GPCAM290C help!!!

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TimBear
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GPCAM290C help!!!

Post by TimBear »

At my wits end.

I’ve got an Altair GPCAM 290C which I’m using with a Celestron AstroFi 102 with Starsense.

I’m disabled and just want a camera that acts as an eyepiece replacement so that I can sit comfortably and view what my scope is pointing at on my laptop.

I thought the GPCAM would be ideal but so far it’s a non-starter. I get the scope perfectly focussed and swap the eyepiece for the camera and…nothing. Video, trigger mode, sharpcap, Altair Capture, darks, flats; the whole caboodle and nothing. In daylight I can view terrestrial targets easily but at night it’s hopeless.

I’m quite prepared to believe I’m doing something dumb but if will happily wear the Dunce’s cap for a month if someone can put me right.

I’m writing this in a gîte in France, under a clear, moonless Bortle 3 sky and I could weep.

Thanks in advance

Tim
Brian
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Re: GPCAM290C help!!!

Post by Brian »

Hi Tim, Welcome!

Well if it all works in the daytime then it should work at night as well.
I suspect that your problem with astro-targets is the focusing. Generally the camera focus will be quite a way from your eyepiece focus as I'm sure you've found with daytime viewing. However the astro-focus (at true infinity) will also be different to the terrestrial focus even if that terrestrial target is a "long" way off. Still it can be quite useful to mark the position of the best terrestrial focus on the telescope drawtube with a lead pencil line to make approximate focus easy to set subsequently.

Another hurdle you will have with the camera is that astro-focus needs to be spot-on. Particularly for fainter objects (even "bright" planets) the target can be in the field of view but if out of focus the image will be smeared out and you won't see it. Also, the imaging chip on the camera is tiny and your target can easily be just outside the field of view and you won't see it.

So I think you need to establish just where the astro-focus point is with your camera. I would suggest that as Jupiter is very bright and quite high in the south at the moment, you use it as a means to get your set-up working. Start with your finderscope and eyepiece. Get Jupiter in the center of the eyepiece view and focused. Then adjust the finder so that Jupiter is dead center there also.

Now swap the camera in. Set the camera to maximum sensitivity i.e. Gain on full, shutter 1/5-1/20 sec (say) and make sure the image window is set as large as possible. Watch the preview screen. Even if the Jupiter is just off the chip you may be able to see a diffuse ring of light crossing the field. Use the mounts positioning buttons to bring the target onto screen - you will see by the way the light pattern moves which way the mount needs adjusting. If the preview screen is dark then you will need to adjust focus in/out until you pick up Jupiter and can get it into the middle of the view. Jupiter is very bright and you will know when you have it on-chip for sure. When you 'scope is tracking with Jupiter on chip you can adjust gain and shutter down for the best image. Also set your "region of interest" ROI to give a reasonable size on-screen image.

If I understand correctly You just want to watch the screen in real time. If you want to record and produce images with the camera then that would be another learning curve to climb :D

Hope this helps you get started,

regards,
Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
Ro-Ro roof shed
Brian
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Re: GPCAM290C help!!!

Post by Brian »

P.S> should have said that when you arrive at the focus you want for astro then put another pencil mark on the focuser tube so you can go straight to that position next time,

regards,
Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
Ro-Ro roof shed
TimBear
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Joined: Mon Sep 06, 2021 10:21 pm
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Re: GPCAM290C help!!!

Post by TimBear »

Hi Brian

Thank you so much for such a long and helpful reply. Makes sense! I’ll definitely try with Jupiter as suggested.

Will let you know how I get on. Thanks again.

Tim
SkyBrowser
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Re: GPCAM290C help!!!

Post by SkyBrowser »

If all else fails, try the Moon. Bright, and easy to find :)
Brian
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Re: GPCAM290C help!!!

Post by Brian »

Hi Tim,

could you provide a bit more info about your telescope? I have assumed that a 102 is a short-tube refractor (f/5 with relatively wide field of view), but looking it up I think now that it is probably a 102mm Maksutov instrument (f/13 with a relatively small field of view).

Can you confirm as this info would help us advise you more appropriately if required in the future :D

Cheers,
Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
Ro-Ro roof shed
TimBear
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Joined: Mon Sep 06, 2021 10:21 pm
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Re: GPCAM290C help!!!

Post by TimBear »

Hi Brian

Yes, it’s a Mak.

Full specs here:

https://www.celestron.com/products/astr ... -telescope

I know it’s never going to be a great imaging scope but it’s got a lot of features (notably the app control) that work for me.

Skies unexpectedly clearing here so will hopefully be able to have a crack at Jupiter as per your advice.

Thanks again

Tim
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