best camera for all sky use

[Horwig]

hang about !

Are we talking about an 'all sky camera' that is used for deciding about whether the sky is clear enough for telescope use, or something else I wonder ?

You will note Cath, that the fov excludes any windows, and anyway, there are no other houses within its fov. So the only people I'm snooping on are me and the Mrs. 

Huw

[Cath]

no no that's not what I meant Huw .. eeek

Was just referring to what is being expected as to image quality - assuming what the average all sky camera is used for in the astro world.

[Horwig]

I wonder if it's also worth flocking the inside of the box, to reduce internal reflections?

James

The reflection in the dome is very clear of the black lens in the centre, with the white panel around it, at night, hopefully there will be a lot less reflection, lets see what happens tonight.

Huw

[Horwig]

no no that's not what I meant Huw .. eeek

Was just referring to what is being expected as to image quality - assuming what the average all sky camera is used for in the astro world.

Wasn't sure what you were getting at Cath  . But Yes, image quality will be certainly up to spotting cloud and rain, stars might not be too pretty.

Huw

[pete_l]

I wonder if it's also worth flocking the inside of the box, to reduce internal reflections?

James

I think that once your camera / dome has been out in the weather (and the bird .... ) for a few weeks, internal reflections will be the least of your worries.

[Horwig]

Sharpcap still going, after 75 minutes, but EZP would do that, so nothing proven so far. Have experimented with the height of he dome, lifting it by an inch and a bit removes that annoying reflection of the lens.

One interesting thing, Sharpcap does not save jpegs, so saving as png and using pohotoshop to generate the jpeg, Photoshop opens the pngs north up, sharpcap displays them North down.

Huw

[Horwig]

I think that once your camera / dome has been out in the weather (and the bird .... ) for a few weeks, internal reflections will be the least of your worries.

Yes indeed, we have a bird feeding station at the other end of the shed, it's like final approach to Heathrow here at the moment.

Huw

[Horwig]

Just back from work. Sharpcap has been running for over eight hours.

This is a 30 seconds exposure:

[Gina]

Interesting and looking good   Moving the lens to dome distance has certainly improved the resolution and colour fringing   The sensitivity looks at least as good as my mono QHY5.

[Horwig]

Thanks Gina, it worked well last night, for about 12 hours, till I started fiddling with it 

I got bored about two this morning,hence the fiddle, an imaging run was going well, (started using sgp, excellent piece of software, if you haven't tried it, do).

Anyway, sharpcap froze when I fiddled, and when I re started it, it didn't see the camera. So better, but no cigar.

Huw

[Gina]

I've had problems with software not seeing the camera after failing.  I found I had to go out and unplug and replug the USB plug for the camera.  Makes me think about remote USB connection control   Will the need for extra controls never end????

Yes, I have  been planning to get SGP for some time now but haven't got round to it   I keep getting distracted

[Gina]

That camera is certainly much better than the QHY5 for hot pixels   It confirms my thoughts of the mono version for an all sky night imaging camera.  The lack of hot pixels could mean that dark frame subtraction may not be necessary which would save both the mechanical shutter and the dark frame subtraction software.

[Horwig]

For the successful run last night with Sharpcap, I had the house PC in the obsy, today, I swapped back to the obsy PC, uninstalled and reinstalled the QHY drivers, still no joy with it. I think I might reinstall windows on it tomorrow.

H

[aruangra]

FYI, I use EZplanetary with Win8.1 (32bits). I haven't had the freezing issue so far.  I have both QHY5Lii-mono and QHY5Lii-color. In my opinion, the color version may be more suitable as an all sky camera because

1) during daytime, we can differentiate the blue sky and dark cloud. 

2) during nighttime, we can differentiate stars from noise. Noise is in color but stars are white.

The dew heater should not be in contact with metal otherwise heat is absorbed by metal. ABS plastic is good for insulation.

Best regards,

Anat

[aruangra]

I use usb-powered heat pads in beneath the dome. I can get about a 20C delta.

[Gina]

I favour a mono camera for night-time for greater senjsitivity, resolution and better signal to noise ratio.  But I agree that colour would be better for daytime (as I've said before) to differentiate between cloud and blue sky, as you say.  I think the best idea would be to have separate day and night cameras as the requirements are quite different.  For night use we want maximum sensitivity whereas for daytime we don't - there's plenty of light.  This makes me think an ordinary webcam would be quite sufficient and we don't need a wide aperture lens, just wide angle (fisheye).  There are fisheye CCTV lenses available at much lower prices than the f1.4 lens most of us use for night imaging.

[JamesF]

I was wondering if one of the Lifecam models might be suitable for a daytime camera given a suitable lens, but I'm not at all certain the chip is big enough.

James

[Gina]

Exactly what I was thinking   I think I have some info somewhere.

[Gina]

Hmm - edit went wrong   This is what I added :-

A bit later...  Better than that, I've found a LifeCam Studio that I converted for astro use by taking the PCB with sensor out of the original casing and mounting it into a 1.25" eyepiece tube.  I've roughly measured the sensor and it looks like about 3.5mm high.  The width is irrelevant as it's HD format but it looks like 6mm.  So ideally we want to cover a 3.5mm square - that's just under 5mm diagonal.  1/4" is 6.35mm and the Fujinon lens we have is for 1/3" chips.  0.33" =  8.4mm so assuming 4:3 aspect ratio, this gives a height of 8.4 x 3 / 5 = 5.07mm.

Hmm... the LifeCam Studio is too small then.  The image circle of the lens would seem to be about 5mm whereas the height of the LifeCam is about 3.5mm - certainly less than 4.

This is how I think the Fuginon 1.4mm FL view compares with the LifeCam Studio.

I estimate that to cover 180 degrees all round with a LifeCam Studio we would need a focal length of just 1mm

[JamesF]

That's a shame.  I wonder if there are any other cheap webcams that might be pressed into service.

James

[Gina]

Oh well... it was a thought   So we need a 1/3" sensor in a camera and the only ones I know of as big as this are CCTV cameras and these are generally very low resolution unless you go for an expensive one

I wonder if anyone knows of a large webcam that doesn't cost the earth   The QHY5L-II C (or equivalent ZWO offering) doesn't look so expensive after all comparatively speaking.

[JamesF]

The Logitech HD C920 looks like it might have a 1/3" sensor.  I wouldn't describe it as "cheap", but it is cheaper than a QHY5L-IIc.  Of course there's still the pain of modding it, assuming that is possible.

James

[Gina]

I can never seem to find the sensor size of webcams however much I Google   Where did you find this info?

[Dr_Ju_ju]

http://www.rkblog.rk.edu.pl/astro/kamery-ccd/  http://cameraimagesensor.com/size/

[JamesF]

I can never seem to find the sensor size of webcams however much I Google   Where did you find this info?

I found it via google, but had to go through several pages of results to get there.  Unfortunately I can't now find it again

I'm thinking that actually we need more information than just the sensor description as 1/3" (or whatever).  I'm not completely convinced at the moment that a 1/3" HD sensor would work even if a 1/3" SD sensor would.

James