The "No EQ" DSO Challenge!

[Stefan87]

And it would appear the TIFF does not preview on these forums. I honestly cannot decide which format looks better between the JPG (TOP) and the PNG (bottom)
What are your thoughts everyone?

[The Admiral]

4 hours ago, Stefan87 said:

One point of discussion I wish to raise is export formats.

JPEG is only 8-bit and of course is highly compressed. TIFF can be in 8-bit or 16-bit. To be honest, don't know much about PNG.

You should always work with the highest bit-depth uncompressed, linear data you can. It is customary to use the 32-bit FITS format with astro files (they are large files ). So, import RAW files into DSS, export the output of DSS as a FITS, and import the FITS into StarTools. It is only when you come to export the output from StarTools that you can decide what file format to use, it will depend on what you want to do with it. Personally, I export as a 16-bit TIFF, because I can always create a JPEG from that later if I want. Don't forget, data is lost during compression to form a JPEG, and that is lost data that can never be recovered.

For StarTools, there is specific guidance on what settings of DSS you should use to provide the optimum input. https://www.startools.org/links--tutorials/starting-with-a-good-dataset/deep-sky-stacker-settings

Hope that helps.

Ian

Edited July 22, 2021 by The Admiral

[happy-kat]

For sharing I just use jpeg as it's for discussion web use. If better web quality is needed I'll do png. I don't share tiffs as files are big and even when using jpeg don't find for web use the compression is a problem. 

[The Admiral]

I agree with happy-kat, JPEG is perfectly adequate for web use. If you are ever wanting to produce a large format print of your results, then 16-bit TIFF would be my choice. If you ever want to present an image for others to process, then use FITS or 16-bit uncompressed TIFF as a file for others to download. Given the sizes, you might need to use a link to a cloud service (I use Microsoft's OneDrive as I have an Outlook account). Mind you, having said that, I see that this sites upload file size is 1GB!

Ian

[Ags]

Deleted. @rotatux corrected me below.

Edited July 22, 2021 by Ags

[rotatux]

Just to add precision, but PNG is the open spec/rights successor to GIF. JPEG is still perfectly adequate and valid as a lossy compression.

BTW like other comments, use JPEG for web publication, since it will display by a browser and on 8-bit displays mostly.

PNG has 8- and 16- bits variants, all with lossless compression, but 16-bits isn't much used. PNG produces (much) bigger image files than JPEG at about any given size, and is much slower to compress (at save time). And again for display / publication to others it's limited to 8-bit, so process your work files correctly and publish as Jpeg at the end. Adjust the JPEG compression in relation to your resulting image quality : no need to use q=95%, for most images between 65 and 80% is perfect and will produce as much lightweight files as is possible.

[Stefan87]

That clears up alot. And thanks for the link Ian! I glossed over that one previously but never applied the settings as at the time I was between StarTools and Gimp. I will reprocess some data using those settings and see what kind of difference it makes.

[lainev]

NGC 6946 Fireworks Galaxy with an Alt-Az mount on 210804. Average transparency and average seeing. Bortle 6. 30 minutes total integration of 10 second subs, 355 gain. Exposure and gain were determined by the SharpCap Histogram Brain Function. Camera cooled to 0c. Darks, Flats, and Dark flats. Celestron Nexstar Evolution 9.25, Celestron .63 Focal Reducer, ZWO ASI533 camera, IR/UV filter, CPWI for telescope control, and SharpCap for image capture. Image processed in DeepSkyStacker, Startools, and Photoshop. I use Celestron StarSense for initial alignment (really works well for me), Celestron Electronic Focus Motor (eliminates scope shake when focusing). All of this is attached to an old Dell laptop. The laptop also allows me to run the scope over WiFi from the comfort of my home office.

