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'Shark Fin' Prom - 25th May 2020


TakMan

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Sorry for the delay in posting, this has put us out of sequence now!

I missed the opportunity to see how it had progressed yesterday and missed out on getting some great images after seeing the results on here!

Still plenty of data to go through, but I'm pleased with this... perhaps my best solar image to date.

Was very lucky with the superb seeing around 8.56am. Took my usual 6000-9000us exposures (which should allow me to process the solar surface and prom in one exposure), but as the seeing was so stable, I tried a 18000us exposure and went just for the prom.

Best 400 frames from 1661.

TSA102s > Baader 2" UV/IR on the TV diagonal > Quark Chromo > Basler acA1920-155um (Sony IMX 174m). Captured in Basler's Pylon software as separate Mono12P (packed).tif files on a MacBook Pro as it doesn't allow saving out as a movie file)!

Processed in AS!2 and ImPPG (via Wine), then PS CC2017

1739864232_SuperProm_BW.thumb.jpg.cd3781a825ffc9683d5ce052e8557d96.jpg

 

Two colour variations:

949257419_SuperProm_colour1.thumb.jpg.b97def9564a99945e36469b1186b0d68.jpg

2092090507_SuperProm_Colour2.thumb.jpg.c60a27079eec7dd1973ef739326137b2.jpg

I've tried making a rough 'scale image' using this chaps resource (it was linked to a week ago or so):

https://sites.google.com/site/astroblue1/astronomie/brico-utiles

1685249515_SuperProm_Scale.thumb.jpg.5d92d986323d528e7b826a25ca477103.jpg

 

And now onto my issue. As some of you who've read my previous posts will be aware, SGL member Vlaiv has been helping me sort the optimum gain and offset for this Sony 174 based camera (all new to me being a CCD based deep sky imager). We started with Mono12P as it offered increased bit depth but faster capture rates (32fps more), over 'standard' Mono12.

Then I switched to Mono8, to sort the best settings.

In Mono8, I’m getting very obvious vertical lines in the Dark/Master Dark Flames. They are also apparent in the master BIAS frames (that we used to measure the correct gain/offset), the flats/master flats and also the dark ‘void of space’ areas in the lights and in the final image.

We have no idea why. I've changed cables, exposure settings, computer ports. Until James who writes OACapture supports the camera, I can’t test to see if it is perhaps a software issue…

They are not (or no where near as obvious) in the Mono12 or 12P data...?

Before anyone asks, Mono12P isn’t something that most software would recognise, but the Basler software obviously sorts and saves the .tif files in a standard way, so that AutoStakkert, Photoshop, etc can open.

Does anyone have any ideas...? Have any other 174 chip camera users seen these vertical lines (see screen grabs below)..?

 

For reference, the settings we came up with are:

 

Mono8 - Gain 30.5 Db / Offset (Black level Dn) 15

Mono12/12P - Gain 18.5Db / Offset (Black level Dn) 40

-----

Mono12P master dark_stretched in Ps 

1505803811_Mono12Pmasterdark_stretchedinPs.thumb.png.911c233868da92002242b8355ec8e725.png

 

Mono8 master dark_stretched in Ps - see vertical lines

444308305_Mono8masterdark_stretchedinPs.thumb.png.7ea5def063791a2358278411433c0e48.png

 

Mono8 master flat 2000ms_stretched in Ps - again you can see stronger vertical lines in the Mono8 over the Mono12P...

540778778_Mono8masterflat2000ms_stretchedinPs.thumb.png.7ab6235d4fdb4af0c82b3ad4575e397e.png

 

Mono12P master flat 11000ms_stretched in Ps 

404058848_Mono12Pmasterflat11000ms_stretchedinPs.thumb.png.500264408e01c6e283d27fa908a9efe8.png

Regards,

Damian

Edited by TakMan
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Just a guess but maybe the mac handles the global shutter a bit slowly with camera refresh rate and data capture rate? 

 

IF monoP  stands for "progressive", then this could relate to image flicker and scan line writing.    Back in the early days of hdtv's , interlacing was a big problem where the image was made of individual odd/even lines that refreshed a bit slow so you could see them visually.   Then progressive scan came out, but the rate of refresh took a while to catch up with it and special hardware had to be adapted to allow quicker image processing .     (most nvidia cards have no problems reproducing the video and all the video encoders are built into the windows devices by default)      Mac's are a bit slow on industrial standards, and are typically proprietory based so they have issues with 3rd party software development that doesnt pay for some patent or trademark support. 

 

https://en.wikipedia.org/wiki/Progressive_scan

 

Not sure on the video writing / handling of mac, but i know there are tiny bugs like this in reference to how the images are refreshed on the screen in apple products compared to microsoft products.  Basler pylon is not exactly an industry standard program that apple would be looking at for compatibility.  You may have to rummage through the "pylon guru" settings for an interlace button, or rate of refresh button.

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Thanks for your thoughts on this.

P stands for packed, not progressive. Plus it's the Mono8 data that is showing the vertical lines, Mono12/12P is fine...

Here is the info from Basler:

1863192092_Screenshot2020-05-28at00_30_19.png.8aa310107f1f326feb8520c3032b7d5b.png

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