Ho do I know the best brightness to use/try

Somewhere to ask questions about the best way to use SharpCap
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directgumby
Posts: 17
Joined: Tue Sep 10, 2019 4:17 pm

Ho do I know the best brightness to use/try

Post by directgumby » Thu Sep 12, 2019 6:47 pm

Hello,

I had a great progress last night when doing my second capture with SharpCap and made some progress on using the ASI178MC and getting good images with the “auto” settings.
In my work last night, I wasn’t sure when to adjust the brightness and what a good starting location is for the brightness.

Any thoughts on where to start and/or when to adjust the brightness would be greatly appreciated.

Thanks,
Brett
SharpCap 3.2
SkyWatcher AZ GTI Mount (In AZ mode)
SynScan App Pro (Windows: 1.17.3)
ZWO ASI 187 MC
Apatura 60
Windows 10 (1903 build 18362.295)
Laptop SurfaceBook (16 gigs of RAM)

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admin
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Re: Ho do I know the best brightness to use/try

Post by admin » Sun Sep 15, 2019 12:23 pm

Hi,

The best way to pick your brightness is to set the exposure and the gain to roughly the values that you expect to use, then cover the telescope to allow SharpCap to start showing dark frames, show the histogram and then adjust the brightness if necessary to make sure that the peak of the histogram is clear of the left-hand side of the graph. It doesn't have to be clear by a great distance just by a small amount will be fine.

Cheers, Robin

directgumby
Posts: 17
Joined: Tue Sep 10, 2019 4:17 pm

Re: Ho do I know the best brightness to use/try

Post by directgumby » Mon Sep 16, 2019 11:08 pm

Hello,

Thank you for the suggestion, i'll give it a try the next night I have a clear sky.

Thanks again,
Brett
SharpCap 3.2
SkyWatcher AZ GTI Mount (In AZ mode)
SynScan App Pro (Windows: 1.17.3)
ZWO ASI 187 MC
Apatura 60
Windows 10 (1903 build 18362.295)
Laptop SurfaceBook (16 gigs of RAM)

FWI
Posts: 5
Joined: Sun Aug 18, 2019 8:27 pm

Re: Ho do I know the best brightness to use/try

Post by FWI » Sun Sep 22, 2019 7:07 am

Hi Brett ... (aka DirectGumby),

I noticed that you bit the bullet and picked the ASI178 Camera. Heck of a little camera isn't it? The reason I say this is due to the Very-Small Pixel-Size at 2.4um (i.e. very small for extreme detail; and the reason I own both the Color and Monochrome versions). The only other ZWO Camera with that small of a pixel size is an ASI183 but you need a lot of horsepower to process images of 20 Mega Pixels !!!

I use the Skywatcher ED80 Double APO with the 0.85 Reducer which makes for a 510mm Focal Length and a fast F/6.3 Focal Ratio.

Your nice little Apertura 60mm FPL-53 Doublet APO Refractor appears to have a 360 Focal Length and a Fast F/6 Focal Ratio ... i.e. I think we're in the same ballpark together.

I don't use any Auto Settings because I SCAN the Sky for Comets where I need the same exact exposure in/on all of my images.

The Normal-Gain for the ASI178MC (Color Camera) is 255 ... Any higher gain, you will begin to start noticing Grain getting into your images.

To let you know, with your camera, you may be getting a lot more in your images than you realize ... or are seeing in the SharpCap Image-Window.

Be sure to use SharpCap to capture and use a "Dark Frame" for your images ... otherwise you will be getting/seeing those UGLY HOT-Pixels in your images.

Try playing with the "Display Histogram Stretch" in the lower right corner within SharpCap. There are actually three Vertical-Dotted-Lines in the "Display Histogram Stretch" (Left, Middle, and Right). Try slowly sliding the Right-Most Vertical-Dotted-Line to the Left and you will see your stars begin to POP-OUT at you !!! ... (Note: If you have too much trouble finding that "Right-Vertical-Dotted-Line", try clicking that "Lightning Bolt" Icon on the right-side because it will likely move the verticals enough for you to see them.

My Images were taken with SharpCap with ONLY Fixed-Settings (nothing automatic): Exposure=8.0 Seconds, Gain=300, and "Display Histogram Strecht" settings. The Brightness I used was set to ZERO.

When you can afford it, I would recommend PixInsight to further push your images. There is one very special function that I use on all of my images called "CurvesTransformation" with the Input set to 0.40 and the Output set to 1.00. There is also a batch-like way to process a bunch of images automatically in what's called an "ImageContainer" which I used to place 924 images into and Process them with the "CurvesTransformation" Process.

I have read where folks try the free imaging software, then move to a few $100 stuffs, then a few $150 stuffs, and finally end up with PixInsight; wishing they had saved all of that money and simply taken the plunge starting with PixInsight in the first-place !!!

PixInsight is OVERWHELMING at first because it has an ENORMOUS NUMBER of Processes. Currently that ONE Process that I use makes that software worth it to me.

You can see examples of my images on Google-Drive:
https://drive.google.com/drive/folders/ ... Peex4Svc27

You can find more detail of my images by finding and reading my NOTES.txt file before moving on into the Folders with my Images.

When the time comes, I will take advantage of PixInsight's COMET Processing, and MOSSAIC Processing.

I will offer THIS: IF one tries to See or Figure-Out everything-at-once, they will likely become so Overwhelmed and to the point of not even using the PixInsight Software. The KEY is to find ONLY the Functions/Processes that work for what you are trying to do ... and just ignore the remainder until you discover a need for any of them.

SharpCap Pro, PixInsight, and a VERY OLD (Year 2000) COPY of Paint Shop Pro is ALL of the Imaging Software I think that I will ever need.

For me, a HUGE, HUGE FEATURE for my choosing to COMMIT to SharpCap was its providing Scripting and/or User-Programming-Abilities so that I can Programatically-Control-BOTH-The-Camera-And-Mount ... AND ... It has many other features to offer too like Stacking, Aligning, Guiding, Image Enhancments, etc., etc., etc.

An Example of this can be seen within this SharpCap-Forum-POST ... (my latest code I use is at the bottom of this post):
viewtopic.php?f=19&t=1845

AND

Good Luck ... AND ... Try to Keep Things Simple ... AND ... WE BOTH Have A Very Long Ways To Go !!!,

Farley

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