 

[The Lazy Astronomer]

18 hours ago, lainev said:

NGC 6946 Fireworks Galaxy with an Alt-Az mount on 210804. Average transparency and average seeing. Bortle 6. 30 minutes total integration of 10 second subs, 355 gain. Exposure and gain were determined by the SharpCap Histogram Brain Function. Camera cooled to 0c. Darks, Flats, and Dark flats. Celestron Nexstar Evolution 9.25, Celestron .63 Focal Reducer, ZWO ASI533 camera, IR/UV filter, CPWI for telescope control, and SharpCap for image capture. Image processed in DeepSkyStacker, Startools, and Photoshop. I use Celestron StarSense for initial alignment (really works well for me), Celestron Electronic Focus Motor (eliminates scope shake when focusing). All of this is attached to an old Dell laptop. The laptop also allows me to run the scope over WiFi from the comfort of my home office.

 

That is incredible for just 30 mins!!

[Nerf_Caching]

Taken a couple nights ago with a stock Celestron Nexstar 5SE on its alt-az mount, featuring M2. Camera was a stock Canon 650d without any LP filters used. 30x15 seconds at iso 3200 under Bortle 9 skies.

[Stu1smartcookie]

6 minutes ago, Nerf_Caching said:

Taken a couple nights ago with a stock Celestron Nexstar 5SE on its alt-az mount, featuring M2. Camera was a stock Canon 650d without any LP filters used. 30x15 seconds at iso 3200 under Bortle 9 skies.

Great …. Love this thread . 

[powerlord]

On 22/07/2021 at 08:22, The Admiral said:

JPEG is only 8-bit and of course is highly compressed. TIFF can be in 8-bit or 16-bit. To be honest, don't know much about PNG.

You should always work with the highest bit-depth uncompressed, linear data you can. It is customary to use the 32-bit FITS format with astro files (they are large files ). So, import RAW files into DSS, export the output of DSS as a FITS, and import the FITS into StarTools. It is only when you come to export the output from StarTools that you can decide what file format to use, it will depend on what you want to do with it. Personally, I export as a 16-bit TIFF, because I can always create a JPEG from that later if I want. Don't forget, data is lost during compression to form a JPEG, and that is lost data that can never be recovered.

For StarTools, there is specific guidance on what settings of DSS you should use to provide the optimum input. https://www.startools.org/links--tutorials/starting-with-a-good-dataset/deep-sky-stacker-settings

Hope that helps.

Ian

tiffs can be 32 bit too. In fact that is what I usually use with affinity photo.

JPG is the most compatible for posting to forums - and there' it is fine - however do make sure you realise that it has adjustable compression. usually for this sort of stuff set it to 100% quality. IF that is too big, reduce to as much as 80%.

It is lossy, so not to be used for archiving or printing. A jpg at 100% quality (still lossy) vs a tiff or png for viewing on a forum will be identical, hence for forum posting, JPG is fine. IF you are posting for help and expect others to edit or process the image, THEN post a tiff.

[lainev]

Globular Cluster M2 in Aquarius on 210901. This is 2 different crops of the same image. Above average transparency and below average seeing. Bortle 6. 13 minutes total integration of 8 second subs. Camera cooled to 0c. Darks. Celestron Nexstar Evolution 9.25, Celestron .63 focal reducer. ZWO ASI533 camera, IR/UV filter, CPWI for telescope control, and SharpCap for image capture. Image processed in DeepSkyStacker, Startools, and Photoshop. I also use Celestron StarSense for initial alignment (really works well for me), Celestron Electronic Focus Motor (eliminates scope shake when focusing). All of this is attached to an old Dell laptop. The laptop also allows me to run the scope over WiFi from the comfort of my home office.

 

[lainev]

Andromeda Galaxy Messier 31 (M31) on 210906. In 4.5 billion years M31 will collide with our Milky Way Galaxy. Bortle 6 skies, average seeing, above average transparency. 198 light frames at 15-seconds, f/2.4, and iso 800 for a total integration of ~47 minutes. 40 darks, 40 flats, 40 dark flats, and 40 bias frames. Sony a6400 camera, Samyang 2.0/135mm lens, Celestron Nexstar Evolution Alt-Az mount. DeepSkyStacker, StarTools, and Photoshop.

