Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-03-2013, 11:06 AM   #1
Site Supporter
grhazelton's Avatar

Join Date: Jul 2007
Location: Jonesboro, GA
Photos: Albums
Posts: 1,829
Can your Pentax DSLR "see" infrared?

Wanna find out? Page 58 of the January 2014 Shutterbug outlines a quick and dirty test. Simply aim a remote control from your TV or some such at the lens and take a picture while pressing the remote's button. I tried it with my K 5 using live view, and, lo and behold!, a fuzzy flickering spot of light appeared!

I'll have to charge up the batteries for my faithful K 10 and see if it can see into the infrared, too.

So, now to find an infrared filter, hopefully second-hand, and experiment. I'll bet the ISO for infrared is lower than can be imagined. I seem to remember that for film it was in the single digits. Anyone out there experimented with this?

12-03-2013, 11:15 AM   #2
Senior Moderator
Loyal Site Supporter
Parallax's Avatar

Join Date: Apr 2008
Location: South Dakota
Photos: Gallery
Posts: 15,618
Remember that the focus will be different too, so may need some focus tweaking as well.
12-03-2013, 12:07 PM   #3
Veteran Member




Join Date: May 2012
Posts: 698
My K-r and K-30 see the TV remote IR very clearly but the K-3 just barely sees it, and only in very dark conditions.

The K-r also 'sees' a soldering iron glow in absolute darkness even though it is nowhere near being red-hot..

Most cell-phone and CCTV cameras are very sensitive to IR and will also see very hot objects in the dark, more so than the K-r.

It is odd that the IR turns up as purple. I guess it's because unlike visible light it goes more or less equally through all three colours of the bayer filter, perhaps a little less through the green than the blue and red.
12-03-2013, 01:46 PM   #4
Site Supporter
grhazelton's Avatar

Join Date: Jul 2007
Location: Jonesboro, GA
Photos: Albums
Posts: 1,829
Original Poster
Infrared redux

QuoteOriginally posted by Parallax Quote
Remember that the focus will be different too, so may need some focus tweaking as well.
Back in the day most "serious" lenses and cameras had an IF mark on the focus ring. It was a little short of infinity. So much for autofocus!

Shooting IR with digital has got to be easier than with film. I seem to remember needing to load the film in total darkness....

12-03-2013, 03:54 PM   #5
Pentaxian
kh1234567890's Avatar

Join Date: Sep 2010
Location: Manchester, UK
Photos: Gallery
Posts: 2,406
QuoteOriginally posted by grhazelton Quote
So, now to find an infrared filter, hopefully second-hand, and experiment. I'll bet the ISO for infrared is lower than can be imagined. I seem to remember that for film it was in the single digits. Anyone out there experimented with this?
It is possible with a K-7, but not something I'd do every day :




15sec at f5.6 ISO1600
12-03-2013, 05:45 PM   #6
Pentaxian
ScooterMaxi Jim's Avatar

Join Date: Jul 2009
Location: Minnesota
Posts: 1,501
Over the years, all of the manufacturers have increased the IR filtering to a point where the R72 is very difficult to use for serious IR photography. However, most of the early 6mp are somewhat capable (about a six stop exposure penalty). This might be my best excuse for keeping the *istD - but I doubt I would ever convert it. Here is a shot taken with a 50mm f/1.4 (probably at f/5.6 or 8):
Taos - December 2010 - James Robins - Powered by Phanfare
12-06-2013, 12:38 AM   #7
Senior Member




Join Date: May 2013
Posts: 140
Since I got a 750nm IR-filter for my film SLR, I also put it on the K5 for a short test. With very long exposure time in the range of two hours, I got some somewhat useable pics. Bur that was at base iso in a dark room. I want to do some more tests outside and in sunshine.

Dont know if the sensitivity of the K5 is >zero above 750nm or if the filter wasn't completely black at visible, so I don't know if it really was IR that i recorded. Well have a look outside and test if i can get white leaves!


rgds,
Gerd.
12-06-2013, 08:29 AM   #8
Pentaxian
ScooterMaxi Jim's Avatar

Join Date: Jul 2009
Location: Minnesota
Posts: 1,501
You are still getting some visible spectrum at 750 and even 760 nm, but a lot more at 720, of course. If I had a digital camera with the IR blocking filter removed, I'd probably go with an 800 or 850. As it is, I realize that my 720 is a compromise that isn't truly IR photography but still yields interesting effects. As an occasional diversion (every few years), I'm not about to put a lot of cash into the proposition.

12-06-2013, 08:55 AM   #9
Pentaxian
Clavius's Avatar

Join Date: Feb 2011
Location: De Klundert
Photos: Gallery
Posts: 4,122
Infrared sensitivity depends on the size of the sensels and the IR blocking filter. My ancient Olympus 2020c point&shoot was famous for being very sensitive to IR. It can easily shoot handheld IR photos of moving subjects with just about any IR filter in front of it. Fun while it lasted, mine died about a year ago.

Pentax cameras have very thick (and increasingly thick) IR blocking filters. My K20D was still ok on a tripod. Manual focussing in its pseudo live-view still possible on bright summer days. My K-5 can't see anything anymore. I wonder why they do that? I don't think IR light messes with IQ of normal photography. At least, the K20D had excellent quality pictures, no reason for the IR blocking filter to be stronger.

I would really enjoy doing some old fashioned IR black & white portraits on a DSLR. For some reason I can't find anybody to mod any of my old Pentaxes for a reasonable price.
12-06-2013, 09:21 AM   #10
Pentaxian
Just1MoreDave's Avatar

Join Date: Feb 2007
Location: Aurora, CO
Photos: Gallery | Albums
Posts: 4,862
The K-7 can do it. It's about 7 stops less sensitive than the *ist DS (Hoya 72 filter) but the (false) colors are more interesting. I usually use a Sigma 28mm f1.8, older version with 58mm filter size. I focus using live view. I set the color temperature to 2500K (the minimum) in-camera for a better idea of color channel saturation. I shoot RAW. A good starting point here in full sun is f8, 15 seconds, ISO 100. Remember the viewfinder blind. For processing, I start at 2000K and -50 tint (ACR 6.7) and adjust from there.

12-06-2013, 04:57 PM   #11
Pentaxian
ScooterMaxi Jim's Avatar

Join Date: Jul 2009
Location: Minnesota
Posts: 1,501
Yeah, that's pretty close to my RAW process formula. In Capture One, I can get down to a nicer, brighter sepia at around 1200 color temp (C1 goes all the way down to 800) - but the noise reduction isn't in the same league as current LR - and that's pretty darn important with so much data loss.

I'd really like to try shooting some near-IR on the K-01 and not have to worry about the VF issues. So, I decided to order a cheap 650nm filter and will see how close to real IR I can get with some processing manipulation. It will head over on a slow boat, but I'm not in a hurry.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, dslr, infrared, infrared exposure, k 5, k10, pentax dslr, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Thematic Infrared Photography - Post your "invisible world" pictures here photocanadian Mini-Challenges, Games, and Photo Stories 21 09-13-2016 07:55 AM
Can't get Photoshop CS6 to "see" Camera Raw 8.1 TimKierath Digital Processing, Software, and Printing 12 07-31-2013 12:19 AM
Can't see any "downside" here.. snicker jeffkrol General Talk 7 10-14-2012 12:24 AM
Have you "outgrown" your pentax DSLR? slip Pentax DSLR Discussion 68 08-23-2012 06:48 AM
"what people may like to see in a Pentax DSLR ;-)" txsbluesguy Pentax DSLR Discussion 21 01-16-2009 07:45 AM



All times are GMT -7. The time now is 02:27 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top