HI Guys,
took this galaxy last night. stupid me forgot to take darks and flats with it. Can't use the old ones as this is a longer exposure shot. 5 x 5 minutes with UHC-S filter (i know, i was lazy doing refocusing and i guess it helps darkens the background ). Not that particular happy with it, compare to my DSI II pic, there were more details to it.
hi tony, here's a shot of my flat taken at about 3 metres from the laptop screen. I created a plain white .jpg file and fullscreen on the laptop. The blue is from the UHC-S filter i believe.
Never thought of that - I wonder if it is gradient free enough though, they are lit from the edges, having said that, the section of screen observed would be small....maybe the gradient would be insignificant.
I would think you need to leave the OTA focus alone too, that might help blurr out any gradient - better make sure there are no fingerprints on the screen too...
Any experts out there care to comment - if this is a reasonable approach I can see adding flats to the end of an imaging session father than relying on stock shots taken with the same imaging train...
Yes very interesting technique.....I am bit concerned why there is so much gradient from dark right to bright left in the flats...this is noticeable in your images.
Do all your images have this type of gradient...?????
Yes Octane takes sucessful flats by using his laptop screen as a even light source. For me, I illuminate the wall of the garage with a hand held fluro light while pointing the scope at it. Thats okay for me but we would get shot if we did that at a viewing night lol. I have to take a flat after each image as the off axis guider rotates the whole assembly, camera included each time I look for a guide star.
Eric, with a smallish object like that, if you have Gradient Xterminator you can draw round it then run it, it will flatten the field around the galaxy.
Iris is pretty good with flats even if not the same length or temperature, of course best results are if the darks are the same but even if not its worth trying.
Scott
I would think you need to leave the OTA focus alone too, that might help blurr out any gradient - better make sure there are no fingerprints on the screen too...
Hi John
For a Flat Frame, you should not change the focus or any other variable such as camera angle, otherwise the Flat Field image and the real world optical system with all its dust donuts, vignetting and other defects simply will not match up.
). Not that particular happy with it, compare to my DSI II pic, there were more details to it.