Edited September 6, 2021 by lainev
Rotate image.

[lainev]

M1, The Crab Nebula, on September 9. Average transparency and average seeing.  Bortle 6. 18 minutes total integration of 10 second subs at 480 gain. Camera cooled to -10c. No calibration files. Celestron Nexstar Evolution 9.25, ZWO ASI533 camera, IR/UV filter, CPWI for telescope control, and SharpCap for image capture. Image processed in DeepSkyStacker, Startools, and Photoshop. I also use Celestron StarSense for initial alignment (really works well for me), Celestron Electronic Focus Motor (eliminates scope shake when focusing). All of this is attached to an old Dell laptop. The laptop also allows me to run the scope over WiFi from the comfort of my home office.

[lainev]

Cat's Eye Nebula (NGC 6543) on 210924. The Cat's Eye Nebula is a planetary nebula. The central star has expelled its outer layers in the last stage of its life. 5-second exposures at 145 gain. 14 minutes total integration, darks. Bortle 6 skies. Average seeing and transparency. Celestron Nexstar Evolution 9.25, ZWO ASI385 camera, CPWI for telescope control, and SharpCap for image capture. Image processed in DeepSkyStacker, Startools, and Photoshop. I enlarged the insert with Topaz Gigapixel AI. I use Celestron StarSense for initial alignment (really works well for me), Celestron Electronic Focus Motor (eliminates scope shake when focusing), and furnace antivibration pads. All of this is attached to an old Dell laptop. The laptop allows me to run the scope over WiFi from my home office.

 

[lainev]

NGC 7331 and visual neighbors on 210925. NGC 7331 is an unbarred spiral galaxy about 40 million light-years away in the constellation Pegasus. The mark ups in the annotated version were generated by http://nova.astrometry.net/upload after platesolving. Average transparency and average seeing. Bortle 6. 27 minutes total integration of 8.5 second subs. Camera cooled to 0c. I used the Histogram Brain Function in SharpCap to measure sky brightness and determine exposure parameters. Flats and Dark Flats. Celestron Nexstar Evolution 9.25, ZWO ASI533 camera, Celestron .63 Focal Reducer, ZWO UV/IR Cut Filter, CPWI for telescope control, and SharpCap for image capture. Image processed in DeepSkyStacker, Startools, and Photoshop. I also use Celestron StarSense for initial alignment (really works well for me), Celestron Electronic Focus Motor (eliminates scope shake when focusing). All of this is attached to an old Dell laptop. The laptop allows me to run the scope over WiFi from my home office.

Autosave.fitsAutosave.fits

[patraip1]

Hello everybody

Here is one of my first tries at this sport. Skywatcher heritage 130p on an az gti in alt az mode. Nikon D5500 prime focus. 78 subs of 13 sec exposures @ iso 800, 18 darks, 35 bias, 25 flats. Dss, Gimp and final touches of the jpeg on Snapseed on my smartphone. M31 on 1 oct 2021 at 23:00,  60deg up in the sky from my bortle 5 backyard 

[AstroNebulee]

11 hours ago, patraip1 said:

Hello everybody

Here is one of my first tries at this sport. Skywatcher heritage 130p on an az gti in alt az mode. Nikon D5500 prime focus. 78 subs of 13 sec exposures @ iso 800, 18 darks, 35 bias, 25 flats. Dss, Gimp and final touches of the jpeg on Snapseed on my smartphone. M31 on 1 oct 2021 at 23:00,  60deg up in the sky from my bortle 5 backyard 

Lovely image and nice to see a 130p being used on the az gti mount. I have a 72ed in EQ mode on mine. Great image 👍

[patraip1]

thank you astronebulee!! 

I will be trying again a little sooner in the night to catch m31 at a lower altitude so I can take 25 sec subs. I will also give a try at ISO 200 and restack my original data without the darks to see if it will make any difference in the noise level. Will be reporting back

[happy-kat]

Great to see the heritage OTA used, as the trusses are dropped if you've collapsed it after use I'd take new flats and dark flats with each session.

