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 Post subject: Phillips SPC webcam problems
PostPosted: Mon Mar 05, 2012 9:38 pm 
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Hi all,

I have recently bought one of the above from Sherwoods. I have tried it during the daytime on my Skymax Synscan 127 goto and have managed to get some very impressive pictures of bolts on far off aerials!

However, trying to use it at night, even on the moon last night has proved fruitless...I simply cannot get any sort of image, not even vague lights. I am using wxAstrocapture, but am concerned that I might not have the right settings, though I have played about with them.

I am going to try the society webcam tonight, that I borrowed recently, though am not convinced I will fare any better.

Has anyone any advice or ideas where I am going wrong?

Thanks in advance for your assistance.

Regards,

Callum


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 Post subject: Re: Phillips SPC webcam problems
PostPosted: Mon Mar 05, 2012 9:42 pm 
If you click onto the members area and then the projects tab on the left you will find a quick start guide for using these webcams, should answer your questions and solve your problems.
Hope this helps.


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 Post subject: Re: SPC webcam
PostPosted: Tue Mar 06, 2012 7:09 am 
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Well Callum, it's encouraging that you've had it working in daylight - so there shouldn't be any difference when imaging the Moon, which is also a Sun-lit subject. And the Moon is the perfect choice for tests, as it's such a big target!

Let's consider the four main aspects of the system:

Function: you've already had the webcam working in daylight, so you must have got the right driver software loaded. But did you use wxAstroCap for these tests, or some other video application? If not, go back and repeat using wxAC, to get the hang of using the program.

Aiming: it's surprisingly tricky to get the 'scope pointed accurately enough that the Moon's image falls onto the tiny CCD sensor. The field-of-view of the webcam at the focus of a 1.5m focal-length 'scope is around 9 arc-minutes, which is just one-third of the Moon's diameter. So even if you've first centred the Moon in your highest-power eyepiece, if you nudge the 'scope at all when swapping over to the webcam, you may lose the target.

Focus: you can check with daylight tests on distant aerials where the 'scope's focus needs to be with the webcam. Then you need to get an eyepiece which is nearly parfocal (achieves focus without re-adjusting the 'scope) - sometimes it's possible to slide the eyepiece partly out of the holder to improve the focus (but not so far that it's in danger of falling out). This eyepiece is just used to aim the 'scope at the object, and then the webcam is swapped in, as explained above.
If you'll be doing a lot of planetary work, the a flip-mirror is a very useful accessory - here you can switch between the camera and eyepiece with a lever (my old Meade ETX90 had one built-in)

Tracking: once you've got the target on your sensor how long will it stay there? That depends on how accurately you aligned the mount. But if you watch the live video from the webcam, you'll soon see which direction the target appears to drift, and which buttons on the handset you need to press to re-centre it. But if you let it drift out of the frame, you may need to go back to the eyepiece to re-centre it.

Once you've got all this sussed, it's then a case of optimising the "shutter" and "gain" settings, and then capturing some AVI-streams...


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 Post subject: Re: Phillips SPC webcam problems
PostPosted: Tue Mar 06, 2012 11:05 am 
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dean_kos wrote:
If you click onto the members area and then the projects tab on the left you will find a quick start guide for using these webcams, should answer your questions and solve your problems.
Hope this helps.


Thanks Dean, I will look again (I did read it all before but it was a couple of weeks ago). I think I need to understand the software settings....and not being much of a photographer, it doesn't seem too simple :D


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 Post subject: Re: SPC webcam
PostPosted: Tue Mar 06, 2012 11:14 am 
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rwilkinson wrote:
Well Callum, it's encouraging that you've had it working in daylight - so there shouldn't be any difference when imaging the Moon, which is also a Sun-lit subject. And the Moon is the perfect choice for tests, as it's such a big target!

Let's consider the four main aspects of the system:

Function: you've already had the webcam working in daylight, so you must have got the right driver software loaded. But did you use wxAstroCap for these tests, or some other video application? If not, go back and repeat using wxAC, to get the hang of using the program.

Aiming: it's surprisingly tricky to get the 'scope pointed accurately enough that the Moon's image falls onto the tiny CCD sensor. The field-of-view of the webcam at the focus of a 1.5m focal-length 'scope is around 9 arc-minutes, which is just one-third of the Moon's diameter. So even if you've first centred the Moon in your highest-power eyepiece, if you nudge the 'scope at all when swapping over to the webcam, you may lose the target.

Focus: you can check with daylight tests on distant aerials where the 'scope's focus needs to be with the webcam. Then you need to get an eyepiece which is nearly parfocal (achieves focus without re-adjusting the 'scope) - sometimes it's possible to slide the eyepiece partly out of the holder to improve the focus (but not so far that it's in danger of falling out). This eyepiece is just used to aim the 'scope at the object, and then the webcam is swapped in, as explained above.
If you'll be doing a lot of planetary work, the a flip-mirror is a very useful accessory - here you can switch between the camera and eyepiece with a lever (my old Meade ETX90 had one built-in)

Tracking: once you've got the target on your sensor how long will it stay there? That depends on how accurately you aligned the mount. But if you watch the live video from the webcam, you'll soon see which direction the target appears to drift, and which buttons on the handset you need to press to re-centre it. But if you let it drift out of the frame, you may need to go back to the eyepiece to re-centre it.

Once you've got all this sussed, it's then a case of optimising the "shutter" and "gain" settings, and then capturing some AVI-streams...


Thanks Ross, so it is possible I actually missed the moon?! Gulp.....it's more difficult than I thought :roll: I have been using wxAstroCapture BTW.

I did try the borrowed camera last night and think I did manage to get some of the moon, but it was relatively dim (I will try to process images later). However, it was the settings that I was really struggling with....I haven't a clue and have never really done much by the way of photography. There are so many variations.

Also, I was totally unable to get Mars or Saturn on screen, despite thinking I had them well in shot. Again, I'm worried that my lack of appropriate settings might be to blame, though from what you have said I might just be struggling to centre things.


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 Post subject: Re: SPC webcam
PostPosted: Tue Mar 06, 2012 2:29 pm 
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cmcdougall wrote:
it was the settings that I was really struggling with....I haven't a clue and have never really done much by the way of photography.


Start off with the camera set to Full Auto, so that it will display anything no matter how dim or bright whilst you're aiming.
Once you've got the target centred, drop the Frame Rate to 5fps and then Freeze the White-Balance.
Finally, switch off Auto Exposure and set the gain to mid-way or less, and the "shutter" slow enough to produce a well-lit image, but not so slow as to burn-out (use the Histogram function in wxAC to check).

I'll be doing another demonstration of this during the talk on 17-Apr.


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 Post subject: Re: SPC webcam
PostPosted: Tue Mar 06, 2012 4:37 pm 
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cmcdougall wrote:
rwilkinson wrote:
cmcdougall wrote:
it was the settings that I was really struggling with....I haven't a clue and have never really done much by the way of photography.


Start off with the camera set to Full Auto, so that it will display anything no matter how dim or bright whilst you're aiming.
Once you've got the target centred, drop the Frame Rate to 5fps and then Freeze the White-Balance.
Finally, switch off Auto Exposure and set the gain to mid-way or less, and the "shutter" slow enough to produce a well-lit image, but not so slow as to burn-out (use the Histogram function in wxAC to check).

I'll be doing another demonstration of this during the talk on 17-Apr.


That is exactly the sort of advice I needed, thanks very much Ross. See you later if you are going tonight.


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