[UncleVanya]

I have decided to try some infrared photography using my k100d or k100d super. I’m going to start with an unmodified camera as I understand the ir cut filter is weak on these cameras. What I wanted to know is if anyone had tried the STC 720nm clip in filter for this purpose:

https://www.stcoptics.com/products/infared-photography-clipfilter-pentax-cam...40607250350233

In reading about IR filters it was pretty clear that the poor ones pass too much red and work fine on converted cameras but poorly on unconverted ones. So I’m hoping someone has tried this before me. If not I’ll be getting a front mounted filter like an R72 or similar. If I really enjoy this the. A conversion of a camera is possible in my future.

[k0og]

I've used an R72 filter on my K100D Super, and it seemed to work well. The trick of course is to use a tripod, frame and focus the scene, take some light measurements, then put the filter in place and adjust the settings (long exposures will be needed), shooting in M mode. A camera converted so that no R72 filter is needed would be nice.

-Joe-

[UncleVanya]

I've used an R72 filter on my K100D Super, and it seemed to work well. The trick of course is to use a tripod, frame and focus the scene, take some light measurements, then put the filter in place and adjust the settings (long exposures will be needed), shooting in M mode. A camera converted so that no R72 filter is needed would be nice.

-Joe-

Any examples that you can share? What brand filter? Hoya?

[kypfer]

I have decided to try some infrared photography using my k100d or k100d super. I’m going to start with an unmodified camera as I understand the ir cut filter is weak on these cameras. What I wanted to know is if anyone had tried the STC 720nm clip in filter for this purpose:

https://www.stcoptics.com/products/infared-photography-clipfilter-pentax-cam...40607250350233

In reading about IR filters it was pretty clear that the poor ones pass too much red and work fine on converted cameras but poorly on unconverted ones. So I’m hoping someone has tried this before me. If not I’ll be getting a front mounted filter like an R72 or similar. If I really enjoy this the. A conversion of a camera is possible in my future.

Do note the proviso on the page you linked to :- "I understand this product can only be used with modified cameras"

I've not tried the K100D, but my other 6Mpixel Pentax DSLRs all work well with an R72 (and darker) filter … with a wide-aperture lens it's even possible to work hand-held with an R72!



Using a Lee 87 on an unmodified *istDL2 (on a tripod) with a 28mm f/2.8, if I remember correctly.


Use your Digital Preview facility in conjunction with the histogram in Manual mode for correct exposures … the light levels on the sensor are too low (and/or the wrong wavelength) for the built-in meter to be accurate on these older cameras.
To save having to fit and remove the filter for framing, a clip-in viewfinder in the hot-shoe (as used on older r/f cameras) can help a lot
Enjoy

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Last edited by kypfer; 12-31-2022 at 03:40 PM.

[fwwidall]

I have a number of cameras I use for infrared.

I started out with my istDS. As has been mentioned the UV/IR cut filter is fairly weak in the early DSLRs so IR is possible, although long shutter speeds are required. False colour infrared images are easy to produce with a simple channel swap, as well as the usual B&W. I use a Hoya R72 filter on it.

Here's an example.



Then I picked up a Sigma SD14 which like a number of the early Sigma DSLRs has an easily removed UV/IR filter, converting it to a full spectrum camera. I picked up an M42/SA mount adapter so I was able to use my M42 Pentax lens on it.

I never had success generating false colour images but for B&W I find it excellent.



I also found an article on simulating the old Kodak Aerochrome look. Set the white balance to tungsten and use a green filter. The resulting image has a very distinctive look.



Then I acquired converted istDL2 where the UW/IR cut filter has been replaced with a 720nm filter. This allows for regular shutter speeds and lets me choose from all my lenses. A converted camera is the easiest to use.



I also have a 720nm converted P&S camera, a Luminx DMC-SZ7 but I've never been happy with the results I get with it.

Lots of other examples in my infrared album on Flickr.

p.s. Hmmmm, now I understand what my wife means about me having too many toys

Happy New year all.

[UncleVanya]

Do note the proviso on the page you linked to :- "I understand this product can only be used with modified cameras"

I suspect that’s mostly about modern sensors not working with the cut filter. I am asking them for more info.

Thank you for your info.

[UncleVanya]

I use DXO Photolab - does anyone know how to color swap channels using that tool? Or another tool I can easily use that’s free? I don’t want to add another paid tool.

[tduell]

...Or another tool I can easily use that’s free? I don’t want to add another paid tool.

