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08-08-2013, 01:49 AM   #1
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Pentax K-5 and infrared photography

Hello everybody!

I wanted to ask for a little advice. I try to make infrared photos with my Pentax k-5 Hoya 72 filter ( using Sigma 17-70mm lens). As it is said in many forums and tutorials, I set WB manually (using grass), ISO 200, f 8-13, exposure 1-30 seconds and so on. In my computer I use photoshop CS5, I make changes in channel mixer, then auto levels, curves, then some changes in hue/saturations. And no matter what I do, the result is not that I wanted... Here are some examples of original pictures and after retouch. The main problem that the sky is never blue (I make it using hue/saturation), and the colours of the picture is very uneven.. I would be very grateful for your advice..

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08-08-2013, 01:54 AM   #2
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Hi

True IR pictures can be obtained by removing IR Filter of the camera. Very very difficult and tricky + The high expectancy of you damaging your camera.

Ideally if I were you I would not go that path. I would take a normal picture and then post-process to get the desired results.

If you really really want IR photography - Canon 60Da (a) allows you to do that.

Cheers!
08-08-2013, 03:06 AM - 1 Like   #3
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QuoteOriginally posted by Precious Quote
The main problem that the sky is never blue (I make it using hue/saturation), and the colours of the picture is very uneven.. I would be very grateful for your advice..
As the name suggests, the Hoya 72 IR filters restrict the light striking your sensor to the 720nm and above range; in other words you're not going to get any color information from visible light. You would need a filter that lets lower wavelengths through. The Hoya 72 would restrict your available "palette" too much, even if you played with color channels, so you would never get any appreciable color separation among the features in your scenes. It's late and I'm tired (forgive me) but I believe the "false color" infrared images you see are usually using filters that filter light below 650nm or thereabout. You can buy a 590nm filter (which gives more "false color" but has a less extreme infrared effect) or a 665nm filter from a place like Spencer's Camera. Be aware, though, dealing with Spencer's is playing with fire, as far as I'm concerned.

The B+W IR Dark Red 092 filter blocks light up to 650nm, so that might be the way to go, and of course B+W filters are handled by guys like BH Photo. You can't go wrong buying from them. And of course, the Dark Red filters are not visually opaque, so you'll find your exposure times being far shorter and manageable! You would still need to employ custom white balance and mess around with channels and the like in post processing. However, I think you'll be much closer to your goal and much less frustrated!

Last edited by LowVoltage; 08-08-2013 at 03:07 AM. Reason: spelling
08-08-2013, 03:18 AM   #4
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QuoteOriginally posted by Precious Quote
The main problem that the sky is never blue (I make it using hue/saturation), and the colours of the picture is very uneven.. I would be very grateful for your advice..
By the way, your question prompted me to confirm a few of my thoughts about the B+W filters. B+W makes a "UV Black (403)" filter which BH Photo has listed with infrared filters (I know the name says UV, but apparently it also has IR characteristics as well). One reviewer says she gets what you were looking for; blue skies and water, but white foliage. That 403 filter may be something to think about.

08-12-2013, 02:18 PM   #5
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I've used the B+W 092 on my Q with good results. I edit mainly in Lightroom but channel-swap in Photoshop, but it doesn't take a lot of work to get the false color effect I'm looking for.
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Last edited by sundr; 08-12-2013 at 02:26 PM.
08-13-2013, 08:16 AM   #6
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The B+W is mean to be an UV pass filter. However, it also leaks infrared. When using UV film in a film camera the IR leakage didn't matter. But today, the sensors are so sensitive to IR, that the IR leakage easily overtakes any UV sensitivity. However, the IR block filters in front of the sensors cuts almost all IR, and a some UV. Because the (blue) sky scatters so much UV, the sky is really "UV bright" and the camera is actually able to record the UV, which gives the sky a color, along with the IR effect of the highly IR reflective foliage.

I converted a K10D that has a CCD sensor to wide spectrum, and have a whole slew of filters for various interesting effects.
08-13-2013, 10:11 AM   #7
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QuoteOriginally posted by Eric Seavey Quote

I converted a K10D that has a CCD sensor to wide spectrum, and have a whole slew of filters for various interesting effects.
Where (and when) did you IR-convert your K10D if I may ask ? How much they charged you and what glass did you supply with the camera for calibration ?
Thanks
08-13-2013, 01:57 PM   #8
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It was a bit of a combination of luck actually, and a little story. I bought a used K10D on ebay that I was going to have modified. However, my camera was exhibiting various problems. So I contacted the seller about it, who seemed to know about how to repair them, so i asked him about it. As it turns out, he did buy up used products, repaired them and sold them off. I asked him if he was willing to replace the IR-cut filter if he provided me the exact dimensions of the IR-cut filter and if he would be willing to install it in the replacement camera. He agreed to help me out, and I custom ordered a clear glass with good UV transmission, and sent it to him. He basically put it in for free to make up for the hassle of sending me a bad camera. The auto focus works OK in UV and IR... it is a little off, but I can adjust manually. The camera calibration is important if you have it modified as an IR/UV camera without external filters, where you want to use the viewfinder.

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