Another alt-az M42

[Davo]

Here is my latest M42

http://zoom.it/UaKB#full

and the story behind it is here

http://starrydave.com/?p=302

Dave

[Davo]

I reworked this using all 114 good lights I captured that night.

http://zoom.it/Ajr1#full

The extra frames seem to help with the fainter details.

[admin]

I reworked this using all 114 good lights I captured that night.

http://zoom.it/Ajr1#full

The extra frames seem to help with the fainter details.

Great results!

Color are very good, except maybe for the brighter stars - any idea on why they are yellow?

[Davo]

I reworked this using all 114 good lights I captured that night.

http://zoom.it/Ajr1#full

The extra frames seem to help with the fainter details.

Great results!

Color are very good, except maybe for the brighter stars - any idea on why they are yellow?

Not sure about the yellow stars. I managed a similar capture a few nights later and got the same thing. What I did was Autodev>Crop>Bin 50%>Develop 80%>HDR reveal and then pressed the Color button. You can see on the attached screenshot that the initial color settings gave yellow stars again (they were white up to that point). I can turn them white by setting all the biases to 0.

[admin]

Hmmmm.... seems like something is meddling with the colors in the highlights (DSS or dcraw?). Any idea what might be the culprit here?

[Davo]

Hmmmm.... seems like something is meddling with the colors in the highlights (DSS or dcraw?). Any idea what might be the culprit here?

I don't think it is DSS - here is a DSS screenshot of the stacked image and you can see the stars seem to be white. The cursor is over the Trapezium and you can see them in the zoomed window at top left. Like I said, if I set all the ST color biases to zero the stars turn white.

[admin]

Hmmmm.... seems like something is meddling with the colors in the highlights (DSS or dcraw?). Any idea what might be the culprit here?

I don't think it is DSS - here is a DSS screenshot of the stacked image and you can see the stars seem to be white. The cursor is over the Trapezium and you can see them in the zoomed window at top left. Like I said, if I set all the ST color biases to zero the stars turn white.

The histogram curves in DSS screenshot very suspiciously line up; this virtually never the case with virgin RAW data. It appears to me some sort of color calibration/alignment has been done in DSS. This will have introduced 'false' color information in the highlights.
StarTools' color module (specifically the 'Color Constancy' feature)does its utmost to recover color, even in the highlights. It definitely appears that DSS has introduced this false color information by aligning the histograms.
It also appears to me that M42 is way too visible for the data to be still linear. The luminance data too seems to be modified. You're not shooting in JPEG, are you?

[Davo]

Hmmmm.... seems like something is meddling with the colors in the highlights (DSS or dcraw?). Any idea what might be the culprit here?

I don't think it is DSS - here is a DSS screenshot of the stacked image and you can see the stars seem to be white. The cursor is over the Trapezium and you can see them in the zoomed window at top left. Like I said, if I set all the ST color biases to zero the stars turn white.

The histogram curves in DSS screenshot very suspiciously line up; this virtually never the case with virgin RAW data. It appears to me some sort of color calibration/alignment has been done in DSS. This will have introduced 'false' color information in the highlights.
StarTools' color module (specifically the 'Color Constancy' feature)does its utmost to recover color, even in the highlights. It definitely appears that DSS has introduced this false color information by aligning the histograms.
It also appears to me that M42 is way too visible for the data to be still linear. The luminance data too seems to be modified. You're not shooting in JPEG, are you?

All my frames are .CR2 raw. It's funny, here is a screenshot after stacking in DSS. I then save to integer FITS to load up to ST. Reloading the FITS (or even the autosave.tif) gives me a result just like the screenshot above.

[admin]

There should be a setting along the lines of "don't save any settings made in DSS". Be sure to use that setting!

[Davo]

There should be a setting along the lines of "don't save any settings made in DSS". Be sure to use that setting!

Yep, I always use that setting. I will ask a question on the DSS group.