D

I've been doing some infrared photography with my K10D of late, and I figured I would share a little with the crowd about what I have found. A couple notes first: All of the thumbnails below can be clicked and should open in a new window at a larger, though not gigantic size. Secondly, there are a number of good primers on infrared photography available online that you should read if you want to have an idea about what you are doing. Thirdly, my steps are what I do on a K10D. My understanding is that the K100D has a much less effective IR block filter, and therefore your settings would be very different if you use the K100D. Fourth, I am a beginner at this and welcome any feedback. Enjoy!

The equipment I use:
1) K10D. Unaltered. As you would buy it at the store
2) 720nm Infrared filter. There are a couple different filter choices with regard to what wavelength of light you want to allow through. 720 is a good starting point and the one that most websites recommend. I have no experience with other wavelengths. Some red light will get through, but very little. No other color will get through.
3) I have three lenses I've used so far. A Pentax -M 50mm F1.7, an -FA 35mm F2.0, and a Vivitar 28mm F2.8. I use the 35 and the 28 the most because of the larger field of view. There is a picture of the vivitar lens below. Pics of the Pentax lenses can be found elsewhere on this site.
4) Corel Paintshop Pro X. Many of you probably use photoshop. That's fine. My terminology will be a little different but I'm sure you have the same functions.
5) A tripod. Any will do.



My Exposure Value Settings:
I find that I generally shoot at what would be an EV of 0 or -1. I am not talking about EV compensation. I am talking about the EV that says a bright sunny day is typically EV 15. Infrared photography is best shot under bright sunny skies, but if you follow the Sunny 16 Rule and shoot at ISO 100 and F16 for 1/125th of a second, you won't see much. This is because the IR filter in front of the lens will block so much of the visible light, and the IR block filter on the sensor will block so much of the IR light, that nothing actually hits the sensor. So I pretend I'm shooting in an EV 0 to -1 range. I shoot at ISO 1600 at F4.5 with the shutter open for 2 seconds. If I shot at ISO 100, I would need my shutter open for 30 seconds. You would need an awfully stationary subject for that. I shoot at 1600, because I don't want the wind to blow the trees around too much. Two seconds of stillness is easier to come by than 30. I use the "user" setting on my K10D for this, which is very helpful. When I switch to "user' it goes to ISO 1600, manual mode, and smallest possible image size. The small image size is my preference when shooting at ISO 1600 for noise reasons. I use automatic white balance and I shoot in color, not black and white. I usually edit to black and white later, but I can control the parameters, as you will see.

So what does the image look like?
Here is an unedited picture with the settings talked about above.


Notice the purple-blueness of the greenery and the pronounced red and yellow of everything else. We are starting to see how the K10D captures infrared light. It appears that the blue pixels on the image sensor are "hot" to IR light, while the green and red are much less so. I will use this to my advantage.

There are many directions we could go from here. If the image looks roughly like this one, I know I am in good shape and the editing will be easy. If there is almost no purple-blue and all red and yellow, the work gets harder. If people are interested I will post again about coaxing IR data out of an image that doesn't show much. For today, let's work with the picture above and assume decent infrared effects (i.e., the purple-blue stuff).

How I edit the picture:
I am going to take advantage of the fact that most of the IR effect shows up in the blue channel. My favorite way to do this is with something Paintshop Pro calls "channel mixer." I don't know what it is called in Photoshop, but I bet they have something similar. In channel mixer, I leave the output as grey, which will produce a black and white image similar to old black and white infrared film. I crank up the blue channel to 100, and crank down the red and green to 0. This displays prominently what the blue pixels recorded and subdues greatly what the red and green pixels captured. The pic below shows what I just talked about.


When I apply these settings, I get the following picture:


This shows the Infrared effect quite drastically. Essentially, only the infrared light is being represented here. What I will do next is allow in a little of the non-infrared light captured by the red and green pixels to balance the picture out a little bit. Starting with the original picture (the red, yellow, and purple-blue one), I will use the channel mixer to crank up the blue to 100, the red down to 0 and the green up to 30. The red channel is where all the visible red light went and it is completely washed out and all but useless. The green channel is still useful to me, so that is what I am mixing in with the blue. Detail below:


By allowing some of what the green channel captures, I get the following picture:


That is more balanced, and I think, more pleasing to the eye. There is a certain graininess to the picture that is reminiscent of old black and white IR film, and I kind of like that, but you may like it better some other way. That's fine.

Editing a slightly more difficult picture:
In this next picture the IR effect is less pronounced, but still there. I will have to brighten up the pictures a little. No big deal. Here is the original:


As you can see, there is less purple-blue. There is still some, so I don't have to do anything drastic. Drastic measures can be the subject of a later post if people are interested. First lets do what was done before. I will use the channel mixer at blue 100, red 0, green 0 and take a look. I get the following:


The picture above is very dark, but you can see the IR Woods effect in the trees and grass. I will use the histogram to brighten this image a little. I have included no image of me doing this, because this should be straight forward to editing software users. The result is below:


I think that is better. I still wouldn't mind seeing a little of the objects that reflect no infrared light. I will go back to the original image, and apply the channel mixer settings that allow some green light in. My settings, as before, will be blue 100, red 0, green 30. I get the following:


The rest of the landscape starts to show up again. Cool. But I might like it a little brighter again. I can use the histogram to brighten it up, and I am left with the picture below.