I get the impression that it can be done using darktable...quite a few entries pop up as a result of a search on that subject.
There may be other simpler tools that might suit you better, as darktable is a full-blown raw converter and image editor, as you probably know.
Hope this helps.

Cheers,
Terry

[UncleVanya]

I get the impression that it can be done using darktable...quite a few entries pop up as a result of a search on that subject.
There may be other simpler tools that might suit you better, as darktable is a full-blown raw converter and image editor, as you probably know.
Hope this helps.

Cheers,
Terry

Thanks. I do want something simple but if I can use it on a windows 11 machine I’d be willing to try it. I have a passing familiarity with the product.

[tduell]

OK, color swap is handled by the color-calibration module.
Have a look at the doc entry for version 4.0, to see if this helps at all, it's a little way down in the story about that module. <https://docs.darktable.org/usermanual/4.0/en/module-reference/processing-modules/color-calibration/>
The latest release is v4.2, I'm not sure if it's different.

Cheers,
Terry

[kypfer]

I use DXO Photolab - does anyone know how to color swap channels using that tool? Or another tool I can easily use that’s free? I don’t want to add another paid tool.

Irfanview IrfanView - Official Homepage - One of the Most Popular Viewers Worldwide will do channel swapping … it's on the Image menu under Swap Colors
It's certainly not a total image editing package, but it's a lot more than just an image viewer and it'll do a lot of basic editing stuff very easily … levels, spotting, resizing, sharpening, cropping etc., all a keystroke away!
Enjoy

[UncleVanya]

Irfanview IrfanView - Official Homepage - One of the Most Popular Viewers Worldwide will do channel swapping … it's on the Image menu under Swap Colors
It's certainly not a total image editing package, but it's a lot more than just an image viewer and it'll do a lot of basic editing stuff very easily … levels, spotting, resizing, sharpening, cropping etc., all a keystroke away!
Enjoy

I used to use it years ago. Does it do raw? Or would I need to first convert to jpg or tiff?

[kypfer]

I used to use it years ago. Does it do raw? Or would I need to first convert to jpg or tiff?

It certainly "reads" Pentax RAW files, either PEF or DNG, but whether it's viewing with the in-camera (Custom Image) settings or not I can't decide.
Initial comparisons with a couple of RAW+ combinations suggest that the in-camera settings are applied at viewing time, the on-screen presentation looks identical.
I'd be tempted to "try it for size", if IrfanView doesn't do exactly what you want, DCU will save a PEF as a 16-bit TIFF, which may give you more options.

[k0og]

UV,

Here is a sample I took with my K100DS in 2008 with a Hoya R72 IR filter. Here are two images: The first is red but with "normalized" RGB channels, and the second is my quick & clumsy attempt at channel swapping. This is with a Vivitar 28mm lens stopped down somewhat, 1/15 second, ISO400.

-Joe-

[newmikey]

I get the impression that it can be done using darktable...quite a few entries pop up as a result of a search on that subject.
There may be other simpler tools that might suit you better, as darktable is a full-blown raw converter and image editor, as you probably know.
Hope this helps.

Cheers,
Terry

Darktable certainly does channel swaps as well as a whole lot of other stuff I find handy when shootin IR with my 630Nm converted K-5 (with or without a 720Nm filter). Especially the color zones module is great to boost blue skies and bring back foliage from yellow to almost white.

Thanks. I do want something simple but if I can use it on a windows 11 machine I’d be willing to try it. I have a passing familiarity with the product.

Darktable is fully cross-platform. I'm a Linux-only user but it will run on Windows and Mac as well. I hate to say this but DT does have quite a learning curve, I would not call it simple.

OK, color swap is handled by the color-calibration module.
Have a look at the doc entry for version 4.0, to see if this helps at all, it's a little way down in the story about that module. <https://docs.darktable.org/usermanual/4.0/en/module-reference/processing-modules/color-calibration/>
The latest release is v4.2, I'm not sure if it's different.

Cheers,
Terry

Version 4.2 still handles channel swaps in the same way. The German guy who did my K-5's conversion has an awesome tutorial on it on his dual-language website and

Youtu.be

Youtu.be

.

One of the very useful tricks he taught me is to change the order in which the color calibration module is used in the image pipeline so it comes before almost all other modules. I've made that into a default for all of the shots from my K-5.

My own gallery of IR images shot with the K-5 is in my album page here: https://eu-web.online/photographics/index.php?/category/23

A few samples shot at both 630 as well as 720: