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SharpCap 2.9 - Polar Alignment


Andyb90

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1 hour ago, rwg said:

If you look on the beta download page there is a license that you can use with the beta for now. This will continue to be available and updated during the beta period. So yes, you can still use the features for the beta period, but we've got to the point that the license entry/checking code needed to be turned on to make sure it didn't have bugs in it!

cheers,

Robin

Thank you for the quick response. I did have to download a new version of the Beta as when I started it last night, as the previous version had expired. I had not realised that there was a beta licence file to go along with it, probably because the software automatically downloaded the new version for me, so I did not think to go looking for a licence file to go with the download.

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Ah, good point - I didn't think of the auto-upgrade path when putting the license on the download page. I *think* I put something in the release notes that you see when you install a new version of SharpCap, but very few people read those I suspect...

 

cheers,

Robin

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Certainly not at 10:30 at night as I was desperately trying to set everything up and SharpCap was insisting on a reinstall and re-boot, I was clicking OK buttons as fast as they were coming up ;)

I think what you have done is sufficient. If people don't want issues, then they shouldn't be using beta software. I am certainly not going to complain.

One point regarding the software: What is your view on some kind of splash screen? It often takes about 15-20 seconds from the time I double click the icon to the time I get a window. A number of times I have thought I had miss clicked, so I try again and I end up with 2 copies opened.

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1 hour ago, frugal said:

I managed to fiddle with the settings to get SharpCap to recognise about 26 stars last night by tweaking exposure time, digital gain, noise reduction and some others. After a few failed attempts (I know I am trying this at twice the recommended focal length, so I was chancing my arm), I got the image to Plate Solve. Then when instructed, I moved the RA axis 90 degrees and it Plate Solved again. Woot!. Then I clicked Next as told... "Guided Alignment is only available in SharpCap Pro"... [removed word]

This is with the latest beta version. Having a look at the website it says that the beta versions will have all of the licenced features until the end of the beta period. Has this changed?

Does the Polar alignment feature work well in 2.9? Is it worth uninstalling 2.10 beta and installing 2.9?

I had the exact same issue last night, having just updated Sharpcap to the latest Beta.  I was not happy as I didn't realise the new licence was available on their site.

So I decided to take some pictures of the moon and went to bed. 

I have just now downloaded the licence so hoping for clear skies.

 

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On 02/04/2017 at 20:27, rwg said:

Other possible causes of error that I am aware of

* Bad plate solve on either the first or second stage - this could throw out the whole process - I think this is very unlikely and haven't encountered a case yet

* Atmospheric refraction - only significant below 30 degrees of latitude, probably not going to be a problem in NE Essex!

I would advise that if you are having problems, then at the end of the PA process (once adjustment complete), spin the RA axis again and watch the screen - the stars in view should appear to move around the point marked as the NCP. 

If none of this helps, then I am (for now) baffled. It would be helpful to have an image captured (saved using the snapshot button in SharpCap, not a screen grab) for each orientation of the PA process and also if possible an estimate of the PA error from an independent measurement such as PHD drift alignment.

cheers,

Robin

Hi

Set up last night and checked PA and it was how it was left from the previous night at less than 1 minute error. I have attached a screen shot (Sharpcaps Snapshot was greyed out and I couldn't use). Following this check I then took and image without guiding and got the attached image with star trails. I turned RA and the stars appeared to turn around the NCP. I forgot to check the setting against PHD drift alignment. The only saving grace is that PHD guiding gets rid of the star trailing. 

All a mystery. Is there anything I could be doing wrong? Settings etc. How does Sharpcap pick up location, time etc (GMT or BST)

Any comments welcome

58e35bcf7a318_sharpcap2result.thumb.GIF.ffddd70fcc3510172cbaa0f1c1f5b185.GIF

star trail.jpg

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Are you sure that isn't periodic error?

Two reasons I suspect this -

1) the trails are stronger at each end, suggesting it's spending longer with the star near the end than with it in the middle of the trail - that doesn't fit with a PA problem which should be a straight line

2) The trails look like they are almost due E-W (see  http://nova.astrometry.net/user_images/1569527#annotated ) so it looks like you are getting trailing in RA, not DEC. Again this doesn't fit with a polar alignment issue, but does with periodic drive error.

cheers,

Robin

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Look at the PHD guide logs - if it's mostly RA corrections then it's almost certainly periodic error. Polar misalignment would show up as DEC drift being corrected.

cheers,

Robin

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Robin

I did notice when imaging last night that most of the corrections on the PHD graph were RA and only occasional DEC so this bares out what you say. Should I attempt to measure PE and get the software to take it into account or just accept that it is there and simply let PHD guiding take it out? I read somewhere that trying to take it out sometimes confuses PHD.

