Help with SPC900nc

[StuW]

I managed to get set up for about 30 mins tonight before the clouds rolled in (the replacement HEQ5 head seems to be working great, thanks Martin!).

The problem I'm having is overexposure on Jupiter. I set Gain to 0 and exposure to the lowest setting (-14?) but still it's just a white ball! I'm using a 2x Astro Engineering AP Barlow on the 200p giving around 166x (assuming 6mm equivalent for the cam). If i put the Scope end cap on with the small cap removed from it Jupiter is perfect except for the detail level.

Am I going to have to get a 3x or higher to spread the light out a bit?

TIA

[malc-c]

Are you using sharpcap to recover data ?

If so try increasing the frame rate to 10 or 15 fps and have the gain at around 40 or more, then adjust the brightness. I assume you have removed the lens from the camera and fitted a 1.25" nosepiece, and that the planet is in focus

[StuW]

Hi Malc

I'm running at 10fps as any more would introduce compression and lose detail. Yes, lens removed and 1.25in nose piece added. Planet is in focus as best I can get it (nice sharp edges, but no detail)

[StuW]

I just had a thought, could it be because I dont have an IR filter on?

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[Cornelius Varley]

Make sure that you have all the auto settings switched off. A lack of Ir filter shouldn't affect exposure only sharpness.

Peter

[malc-c]

Normally with all the sliders to the left you would expect a black screen in Sharpcap. It this a bog standard camera and not an LX modified one (ie just the one USB lead) ?

[StuW]

It is LX modified, but in normal mode.

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[malc-c]

My guess is that it's not switching, hence the over exposed image. Try selecting "LX modified" camera in sharpcap and then drop the shutter speed down

[StuW]

Thanks malc. If I ever get another clear night when I'm not on crazy shifts I'll give it a try. I would have experimented a bit more last night, but with the clouds coming in and my hands going numb coupled with having been up since 2am, I gave in quite quickly.

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[malc-c]

You can always check by putting the lens on and focusing on something in the room, and then place the camera in a draw in the dark, switch to LX mode, open sharpcap and play with the shutter speeds until you get a result by seeing the contents of the draw.

Not quite the same as testing in a live astro-imaging session, but it should prove the camera

[StuW]

Managed to get out again last night, but tried using wxAstro Capture instead of Sharpcap. Setting the exposure to 1/1000th sorted the problem I was having. I can't find a similar setting on Sharpcap?

[malc-c]

1/1000 exposure is very quick... what are you looking at ?

The idea of an LX modded web cam is to pick up faint objects by having longer shutter speeds. If you are imaging something bright like a full moon a normal mode web cam would suffice.

The settings in Sharpcap can be seen in the attached image

[StuW]

Malc, the camera has a switch to change from Normal to LX mode. I was trying to image Jupiter and had all sliders set to the bottom except colour, brightness and contrast which I left in the middle. I can change to LX mode and image DSO's fine as it shows an exposure length slider shown in seconds as in your image, but in normal mode the slider is set to -14 and the image is still too bright. I'll give sharpcap another go next clear night just to make sure it's not something I'm doing like leaving the mode switch in LX.