NGC 6231 @ 300mm 40x
This post was originally published on my old blog dedicated to amateur astronomy.
The rain season here in Brazil’s north-east region this year is making no excuses. The winter just started and it rains almost every day. I’m taking most of the time to work and read, but last night the sky was surprisingly clear, so I decided to put in practice my plan to stack pictures using the 300mm lens. I grabbed my documents and started to review the plan. I went for the NPF rule (which to me here would be 0.955”) but I arranged it to shoot at 0.8”. Taking lights, darks, bias, flats and then stacking them all using DeepSky Stacker.
I didn’t have a target in mind, so I started looking for jewels close to the zenith, using the APT program to preview the frame. Once I found something nice (NGC 6231) I asked Catarina to keep shooting single frames while I was moving the focuser at the lens. We kept doing it while she would judge the quality of the focus, up to the point we agreed on the focus to be good. So this picture was a collaboration. Thanks to Catarina Dantas. Also, she owns the DSLR camera (and my heart, love you, honey).
Once with a target and in good focus, I just framed the subject so it would pass the center of the picture while drifting in the sky, then programmed APT to take 40 exposures. I did 40 in ISO800, then 40 in ISO1600. The noise is of course bigger with ISO1600, but the DSS and the calibration frames were enough to reduce a lot of the noise from the ISO1600, so I went with it. (Did calibration frames for each)
The result is a low noise picture that got me pleased. Note that the Bortle scale here is between 7 and 6. I did a bit of work with Photoshop in it and then called the night.
I’m still to discover how to mitigate effects of the image that end up looking different on Windows, Linux or Mac. It was edited using Windows, so will look better on those devices.
Also thanks to Terry F. for always teaching me the way to go despite my all my ignorance. Thank you, man.
Author: Fernando Schuindt
License: CC BY 4.0
Camera: Canon EOS 600d
Lens/Telescope: Zuiko Oympus 300mm f/4.5 Manual-Focus OM (Film) Lens
Composition: 40x Light Frames @ 0.8” ISO1600 f/4.5, 25x dark frames, 25x bias frames, 25x flat frames
Processing: DSS stacking and framing, Photoshop crop, Camera Raw Filter, Levels Adjustment
Location Name: Aracaju - Sergipe, Brazil
Location Aprox. Coordinates: 10°58’31.0”S 37°04’26.0”W
Timestamp (Local Time): 06-26-2020 00:09:27
Timestamp (UTC): 06-26-2020 03:09:27
Theme: NGC 6231
Other Gear: OM Lens to Canon EOS adapter, generic tripod, USB cable, APT software.
Astrometry: http://nova.astrometry.net/user_images/3775347#annotated
Full Resolution Images: https://photos.app.goo.gl/ee9VTwSGfyh7G6k2A