Alec

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3 hours ago, alcol620 said:

Thanks for your help Robin

I had exactly the same problem as yours in the past (the same jumps). I discovered that the problem was the parallax portable pier I have on the grass ( filled with sand 80kg). With the berlebach tripod disappeared. Now i'm building a concrete pier and retire the portable pier.

Edited by davidgr1976
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Robin, 

I managed to complete the polar alignment process this evening, but it was not a simple process. I think that most of my problems come from the fact that the field of view is only 0.9 x 0.6 degrees. Plus I need to increase the exposure time to 15 seconds in order to recognise enough stars. I think that this led to a problem where the Solved solution moved around.

It looks like a really nice solution, but I just don't think that my system is setup with a wide enough field of view for this version of Polar Alignment to be successful.

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@frugal

Are you using the 2.10 beta? That has improved star detection and more tweaks to it too - it seems to have fixed issues in 2.9 with faint stars not working well for a number of people, particularly with lodestar cameras which seem to have no gain control :rolleyes2:

Set a digital gain of 2x if you have no camera gain control and see if that helps. With a camera gain control (QHY, ZWO, Altair, etc) I'd usually advise exposures in the 1-4s range and a high gain.

cheers,

Robin

PS. Don't forget to use the trial license key with the latest versions of the beta to unlock the adjustment phase!

 

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12 minutes ago, rwg said:

@frugal

Are you using the 2.10 beta? That has improved star detection and more tweaks to it too - it seems to have fixed issues in 2.9 with faint stars not working well for a number of people, particularly with lodestar cameras which seem to have no gain control :rolleyes2:

Set a digital gain of 2x if you have no camera gain control and see if that helps. With a camera gain control (QHY, ZWO, Altair, etc) I'd usually advise exposures in the 1-4s range and a high gain.

I am using the 2.10 beta with the correct licence key.

I was using a x4 (I think) digital gain and an exposure time of 15 seconds. 8 seconds did not give the required 15 stars.

I think the problem boils down to the field of view just being too narrow for this technique to work. With the ST80 my field of view is only 0.9 x 0.6 degrees

As an experiment I left the alt/az untouched and watched the plate solving for a while. Due to the field of view and the fact that it kept changing which stars were selected, the solved location would change. For one solve it declared that the NCP was at the top right of the screen, and the next time it declared that it was off the screen to the bottom left.

Also as a feature request: There does not seem to be any indication of whether the software is currently plate solving or not. It shows the "Plate solve failed", "Plate solve successful" message, but I do not know which frame that applies to. How can I tell if the software is currently trying to plate solve, or if it has finished?

Also, does it update the frame view with the solved information straight away, or only when the next frame is received from the camera? I.e. if I start taking 15 second frames at t=0, at t=15 the first frame is ready, the software shows the frame with the higlighted stars; at t=19 the software finishes plate solving frame 1. Does it update the view straight away? or does it wait until t=30 and the second frame arrives?

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The solve status for the most recent frame is there - in Stage 1 and Stage 3 it's to the right near the 'Next' button and in Stage 2 it's to the left (I think that was the only space for it in stage 2).

The actual plate solving procedure is fairly quick (fraction of a second usually) as it works over such a limited area of sky. Actually the first solve can take a few seconds as it builds it's search index at that point, but subsequent ones are fast. Anyway, as soon as the exposure finishes the frame gets passed to the plate solver and only when that is done does it get displayed on screen - if you see only stars on a frame and no NCP circles then that means the frame has already failed to solve, not that it's waiting for the solver to run.

cheers,

Robin

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Hi,  just found out about the sharpcap polar alignment and i have one doubt.  

I live in the southern hemisphere and my south view is kind of blocked by a building.  Can i still use it to align my mount with the SCP? 

Thank you. 

 

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Hi @Atreta,

you need to be able to see the region around the pole (north or south) for the polar alignment to be able to work. I have an idea for a version that will work without seeing the pole, but have had no time to even test out whether it works yet, so it's a far while off even if it does work.

cheers,

Robin

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Great news :D

i took a shot with my dslr to see if the scp is visible from my porch, ran it through nova.astronomy plate solver  and it is visible.

Just ran sharpcap polar alignment routine and  i got it polar aligned real quick.

I was getting so disappointed about not managing to polar alignment and it made me excited to continue with this hobby

this is a great software. how can i become a supporter?

thanks a lot, Robin.

 

 

 

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@Atreta

until yesterday there was a donation button on the SharpCap web site. I've removed that because with the release of 3.0 in the next week or two there will be a 'Pro' option available for those who wish to support SharpCap.

cheers,

Robin

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  • 3 years later...

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