White Balance on modded DSLR

[mickw]

I've been thinking - yes I know it's scary

When the camera is modded, filter removal or whatever, the camera is now sensitive to Ha.
With the usual "Daylight" setting and normal photography, the red becomes more saturated which can be corrected using a "Custom" white balance or "Tungsten" (which is fairly close)

I have always done astrophotography using "Daylight" set in software or on camera.

Should I actually be using a custom  WB ?

[MarkS]

The real answer is that it cannot be done properly.  The camera is recording Ha in addition to the usual red and so it is responding in a way that the human eye does not.  Depending on the mix of Ha and Red being recorded, no amount of balancing will fix it so it looks correct to the eye.  Best to use a filter designed for the task. 

If you have to do it, then a custom white balance will probably work best.  But some objects will look right and some will look wrong depending onm the mix of Red and Ha coming from each object.

[mickw]

I guess I'm over complicating it.

I'm only interested in pretty pictures anyway

Just had another thought - Is the WB applied during capture (Raw) or in-camera processing to JPG ?

[MarkS]

The raw looks the same whatever balance is used.  it can be seen in the EXIF header.   This same balance is used during the JPG creation.

[mickw]

So it doesn't matter then what WB is used if you are processing Raws.

I must stop all this thinking malarky

[The Thing]

BTW A lot of software e.g DSS can use the stored white balance, a custom WB will help get the final white balance if you are using DSS and have it set to use it. I believe APT will use it to render the image previews as well, you can tell APT which WB to set on the camera so it gets recorded in the RAW.

[mickw]

Didn't know about DSS but have played with setting APT hence the thoughts about Tungsten - Time for another play

[mickw]

MarkS

My original comments assumed you wanted to use the camera for daytime terrestrial photography. - in which case a filter is the best solution.

For astro I always adjust the balance in post-processing so it dosn't matter which I use on the camera during shooting.  But as Duncan says, some software can use those settings.

I guess it was for either really once I'd got the idea in my head but as you say, if you're dealing with it processing, it really doesn't matter

Anyway, time to stop thinking and start playing - Thanks Mark and Dunc

[Fay]

I THINK IT IS BEER O'CLOCK MICK!

[JohnP]

Not yet... I'm still at work...

[mickw]

Thanks Fay, lost track of time - rectified now 
I've always liked you 

John - never mind 

[JohnP]

Oh well it's Vin O'Clock now so all is OK...