SCB-2000P first light...

[Ben Ritchie]

...and i'm very impressed.

I started out in search of maximum FOV with a 0.5x reducer and an 80mm f/6.25 achromat (William Optics would like to claim it's a semi-apochromat, but lets call a spade a spade ), but that didn't work well - with the IR filter removed from the Samsung I got big bloaty stars from out-of-focus IR, while the 0.5x reducer gave absolutely horrible coma over about half the FOV. Switching to the AP130 + 0.5x reducer got rid of the bloaty stars - that's still very well corrected in the far-red - but kept the coma, so the reducer really doesn't seem to work well, but at the native 1040mm focal length things really started to get interesting.

The EQ6 tracks well enough to keep point stars with the integration time set to maximum with no need to guide, but I found 128x or 256x worked pretty well in general too. I started out with a couple of open clusters, M103 and M52, which were impressively sharp and well defined. The Samsung gets down to pretty faint cluster members too, although the vivid colour of the 11th magnitude M6 giant in M103 is missing in the Samsung, it really stands out in contrast to the other stars in my 14" Dob.

The really impressive target was M27 though, which filled half the TV screen with the mag 13.5 central star very sharp and in colour mode the different clumpy emission from [O III] (green) and H-alpha (red) was very obvious. Looked very similar to (good!) long-exposure CCD images, rather than the usual visual view, and 1040mm was a great focal length for it. The IR filter removal probably helps drag out the H-alpha emission, but I was very pleasantly surprised with how well a cheap video camera did here.

So I need to investigate a better reducer to use as the cheapo 0.5x is awful, and either a UV/IR block or more aggressive filtering if i'm going to use the WO achromat for anything, but first signs are very promising. Really want a Watec now

[West End Wendy]

Thanks Ben, that's a really useful and insightful review. I've learned a few things about my own set up from reading it.

What focal reducer are you using? There are a few around at about the £25 mark but the one I use is from Modern Astronomy and is attached to the end of either a long or short nosepiece to increase or decrease the focal ratio.

I've not seen any coma with this arrangement (with 80mm and 100mm refractors), although there is some vignetting with the long nosepiece.

The Watec is definitely a step up (including unlimited integration times), but you'll miss the colour on something like the dumbbell.

Tim

[Ben Ritchie]

I'm using one of the basic 1.25" ones I picked up from the forum last week, don't think it's branded - appears a bit thicker than the Atik (?) one that Bernard sells. It's combined with the relatively long (?) C adapter from FLO, so probably a fair bit of focal reduction going on, there was quite a substantial increase in the FOV.

Despite the reducer issues i'm very pleased with how the Samsung did, judging by how well it worked last night i'd say it's a complete bargain for the performance you get.

[bhuvfe]

I'm using one of the basic 1.25" ones I picked up from the forum last week, don't think it's branded - appears a bit thicker than the Atik (?) one that Bernard sells. It's combined with the relatively long (?) C adapter from FLO, so probably a fair bit of focal reduction going on, there was quite a substantial increase in the FOV.

Despite the reducer issues i'm very pleased with how the Samsung did, judging by how well it worked last night i'd say it's a complete bargain for the performance you get.

The distance between the focal reducer and the chip is very important. I have a cheap 0.5 that is probably a GSO relabeled by Telescope Service. It works fine till the distance doesn't exceed the 40 mm. Few mm can make a big difference.

I use it on a 80 mm f5 or with a 8' SCT.

CS,

Ant

[Psychobilly]

I haven't tried any of the growing collection of video cams onthe fracs yet.. only had the one clear night with the 2000 on the SCT using the TS 0.5X reducer... I am using a Baader UV/IR Cut filter for "normal" use and an Astronomik IR Pro 742 for IR pass...

Glad you like the "Budget" Samsung...

Peter...

[philj]

Hi Ben glad you got 1st light. If I use the long nosepiece with the 0.5x basic atik focal reducer on my Mintron in a sub F8 scope I get very bad coma, in fact almost fisheye effect on open clusters but swapping the nosepiece for a short one sorts it nicely.

But using teh same set up in a F10+ fl scope gives nice a flat field

What length nosepiece have you been using? perhaps a shorter one may help

Phil

[Merlin66]

I use the ATik (and the generic GSO) reducers as collimating lenses in small spectroscopes...the focal length of these doublets seems to be 80mm, so a distance of 40mm to the chip would give you close to a x0.5 reduction.

HTH

[Rusty Strings]

For my clarification, the nosepiece is the c adapter that screws onto the camera, yes?

How long is a long one and a short one. I have the one that FLO sells, is that long/short?

[Doc]

You done alot better then me Ben, I really struggled at Kelling and came to the conclusion an accurate permanent polar aligned set up is so important to keep that little chip centred in the Watec.

[Ben Ritchie]

How long is a long one and a short one. I have the one that FLO sells, is that long/short?

I have the FLO one too, I don't know quite what counts as 'long' and 'short' but it would seem that it's quite 'long' in this context, I appear to get quite a lot of focal reduction from it. Too much, really. Fortunately the performance at native focal length with the 130 is terrific.

You done alot better then me Ben, I really struggled at Kelling and came to the conclusion an accurate permanent polar aligned set up is so important to keep that little chip centred in the Watec.

I'm lucky that it's all observatory-mounted, so the EQ6 polar alignment is reasonably good and I can run 30s unguided if I need to. I can understand a portable setup might be more of a struggle, and the whole attraction of video for me is convenience - I really wouldn't want to guide to use it effectively.

[philj]

You done alot better then me Ben, I really struggled at Kelling and came to the conclusion an accurate permanent polar aligned set up is so important to keep that little chip centred in the Watec.

Mick, your alignment must have been off, you should be able to keep an object on chip from a roughly polar aligned mount for a few minutes easily.

At SGL I just set the HEQ5 up with the polar alignment scope only, no drift alignment and was keeping objects in centre of chip enough to do 2-5 minute avis. I just looked through the polar scope scope and set polaris in the little circle and that was it.

On my old EQ3 mounted ST120 I just used to point the RA at polaris, (no polar scope) and that was enough for a few minutes as well.

Phil

[Doc]

Mick, your alignment must have been off, you should be able to keep an object on chip from a roughly polar aligned mount for a few minutes easily.

At SGL I just set the HEQ5 up with the polar alignment scope only, no drift alignment and was keeping objects in centre of chip enough to do 2-5 minute avis. I just looked through the polar scope scope and set polaris in the little circle and that was it.

On my old EQ3 mounted ST120 I just used to point the RA at polaris, (no polar scope) and that was enough for a few minutes as well.

Phil

I agree Phil, I have a lot to learn. We did manage to do a polar alignment OK after a while, but for some reason goto's were out so we did a factory reset which helped matters a lot.

[philj]

These ere eqs are a bit more complicated than a dob arent they.

Once you get a few clear nights practice it'll be second nature setting up. Just make sure your polar scope is calibrated as per the instructions then you should get good enough for video alignments by just sighting through that.

Phil