That looks, I believe, at least as nice as our first example where the IR effect was more pronounced in the original image. I shot both of these using the same settings. The first image must have had more direct sunlight on it.

I hope people liked this and I hope it encourages people to go give IR a try. I've only been doing this for a couple weeks, and this is what I've learned, so I figured I would pass my growing pains along to others.

08-06-2008, 08:13 PM   #2
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Fantastic tutorial!

I want to learn how to do Infrared too!
08-06-2008, 10:33 PM   #3
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Great tute. You've done quite a lot of homework putting this together.
Thanks for sharing your experience with the K10D.
08-06-2008, 11:31 PM   #4
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Nice writeup

There is anther pretty nice basic IR post processing tutorial here:
IR basic post processing - ClubSNAP Photography Forums

I've been doing the same w/ most of my IR photos. You guys might be interested to take a look at it.

Here are two very recent IR photos I took two days ago:





08-07-2008, 12:44 AM   #5
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Wow Frank, these are beautiful.

And tutorial too.
08-07-2008, 04:29 AM   #6
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Which IR Filter

QuoteOriginally posted by frank Quote
Nice writeup

I've been doing the same w/ most of my IR photos. You guys might be interested to take a look at it.
Frank, great shots. Which IR filter are you using? Same as the OP?
08-07-2008, 04:49 AM   #7
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QuoteOriginally posted by gamgee Quote
Wow Frank, these are beautiful.

And tutorial too.
Thanks Taking IR photos can be really fun
08-07-2008, 04:53 AM   #8
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QuoteOriginally posted by tubadad Quote
Frank, great shots. Which IR filter are you using? Same as the OP?
Thanks.

Yes, the built-in filter is a 720nm one, but a very thin type, only 1mm. This reduces the amount of AF adjustment required for IR quite a bit, you don't even need to do AF adjustment on some lenses like DA21, M20/4 and etc.

OP used a filter in front of a lens. When taking IR photos w/ K10D this way, the exposure time will be very long, sometimes even above 10 seconds. While using a converted IR camera, the exposure time will be much shorter, pretty much like using a normal camera. But of course it's quite a bit cheaper to just buy an IR filter instead of a converted camera

08-07-2008, 08:38 PM   #9
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Interesting.
On the older 6mp cameras, the IR sensitivity is pretty much restricted to the red channel.. It would seem the newer cameras are more versatile.. But I seem to remember, not as sensitive..

From reading other IR pages, cameras from other manufacturers can't correct such extreme colours.. But in my experience the manual white balance setting on the Pentax can turn my black/red pictures into black and white with no problems.
With these more colourful pictures, it might be able to produce some even nicer output straight from the camera...

The filter I have has a higher threshold so no visible light gets through, and only the red channel really registers anything.. so black and white is fine. Problem is, it makes it very hard to focus with the filter in place..
08-07-2008, 09:22 PM   #10
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Moo,

I would suggest leaving the image in color on your camera and changing to black and white in post processing. When I set the camera to black and white while taking IR pictures I get something that looks like a simple greyscale version of my subject. I don't get the Woods effect at all. I get a black and white image, but it isn't really an IR image. I think this is because even though I'm filtering out most of the visible light, some still gets through and affects the end result prominently. In post processing, I can pull the IR effect out of the image, but I think it is lost in the mix when I have the camera do the black and white conversion.

Take care, and thanks for adding to my thread.
08-08-2008, 07:37 AM   #11
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Thanks for posting the tutorial, Slowpoke.

I had just started thinking about doing some IR work and was trying to figure out what the best approach would be. From the reading that I've done it would appear that the 72 filter would be the choice, at least to start with. I have both a DS and a K10D and the bit of research that I've done, seems to indicate that exposures with the DS would be shorter, given the sensitivity characteristics of the sensor. If there are no compelling reasons to use the K10D (6mp is OK), I'll start by using the DS with a 72 filter; can anyone comment on this?
08-08-2008, 08:21 AM   #12
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Useful post -- thanks! Have wanted a converted K100D for a while, but I need to save for a K20D first.

So many bodies... so little time.
08-09-2008, 06:04 PM   #13
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I like Frank's url for a pseudo color method, I saved it for my next IR session.
08-09-2008, 07:41 PM   #14
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I have also used my K10D a bit for IR (with a Hoya R72 filter), and got a few reasonably interesting shots - but none as nice as the results Frank gets with his converted cam...

Also, an unconverted camera is rather limited compositionally, since it needs such long exposure times (often around 10 seconds).
08-09-2008, 07:57 PM   #15
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PeterAM,

You might very well get better results with the DS. Like I said, in my original post, at 1600 I have to leave the shutter open for 2 seconds. If the DS can go to 1600, you might be able to get by with some quick shutter speeds, which means you wouldn't be restricted to stationary objects as those of us with non-converted K10Ds are.

Good luck,
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