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04-09-2014, 06:34 PM   #1
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Is the pentax k-30 suitable for infrared photography?

I recently got a k-30, and i bought a 720nm neewar infrared filter for it.

Anyway... the images it is producing are just awful. Here's a (bad) example. http://i.imgur.com/pchkQOe.jpg

That one was shot by hand, with a shutter speed of about 1/4 of a second, and 100 ISO... which seems a bit faster than i expected to be using with this filter.

Anyway, am i most likely doing something wrong, or does the pentax k-30 simply not work for infrared images? Or did i simply get a bad filter?

04-09-2014, 07:11 PM   #2
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I'm not sure what you are expecting as results? The lack of sharpness and the blur are more than likely due to your slow shutter speed and hand held shooting. AF (phase detect) may end up being a bit weird because of the limited wavelengths hitting the AF sensor. And exposure could also be off because of the way the camera is expecting the full light spectrum when calculating, easy fix with exp compensation.

Getting rid of the red color (and getting the "look" I'm assuming you're after) can be done in camera with a custom white balance (google, there are a few how-to's) or in lightroom/aperture/whatever. IR filters blocks all color but infra-red so it's normal to end up with a red photo
04-09-2014, 07:20 PM   #3
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Sorry to say, but you're out of luck. The K30 will not give you true IR photos without modification, there's an IR blocking filter in front of the sensor.
04-09-2014, 07:25 PM   #4
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the lower the cutoff point of the filter, the redder the image will be and the more you'll have to tweak the image to get the sort of ghostly images you see online. something closer to 800nm will block out more red and give a more balanced exposure, though you'll still have to tweak it to get a really nice final image.

04-09-2014, 07:25 PM   #5
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QuoteOriginally posted by 13thmurder Quote
I recently got a k-30, and i bought a 720nm neewar infrared filter for it.

Anyway... the images it is producing are just awful. Here's a (bad) example. http://i.imgur.com/pchkQOe.jpg

That one was shot by hand, with a shutter speed of about 1/4 of a second, and 100 ISO... which seems a bit faster than i expected to be using with this filter.

Anyway, am i most likely doing something wrong, or does the pentax k-30 simply not work for infrared images? Or did i simply get a bad filter?
The K-30 is supposed to be capable of IR. I have one, but have not personally tried it yet. I did find an article that I intend to use as a guide when it is time. It seems pretty comprehensive. wrotniak.net: Infrared Photography with a Digital Camera

Best wishes.
04-09-2014, 07:28 PM   #6
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QuoteOriginally posted by Al_Kahollick Quote
Sorry to say, but you're out of luck. The K30 will not give you true IR photos without modification, there's an IR blocking filter in front of the sensor.
ALL dslrs have ir blocking filters (except ones made or modified specifically for ir photography) and none of them block all ir. point a tv remote at the camera with live view on. if you can see the remote flashing when you press a button, the camera is sensitive enough for ir photography.
04-09-2014, 08:01 PM   #7
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QuoteOriginally posted by fgaudet Quote
I'm not sure what you are expecting as results? The lack of sharpness and the blur are more than likely due to your slow shutter speed and hand held shooting. AF (phase detect) may end up being a bit weird because of the limited wavelengths hitting the AF sensor. And exposure could also be off because of the way the camera is expecting the full light spectrum when calculating, easy fix with exp compensation.

Getting rid of the red color (and getting the "look" I'm assuming you're after) can be done in camera with a custom white balance (google, there are a few how-to's) or in lightroom/aperture/whatever. IR filters blocks all color but infra-red so it's normal to end up with a red photo
Well, the thing is, the filter i have seems to just be dark red tinted glass. When i put my eye up to the filter itself, i can see through it when looking outside in the bright sun. It's almost just like welding glass. Is that normal?

Anyway, the blur isn't what i'm worried about, it's the extreme contrast. The highlights, though only being midrange in tone, appear blown out, and even slight shadows are entirely black. Is there anything i can do about that?

---------- Post added 04-09-14 at 08:02 PM ----------

QuoteOriginally posted by maltfalc Quote
ALL dslrs have ir blocking filters (except ones made or modified specifically for ir photography) and none of them block all ir. point a tv remote at the camera with live view on. if you can see the remote flashing when you press a button, the camera is sensitive enough for ir photography.
Yep, i did that test before i bought the filter, just to be sure.

Would less IR sensitive cameras benefit more from a weaker filter, or a stronger one with a longer exposure time?
04-09-2014, 08:50 PM   #8
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QuoteOriginally posted by maltfalc Quote
ALL dslrs have ir blocking filters (except ones made or modified specifically for ir photography) and none of them block all ir. point a tv remote at the camera with live view on. if you can see the remote flashing when you press a button, the camera is sensitive enough for ir photography.
I thought the older Pentax DSLR bodies with CMOS sensors could work with infrared. Were they modified in some way to accommodate infrared?

