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03-14-2010, 11:10 PM   #1
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K-X and infrared photography

I just got my new K-X, and would love to try infrared photography.
I know the K-X can see IR (did the old tv remote test).
Reading through the manual, found out that there is an internal IR monochrome filter. Tried taking a few pictures in monochrome IR filter mode, but they look just like b+w pictures...

Is the K-X internal monochrome IR filter the same thing as the Hoya 72 IR filter? I am new to infrared photography, are IR photographs supposed to look b+w? Are all those amazing pictures I see of IR photography photo-shopped later?

03-14-2010, 11:24 PM   #2
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The internal filter you are talking about is a virtual filter, the Hoya 72 is made of glass and metal so that makes them very different from each other.

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03-14-2010, 11:30 PM   #3
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QuoteOriginally posted by Augustus58 Quote
I just got my new K-X, and would love to try infrared photography.
I know the K-X can see IR (did the old tv remote test).
Reading through the manual, found out that there is an internal IR monochrome filter. Tried taking a few pictures in monochrome IR filter mode, but they look just like b+w pictures...

Is the K-X internal monochrome IR filter the same thing as the Hoya 72 IR filter? I am new to infrared photography, are IR photographs supposed to look b+w? Are all those amazing pictures I see of IR photography photo-shopped later?
No. Some people use the R72 on the lens front to block almost all but IR light.

This can be a typical result (panasonic FZ1 + R72).



Others purchase or have cameras converted specifically for IR photography. It's done by removing the IR blocking filter and replacing it with an IR filter.

IR converted K20d.



The Problem with the R72 option is the White Balance..

See here for a sort of detailed trial and error discussion on doing so with the Kx..

Infrared Photography: Pentax SLR Talk Forum: Digital Photography Review

There's a guy here on the Pentaxforums that had his Kx camera converted by removing the IR blocking filter and replacing it with a clear glass and some sort of heat control device (which I still don't quite understand)..

https://www.pentaxforums.com/forums/pentax-dslr-discussion/91608-kx-irfrared-15-limited.html

Good luck..

03-15-2010, 12:21 AM   #4
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We've had various infrared discussions here. Search the forums and you shall be rewarded.

Briefly -- there are many ways to get into IR:

* Film cameras are cheap, and IR film isn't too expensive. IR filters (not cheap) help with IR film, but even a common R25 red filter is useful. I have a roll of outdated Efke IR 820 film (US$5 from Freestyle) in an old 120 6x9cm folder (US$20 on eBay) that I'd better shoot pretty soon.

* All digicams are sensitive to IR. Virtually all have a "hot filter" placed in front of the sensor. The old Sony "NightShot" line of P&S and vid.cams, like my 5mpx DSC-V1, have a switch to flip the hot.filter out of the way; but Sony built limits into these cams. Still, when used with red or IR filters, fascinating images can emerge.

* IR-converted P&S digicams can be found on eBay, with the hot.filter replaced with clear glass. I bought a 5mpx Minolta F300 for about US$300 a couple years ago. Better cams can cost as much as having your Kx converted (see below).

* You can just put a red or IR filter on your Kx. As mentioned, white balance is a problem, which can be fixed in RAW editing. Just don't expect brilliant JPEGs, and be patient -- using a visible-light-blocking IR filter can mean LONG exposures.

* Do some googling and you'll find a few shops that will remove the hot.filter from any dSLR. This conversion is permanent surgery -- your Kx will be an IR cam forevermore. Of course, you can then add an IR-blocking filter (not cheap) in front of the lens for standard shooting.

* You could remove the Kx's hot.filter yourself, but DON'T TRY UNLESS YOU ABSOLUTELY KNOW WHAT YOU ARE DOING. Or you will be very very sorry.

* Sigma and Fuji make (or made) "forensic" dSLRs (taking Nikon lenses) with easily removable hot.filters. These are used in police and scientific work. The bodies aren't terribly expensive; full sets of spectrum-slicing filters ARE costly, but you don't need to collect those unless you're working CSI or art fraud or science.

Those are possible routes to IR. What to do when you get there is another matter. Search the forums here for endless help. Have fun!

03-15-2010, 09:07 AM   #5
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JeffJS, these photos are beautiful! Are these unmodified photos (no photoshop)?
03-15-2010, 09:13 AM   #6
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RioRico,

I do not intend to take solely infrared photography, so I am not considering modifying my K-X in any way. Although that does seem like an interesting idea, maybe in the future when I can afford 2 cameras...

I have searched the forums, but the answers seemed geared toward people much much more experienced than I, so I did not understand them very well (which is why I posted in the beginner's section).

How long do the exposures for IR photography take? I can only go up to 30 seconds on the K-X as far as I can figure out. Is this enough? Is there any way to make my exposures longer (I am also interested in astrophotography)?
03-15-2010, 09:15 AM   #7
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QuoteOriginally posted by Augustus58 Quote
JeffJS, these photos are beautiful! Are these unmodified photos (no photoshop)?
IR photos need at least some basic white balancing (false IR can also require layering and color channel swapping - none of which I am good at!) - out of camera IR photos will be red typically - white balancing can be done with a raw file by choosing something green as the 'white' area - I have read that shooting with a tungsten white balance setting can give reasonably workable jpegs, but raw is the best option for IR.
03-15-2010, 12:09 PM   #8
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QuoteOriginally posted by Augustus58 Quote
JeffJS, these photos are beautiful! Are these unmodified photos (no photoshop)?
The top photo is unmodified. Straight out of the FZ1. The Second one has had a post processing channel swap. It was taken with an IR modified K20d and a Zenitar 16mm f2.8. IIRC, the Red and Blue channels are swapped.

