[motorhead9999]

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First off, feel free to move this thread to another appropriate forum. I think it could probably equally fit in at several places.

For a while now, I've thought about doing infrared photography. It does seem that the best way to do it is to get the camera sensor modified directly, rather than use IR lens filters. However, after reading the subject somewhat, I'm debating what the best route to go is. Obviously I'm in the K-mount ecosystem.

1) Buy a used Pentax body: I'm not sure whether I'd want to spend the money on getting another K1 and then paying the modification fee (which would get me to about 2 grand cost wise). I felt maybe going with a K3ii crop sensor camera might be the most sensible way to go, especially now that it's been discontinued, and I can probably get a deal on a used one. Obviously this choice allows me to keep my current lens lineup without any issue whatsoever. Does anyone have any other suggestions on another Pentax crop sensor camera body that might work good for this idea? I don't think any of crop sensor Pentax dslrs have tilt screens, correct?

2) Go mirrorless. Based on some articles I read, it seems like mirrorless cameras work better for doing IR photography. The downside to this obviously is that there really isn't a Pentax mirrorless option. I'd have to either go Sony, or one of the Fuji/M43 cameras, and then adapt my k-mount lenses to them (I refuse/can't afford to be buying duplicate lenses for different systems). So the only way this option works is if I can get a good adapter for kmount to another mount. However, none of the adapters I've seen allow any sort of electronic aperture/focus control on Pentax lenses, and are simply mechanical tube adapters. Granted, it's not the end of the world I suppose if I have to manual focus, but aperture control would be another issue I think, give that I don't believe any of my full frame K-mount lenses have manual aperture control.

I know this is a bit of a niche area, and certainly an even more niche area within the Pentax world. any thoughts or experiences?

[cpk]

Taken with a converted K-7: Barns in the County, Series 3 - Charles Kinghorn

Since most of your IR photographs will probably be take outdoors, good high ISO performance is not a necessity. It then becomes a matter of how large a print you will want to make. I've had no problems making 11 x 14s from cropped images and would expect to be able to go to 16 x 20s.

[pcrichmond]

Greetings, I had a K01 converted to full spectrum for IR work and truly loved it. In fact I enjoy it so much I picked up a used K1 and had it converted also.
You might consider the full spectrum route so you can use any filter from 25a/29f to 850 depending on the effect you desire. I find I really like the Tiffen 87 and didn't find this option from any of the conversion places. Also I've started to experiment with UV which the full spectrum would permit in the future also.
Look at cpk's wonderful link and consider if you would like faux color, straight monochrome or both. The K01 has the same sensor as the K5 so anything from the K7 forward should do you well.
One advantage to a straight IR conversion is use of the viewfinder. For filters on the lens you will want a good live view system.
The main issue I've come across is lens hotspots with a few of the newer digital lenses. Here is a link that list several lenses that have been tested, Pentax seems to fair very well.
Lens Hotspot Database - Kolari Vision
Enjoy the world of IR, it is a very pleasing photographic experience.
These examples are with the 87, the vine flower with a plastic optic and the pen and book with the F35-70

[Bob 256]

I have to agree with pcrichmond. I was going to have a K-3 converted until I talked to Isaac Szabo who does conversions and he steered me to the K-01 which is a Pentax mirrorless. Unfortunately, you can't get one new (unless you know someone), but you can get them in very good condition on the used market.

The sensor isn't changed in any way. It is normally sensitive to UV and IR and the camera would produce off-color effects if those wavelengths got to the sensor, so a dichroic (thin film interference) filter is placed in front of the sensor which blocks UV and IR. Converting a camera involves removing that filter which makes it a "full-spectrum" camera. That cost is about $250.

Now that the sensor sees "everything" and you want to do IR photography, a filter is used on the lens which passes only IR. A DSLR with a viewfinder is not the best choice since looking through the viewfinder with this IR filter on the lens would produce a black viewfinder image. A mirrorless on the other hand, will show the IR image on the LCD screen which can be used for composition, focusing, and visualizing the IR image or seeing IR sources. Keep in mind, this is not "thermal" IR where hot objects show up as white. It is near visible IR, and that IR is very nearly the same as visible light but invisible to our eyes. Images can be dramatic though with skies very dark and green plants white. IR photos are actually monochromatic and are often presented as B & W but they can be artificially colored. If different filters are used on the camera, colorations will present themselves due to differences of the Bayer filter used in front of the sensor. Images taken with visible light and one with IR can be combined to obtain a "false color" IR photo but that requires post processing of the separate shots.

My recommendations, like pcrichmond's are to get a K-01 and have it converted. Other than being a crop sensor, it will work almost as good as the K-1 for the application (no tilt LCD) and it's a neat little camera on top of that. I kind of cringe at having a K-1 converted though some have had it done but keep in mind, the optical viewfinder will only be useful for non-IR work. I also have a K-1 but it's my primary camera for visible light.

