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More D850 DSLR White Balance Tests, Dumbbell Nebula

Posted: 20 October 2020

Monday, 19 October 2020, was partly cloudy with some smoke.

Open: Monday, 19 October 2020, 2027 MST
Temperature: 70°F
Session: 1542
Conditions: Clear, some smoke

12" f/8 LX600 w/StarLock
2" 24mm UWA eyepiece


2032 MST: LX600 ON, StarLock OFF, High Precision OFF.

As I did on the previous session, I did more color temperature tests. The previous session I did sky photos; this night I did M27 (Dumbbell Nebula) at prime focus of the 12" telescope.

Mounted the D850 DSLR at prime focus, focused on the star Altair, and locked the 12" primary mirror.

Slewed to M27 (Dumbbell Nebula).

I did StarLock autoguided, 5 minute, ISO 4000, exposures at various White Balance values.

photo photo photo
photo photo photo
photo photo photo

As was the case from my wide-angle sky color temperature tests on the previous session, I have decided to go back to using White Balance 4000K instead of 5560K for prime focus imaging.

Since I had 9 images of M27 I stacked all the unedited images with this result (effective exposure 45 minutes).


2153 MST: viewed Mars, 102X.

2154 MST: LX600 OFF.

2159 MST: did a sky quality reading. The smoke reduced the sky darkness.

Close: Monday, 19 October 2020, 2202 MST
Temperature: 68°F
Session Length: 1h 35m
Conditions: Clear, some smoke, SQM 21.03

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