Saturday, June 10, 2006

Pentax DSLR Infrared Photography

Jens Rösner is a young Pentax user with a great website of resources for Pentax DSLR enthusiasts, including important tips about P-TTL flashes. But one of the most intriguing things you'll find on his site are his experiments with infrared photography using an *ist DS. Jens makes it look easy. Thanks to Pentax DSLRs' high IR sensitivity in the red channel, if you use an IR filter over your lens and then, in post-processing, you remove the extraneous color information and focus on the red channel you're left with a false color IR photo (click here for more information).

Photo copyright Jens Rösner. Pentax *ist DS, Heliopan 715nm IR on a Porst ColorReflex 50mm/1.7 lens.

Jens began by modifying point and shoot cameras before arriving at the Pentax *ist DS. I interviewed Jens about how he accomplishes IR with his Pentax gear and talked with him about his interests.

How did you get into IR photography?

Well, I had read about it, did a google search and found Infrared Basics For Photographers. I was fascinated and ordered a Hoya R72 (filter) for my trip to New Zealand. I never regretted that purchase and was sad when it got stolen. But I replaced it with a Heliopan 715nm. These two filters are very similar, so pick whatever you prefer. My modified digicams were bought as defect on ebay. So the filter is the biggest investment. It depends on the filter size of course, but some common sizes can often be bought cheaply on ebay. If you are serious, get a proper photography filter, not some military thing to screw onto flashlights.

Pentax DSLRs, at least the DS and DL are rather good for IR. I say rather, because doing IR with unmodified SLRs is more of a challenge than with compact digital cameras. With compact cameras, the IR sensitive CCD sees through the IR filter and so focusing, exposure and framing is very easy. On SLRs, this is not the case, you have to work a bit more. On a bright day, you might be able to frame through a mild filter like the R72 or 715nm, but focusing is difficult. Thankfully, the Pentax AF system works quite ok in IR and the focus indicator helps you with manual focus lenses. The metering is off, but it can be corrected easily, of course. The standard way of using an SLR is frame and focus with the filter off, then adjust the focus with the IR mark on the lens (uncommon on modern lenses) and remount the filter for the exposure.

Any special tricks you like to use when you're taking these pictures?

I strongly suggest shooting RAW and bracket on top. As the IR sensitivity is only in the red channel, judging by the luminance histogram on the camera's LCD is not telling the whole story! Unless you are using a bright or wide lens or like high ISO, you will want a tripod for good results. I now am using modified compact cameras for IR, the next step, modified Pentax SLR might follow once I have bought the successor of the D, the K10D.

Jen's Pentax IR setup: Pentax *ist DS, Pentax A 50/1.4, and a Heliopan 715nm IR filter. Photo copyright Jens Rösner.

What Pentax gear do you presently own?

The Pentax *ist DS and various lenses. My main kit is a Pentax DA 12-24, Sigma 18-125, Tokina 80-400, and a Pentax D-FA 100 Macro. I also own various M42 Pentax items, cameras and lenses, but the cameras are more collector's items, I must admit. They are so beautiful, as are the old lenses.

Apart from my main lens kit, I like to bring my Vivitar Macro Focusing Tele Converter and a Metz TTL flash. I use Crumpler's "Brian's hottub" as a well-made and large backpack. My small kit, in contrast, is my DS + Sigma 18-125. Sometimes, though, I step out "armed" with just a single M42 lens, and see where it goes. For smaller trips, I use smart backpack by Holst. It packs a small kit plus some food or even clothes to change. When riding my bike, I use a Hipbag on my back. When doing so, the small size and low weight of the DS really comes in handy!

For lighting, I use a Metz 32MZ-3 or 40MZ-3. But for macro photography light I like to use a cheap DiY bouncer/diffusor. For desktop macros I use simple desktop lights and a tripod.

How long have you been taking pictures?

I started my photography with taking not much more than snapshots during car meetings. I did this for my webpage back then (late 90s). I however was both unimpressed by the quality of my film P&S and the effort necessary in scanning and cleaning up the scans. Plus it wasn't really cheap. So I outgrew the P&S and thought about byung a decent SLR and a film scanner or invest the money in one of those digital cameras that were so "new"...

So, at the end of 2000, I bought an Olympus 2020. At first I only used it for these snapshots, but it got me interested in more stuff, understanding DOF and exposure, for example. I loved that little camera, took it many places and after reading about its ability to shoot IR, tried that. I also tried supermacro with a reversed 50mm lens and external flash. It is a good learning camera, once you leave the P mode! After two very forming (for me) stays in New Zealand, I felt I had outgrown the 2020, and looked for a camera matching my new wants. I thought the Minolta D7 had it all: A useful zoom range, high resolution, many options, AA batteries, high IR sensitivity. But we never fell in love, for various reasons. I did a quick side-step with an Olympus 4040, but I still wanted a wider lens. So I looked at various prosumer cameras, including the Nikon CP 8400.

But in the end (March 2005), the Pentax *ist DS seemed the ideal companion: Small, versatile, AA batteries, great feel and handling. Love at first sight! Only later I found out many of the other nice things and about its relatively high IR sensitivity, which for me is a bonus. While my Spotmatic is much more legendary than my DS, the DS surely has more importance for me. It not only re-ignited my love for photography, it basically was the start of a new era for me. I know this sounds overly huge, but I really was in a dead end, going nowhere.

There's a lot of good IR photography, let alone regular photography. Any favorites?

I must admit that many of the "great names" leave me uninterested. For IR work, I'd like to mention Luben Solev and Andy Williams. Otherwise, the internet is full of great photography. Just take a few minutes to browse through pbase and you will see that those people complaining that digital photography has caused people to produce lesser quality are wrong. I buy a book if it "speaks" to me. I find most technical stuff can be found on the net or in helpful user communities, like the forums at and the images at

Thanks Jens!

Links: Jen's Website, Jen's page on *ist DS infrared photography, Infrared Basics for Photographers,,, Luben Solev, Andy Williams, Crumpler Bags, Holst Bags


Peter Gnemmi said...

Thanks for having the Pentax site. The problem using a true infrared-only filter like a Hoya R72 with a single lens reflex is that you can't see anything.

For $20 on eBay, I picked up an accessory viewfinder originally made for a Kodak Signet that slides into the shoe. Many such shoe-mounted viewfinders are available.

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For $20 on eBay, I picked up an accessory viewfinder originally made for a Kodak Signet that slides into the shoe. Many such shoe-mounted viewfinders are available.

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