SharpCap Forums

Hi there!

I am a complete beginner. Last night was my first time getting to the Live Stack stage. The problem was that when I tried to start live stacking, I kept getting error messages saying either "not enough stars detected therefore could not align" or just "could not align". I'll share every step I took because I had some uncertainties in earlier steps that may have affected later steps

1. Achieved good focus using multistar-FWHM with exposure of 2s and gain maxed at 400

2. Slewed to target Pinwheel Galaxy.
○ Plate solved but kept getting errors until I increased exposure to 16s and decreased sigma to 15
○ After plate solve succeded with those settings, there was just a very faint smudge in the middle of the screen, so faint I'm not even sure it was really there… so not sure if I successfully got the target in the middle
Did increasing my exposure here affect my focus which was done at a lower exposure?

3. Went to the Brain. Initially did not use ROI. The brain advised exposure 23.2s and gain 200. I clicked "apply" and then everything on my screen went dark, I could only see a couple stars. When the gain was maxed before clicking apply, I saw more stars on the screen… should the brain have advised a higher gain?


4. I stayed with the Brain's recommendations anyway and then went to LiveStack. Initially status said "frame not stacked because less than 3 stars found in the frame image… could not align"
○ I then went to the alignment tab and increased Sensitivity to 96. Then got a message at the top saying "could not align". See screen shot 6 for Alignment tab
○ Tried stretching midline of histogram to left, I don’t think there was any change with this
○ Tried maximizing gain and check off Highlight Detected stars (screenshot 7)- this rendered a tonne of red boxes and some green boxes, but stacking still couldn't align
○ Went to the Filter FWHM tab, saw a bunch of red bars over the limit (screenshot 8). Tried increasing the FWHM limit, no change. Tried removing the limit altogether and no change.
§ Did the image go out of focus because I changed my exposure level to plate solve (step 2) after I had achieved focus initally at a lower exposure (as described in steps 1)?
See screenshot 10 for Filter Brightness tab in live stack
○ See screenshot 11 for Histogram tab in live stack
○ See screenshot 12 for stacking log
○ Then I went back to Focus Assist multi-FWHM tool and saw I had only red bars. I couldn’t achieve focus again so packed up at this point.


6. I'm also just seeing now that in the controls group of Livestack, Raw Frames is set to "save none"- would this affect anything?

7. Another issue that could have caused the alignment problem is that sometimes my tracking button would switch to off, even though I didn’t touch it, and on stellarium my reticle would fall away from the target every few minutes- why did tracking keep switching off? I made sure it was on at sidereal rate as soon as I finished plate solving, is this correct to do?

My scope focal length is 430 mm, f 5.9,
My camera is ZWO ASI183 colour CMOS pixels 2.4um. Pixel scale is 1.15 "/pix.
I live in a light polluted suburb but visibility and seeing were average, and moon was crescent and low

I feel like either the red bars in the fwhm tab and/or the tracking switching off are the causes of this stacking problem. It was difficult to troubleshoot in the middle of the night while half awake. Any advice you can give would be amazing !!

Hi,

jumping straight to the screenshots, I can see that the stars in them are badly elongated instead of being round - this is preventing SharpCap from detecting them as stars, and instead it looks like the star detection is picking up on noise in the image instead because the sensitivity is turned up high.

This elongation of the stars is the thing you need to fix - it is going to be caused either by your mount not tracking at all or by the tracking quite doing what it should (poor polar alignment, incorrect mount setup, etc).

For now I would suggest turning off live stacking, but keep the camera settings that you were using (I think it was 23s exposures, gain 200). Make sure that you can see stars and that they are round (or at least close to round) before trying the live stacking again.

cheers,

Robin

Hi Robin thanks!

Yes I was concerned about the star trails and was confused about what to do with the tracking. After I plate solved for my target, I clicked "track" in the SharpCap control panel and set it to sidereal rate. However, every few minutes the track function turned off and I'm not sure why. Does tracking turn off when you change other settings? I was changing settings frequently while trying to troubleshoot.
I'm certain my polar alignment was accurate.

Hi Monika,

it should not turn off automatically, only in response to you using the tracking button or using your handset or EQMOD application. It might be a good idea to let the tracking run for a while without trying anything to see if you can catch it turning itself off (if it does when left alone). Note that SharpCap asks the mount if it is tracking every couple of seconds, so if the mount stops tracking for some reason, the button in SharpCap will untick itself a couple of seconds later.

Note that the tracking will turn off automatically if the mount gets to the meridian or close to the other limits (horizon, etc), but you do not seem close to those in the screenshots.

cheers,

Robin

Okay I will definitely try running tracking without doing anything else and see if it does this again. My programs do sometimes stall when I try to do too many things at once.
I just tried googling the tracking issue again (this time with eqmod as a key word). It looks like others have also experienced the tracking turning off randomly. They attributed it to connectivity disruptions. Last night I moved my laptop around the table frequently while getting up and down to focus- my USB cables may have disconnected while moving. I will check on this next time as well.

Thanks so much for your help very much appreciated!!

Hi,

yep, moving USB cables around can definitely cause things like that - a large fraction of the automatic bug reports that get uploaded for SharpCap come down to 'some device (camera/device/focuser/etc) disconnected while we were trying to use it'. I expect that they are often caused by cables being pulled as the mount moves.

cheers,

Robin