How do you take flats?

[Ant]

with a hyper/fast star.

Normally you can use a EL panel or the white T shirt method to take flats... But with a Hyper/Fast star you have a camera sticking out the front?

Just wondered if I go the fast star route I'll be needing flats.

Cheers

Ant

[Helen]

I'd like to know the answer to that too Ant! You'd also need to ensure that the camera cables always stayed in the same place...

Helen

[Euan]

I would have thought you could stick something like a dew shield over it to extend the tube and then do the usual t-shirt / LCD screen / EL Panel method?

I'm guessing of course I've never actually used Hyperstar

[barkis]

Make a dewshield that extends beyond the Camera, and cover it with a white sheet.?

Same Idea as Euan.

I read that somewhere.

Ron.

[SteveL]

my biggest problem was ensuring the flats werent completely overexposed, even with the very shortest exposure my CCD could take!

[blinky]

Showoff

[SteveL]

It was a huge issue for me... had several layers of grey perspex in front of the EL panel to try to dim it down (NS8GPS + Hyperstar + QHY8 + solid dewshield)

[Euan]

It was a huge issue for me... had several layers of grey perspex in front of the EL panel to try to dim it down (NS8GPS + Hyperstar + QHY8 + solid dewshield)

I can't do skyflats with the 383L+ because of this, the shutter needs more than 0.5 secs really and it's always too bright

A crappy old LCD screen works great, although I really need to join the EL panel gang, those guys are cool

[SteveL]

and I see that Starizona have announced the Hyperstar 3 for the C9.25, which due to the slightly different mirror config on the 9.25 makes this run at a slightly slower f/2.3 rather than the usual f/2.

http://starizona.com/acb/HyperStar-3-Lens---925-Celestron-P3206C773.aspx

[BlueAstra]

my biggest problem was ensuring the flats werent completely overexposed, even with the very shortest exposure my CCD could take!

I think I may have a similar problem. I'm new to the pure CCD club, and when I tried to get a flat with my panel and newly acquired H16 at 0.1s, all I got was this. More attenuation required, or wrong settings?

[Euan]

I think I may have a similar problem. I'm new to the pure CCD club, and when I tried to get a flat with my panel and newly acquired H16 at 0.1s, all I got was this. More attenuation required, or wrong settings?

Looks about right if the black level has been clipped, all you are seeing there is the brighter part of the image, nothing has been saturated (solid white) so it's not too bright

What are you using to capture?

[BlueAstra]

I have a electrolumenescent panel + white cloth over the end of the scope. The scope is a Meade 5000 ED80 + TV0.8FR + IDAS LPF + H16. I control the SXV-H16 with MaximDL. I tried 0.1s, but maybe I need a longer exposure. I think MDL applies a 'stretch' to the image preview, so I'm not sure what I'm actually getting. How do you tell if you have saturated the image?

[adamsp123]

my biggest problem was ensuring the flats werent completely overexposed, even with the very shortest exposure my CCD could take!

Me too! with the Atik, the DSLR is easy peasy

[martin_h]

I use about 6 sheets of A4 paper over the EL panel - it dims it down enough to get about 3.5 seconds.