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Last edited by Bob 256; 03-04-2018 at 09:21 PM.

[pcrichmond]

I was going to have a K-3 converted until I talked to Isaac Szabo who does conversions and he steered me to the K-01 which is a Pentax mirrorless. Unfortunately, you can't get one new (unless you know someone), but you can get them in very good condition on the used market.

Isaac Szabo converted my K01 too and did a great job with support when I asked. After working with the K01 in IR, I felt Pentax might have missed by not making this camera in full spectrum for market. It was a camera before its time.
It has given me great images and from reviews I've read concerning some of the other brand mirror-less it doesn't suffer from sensor artifacts.
(I couldn't bear to have my original K1 converted either, thus the used one when I had the extra money. I find that with the correct "hot mirror" on the lens and custom WB the images are similar to a non converted camera.)

[motorhead9999]

I have to agree with pcrichmond. I was going to have a K-3 converted until I talked to Isaac Szabo who does conversions and he steered me to the K-01 which is a Pentax mirrorless. Unfortunately, you can't get one new (unless you know someone), but you can get them in very good condition on the used market.

The sensor isn't changed in any way. It is normally sensitive to UV and IR and would have off-color effects if those wavelengths got to the sensor, so a dichroic (thin film interference) filter is placed in front of the sensor which blocks UV and IR. Converting a camera involves removing that filter which makes it a "full-spectrum" camera. That cost is about $250.

Now that the sensor sees "everything" and you want to do IR photography, a filter is used on the lens which passes only IR. A DSLR with a viewfinder is not the best choice since looking through the viewfinder with this IR filter on the lens would produce a black viewfinder image. A mirrorless on the other hand, will show the IR image on the LCD screen which can be used for composition, focusing, and visualizing the IR image or seeing IR sources. Keep in mind, this is not "thermal" IR where hot objects show up as white. It is near visible IR, and that IR is very nearly the same as visible light but invisible to our eyes. Images can be dramatic though with skies very dark and green plants white. IR photos are actually monochromatic and are often presented as B & W but they can be artificially colored. If different filters are used on the camera, colorations will present themselves due to differences of the Bayer filter used in front of the sensor. Images taken with visible light and one with IR can be combined to obtain a "false color" IR photo but that requires post processing of the separate shots.

My recommendations, like pcrichmond's are to get a K-01 and have it converted. Other than being a crop sensor, it will work almost as good as the K-1 for the application (no tilt LCD) and it's a neat little camera on top of that. I kind of cringe at having a K-1 converted though some have had it done but keep in mind, the optical viewfinder will only be useful for non-IR work. I also have a K-1 but it's my primary camera for visible light.

So I'm presuming a full spectrum modification means that you still need lens filters on top of the modification in order to get the effect, correct? The reason I'd be hesitant on that is that is that some of my lenses don't have filter threads (notably the 15-30) so I wouldn't really have a way of using that lens.

I presume that's how this listing would work?
Pentax K-01 Full Spectrum IR UV Astro Infrared converted camera 27075215320 | eBay

[cpk]

Images taken with visible light and one with IR can be combined to obtain a "false color" IR photo but that requires post processing of the separate shots.

Actually a false colour IR photograph requires only one image, not two, but does require post processing to get the effect. The extent of the false colour depends on the filter used for the IR conversion or the filter used in front of the lens of a full-spectrum converted camera. See Choosing an Infrared Filter - Kolari Vision. Mine was a 665nm conversion.

Using live view for framing and focusing outside in bright sunlight will be difficult without some shielding device. I use a Hoodman Live View Kit (Hoodman Live View Kit for all DSLR Cameras - HLVKIT) but there are other options. I am very happy with my setup. Also constant use of live view can overheat the sensor (automatically shuts down if that happens but constant overheating would not be wise) and eats up batteries.

Added: Kolari has some good tutorials at https://kolarivision.com/turorials/; and I found this lesson on creating false colour IR images very useful:

You Tube

You Tube

.

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Last edited by cpk; 03-04-2018 at 09:51 PM.

[pcrichmond]

Actually a false colour IR photograph requires only one image, not two, but does require post processing to get the effect. The extent of the false colour depends on the filter used for the IR conversion or the filter used in front of the lens of a full-spectrum converted camera. See Choosing an Infrared Filter - Kolari Vision. Mine was a 665nm conversion.