[rotatux]

A heavyweight DSLR such as D5500 on that delicate focuser... you're fearless ! 🤩

Edited October 6, 2021 by rotatux
add emoji

[patraip1]

it actually handles the 420g quite well.... have not had any issues yet. I did try 20 sec exposures but got elongated stars. I noticed that my tracking is drifting quite a bit though. In 10 minutes the core of the galaxy was almost at the edge of my (4degree by 3 degree) FOV. I had the same issue when I took the 13 sec exposures as well and had to recenter the image every 30 shots. DSS threw out 42 out of 120 subs. Alignment and goto worked ok and I am suspecting that I will need a counterweight as I can see the head of the mount that connects to the dovetail is tilted by the weight of the OTA+camera (specs for the az gti is 5kg my setup is 3400+420). Any thoughts on what else could be causing tracking issues or is the drifting normal ? 

Edited October 6, 2021 by patraip1

[AstroNebulee]

16 hours ago, patraip1 said:

it actually handles the 420g quite well.... have not had any issues yet. I did try 20 sec exposures but got elongated stars. I noticed that my tracking is drifting quite a bit though. In 10 minutes the core of the galaxy was almost at the edge of my (4degree by 3 degree) FOV. I had the same issue when I took the 13 sec exposures as well and had to recenter the image every 30 shots. DSS threw out 42 out of 120 subs. Alignment and goto worked ok and I am suspecting that I will need a counterweight as I can see the head of the mount that connects to the dovetail is tilted by the weight of the OTA+camera (specs for the az gti is 5kg my setup is 3400+420). Any thoughts on what else could be causing tracking issues or is the drifting normal ? 

A counterweight may help you as you've suggested, it's worth a try first or if your confident and not worried about voiding your warranty on the az gti mount you could try taking off the cover to regrease the worm and gears, or try adjusting the motor spring tension to fixed or just adjust it.  I followed this video on adjusting the spring tension https://youtu.be/hgEzeXrhhEg

Or these two videos for tuning and greasing your AzGti https://youtu.be/MoAF6tYcby8

https://youtu.be/iwJdrAFLPpU

 

But only do these if your feel confident to. I stripped mine down and regrease and the tracking was much better. 

Also an easier fix is to update the firmware of the az gti mount to the latest firmware as this says its fixed the tracking issues. 

http://skywatcher.com/download/software/motor-control-firmware/

To update your firmware via WiFi follow this link here, I update via eq mode cable but have done it over WiFi before. 

https://stargazerslounge.com/topic/305296-sw-az-gti-mount-firmware-update/

 

Edited October 7, 2021 by AstroNebulee

[patraip1]

Thanks astronebulee!! 

I will try updating the firmware. mine is 3.26. I will then test the tarcking again. I already constructed a homemade counterweight with a m12 rod an old sprinkler and some wrist weights I had handy... it eliminated the tension on the mount head but clouds prevent me from testing at the moment. Opening the mount will be a last resort. 

 

@happy-kat I don't collapse the rods and my dslr is not detached from the telescope (I don't use it for daytime photography any more). I also have a homemade light shroud on and just move the telescope outside to my backyard, level it, connect the app, north level align, fine focus with the live view in maximum zoom on the second alignment star, go to my target frame it and begign imaging in 10mins tops. I was imaging with my smartphone afocally for 3 months using the astrophotography mode of gcam with actually decent results, as I could not find a nikon focuser adapter locally and the order frim china took over 3 months to arrive to Greece so I got the hang of setting up quickly. 

Here are some examples of my attempts so far.(the milky way is with just the smartohone against a wall!!) Google cam is impressive!! 

The great advantage was that I could have a final image of my target in just 10 minutes including the processing with snapseed!! I remember in Junes new moon capturing 12 targets in 3 hours

I just wanted even  better pictures so here I am trying to image with the dslr and the calibration frames etc. 

Cheers 

 

Edited October 8, 2021 by patraip1