You are accessing this forum with [trillian] as part of the url. This may be happening automatically following a move to a new server, or it may be something you are doing as part of a phpbb3 upgrade. If this is not part of an upgrade then be patient and do not bookmark the link, the old links will be working again shortly. If this is part of an upgrade then make sure the owner finalises it in the control panel and selects to redirect to this version of the forum, then once again the link will return to being the old one within 48 hours or so. NEVER BOOKMARK OR PUBLISH THIS LINK IT WILL NOT ALWAYS WORK.
Posted: Fri Jan 19, 2007 1:44 pm Post subject: Digital Infra-Red How-to
This quick IR tutorial is based on my knowledge and experience from taking infra-red (or technically near infra-red) photos wth my D70.
pre requisites:
1 unmodified camera + ir filter, or ir-modified camera
2 photoshop
There are two ways you can take infra-red photos with a digital camera - getting the camera modified for ir or by placing a near infra-red filter on the lens.
The level of sensitivity to infra-red light varies from model to model, and bodies released by Nikon after the D70 have shown to be decreasingly sensitive to infra-red. This is because the glass ('hot') filter living infront of the sensor has been tweaked to filter out more uv and ir light, to give much better colours in general photography.
Cameras that are modified for ir have this hotfilter removed. It means they take brilliant ir photos, but are useless for normal operation. From what I've read and seen, many people get one of their old bodies modified or buy a pre-modified model that is a step or two older than the current generation (popular models include the Nikon D100 & Canon EOS 10D)
Whether you are able to take photos with an unmodified camera depends on the sensitivity of your dslr to light. Supposedly, you can test whether your camera is adequately sensitive by shining a tv remote at the camera and taking a picture. If you see any light from the end of the remote, your camera is sensitive to ir. I can't say I've tested this out; it's something I've read in an infra-red book that I own
Fortunately for me, the D70 proves sensitive enough to allow reasonable exposure times in good light. Resonable still means using a tripod though; there's not much escape from that without using a modified body.
I use a Hoya R72 IR filter, which blocks wavelengths less than 720nm. It's the most popular from what I've seen, although any equivalent to a Wratten 89B (e.g. B+W Infra-red 89B) will do the same job. The filter is opaque, which means your shot needs setting up before attaching the filter - you'll not be able to see much if anything through the viewfinder once it's on.
Infra-red light also has a slightly different focal point, so any focussing you do sans filter will be slightly out in the final picture. Some lenses supposedly show a red infra red focus mark, so if you're lucky enough to have one of these you can adjust manually as required. Sadly, none of my lenses do. The main trick is to make sure your DOF is wide enough so you have sufficient margin of error, i.e. f/8 or smaller is going to help. I have found, however that my D70 manages to still auto-focus with the filter attached, and it's not _that_ far out, so I use that method
There's some amount of fiddling about though - you'll need to manually set your white balance with the filter attached. If you don't have a white card, then aiming at a sunny area of grass and setting off that will do. Obviously this may mean attaching the filter, setting wb, removing filter, setting shot up, re-attaching filter, taking the shot.. In other words, I think you're going to find it hard to take infra-red shots of fast moving action You're going to need some patience in setting the shot up, but the results are well worth it.
With regard to the sunny grass comment - the best infra red pictures are going to be taken on a sunny day with some clouds around. If properly exposed the clouds will be fluffy and white, the sky very dark and any foliage radiating light, due to the chlorophyl reflecting it more readily than pretty much everything else. Exposure can be tricky with the filter, as there is no well-defined stop loss. Brochures will say "loses 10 to 20 stops of light" which isn't overly helpful when taking a single shot. I started out by manually metering the scene then moving exposure up by 12 stops, then taking 8 shots upping the exposure by half a stop every time, shooting raw. I tended to get maybe 2 or 3 shots that were sufficiently exposed that I could choose from.
Since then, I've found that auto-exposure isn't actually too far off now, so have started using that and AEB. Auto focus and aeb make life a lot easier if they will work on your camera when shooting infra-red!!