04-09-2014, 09:00 PM   #9
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Even the K5 will do IR unmodded, but you have to have a filter, set it on a tripod and do a longer exposure, use live view to focus or pre-focus, switch to manual focus, and then put the filter on. Also, you need to make sure your filter is NOT transmitting visible light or it will wash out all IR light the camera captures. Of course you can get it IR+ color converted and use an IR cut filter for normal pics.
04-09-2014, 09:19 PM   #10
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QuoteOriginally posted by 13thmurder Quote
Yep, i did that test before i bought the filter, just to be sure.

Would less IR sensitive cameras benefit more from a weaker filter, or a stronger one with a longer exposure time?
a weaker filter will give you shorter exposures, but you'll get more red light and therefore a weaker ir image unless you blow out the red highlights. a less ir sensitive camera will block more ir obviously, so you end up with the same result as using a weaker filter, but with longer exposures. basically, the better the camera is at blocking ir, the stronger the filter you need to block out more red light.
QuoteOriginally posted by 6BQ5 Quote
I thought the older Pentax DSLR bodies with CMOS sensors could work with infrared. Were they modified in some way to accommodate infrared?
how good the ir blocking filter is will vary from one camera model to the next, so some models are naturally better suited to ir photography than others even without being modified.
04-09-2014, 09:55 PM   #11
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QuoteOriginally posted by maltfalc Quote
a weaker filter will give you shorter exposures, but you'll get more red light and therefore a weaker ir image unless you blow out the red highlights. a less ir sensitive camera will block more ir obviously, so you end up with the same result as using a weaker filter, but with longer exposures. basically, the better the camera is at blocking ir, the stronger the filter you need to block out more red light.
how good the ir blocking filter is will vary from one camera model to the next, so some models are naturally better suited to ir photography than others even without being modified.
Any idea what wavelength i should go for with the k-30?

I really like the false color type infrared photos.

---------- Post added 04-09-14 at 10:26 PM ----------

I'm starting to wonder if the infrared filter i received was fake. Or could this just indicate that i'm doing something wrong? Have a look at this, a clearer image:

I'm using gimp, and after looking up various tutorials, i've tried a few things. Apparently these methods work for some people quite well, i've seen them work in video tutorials, but for me... i get bad results.

Here's the original, unedited image:


Here it is after using gimp's auto white balance, which from what i've heard is great for infrared shots:


As you can see, that doesn't work for me.

Here's the image with the red and blue channels reversed:


It's just blue now. I've experimented with channels, and no matter what i do, it basically just acts like i'm tinting a grayscale image.

Now, here's the interesting bit, here it is converted to grayscale, with curves:


The leaves are all dark... why are the leaves dark? Is the filter i bought fake? Or am i doing something wrong?
04-09-2014, 10:44 PM   #12
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a 720nm filter just lets through too much red light compared to the amount of ir the k-30's ir blocking filter lets through, especially a cheap filter. try something closer to 800nm. and if you're shooting jpegs, switch to raw. jpegs are useless for the sort of adjustments you need to make with ir.
04-09-2014, 11:10 PM   #13
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QuoteOriginally posted by maltfalc Quote
a 720nm filter just lets through too much red light compared to the amount of ir the k-30's ir blocking filter lets through, especially a cheap filter. try something closer to 800nm. and if you're shooting jpegs, switch to raw. jpegs are useless for the sort of adjustments you need to make with ir.
Will 800nm still allow any color through? I want to do false color, not grayscale.
04-10-2014, 12:14 AM   #14
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you know, if you just use the filter you have, but with a longer exposure so that the blue and green channels are properly exposed but the red channel is overexposed, you can just swap out the ruined red channel for one of the other two and probably get decent ir images with some false colour. or you could take 2 shots, 1 with the red properly exposed and one with the green and blue properly exposed, then just copy and paste the red from the first photo into the second photo.

Last edited by maltfalc; 04-10-2014 at 12:28 AM.
04-10-2014, 12:29 AM   #15
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True, i could edit it any way i want after that.

I think i may have found my problem though... is it necessary to shoot in raw mode to get a proper infrared image? Because i've been using jpeg mode...

If so, how do i edit raw images? All i have right now is gimp, and that can't do it. Are there any free programs that can do it? Or at least ones far cheaper than photoshop? Preferably something in the ~$50 or under range. It took me about 6 months to save up for my $500ish camera setup i have now, so trying to buy photoshop is out of the question.
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