Author Topic: A Guide To Infrared Photography  (Read 42956 times)

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Offline Rob aka [minolta mad]

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A Guide To Infrared Photography
« on: March 30, 2008, 08:08:40 PM »
As promised i have written a guide as to how I take my Infrared Photographs.


Rob

Introduction


Infrared light is technically not a light source, it is invisible radiation, that our eyes cannot see but the sensors of our digital camera’s can.
By shooting in infrared, we can get some weird and wonderful effects, green foliage ends up looking like it has snow settled on them, due to the way it reflects IR wavelengths, blue skies and water end up very dark (near black) depending on which IR filter you use, as they absorb IR wavelengths.

If we shoot colour IR with custom white balance settings then truly weird colour combinations can be seen.

There are however some special problems that IR photography presents, focussing, exposure and some lenses do not allow the shooting of  IR photography.


So what do we need to take IR photographs.
1.   IR sensitive DSLR
2.   IR suitable lens
3.   IR filter
4.   Tripod
5.   Cable release (essential for shutter speeds in excess of 30-200 secs)

That’s really it.

In the tips below is what I have picked up and learnt from shooting Infra Red,
and what I believe to be correct.
If any information is inaccurate then I apologise and stand to be corrected.

Hopefully this information may answer a few of the myths around this type of photography and may encourage some other people to give it a go.


If anybody has any questions or queries then or myself or someone else will try to answer them.
Or indeed any tips themselves, then paste them in this thread so we can all benefit from them.
« Last Edit: April 02, 2008, 08:36:03 PM by minolta mad »

Offline Rob aka [minolta mad]

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Re: A Guide To Infrared Photography
« Reply #1 on: March 30, 2008, 08:09:02 PM »
Testing camera for sensitivity


All camera manufacturers go to great lengths to block out as much IR light from reaching the sensor as possible, as this causes focusing,colour,metering and exposure problems.
The way they do this is to place a filter in front of the sensor called an Internal Infra Red Cut-off-filter (IIRC’s) often called Hot Mirrors.
Different manufacturers use different “hot mirrors” so some DSLR’s respond better to IR light than others.

To test whether or not your particular type of DSLR is suitable for IR photography the easiest way of doing this is the “TV REMOTE” Test.
Basically take a picture of your tv remote with your camera whilst pressing one of the buttons so a IR signal is transmitted from the remote.
Take the picture using an exposure of 5 secs at f/5.6. You should see a white light emmited from the sensor of the remote, the brighter the light the more sensitive the camera is to IR light. If no light is seen then your camera is probably not any good for taking IR photographs.

Image taken on A700, iso 200, f/5.6, 5 seconds



All you need to do now is buy yourself an IR filter.


From experience we as Minolta/Sony owners are lucky as our DSLR’s are suitable for taking IR photographs.
I have used the
5D
7D
A700

And successfully taken IR photographs with them, although I have not used the following camera's, I have been informed by other members that these are also suitable for IR.
A100
A300

« Last Edit: September 16, 2011, 09:19:24 PM by Rob aka [minolta mad] »

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Re: A Guide To Infrared Photography
« Reply #2 on: March 30, 2008, 08:09:36 PM »
Lenses


As with DSLR’s not all lenses are suitable for taking IR pictures.
Some produce what are referred to as “hot spots”, no one knows exactly what causes these hot spots but it is largely believed that it is the IR wavelengths effectively reflecting at different angles within the inside of the lens, and more “IR light” hitting the sensor in one “spot” rather than being evenly distributed.

A hotspot pic -


Its not always in the shape of a “spot” the hotspot, sometimes it causes a streak or streaks.

Streak pic -


Thanks to Springtide for this image.


There is no way of telling which particular lens will cause hot spots until it is tried and it either produces them or it doesn’t.
It is believed that wide angle lenses and especially  zoom lenses are more likely to produce hotspots than fixed lenses due to their complicated optical systems.