Once you've taken your picture, it may end up looking something like this:
This picture was taken on my first ever outing with the IR filter, and i didn't get the white balance set particularly well, hence why it's so red. The contrast isn't fantastic either.
Even though the whitebalance isn't perfect, we can still carry on.
Next step, auto levels:
It never ceases to amaze me what auto levels will do for ir
At this point, if you want a black & white infra red image, you can remove the colour. If you're wanting a colour infra red image, and haven't desaturated the image, you'll want to swap the blue and red colour channels using the channel mixer tool. Select the red channel and reduce the saturation of red to 0 and increase blue to 100. Then go to the blue channel, increase red to 100 and reduce blue to 0. If your white balance was set right, that'll give a pretty good rendition:
As you can see, this image is far too blue: a result of my inaccurate wb setting. To try and fix it, i've reduced both cyan and blue saturation to 0:
Quick fiddle with the levels again:
Now the 'artistic' tweaks. These are all optional, of course
1: Sharpen the image. Although traditionally you'd do this last, the other effects that we can optionally add will want to be done after sharpening. Personally, I use the high pass filter for sharpening, but use whatever floats your boat to make what you want sharp, sharp.
2: Add noise. If you want to recreate more of a film-like look, you'll want to add some noise to the image. Choose Add Noise from the Noise submenu on the Filter menu. Start with values of 20% and Uniform and tweak as desired. Alternatively, select Grain from the Texture submenu on the Filter menu. Start with values of Soft, 15% Intensity, and 50% Contrast and fiddle with it until you get something you like.
3: Add bloom. Film ir shots have an eerie bloom (glow) which is one of the reasons infra red shots look so unique. The amount of bloom you get on a digital image will depend on your exposure and camera.
Select Diffuse Glow from the Distort submenu on the Filter menu. Start with values of 6 for Graininess, 5 for Glow Amount, and 20 for Clear Amount. Again, the exact values will depend on your intended result - feel free to play with the settings.
For this particular image, I've not sharpened, or added any grain or glow - it's really down to personal preference and what the image will take.
And there you go the amount of colour fiddling you do, assuming you want it in colour is of course, entirely personal. I'm sure you'd all come up with slightly different renditions of this image. What I can tell you though, is this particular image looks great on a black mount on my mum's living room wall
I've still only managed to get out twice with the filter, so I've still got an awful lot to learn and improve upon. I fully hope to be able to update this as time goes on with better images and more info. There's so much scope to infra-red photography - this is just the tip of the iceberg.
Heres a flickr tool mosaic thingy of some of the shots I've taken so far, all of which can be seen in my infra-red set on flickr
_________________ There is nothing in life that cannot be improved with either monkeys, pirates or ninjas NPU Member
Last edited by jonH on Sun Jan 21, 2007 11:24 pm; edited 4 times in total
thanks guys, it'll be more meaningful once i can get a couple more screenshots & example settings up ;) _________________ There is nothing in life that cannot be improved with either monkeys, pirates or ninjas NPU Member
i've updated the original post with a bit more stuff. _________________ There is nothing in life that cannot be improved with either monkeys, pirates or ninjas NPU Member
Sticky?? nice one jon. _________________ The sun cannot set,
Because you are not here,
To see it,
The day cannot end,
It can't be right,
That night will come,
Without you.
That picture does not look real - surreal (not too sure what that means but it sounds about right, just also realised its almost 3D
Brilliant update to an already good post
So how do I do it with a D200? Cannot do camera mod for obvious reasons. Got rid of the D70 (now I'm thinking should have kept hold of it)
Thank you
Last edited by hil26 on Sat Jan 20, 2007 12:16 am; edited 1 time in total
Marvelous and riveting, Jon. Thank you for the time you've put into this. Although I don't have a desire to 'do' IR camera work, it has certainly fed into my PS habit and got my juices flowing.
How about Post of the month Mike? _________________
get one from ebay - they're a _lot_ cheaper. i got mine from 'chinaarts' _________________ There is nothing in life that cannot be improved with either monkeys, pirates or ninjas NPU Member
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
FAQ
Search
Memberlist
Usergroups
Join! (free) 
Profile
Log in to check your private messages
Log in