Here are some more...

More From the FZ1

FZ1v2Infrared pictures by jjmel - Photobucket

And here is a set from the K20dIR

K20d Infrared - a set on Flickr

Most have had some sort of color manipulation from drastic, to a simple levels adjust.


QuoteOriginally posted by pxpaulx Quote
IR photos need at least some basic white balancing (false IR can also require layering and color channel swapping - none of which I am good at!) - out of camera IR photos will be red typically - white balancing can be done with a raw file by choosing something green as the 'white' area - I have read that shooting with a tungsten white balance setting can give reasonably workable jpegs, but raw is the best option for IR.
While in theory that's true, in practice, not always so. See the DPR link I posted in my other response for the problems doing this with a unmodded Kx. It's always best to get the WB correct from the get go. That means setting the Manual WB with the filter (whichever one used) On the camera. From there, simple slight color casts can be corrected easily.



03-15-2010, 12:10 PM   #9
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QuoteOriginally posted by Augustus58 Quote
How long do the exposures for IR photography take? I can only go up to 30 seconds on the K-X as far as I can figure out. Is this enough? Is there any way to make my exposures longer (I am also interested in astrophotography)?
I imagine some of our astro.friends will chip in on that subject. For long exposures, your mode dial has a B (for bulb) setting. Plug in a wired remote (preferably one that latches) and the shutter stays open as long as you want. Here's how to make a DIY Pentax DSLR cable release: booleansplit.com DIY Pentax DSLR cable release

The exposure time for IR depends on how deep a filter you use, as well as f-stop and ISO. Since most or all visible light is blocked, only the red pixels on your cam's sensor (1/4 of the total) gather light, so your effective resolution drops from 14.6mpx to 3.65mpx, and you lose 3/4 of the sensitivity. That's why digital IR shots are usually rather grainy. IR film is another story, but why fret...

A mild IR filter like a 680nm or 720nm (or for less money, a red R25A filter) lets you shoot hand-held, lens wide open. My deepest 1000nm filter requires several minutes on a tripod, up to many minutes if I use a small aperture and a ND4 or darker to eliminate all motion.

For your amusement, here are a couple references.

Shooting IR with a normal unmodified DSLR is a 2 step process: https://www.pentaxforums.com/forums/559973-post33.html

Using DSLRs for Astronomical Imaging: Digital SLR Astronomical Imaging
(note: w/Pentax interval shooting, Canon remote isn't needed)

Books on digital IR exist. Some can be found in torrents. (Did I say that? Shame on me!) Other IR guides exist online. Spectrum-slicing is great fun and not all that hard, once you get the concepts and tools. Enjoy.
03-17-2010, 08:01 AM   #10
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You all are great!!
Thank you so much for the information and interesting links!
03-17-2010, 11:45 AM   #11
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I just checked my K-x with a Hoya R72 IR filter.

I pointed the lens towards an overcast sky at f:8; the exposure time was 1/500 sec. I then put on the R72 filter and the exposure time increased to 1/4 sec. That's a difference factor of 125, or 7 stops. I could hand hold a 50:1.7 @ 1/125 sec, 6400 ISO- it needed +3EV compensation and was still somewhat underexposed...
Dave in Iowa

The R72 filter gives more of an "Infrared effect" than the 25A..Here's an example with a Panasonic FZ30:

Last edited by newarts; 03-17-2010 at 12:01 PM.
03-17-2010, 01:24 PM   #12
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Dave in scenic Iowa,

Have you tried the IR filter in the K-X? It's under filter-monochrome-IR filter in the menu. What would happen if you use the K-X internal IR filter with the Hoya R72 IR filter (other than becoming monochrome)? I know the internal IR filter is no match to the Hoya R72 filter in terms of cool effects. In fact, I cannot tell the difference between the internal IR filter and a regular b+w picture.
03-17-2010, 02:37 PM   #13
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QuoteOriginally posted by Augustus58 Quote
Have you tried the IR filter in the K-X? It's under filter-monochrome-IR filter in the menu. What would happen if you use the K-X internal IR filter with the Hoya R72 IR filter (other than becoming monochrome)? I know the internal IR filter is no match to the Hoya R72 filter in terms of cool effects. In fact, I cannot tell the difference between the internal IR filter and a regular b+w picture.
You can't tell the difference because it's not an IR filter, it's an IR *effect* simulator, and not very good at that. It looks like it's a Red simulator with darker tones. An optical IR filter blocks a major portion of visible light, but passes IR light -- which, in an unaltered camera, is blocked by the "hot filter". No free lunch here.
03-18-2010, 12:23 PM   #14
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I was trying to make sure my photoshop has some kind of channel mixer and lo and behold, I cannot find it. I have photoshop elements 6 that came bundled with my wacom tablet. I read things about photoshop having 'hidden' filters and such, but I cannot locate it on my disk.
Some internet searches resulted in some long, confusing, and convoluted answers that did me no good.

What do I have to do to get the channel mixer onto my photoshop elements 6? Do any of you know any reputable sites where I can download the plug-in for the channel mixer???
03-18-2010, 12:55 PM   #15
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In Photoshop it's under Image>Adjustments..

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