14 replies to this topic

[celeron787]

First light for my Redcat 51. Was not a planned imaging session, I just wanted test how well the Star Adventurer can handle the Redcat, test drift align using DARV and test out 30sec subs. Things went quite well and skies remained clear, so I pointed the scope towards Orion and began snapping away.

 

Sony A6000

William Optics RedCat 51 Petzval APO

Sky-Watcher Star Adventurer

Tripod

 

Bortle 8

ISO400

Light frames - 119 x 30secs (manually dithered in RA and DEC)

Dark Frames - 30 x 30secs

Flat Frames - 35

Bias Frames - 50

 

Deep Sky Stacker

StarTools - Autodev, Crop, Wipe, Super Structure, Color, Contrast, HDR

Lightroom - Exposure, Vibrance, Highlights

 

[abcdefghii]

Nice. I'm in the middle of doing much the same, but with a Z61-II. 

[Sonya6500]

Is your a6000 modified?

[celeron787]

Nice. I'm in the middle of doing much the same, but with a Z61-II. 

Nice! 

 

Is your a6000 modified?

Nope, stock A6000. I'm considering getting a modded Nikon D5300.

[Sonya6500]

I am using a modified A6000,  Z61, Skyguider Pro mounted on a pier. Interesting that you use Iso 400 and I have been using Iso 1600. I had read that 1600  was not as noisy as others. Maybe I will try  your method. Are you using any filters ? I have bortle 5 skies here in South Carolina and also use DSS

and Star Tools. 

[celeron787]

I am using a modified A6000, Z61, Skyguider Pro mounted on a pier. Interesting that you use Iso 400 and I have been using Iso 1600. I had read that 1600 was not as noisy as others. Maybe I will try your method. Are you using any filters ? I have bortle 5 skies here in South Carolina and also use DSS
and Star Tools.

Haha both our setups are very similar. I follow the suggested ISO from http://dslr-astropho...-sony-cameras/. So far I think I'm quite happy with my results, but I'm thinking of trying ISO 1600. No filters used too.

[Borodog]

I've done a lot of research on the a6000 (using one as well) and from what I've read and been able to test, the a6000 is basically ISO independent at ISO 800 and up. I would not recommend ISO 400, as it definitely seems to have significantly more noise than ISO 800. But when exposure corrected, the SNR between 800, 1600, and 3200 at least seem identical. But then again my understanding is that ISO is really just digital gain. I don't know that it gets you anything in the final result; it's just a way to make individual subs appear brighter. Which is perfectly fine, but it doesn't mean that you can get away with fewer subs, for example.  You still need the exact same amount of total integration time. And it also means that you may blow out bright stars at a given shutter speed where a lower ISO would not.

[DoubleStaRR]

I use a Sony a7iii and have been using the lowest possible ISO setting I can. I’m not certain this is the best thing to do but I’m of the line of thinking that ISO is basically the same as exposure adjustment in post processing. The idea is to get as much signal as integration time as possible. I recently imaged Orion with 30 x 600s at iso 320 and still the brightest part of Orion is blown out. I was using SCT 9.25 with focal reducer, so very different from your redcat but thought I would share.

Edited by DoubleStaRR, 22 January 2021 - 06:45 AM.

[Sonya6500]

So here an iso 1600 image from my a6000. No guiding. Cls filter. 90 sec exposures. Star Tools and DSS. I would like to try a lower iso. I think Sony cameras are under rated. I will never get an APOD but it is always exciting to see results. 

 

[asanmax]

Nice image! My hat's off to you for handling the manual dithering. Your stars are pin-point and look amazing!

[celeron787]

I use a Sony a7iii and have been using the lowest possible ISO setting I can. I’m not certain this is the best thing to do but I’m of the line of thinking that ISO is basically the same as exposure adjustment in post processing. The idea is to get as much signal as integration time as possible. I recently imaged Orion with 30 x 600s at iso 320 and still the brightest part of Orion is blown out. I was using SCT 9.25 with focal reducer, so very different from your redcat but thought I would share.

For this image, at ISO400 at 30secs, the histogram is nearly to the middle. I'll probably blow it out if I increase the ISO but then again I could decrease the exposure time. Which do you think is more helpful?
 

Autosave131try99.tiff-002.jpg
So here an iso 1600 image from my a6000. No guiding. Cls filter. 90 sec exposures. Star Tools and DSS. I would like to try a lower iso. I think Sony cameras are under rated. I will never get an APOD but it is always exciting to see results.

Nice! I'm very happy with what I'm getting with the A6000, just the lack of software support is making me move to another brand.
 

Nice image! My hat's off to you for handling the manual dithering. Your stars are pin-point and look amazing!

Thanks! I have to babysit my mount throughout the session so I might as well do it. Had 2 images plagued by walking noise, I decided I rather spend time doing manual dithering than trying to get rid of walking noise in post-processing.

[Sonya6500]

Star Tools version 7 has a walking noise tool. You use your mouse to click and drag parallel to the walking noise lines. You then adjust the sliders till you can't see it and then let the processor work on it.

[Sonya6500]

Doublestarr, If you can get 10 minutes with no trailing stars that is excellent. My mount is maxxed out at two minutes but it only cost 400.00. Nobody wants to waste valuable imaging time but you might want to up iso to 1600 and try some shorter times . Just do one exposure of Orion for two minutes and see what it looks like in review. Zoom in and look at it close. If you like it take 60 frames do some bias and darks. Stack and develop. I use DSS and dump the FTS file into Star Tools. For 50 dollars or whatever it is now you can't beat it. Within 10 minutes and 10 steps you will have a decent image. Not sure what megapixel a 7ii is but the 6000 is 24mp. You can bin that to 25% in Star Tools and get rid of huge amounts of noise and still lose no detail.

[DoubleStaRR]

Doublestarr, If you can get 10 minutes with no trailing stars that is excellent. My mount is maxxed out at two minutes but it only cost 400.00. Nobody wants to waste valuable imaging time but you might want to up iso to 1600 and try some shorter times . Just do one exposure of Orion for two minutes and see what it looks like in review. Zoom in and look at it close. If you like it take 60 frames do some bias and darks. Stack and develop. I use DSS and dump the FTS file into Star Tools. For 50 dollars or whatever it is now you can't beat it. Within 10 minutes and 10 steps you will have a decent image. Not sure what megapixel a 7ii is but the 6000 is 24mp. You can bin that to 25% in Star Tools and get rid of huge amounts of noise and still lose no detail.

Thank you for the reply. I will try this. One issue I had with the ISO 320 used on the attached image is the blown out bright areas. Eventually I will find the right combination of settings. Again thanks for the suggestion.

Attached Thumbnails

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[asanmax]

Thank you for the reply. I will try this. One issue I had with the ISO 320 used on the attached image is the blown out bright areas. Eventually I will find the right combination of settings. Again thanks for the suggestion.

The Orion nebula is a bright object and has uneven brightness in its structure.

The best approach to image it is to use 10 or even 5 sec exposures for the core, then 15-20 sec exposures for the core surrounding area and then longer exposures for the outskirts.

All three sets of images are stacked separately and combined in postprocessing using layers.

This way you will have full control of the brightness of the nebula regions.

Edited by asanmax, 29 January 2021 - 11:28 AM.