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Is this vignetting?
Posted: Mon Mar 16, 2020 2:30 pm
by Larry 1969
Hello all!
I've recently noticed this in my images during processing and, being pretty new to it, was wondering if this is what you all call vignetting
and, if so, what to do to reduce or eliminate it. This is the result after the "Auto Dev" module in StarTools. This time I chose to keep it
and crop it because my target was unharmed. Other times I use the "vignetting" selection in the "Wipe" module and it helps but I think
it does affect the center of my image a bit as well.
Any tips?
Thanks!
Larry
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 2:54 pm
by Larry 1969
This was my next target. Notice how it changed?
Larry
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 3:00 pm
by yobbo89
i can't view the items , sorry
edit: nvm, if i right click to a new window then it will download the file, i'll have a look
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 3:08 pm
by yobbo89
wow, i've never seen that before,maybe some stacking artifact , are these single frames or stacked ?, vignetting is typically circular, and it's caused by obstruction of the draw tube or filter and the shape is pretty prominent of something round obstructing the light path on the edges , a diagram can show this . the only thing i can think of that is remotely rectangle is a clip in filter.
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 3:51 pm
by Larry 1969
Thanks!
I have a filter but I'm not using it.
Here's my 3rd object from that same session.
Note: I didn't change anything between these pics. I didn't touch the camera or any settings. Just changed targets.
Also note this one had a meridian flip but I don't think that matters as DSS seemed to handle the flipped image well.
Luckily it was another fairly small target and I was able to crop it.
Again, this happens after using the "Gradient" option in the "Wipe" module in StarTools.
The "Vignetting" option greatly reduces this but it does seem to impact the target as well.
Larry
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 4:03 pm
by yobbo89
if you haven't done so, you might want to upload a raw un calibrated frame.
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 4:56 pm
by UlteriorModem
Unless you have a square lens and telescope that is not vigenetting. You are getting some strange results from image registration, stacking, and calibration.
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 5:50 pm
by Larry 1969
I'm not sure how to upload a single frame... No matter what I convert it to it's too big.
I could DropBox one if anyone would be interested but let me know what format to upload.
It's currently .CR2 but I can convert it.
Thanks!
Larry
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 5:51 pm
by UlteriorModem
Yes use Dropbox. Cr2 is fine. Might also include your calibration files if you use them.
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 5:52 pm
by Star Dad
If this is a stacked image I have had a similar experience. In every case I can think of it is because the the mount was not tracking properly and so the edges of the stacked images don't overlap precisely. I occasionally get them when guiding is going well, so I usually have to crop the image by, oh, say, 100 pixels. Then do the gradient tool. So to be clear - load the image, ST should complain about possible stacking artifacts, autodev, crop the borders, then wipe. I then go back and this time do a manual develop to get as much signal as possible vs noise.
If this is a single image - I'm stumped!
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 6:10 pm
by Larry 1969
Thanks Tom!
You want my master dark, flat and bias?
Larry
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 6:14 pm
by UlteriorModem
The more you can share the better so yea some lights, flat, bias and darks if you have them.
The more data we have to look at the better we can analyze the data.
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 6:24 pm
by Larry 1969
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 6:51 pm
by UlteriorModem
I will have a look at this tonight.
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 6:58 pm
by Larry 1969
Star Dad wrote: ↑Mon Mar 16, 2020 5:52 pm
If this is a stacked image I have had a similar experience. In every case I can think of it is because the the mount was not tracking properly and so the edges of the stacked images don't overlap precisely. I occasionally get them when guiding is going well, so I usually have to crop the image by, oh, say, 100 pixels. Then do the gradient tool. So to be clear - load the image, ST should complain about possible stacking artifacts, autodev, crop the borders, then wipe. I then go back and this time do a manual develop to get as much signal as possible vs noise.
If this is a single image - I'm stumped!
This is stacked and yes, ST warns that there are stacking artifacts. The first AutoDev doesn't reveal much at all. This doesn't show up until after gradient wipe. It's only after that that I can see what needs to be cropped and it's quite a bit! I struggled with
DSS settings in the past. I wonder if I have something screwy in there...
Larry
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 7:01 pm
by yobbo89
you might want to try some different stack settings or different software, i had no problems at all .
un process straight from calibration and the other is colour corrected and stretched .
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 7:10 pm
by Larry 1969
Thanks yobbo!
Do you use DSS and ST or something else?
Larry
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 7:21 pm
by yobbo89
Larry 1969 wrote: ↑Mon Mar 16, 2020 7:10 pm
Thanks yobbo!
Do you use DSS and ST or something else?
Larry
Yes I use
dss aka deep sky stacker, I can help you on some settings if you choose that route to stack your data
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 7:25 pm
by Larry 1969
yobbo89 wrote: ↑Mon Mar 16, 2020 7:21 pm
Larry 1969 wrote: ↑Mon Mar 16, 2020 7:10 pm
Thanks yobbo!
Do you use DSS and ST or something else?
Larry
Yes I use
dss aka deep sky stacker, I can help you on some settings if you choose that route to stack your data
Thanks! I'm looking at my settings now but I'm afraid there's a lot I don't understand...
I'm using the beta of
StarTools that was supposed to work with no white balancing. Is that the version you're using?
If so, I'd be curious to see your settings. Maybe you could upload the
DSS settings file to DropBox and I can import it to try if you have some time?
Thanks again!
Larry
Re: Is this vignetting?
Posted: Mon Mar 16, 2020 7:32 pm
by Larry 1969
I may have found the problem. I had the stacking mode set to "intersection". I set it to "standard" and I'm restacking...
Larry