You can always convert faux color to monochrome in post. You can also put darker filters on a lens if the camera is converted to 590 or 665 if you want more contrast to the monochrome. The only advantage full spectrum brings is the possibility to photograph in UV or to photograph in normal spectrum with an external "hot mirror" on the lens (there is no more point and shoot though, you should take the time to set a custom WB). UV takes some very special filters and lenses ($$), so if you're not inclined to this style then you might consider an IR specific conversion of a second older camera.
Also a few companies (Lee?) still make IR filters in gels. I've cut down a few of these and mounted on the inside of a lens with no filter thread mounts and have been able to do a makeshift gel mount on the outside as well. Kolarivision is who I bought my second K1 from and they have a wealth of information on their site, also they were helpful with answering questions via email.
There are many possibilities. The trick is to decide what style you like without limiting yourself for expansion mixed with not going for the broadest conversion and then using just a small touch.

[geomez]

I had my K-01 IR modded a few years ago and love it. I would recommend the K-01 if you want to convert K mount. It's more compact, and the CDAF works flawlessly with IR lenses. You also get so see what your image will look like directly, unlike looking though the mirror box. In all honesty it's as easy to use as an unmodded K-01. The modification cost me $250, and a good condition, low shutter count K-01 will run you $200-$250.
Here's a link to some of my K-01 IR images...

Geoff Meza - Infrared | Flickr

[Medex]

There are pro and cons using IR filter on the sensor (stable conversion) vs. IR filter on the lens. I have two Pentax cameras (K-5 and K-30) converted to 640nm IR. The filter is placed on the sensor.
Pros:
1. The optical viewfinder can be used for focusing ant composition (the LiveView is less needed, just in some situations).
2. The battery can be used longer.
3. Any lens can be used, even that "can't use" external filters like Pentax 15-30 or Samyang 14/2.8.
4. You can use higher nanometer (longer vawelenght) external filters on you demand in LiveView mode.
5. In case you don't use different filters a lot, you can save money, because good IR filters are pricey.

Cons:
1. You can't use IR converted camera as normal camera with external Hot mirror filter.
2. Autofocus with optical viewfinder system (Phase detection auto focus - PDAF) has limitations - the best way is to choose your most usable lens and adjust AF for it. E.g. I use wide angle lenses like Pentax 15-30, Sigma 18-35 Art, Samyang 14mm. The problem is that with longer focal lenght lenses (e.g. 50, 100 mm etc.) the PDAF starts to "lie", because your camera's PDAF is calibrated to shorter focal lenght. In that case LiveView (Contrast detection AF) can be used with high precision (of course you can use it always if you prefer). But how often do you shoot with longer lenses landscapes or cityscapes? Very rare in practice.

[angerdan]

Sensor spectrum is just one point. Bigger step is the IR transmission of a lens:
What lens has the most clinical color? - PentaxForums.com
Infrared compatible lenses - PentaxForums.com

[Medex]

Sensor spectrum is just one point. Bigger step is the IR transmission of a lens:
What lens has the most clinical color? - PentaxForums.com
Infrared compatible lenses - PentaxForums.com

In my opinion IR transmission of a lens has no big real-life significance, because in case (as an example) of Pentax lenses, most of them are SMC couted with quite the same or very similar transmission curve in the IR region. It is quite normal behavior for such lenses to transmit less intensively IR light, let's say from 90 percent in 720 nm region to 30 percent in 900 nm region. Such a cut of IR spectrum is desirable to achieve good autofocusing.
The difference exist when you use IR-couted special lenses. According to one internet source, that couting permits up to 75 percent transmission in 900 nm region.
diglloyd.com: Zeiss ZF Lenses for Infrared
The good thing is no hotspotting with IR-couted lenses, more intense white color in the picture, better contrast. But they are quite rare and not suited for normal photography (huge CA's, not usable at all unless soft-focus efect is desirable in black and white photography). I have 2 IR couted lenses, they are from milirary equipment. One is 100 mm f1,5. The sharpness of this lens on IR modified sensor is outstanding even wide open.
This is why I think, that in normal situations, when you use normal lens (corrected for visible light color aberations), transmission in IR region is not significant factor. If you want more whitening effect, you can use longer vawelenght filter and longer exposure.

[motorhead9999]

With going mirrorless, do you have the same focusing issues?

[Medex]

With going mirrorless, do you have the same focusing issues?

I don't call them issues because I know how to deal with them. But with mirrorless camera you have not PDAF, just CDAF, so - no focusing issues due to different focal lenghts.
There are other ''issues'' with mirrorless - quicker battery draining, dificult work in bright sunlight, heating of sensor in extensive use, extra shutter count due to work in liveview.

[Bob 256]

If you use a magnified image (such as the K-01 and K-1 allow) to critically focus, you avoid any issues with the optical focus shift IR introduces, however, you need to use liveview which, as has been pointed out, consumes more battery power and can be washed out in bright sun. Otherwise, you're relying on the camera AF system to properly focus since the optical viewfinder is useless (for IR), and there can be errors (I'm not saying there will be focus errors, but if they occur, you won't know it). Liveview lets you actually see the IR image and apply best focus to it.