DSLR Settings

[pscammp]

Hello all,
    New here so im hoping i can get some good advice from the masters......

I use a Canon EOS 1000D at the moment for my images and it's had the IR
filter removed to make it more sensitive to HA etc. Nothing has been put in
it's place though as i only use it for AP and i dont use a refractor.

I see loads of opinions relevent to this situation regarding white balance but
as im about to start a Pixinsight trial i'd like to get this right before starting.

Some say to leave white balance set to auto even though it increases the
sensitivity to red thus more light polution captured ( i use a 2" ADAS P2
by the way)

There are others who say to take a pic of an evenly cloudy sky at night in
my area and use that image to do a custom white balance which will lower
the sensors sensitivity to red and result in less light polution captured.

If im to use Pixinsight to process, what would be my best option:

Auto or Custom   

I'd also be curious as to why one option would be better than the other, it's
all about the learning as they say.

Many Thanks for any help

Regards
Paul

[Nocturnal]

Hi Paul,

I don't think any white balance changes the sensitivity of the camera. Sensitivity is determined by the sensor and white balance is a post processing step in the camera. Picking the 'right' white balance in the camera is a fool's errand. You'll never get it quite right. What that means is that even if you are close you still need to learn how to correct it during post processing. So skip the white balance worries and learn how to do color balance correction using Background Naturalization and Color Calibration.

[pscammp]

Nocturnal,
    You may have to forgive my incorrect use of term, but i understand exactly that processing
skills is the key. I look forward to discovering the tools you speak of.

I will leave the camera white balance alone.

Many thanks for taking the time to answer.

Paul
 

[Physicist13]

for DSLR always shoot in RAW, so "white balance" is irrelevant.
Pat

[Phil Leigh]

When using RAW files (which is what you always do for AP) the White Balance setting of the camera has no impact at all on the IMAGE data recorded by the camera.

Correct colour balance is established in Pi using the  Dynamic Background Extraction (DBE), Background Neutralisation and Colour Calibration tools.

[pfile]

right - to be clear here is what happens.

the white balance data is simply stored in the EXIF of the CR2 file. it is two multiplier values (the 3rd value is assumed to be 1 and the other two values are relative to that channel).

when a program that understands how to debayer a CR2 file processes the CR2, it can optionally look at those white balance multipliers and scale the channels. this includes the in-camera firmware which to my knowledge always applies the multipliers when creating a JPEG file. this is one of the (many) reasons to use RAW in astrophotography - the camera "bakes in" all kinds of stuff to the jpeg file, including a default stretch and saturation boost.

PI uses DCRAW and accordingly DCRAW can be set to compute it's own color balance ("auto" ticked), to use the camera's setting as stored in the CR2 EXIF ("use camera white balance" ticked), or to simply ignore it all (both unticked).

you can see these settings from View > Explorer Windows > Format Explorer and then double-clicking on "DSLR_RAW". this brings up the DCRAW control panel.

rob

[papaf]

One must also keep in mind that, by using BatchPreprocessing script, all of this is ignored, I think. Can somebody confirm DSLR settings are overwritten by BPP?

[pfile]

yeah i think BPP calls DSLR_RAW with the format hint "raw cfa" when it's configured for OSC. the question is whether or not "raw cfa" overrides the white balance settings as well as the debayer/file format settings in DSLR_RAW.

rob

[Juan Conejero]

the question is whether or not "raw cfa" overrides the white balance settings as well as the debayer/file format settings in DSLR_RAW.

Yes, completely. The "raw" hint is equivalent to:

bayer-drizzle
no-super-pixels
no-cfa
no-auto-white-balance
no-camera-white-balance
no-black-point-correction

The "cfa" hint removes "no-cfa" from the above list, so "raw cfa" loads pure raw images as single-plane CFA matrices. In other words, these hints provide exactly what is stored in the camera as a raw file (whether that is true raw data or not, i.e. what the sensor acquired when the image was taken, is another story).