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07-26-2020, 01:05 AM   #1
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IR Filter for the K-70/18-135mm?

I'm new at serious photography, and I find I have a strong urge to explore infrared at the moment. I would appreciate suggestions for IR filters for my camera/lens combo, as well as any advice for a n00b getting into infrared photography.

Thanks.

07-26-2020, 02:20 AM   #2
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QuoteOriginally posted by CoolBreezeRandy Quote
I'm new at serious photography, and I find I have a strong urge to explore infrared at the moment. I would appreciate suggestions for IR filters for my camera/lens combo, as well as any advice for a n00b getting into infrared photography.

Thanks.
One never likes to be the bearer of bad tidings, but to paraphrase whoever ... "if I wanted to go there I wouldn't start from here"

As capable as the K-70 is, one characteristic of (probably) all modern digital cameras is the lack of sensitivity to infra-red light, due to efficient internal filtering.
The best you can hope for is to use a very dark red filter, R72, Wratten 89B, Ilford SFX or similar, and be prepared for an amount of adjustment in software.
Take a white-balance reading through the filter, ideally of an area of sunlit green grass, but a grey card or even a sheet of white paper, in sunlight, will suffice.
You'll probably need a tripod, exposure times are likely to be long.

All the above assumes monochrome imaging, I've no experience with false-colour work.

If you "get into" the concept, an investment in a more suitable body might be considered. The older CCD-sensor 6 and 10 megapixel bodies have greater infra-red sensitivity than the newer CMOS-sensor cameras. I have particular success with my *ist DL2 (unmodified).


Good luck

Last edited by kypfer; 07-26-2020 at 02:30 AM.
07-26-2020, 07:16 AM   #3
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The other option is to have a camera converted for IR use. There are several places where you can get the conversion (I used IsaacSzabo's services) in which the IR rejection filter located in front of the sensor is removed and replaced with an equivalent thickness of optical glass (to maintain autofocus functions). There are several forms of the conversion but full-spectrum provides the most flexibility. I had this done to a used K-01 mirrorless camera since the optical viewfinder is usually non-functional when an IR filter is placed over the lens, and the K-01 doesn't have an OVF. Isaac suggested this and It makes a great working IR camera. You can see the IR image on the rear LCD panel, and autofocus works as it does for visible light. If you want to use the camera for regular use, you can obtain the UV/IR reject filter for use on the lens, and the camera works in visible light (assuming you had full-spectrum conversion)..

Isaac Szabo
07-26-2020, 08:48 PM   #4
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QuoteOriginally posted by Bob 256 Quote
The other option is to have a camera converted for IR use. There are several places where you can get the conversion (I used IsaacSzabo's services) in which the IR rejection filter located in front of the sensor is removed and replaced with an equivalent thickness of optical glass (to maintain autofocus functions). There are several forms of the conversion but full-spectrum provides the most flexibility. I had this done to a used K-01 mirrorless camera since the optical viewfinder is usually non-functional when an IR filter is placed over the lens, and the K-01 doesn't have an OVF. Isaac suggested this and It makes a great working IR camera. You can see the IR image on the rear LCD panel, and autofocus works as it does for visible light. If you want to use the camera for regular use, you can obtain the UV/IR reject filter for use on the lens, and the camera works in visible light (assuming you had full-spectrum conversion)..

Isaac Szabo
I'm going to try kypfer's advice, if nothing else simply as a technical exercise and learning experience, but I can also see that I'm going to end up getting a dedicated IR camera sooner or later. Looks like they can be had for not-outrageous amounts of money.

07-26-2020, 10:08 PM   #5
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I've taken perfectly fine IR photos with an IR filter over my K3/16-50 2.8. It just takes a tripod and time. I have a converted K10 (ccd) and a p&s (CMOS) converted to do IR.

Give the unconverted camera approach a try first to see if you like it.

Give me a minute or two to pull up an old thread.
--------------
Here is an old thread about this.
Infrared Photography, and the Pentax world - Page 2 - PentaxForums.com

Last edited by lmd91343; 07-26-2020 at 10:20 PM. Reason: Added old thread reference
07-27-2020, 05:35 PM   #6
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QuoteOriginally posted by lmd91343 Quote
I've taken perfectly fine IR photos with an IR filter over my K3/16-50 2.8. It just takes a tripod and time. I have a converted K10 (ccd) and a p&s (CMOS) converted to do IR.

Give the unconverted camera approach a try first to see if you like it.

Give me a minute or two to pull up an old thread.
--------------
Here is an old thread about this.
Infrared Photography, and the Pentax world - Page 2 - PentaxForums.com

Thanks. I'm going to try it; we'll see how it works.
07-27-2020, 07:11 PM   #7
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Good.
It is cheaper to try IR with just a filter first to see if you like it. If you like it then you can convert a camera
If you donít like it, the out of pocket cost is only a filter!

P.S.
IR photography is addictive. It seems I take more shots with my converted K10 than my normal K3.

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