Lenses that I have used or know that don’t cause hotspots

Minolta 35-70 f/4
Minolta 50 f/1.7
Sony CZ 16-80
Tokina 28-80 ATX-Pro
Sigma 28-70 EX DG 2.8


Lenses that I have used or know that do cause hotspots

Konica/Minolta 17-70 kit lens
Minolta 17-35 G
Minolta 28-70 G
Tamron 17-50 f/2.8


I know this list doesn’t have a lot of lenses on it at the moment, but it will be updated as myself and others find lenses that do or don’t work.



« Last Edit: September 16, 2011, 09:20:53 PM by Rob aka [minolta mad] »

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Re: A Guide To Infrared Photography
« Reply #3 on: March 30, 2008, 08:10:14 PM »
Infrared Filters


Like everything in photography there are several IR filters to choose from. These range in price from £25 up to £200. The more expensive one’s it is alleged tend to give more even results as they have stricter controls in place to ensure they are of the highest quality when they leave the manufacturers.
 
Different IR filters block some or all visible light and allow different amounts of  IR  light to pass through them, giving very different results.

Infra Red filters are measured by how much IR or near IR light they allow to pass through them, as there is no “standard” for how this is measured, it is difficult to really know what effects different filters will have until they are tried.

These filters are measured in ‘nm’ (nanometers) and the range used in photography is between 520 nm and 900 nm
I do not fully understand all of the transmission rates and effects these rates will have and how they will look when taking IR photographs.
 
So recommendations and seeing the effects different filters have by other people’s results are the way to go
The Hoya R72 filter will give the images taken a complete red colour until processed or converted to Black and White, as this allows some visible light in the far red spectrum to pass through the filter. Whereas the B+W 093 filter completely blocks all visible light and gives True IR pictures, but a sensitive IR camera will be needed to record the images or extreme exposures would need to be used.



IR filters manufactures.

Hoya      See Here
B+W       See Here
Cokin       See Here
Lee         See Here
Sign Ray  See Here
Tiffen      See here   
Heliopan   See Here

One possible problem with the square type slot in filters is that light can creep around the sides of the filter and ruin the shot ( I have heard of this but have not used this type of IR filter, so cannot comment)


By far the most popular IR filter is the Hoya R72, probably because it’s the cheapest filter and most easily available and gives good results.

For a reputable Ebay dealer in the UK See Here

I have used this dealer several times and the filters costs under half of what they cost in the shops. 


« Last Edit: April 02, 2008, 08:37:59 PM by minolta mad »

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Re: A Guide To Infrared Photography
« Reply #4 on: March 30, 2008, 08:11:03 PM »
Focussing


One of the major obstacles in IR photography can be focussing,
“But only if you let it be”

First of all you’ll need to use manual focus, and secondly, because of the wavelengths IR light are transmitted at, it causes a focus shift of  1/400 th of the focal length used.
And unless the focus is adjusted your images will be out of focus.

A lot of the older lenses have a red R, a red line or a red dot, this indicates the IR focal shift point.
 


To use this – focus on the subject that you wish to be your main focal point and make a note of what distance this is, eg 30 ft, Then place your IR filter on your lens and then align the distance your subject was at on the red dot/line/R
The image below is focused for 30 ft at 35mm, where as the lens is at 50mm, i will change this pic soon :-(



Then the focus will be spot on for the subject at that given distance.


For newer lenses that don’t have the IR mark on them then the only way to ensure your pictures are in focus is to use the Hyperfocal Distance.

The goal of hyperfocal distance focusing is to maximise the DOF (depth of field) and ensure that the maximum amount of the image is in focus. Effectively focusing
½  way into the image, so everything from 1/3 to infinity is in focus.
For a more detailed explanation  See Here


Below is a Hyperfocal Distance chart for APS c sized sensors.

                                   Chart in feet
Focal length
       15 mm 17 mm 20 mm 24 mm 28 mm 35 mm  50 mm 100 mm
f 2.8  8.79    11.29    15.62    22.50    30.62    47.85   97.64    390.58
f 5.6  4.39     5.64       7.81    11.25     15.31   23.92   48.82    195.29
f 8     3.08     3.95       5.47      7.87    10.72    16.75   34.18    136.70
f 11   2.24     2.87       3.98      5.73      7.79    12.18   24.85      99.42
f 16   1.54     1.98       2.73      3.94      5.36     8.37    17.09      68.35
f 22   1.12     1.44       1.99      2.86      3.90     6.09    12.43      49.71

