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01-03-2010, 12:52 PM   #1
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K7 infrared built in option

I do have IR filters and have used them successfully before. I discovered by accident that the K7 has built in filter options for emulating filters commonly used with BW film. I used to use red and orange filters for darkening blue sky and showing clouds better.

In normal capture mode press right 4-way controller, choose monochrome then select a filter. Is it that easy?

I searched the forum for infrared but all messages alluded to glass filters, of which I have a few - but do I need them if it's just a quick setting?

I'd be interested to see any examples of IR taken just using the 4 way controller setting. This one used a glass filter:

01-03-2010, 02:14 PM   #2
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As you said it is for emulating filters. It is not a real filter (like something built in camera you can enable), but just a digital post processing action.
So the image looks similar - it is grayscale and has emphasis on reds, but it wont have the qualities of true near infra-red image (like winter looking foilage).

It works like channel mixer conversion to monochrome, in image processing software.
If you shoot RAW, you can apply this filter later in Pentax Photo Lab.


Technically you need much longer exposure to allow enough true near infra-red light to pass the IR hot mirror in camera to reach usable levels.

Since this is not happening, you can get somewhat similar image by processing the red channel, checking blue channel and subtracting some of the green (to remove the part of red which overlaps with green). This is as far as you can get with post processing. But there is only a very small amount of true near infrared information in this red channel.

That's why i've ordered a real IR filter myself (still shipping )

Here i've added two images. Shot in RAW - one out of camera JPEG preview, other with the mentioned IR filter effect applied. In addition contrast has been boosted and curves were adjusted to get higher gamma, for maximum IR look. As you can see it is generally just "red" with some other tweaks.:
Attached Images
   

Last edited by ytterbium; 01-03-2010 at 02:28 PM.
01-03-2010, 05:25 PM   #3
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sadly come to the conclusion that for infrared the k7 sucks - the inbuild ir filter is just to strong - none of my attempts are real IR have worked with it =(
01-03-2010, 06:35 PM   #4
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QuoteOriginally posted by stormcloud Quote
sadly come to the conclusion that for infrared the k7 sucks - the inbuild ir filter is just to strong - none of my attempts are real IR have worked with it =(
As stated in a post above, there is no such thing as "the inbuild ir filter" (BTW, it's built-in, not inbuild) in the K-7. It is just post processing, emulating a photo taken with an IR camera. You can do the same thing (and have better control) with a "normal" photo in post-processing.

01-03-2010, 10:47 PM   #5
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SOldBear, I believe stormcloud was referring to the built-in "hot mirror" in front of the sensor in the camera. The thing that filters out IR light, not the software "filter" that this thread is about.

And he's right...the K-7's filter is very strong, and makes taking real IR images very tough. I put the same Hoya R72 filter on my K-7 and my K100D, and I have to expose the K-7 about 6 stops more to get a comparable image. The K100D was always known for having a pretty weak IR filter, which is good for taking IR shots. The K-7 obviously has a near-impermeable hot mirror. Bummer...but I knew there was a reason I kept the K100D around!
01-04-2010, 03:19 AM   #6
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Thanks to all for the comments. Looks like I might be better to use my *ist DL for IR.
07-20-2010, 04:47 PM   #7
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Hey Aerodave,

I also have a K-7 and the Hoya R72 filter. I am pretty new and have used it on my Pentax 12-24 camera. However, I always get a hotspot in the middle of my picture. Maybe my exposures are too long? Have you experienced this or would you be able to give any advice on this.

Also do you use Auto white balance with this filter or change any setting?
07-20-2010, 05:02 PM   #8
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QuoteOriginally posted by stevemgap Quote
Hey Aerodave,

I also have a K-7 and the Hoya R72 filter. I am pretty new and have used it on my Pentax 12-24 camera. However, I always get a hotspot in the middle of my picture. Maybe my exposures are too long? Have you experienced this or would you be able to give any advice on this.

Also do you use Auto white balance with this filter or change any setting?
Some lenses have hotspots when shooting IR. There are a couple lists of lenses, you can google for them, but most focus on Canikon.

For WB, you typically set a custom balance off of grass (with the filter on). If you try to fix WB in post, the software you use may limit how much you can adjust. Lightroom for example only goes down to 2000 degrees kelvin.

07-20-2010, 05:20 PM   #9
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QuoteOriginally posted by stevemgap Quote
Hey Aerodave,

I also have a K-7 and the Hoya R72 filter. I am pretty new and have used it on my Pentax 12-24 camera. However, I always get a hotspot in the middle of my picture. Maybe my exposures are too long? Have you experienced this or would you be able to give any advice on this.

Also do you use Auto white balance with this filter or change any setting?
The DA 12-24mm like the DA 16-45mm does show a noticeable hotspot in the center of the image. The DA 14mm and the DA 15mm Limited fortunately don't show any hot spots. I did a list of known and tested Pentax lenses that are IR friendly sometime ago in this forum. Do a search.
07-20-2010, 05:21 PM   #10
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I don't know about the K-7, but I've found it nearly impossible to custom white balance my KX with the R72 IR filter on it. It just says "action could not be completed" when I try to do it with anything green.

-- Chris
07-20-2010, 06:41 PM   #11
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The camera's White Balance processing is likely tuned to cope with various Colour Temperature related to visible light.
I doubt if it can cope with Infra-Red. Just switch to RAW.
07-20-2010, 06:53 PM   #12
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QuoteOriginally posted by Internetpilot Quote
I don't know about the K-7, but I've found it nearly impossible to custom white balance my KX with the R72 IR filter on it. It just says "action could not be completed" when I try to do it with anything green.

-- Chris
QuoteOriginally posted by kittykat46 Quote
The camera's White Balance processing is likely tuned to cope with various Colour Temperature related to visible light.
I doubt if it can cope with Infra-Red. Just switch to RAW.
Try something white. It's hit or miss but can be done. RAW is helpful to a limit but you still want to get it close at picture time. The problem becomes, the length of the exposures.

A quick experiment from a couple months ago (K7, Tamron 70-300)



You're far better off buying (or having one modified) a dedicated camera.

K20d IR



Either way (buy a camera or modify one), it's an expensive option so it should be something you have more than a passing interest in.

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