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03-01-2008, 05:14 AM   #1
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K20d Infrared capability

Hello all, I've just joined this wonderful forum.

As I'm seriously thinking of getting a Pentaxian, I wonder if anybody has tried shooting infrared with the great-looking K20d.

I was shooting a lot of IR with my compact and am looking for a better tool. As far as I've read, the K100d did Infrared perfectly with hand-holdable shutter speeds, while the K10d can do IR, but always requires a couple of seconds exposure.

Any experiences?

Thank you!

03-01-2008, 05:53 AM   #2
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QuoteOriginally posted by Noisychip Quote
Hello all, I've just joined this wonderful forum.

As I'm seriously thinking of getting a Pentaxian, I wonder if anybody has tried shooting infrared with the great-looking K20d.

I was shooting a lot of IR with my compact and am looking for a better tool. As far as I've read, the K100d did Infrared perfectly with hand-holdable shutter speeds, while the K10d can do IR, but always requires a couple of seconds exposure.

Any experiences?
None here but reports from those that have tested the IR response of their new K20Ds indicate similar IR response to the K10D.
03-01-2008, 06:31 AM   #3
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Someone needs to post a photo taken with the K20D using it's built-in infrared filter. Apparently it does in-camera IR conversion.
03-01-2008, 06:42 AM   #4
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I took one yesterday, but I believe it's just a particular set of levels for the b/w conversion, not a true infrared shot. Too bad but not really surprising.

Of course, I could be wrong. If I get time, I'll try to shoot another few today.

03-01-2008, 06:45 AM   #5
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QuoteOriginally posted by Tom M Quote
Someone needs to post a photo taken with the K20D using it's built-in infrared filter. Apparently it does in-camera IR conversion.
I think in-camera IR is nothing but a Photoshop-like filter. It's just mocked IR. You can easily distinguish by looking at plants: Real IR generally makes foliage or lawn very bright, photoshopped does keep the brightness.

Or am I wrong? A built-in R72 would be perfect!
03-01-2008, 06:56 AM   #6
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Just found this thread.

K20D and IR: Pentax SLR Talk Forum: Digital Photography Review

K20d seems to be similarly sensitive to IR as the K10d is. Live View doesn't seem to help a lot for framing.

I'd really like to see some samples
03-01-2008, 09:10 AM   #7
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Photoshops filter for converting colour images to black-and-white has a preset called "Infrared", which is just some combination of coefficients for different colours to give a "infrared-ish" look to the resultant B&W image. K20D very very likely does just that. I really can't imagine the camera really physically moving the IR-cut filter (that's the thing in front of sensor that gets rid of most of the infrared) aside from the sensor and later back. Imagine the horrible cleaning problems if dust gets between the IR-cut filter and sensor.... I'm not even talking about scratches made by sand particles so near to sensor ....it would look awful. So unless they have moved the IR filter somewhere between the mirror and the lens (which would kind of show ) I don't believe a real IR mode exists.
03-01-2008, 06:43 PM   #8
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K20d Infrared

I think that the K20D is slightly better than the K10D. Here is a pic I took outside work with a hoya r72 filter on the 18-55 lens. It is ISO 800 1.3 sec at f4. the blurry spot is some balloons blowing in the wind.

Nick

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03-01-2008, 07:00 PM   #9
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Thanks a lot for that sample!

That looks pretty good, doesn't it? It seems to be very sunny weather, but around one second isn't that bad And for what I've seen, ISO 1600 seems quite usable, so less than a second should be possible.

Did AF work with the filter on? How about Liveview, can it be used for framing with the R72?

Will try to swap channels of the pic, let's see how it works.
03-01-2008, 10:43 PM   #10
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I have not tried it with live view yet. I will see if the sun comes out tomorrow and see what it can do. The Af did work, but the metering did not. The exposure was a little bit of trial and error.
03-04-2008, 09:32 AM   #11
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The live view does allow you to compose with the LCD screen. It is not really bright and easy to see, but it is easier than composing and then putting the filter back on.
03-04-2008, 02:10 PM   #12
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QuoteOriginally posted by cardnick Quote
The live view does allow you to compose with the LCD screen. It is not really bright and easy to see, but it is easier than composing and then putting the filter back on.

Thanks for trying, cardnick!

Is that for bright sunlight, meaning ideal conditions? Or could it be better on a really bright day?

There are other threads mentioning that the K20d's LV is close to unusable for IR, at least that's my interpretation. It would be really interesting to see what this means in a picture - can anybody take one of the LV with R72 in action?

LV doesn't help judging the exposure's brightness, right?

Maybe one should go for two cameras, one for IR, say a compact with LV or a K100D, and one for normal visible light photography ...
03-04-2008, 08:28 PM   #13
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the test was in bright sunlight conditions. The live view was not useful in seeing exposures brightness. The screen was hard enough to see because of the glare from the sunlight. I am still excited about the K20's IR capabilities. It is much better than my K10.

Nick
09-15-2010, 04:59 AM   #14
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What is the sensitivity range of the K20D sensor

I scoured Google but I cannot find a chart showing the light frequency sensitivity range of the K20D sensor.

I used to do a lot of IR (and UV) photography back in the days of film. I had a chance to try an IR filter on my K20D a while back and I results were pretty good for a relatively short exposure (about 2 seconds).

So finally, I ordered my own 72mm IR filter but my results are far worse than expected. Granted, it was later (about 6pm) but I did expect a little better. In the attached sample, I needed 6 minutes @ ISO 400, f8 to barely capture the screen. You can also see horrible sensor noise (something I really hate about my K20D on any long exposure).

I suspect that the filter cutoff frequency is too long. The filter I purchased cuts off any light shorter than 850nm. Digital IR photographers usually recommend the Hoya R72 filter, which cuts off at a much shorter 720nm.

I think I got the wrong filter.
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09-15-2010, 08:49 AM   #15
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As you've already noted, you need light to do IR. I am not really an expert on the subject but I do believe it possible with the R72 (the only one I've ever bought)..

K20d, FA43mm L, 30 seconds, f9, ISO100



Part of the key is you need to set the White balance with the filter on the camera. In the end though, enjoying IR photography, I chose to purchase a dedicated camera for it.

K20d Infrared - a set on Flickr

I think the K7 (for info purposes) has a stronger blocking filter than the K20d..

k7IR - a set on Flickr

If I were to buy another (or have converted) camera, I would probably go with a clear glass over the sensor rather than an IR filter. That way, I could use Any filter I wanted to.

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