                                    Chart in meters
Focal length
        15 mm 17 mm 20 mm 24 mm 28 mm 35 mm 50 mm 100 mm
f 2.8   2.68      3.44     4.76      6.86     9.33    14.58    29.76    119.05
f 5.6   1.34      1.72     2.38      3.43     4.67      7.29    14.88      59.52
f 8      0.94      1.20     1.67      2.40     3.27      5.10    10.42      41.67
f 11    0.68      0.88     1.21      1.75     2.38      3.71      7.58      30.30
f 16    0.47      0.60     0.83      1.20     1.63      2.55      5.21      20.83
f 22    0.34      0.44     0.61      0.87     1.19      1.86      3.79      15.15


Another annoying thing with focusing in IR is that if you have to re-focus or re-frame your shot at any time the filter has to be removed and the shot  re-framed/re-focused before replacing the filter onto lens.


So to sum up :-

1.   Compose picture
2.   Determine focus
3.   Place filter onto lens
4.   Re-focus (using red dot or hyperfocal distance)
5.   Take photograph
« Last Edit: September 16, 2011, 09:22:42 PM by Rob aka [minolta mad] »

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Re: A Guide To Infrared Photography
« Reply #5 on: March 30, 2008, 08:11:28 PM »
Exposure and Metering


Your camera’s metering system is totally useless when it comes to shooting in IR, so in much the same way as focussing manual will need to be used.

Exposure times will vary between 10 secs and 200 seconds.

I nearly always use either f/8 or f/11 when shooting IR as I am after the maximum dof in my images.
As a starting point for exposure times in the height of summer I would expect shutter speeds of around 25 seconds with f/8, so this is what I would take my first shot with.
It is possible to take IR pictures at any time of the year, its just that most of the time it is suited better to the summer months as there is more foliage on the tree's and ulimately this is what tends to make IR shots what they are.

The below picture was shot using f/8 and 190 seconds,taken in February 2008, using the A700.



The most important part of your camera for IR photography is your camera’s histogram. As this is the only way of telling whether your shot is exposed correctly or not.


When shooting IR you are looking for your histogram to have a range with a mix of shadow and highlight detail, much like any other photograph.
I have found with IR though, that it is often to the right of the histogram due to the nature of the “white foliage” and providing there is no highlight clipping this should no be a problem, as it is easier to recover in RAW than clipping in the shaddows.
« Last Edit: March 31, 2008, 08:55:07 PM by minolta mad »

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Re: A Guide To Infrared Photography
« Reply #6 on: March 30, 2008, 08:11:56 PM »
What Makes A Good IR Image


In a way, any image can make a good IR image. But there are restrictions with the length of shutter speeds that are involved.

There are some people that specialise in IR wedding photography with converted digital slrs that allow normal shutter speeds to be used when shooting IR.

But generally because of the effects that grass, trees and plants produce images with these in make for good IR images as do ones with water and lots of sky.

But try anything, as recently I took an IR image on our coastline with seaweed on the rocks in the foreground, not expecting anything of note to come of it, I was pleasantly surprised with the result I got.

A700, iso 200, f/8, R72 filter, 55 sec exp



« Last Edit: September 16, 2011, 09:44:41 PM by Rob aka [minolta mad] »

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Re: A Guide To Infrared Photography
« Reply #7 on: March 30, 2008, 08:12:27 PM »
Custom White Balance Settings


Until very recently I used to use CWB (custom white balance) settings.
To get these I used to take a white balance reading (with the filter in place) from various subjects, ie grass, water, leaves, tree bark etc, and when i found one i was happy with i stored it in the camera's memory. Then when i wanted to use it, it was just a case of selecting the CWB setting and away you go !
By doing this the camera would take whatever you told it was white and adjust all other colours accordingly. So rather than the whole image looking red, the image had some weird colour combinations.

This is what a IR image will look like straight out of camera
5D, iso 100, f/11, 30 secs


A few weeks ago in another thread Stef  pointed out about using the WB tool in RAW.

