custom white balance for infrared to get BxW from camera.

[thakurdalipsingh]

My camera Canon 5D MkII is 720nm converted for IR permanently. I shoot RAW. (As I read every where), I tried to do its custom white balance from green grass but still it gives me purple cast. I have tried other colours also for custom white balance= brown, black, white etc. but of no use. I want to get BxW direct from camera w/o any post processing as I was getting with my Fuji 9600/9100 with custom white balance from green grass. (Fuji was not converted permanently for IR but only its IR blocking filter was removed. Thus I was using 720nm filter in front of lens.)

When contacted ACS for this they replied- <em>"</em><em>With a 720nm filter it is not possible to do black and white from the camera with custom white balance, but you can switch the camera to monochrome. This will give black and white images straight from the camera.</em>"

If I shoot BxW direct in camera or I shoot color in camera and convert it later to BxW, will that make any difference to image quality?

Pl advise -How can I get custom white balance adjusted which can deliver BxW direct from camera.

I got converted my Canon 5D MkII from ACS U.K. for 720nm Infrared (permanently) few months back. They have done great job for conversion. Its autofocusing (in IR w/o calibration) with 24-105L lens is so good I can shoot flying birds in focus with it. (Though this camera and lens are not meant for BIF). They delivered me camera before time as per my request w/o any extra charges. I am very happy with their service, no doubt it is expensive when compared to USA.

 

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[William Michael]

<blockquote>

<p>I <em><strong>shoot RAW</strong></em> . . .I tried to do its custom white balance from green grass but still it gives me purple cast. I have tried other colours also for custom white balance= brown, black, white etc. but of no use. <strong><em>I want to get BxW direct from camera w/o any post processing.</em></strong></p>

</blockquote>

<p>Firstly the suggestion to set the camera to monochrome implies that the capture will be in <em>JPEG</em> – so IF you want images SOOC then you will need to shoot JPEG.<br />On the other hand: if you want to capture in <em>raw: </em>then you CANNOT use the images SOOC anyway – as you MUST use some Post Production program – so you might as well dispense with the Custom White Balance and simply remove the cast in Post Production.<br />On the question of ‘better quality’ – you should judge for yourself: one method would be to capture <em>raw + JPEG (L)</em> and compare the results for your particular requirements (obviously setting the JPEG capture to monochrome).<br />I capture <em>raw + JPEG (L)</em> almost exclusively and I often used the JPEG SOOC.<br />But I have a set of guidelines, specific to setting the JPEG Picture Styles: and each is separate set, for each of my EOS Cameras.<br />I don’t have a dedicated IR Camera – but it should not take too long for you to run various tests and set the Picture Styles to suit your personal tastes.</p>

<p>WW</p>

[thakurdalipsingh]

<p>Thanks for reply. <br>

I know I have to do PP on raw files , what I want is <strong>color cast less BxW SOOC,</strong> to which I can do PP for contrast/exposure etc.</p>

[William Michael]

<p>OK. It seems I could have misinterpreted your understanding, or your question, or both. So let me state what I mean another way:</p>

<p>According to the response you received from ACS , I understand the company to be making two points which are paraphrased in my words here:</p>

 

<ul>

<li>‘it is impossible with that camera and the modification we have made to it, for you to make a White Balance such that the file whether it be either <em>raw</em> or <em>JPEG</em> always comes out of the camera without a colour cast.</li>

<li> ‘if you want B&W without a colour cast straight out of the camera, then you need to capture in JPEG mode and select the monochrome option in Picture Style’</li>

</ul>

<p>On the point you ask about quality: in theory for the best quality end result <em>raw</em> capture is better than JPEG. But whether you will see that quality difference is another question.</p>

<p>So as I see the bottom line: you mention that you want to do some Post Production anyway, then I can’t understand why you do not want to capture in <em>raw</em> and remove the colour cast as one of the steps in your Post Production.</p>

<p>But, on the other hand JPEG (monochrome capture) is also an option for you, which satisfies the requirement of obtaining a B&W image, SOOC. </p>

<p>WW</p>

[zml]

<p>I generally find that no matter what I do I always get color cast on IR capture on my 40D modified for IR by Lifepixel (their standard conversion.) Of course B&W and, to a degree, false color is achievable in post processing and done best on RAW files but you may want to try Picture Style editor (software that comes with Canon DSLRs) and play with the color axis and try to eliminate color cast from the JPEG B&W capture. Becasue you are dealing with both IR and visible spectrum at the same time even this method is very aproximate. Shoot RAW and post process is my best advice.</p>

 

[sarah_fox]

<p>Thakur, there may be a misunderstanding here. Even with conventional photography (with an unmodified camera), a custom white balance does nothing more to a raw file than (1) noting relative RGB levels that achieved a neutral balance in the test frame and (2) applying those RGB adjustments to the little JPEG thumbnail embedded in the RAW image. However, the primary RAW image data are simply the unadjusted, unprocessed output from the sensor. As far as I'm aware, only the ISO setting directly impacts the RAW data, by setting the gain of the amplifier/ADC.</p>

<p>Given that all you want to do is to neutralize certain tones in the photo (e.g. the grass), all you need to do is to adjust the WB in post. Select a custom WB, and click on the grass. Doing so will cause the grass to go gray. That doesn't mean the trees will be a neutral gray as well. In fact you will find this also to be the case with an ordinary color image. It's just the nature of color and light: Not all greens are the same green. I'm sure this is especially true with IR photography!</p>

[dfperrault]

<p>Did you try to WB on a white cloud? Maybe the IR trasnmission of the optical coatings on each of the RGB pixel groups is slighly different, it is just a guess. However I would expect WB to correct for that.<br /><br /> I have a 40D converted to IR w/ 670nm Filter. So I always see a red color cast. I set the jpg to BW so I can see the BW image on the camera screen. I don't use WB. I edit images in raw and then convert to BW in lightroom. for two main reasons:</p>

<p>1. Better noise reduction w/ raw images in LR</p>

<p>2. Adjusting the tint/WB on the BW converted raw image gives me intresting BW contrast changes and tonal inversions. You may have less of this effect since you are filtering out the red light below 720nm. But is worth experimenting with.</p>