WDR camera and tracking

[rikyuu]

hi,

I've been looking into the different ways to do imaging and came across these new WDR cameras capable of very low light operation.

http://www.astrophoto.co.uk/cameras.htm

I was wondering if anyone had any experience using these or any comments on their capability. In the absence of a laptop, the advantage I see is to have a nice little LCD monitor next to the scope to plug the video signal into for LIVE viewing of DSOs. The cameras do colour for brighter objects then switch to B&W for dimmer objects. I believe they operate down to 0.0005lux.

Another question; when performing long exposure imaging using a motorised equatorial mount for a DSO that you can't see through the lens, how do you find and track it? Am I correct in thinking you have to use it's RA and Dec location and hope it's pointing correctly? Also, how do you set the tracking motors to the correct speed, again when you can't see the DSO?

Thanks Lee

[blinky]

To answer your first question, I believe these do work for quite a few DSO's. They would be ideal for publice viewing etc.

In answer to your other questions, Finding the DSO's with a camera attached is very tricky! You can either use a normal eyepiece and when you have the DSO Centered swap in the camera. If you have GoTo then you dont need to bother as GoTo should take you to the DSO anyway. The other ways would be an accuratly aligned Finder or a 2nd scope piggy backed.

As for tracking, all stars move at the same speed (The rotation of the Earth is what is responsible for the apparent movement) so as long as your mount is polar aligned correctly you just switch on the motor.

[rikyuu]

Thanks Craig, the WDR camera (actually a SK-B407) seems pretty good to capture both planets in colour and DSOs in B&W. Has a lux rating of 0.0005lux, which from what I can find on the internet, is better than the human eye (but don't take my word for it). I'm wondering if a cheaper 0.003lux CCD (£55 as oppose to £200) would be worth while. I'm thinking of a greater sensitivity/faster shutter camera as oppose to a lower sensitivity slow shutter camera incase my equatorial platform (under construction) isn't good enough for accurate tracking.

as for finding a DSO, I thought about finding an easy to spot star near the DSO and zeroing the ALT/Az readout on my dobs, then moving the difference in degrees between the two, as this barely changes over a short period of time. Should find it pretty accurately, but still to be tested in practise.

[bern]

I tested this camera and found it disappointing.

Colour performance was only so so and mono performance was dire because of amp glow.

I did some comparisons and dark frames, if I can find them I'll post them.

bern

[rikyuu]

Bern,

they will be interesting, because on the website I posted a link to, which says it out performs the Mitron, they haven't actually posted any example images from the WDR, only from the Mitron.

[Tiny]

You could try one of these mallincam.tripod.com. They are a bit more expensive and theres a waiting list for them but the performance speaks for itself.

[bern]

A quick trawl through my flash drives found the following dark frames for the WDR in mono and colour modes

bern

[bern]

Bern,

they will be interesting, because on the website I posted a link to, which says it out performs the Mitron, they haven't actually posted any example images from the WDR, only from the Mitron.

Here's a direct comparison between the Mintron and WDR on M27 with a 4" scope last year.

Integration of 4 frames from each camera, making a total of just over 10 seconds exposure for the Mintron and 41 seconds for the WDR.

I later discovered I'd used slightly sub optimal capture settings for the Mintron.

bern

[rikyuu]

Bern,

that's very interesting, thank you for taking time to make the comparison. I'm wondering if the WDR has amp glow due to the longer exposure, 10s vs 2s, than the Mintron. If the integration period is reduced to two seconds on the WDR, is the amp glow as good as the Mintron? Is the WDR (with 10s integration) actually capturing fainter details than the Mintron or just the same detail but with more amp glow and worse contrast? Was it done in colour or B&W on the WDR? The B&W dark frame on the WDR is very bad.

Was M27 visible by eye through the scope or did it require the extra sensitivity of the cameras? I'm trying to judge how much more they see than the human eye.

When you say integration of 4 frames, do you mean using your PC (eg registax) or internally on the camera? Is each frame on the WDR a 10s exposure, ie. the shutter is open for 10s and is this user setable?

Sorry for all the questions, open to anyone for comments!

[bern]

Bern,

that's very interesting, thank you for taking time to make the comparison. I'm wondering if the WDR has amp glow due to the longer exposure, 10s vs 2s, than the Mintron. If the integration period is reduced to two seconds on the WDR, is the amp glow as good as the Mintron? Is the WDR (with 10s integration) actually capturing fainter details than the Mintron or just the same detail but with more amp glow and worse contrast? Was it done in colour or B&W on the WDR? The B&W dark frame on the WDR is very bad.

Was M27 visible by eye through the scope or did it require the extra sensitivity of the cameras? I'm trying to judge how much more they see than the human eye.

When you say integration of 4 frames, do you mean using your PC (eg registax) or internally on the camera? Is each frame on the WDR a 10s exposure, ie. the shutter is open for 10s and is this user setable?

Sorry for all the questions, open to anyone for comments!

OK here goes,

1, IMO the WDR is not much use in Mono mode as the amp glow is just too bad, reducing exposure reduces sensitivity so you can't win!

2, In colour mode exposing for 10 seconds the WDR is not as good as the (mono) Mintron exposing for 2.5 seconds and I saw only very faint colour in M27.

3, The night I took these images was a bit murky, M27 was setting and I live near London, so the images are not as good as can normally be seen or achieved. I looked through the scope and could see M27, but barely, whereas on my CCTV monitor M27 had a shape and structure. On a good night from my house you can see the wings with a Mintron or Watec but not with the eye or the WDR.

4, The frames were taken at the maximum exposure of each cam ie 10.24 for the WDR and 2.56 for the Mintron, 4 frames were then added to more accurately match the view on my monitor but I should have added a few more tbh.

5, The scope was a 4" F9 refractor used with a bit of focal reduction, but not enough, as I was just testing. A better view could have been had, albeit with a slightly smaller subject, using more focal reduction.

bern

[rikyuu]

hi Bern,

just out of interest, was it the Mintron 12V1 or the 12V6 which you tested? I believe the 12V6 has less noise and amp glow (oh and I just bought one, favouring it over the WDR!! The B&W sensor is several times more sensitive than the colour sensor in the WDR so doesn't require such long expsosures, plus it seems better overall.)

Thanks Lee