Basically for those who are not aware of  it (like myself) you set the dropper over a part of the image and click it and it takes that colour as white, and adjusts the other colours accordingly, in exactly the same way the CWB way I used to set.
I tried this the other day and it produces exactly the same results.

You also have the added advantage of being able to try several CWB setting in next to no time at all, and if you find one you like then remember the temperature of it and set this as a CWB in camera.

This was my first CWB attempts.

5D, iso 100, f/8, 15 seconds



« Last Edit: September 16, 2011, 09:26:04 PM by Rob aka [minolta mad] »

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Re: A Guide To Infrared Photography
« Reply #8 on: March 30, 2008, 08:13:02 PM »
Processing in Black and White


You have now taken your first IR pictures, so how do you process them ?

Well, in a way the same as any other picture !

Once you’ve opened up your image in Elements or then convert to Black and White using either of Stefs many tips See Here

 
My way of editing are as follows.

Open up image in RAW, you’ll notice that the image is very red and will almost certainly contain some blown out highlights



Next would be to remove all blown highlights using the temperature and tint sliders first, then if there are still blown highlights remaining use the exposure and recovery sliders. 



Next would be to use a convert to black and white layer, I would move the sliders until the desired effect is achieved. Usually its only the red and yellow sliders that will have any effect.



Next would be a levels layer. With levels I usually move the sliders indicated to the start of the histogram where the detail rises. This may be done to one or both sliders it depends on what effect each one has.



Next I have added a contrast layer and added + 8 contrast. I have also used the dodge and burn tool on parts of the waterfall to make the water stand out a bit more.




I have not used a method I favour a lot when editing this image as it didn’t require it, but it is one that Stef came across almost straight away when editing in B/W.
And that is,  because the image is largely red only the red and yellow sliders have much effect in the convert to black and white mode, so when you try darkening the sky in the image the whites also end up becoming too dark.
Likewise when you try lightening the whites the sky becomes too light.
The way to overcome this is to make a selection of the part of the image you wish to darken or lighten using the lasso tool, when you have made the selection use the refine edge or feather tool so that the changes blend in and don’t stand out too much.
A figure of 30-40 pixels is usually about right.
Then using either a levels or convert to black and white layer, adjust only the particular part of the image that you want to adjust, like making the sky darker or making the whites of the tree’s whiter.




« Last Edit: September 16, 2011, 09:33:38 PM by Rob aka [minolta mad] »

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Re: A Guide To Infrared Photography
« Reply #9 on: March 30, 2008, 08:13:38 PM »
Basic Colour processing


My colour processing is very similar to my black and white processing in the layers I use, I find that these work well so I tend to stick with them.

This is the image as opened in RAW, it was taken with the CWB setting I had saved.



First of all I used the WB tool and set the WB off the leaves of the tree’s, as I gave a slightly better result.

Next was a levels layer, I moved the arrows indicated, this darkened the sky and lightened the whites of the tree’s.



Next because the tree’s to the right of the building were quite dark I made a selection with the lasso tool and refined the edge to around 35 pixels. I then applied a shadow/highlight layer and put a value of 25 in the shadows box, to lighten the particular tree’s.



Then I added a contrast layer with +10 to exaggerate the definition in the colours.



I then removed the light in the right of the pic with the clone tool and finally used the dodge tool on the clouds and that is it.





Sometimes if the image requires it, (as in the black and white processing) I may make a levels adjustment to the whole image and then select only the sky with the selection tool and use levels again to darken more.
« Last Edit: September 16, 2011, 09:37:47 PM by Rob aka [minolta mad] »

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Re: A Guide To Infrared Photography
« Reply #10 on: March 30, 2008, 08:14:05 PM »
Links


Here is a list of links to websites and resources that I have found very useful in helping me understand IR photography and how to improve.


http://photonotes.org/articles/ir-myths/

http://www.pbase.com/dlarson2/ir_work_flow

http://heim.ifi.uio.no/~gisle/photo/ir.html#lenses


Too see more of my IR images, please check out the Infrared gallery on my website www.rnkendall.com

« Last Edit: June 25, 2011, 05:03:50 PM by Rob aka [minolta mad] »

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Re: A Guide To Infrared Photography
« Reply #10 on: March 30, 2008, 08:14:05 PM »