Planetary/DSO CCD imaging question.

[parallaxerr]

Now I'm a complete noob as far as imaging goes really. I have taken some nice moon shots with a compact digital on a digiscoping adapter but that's about it. Having seen Saturn for the first time a few nights ago (WOW:eek:), I was desperate to get some good shots but the compact wasn't up to it so I checked out eBay for a CCD and won an auction for a Celestron NexImage camera for £59! Bargain!...

I've already started to read up on the mine field that is CCD imaging and have already decided to go down the RAW modification route but stumbled across a few articles about modifying for long exposure CCD photography. Am I right in saying this is only necessary for DSO imaging and not for planetary?

[Cornelius Varley]

You are correct in thinking the LX mod is for DSO photography. Planetary and lunar photography require lots of images captured in the form of an AVI which is then processed in Registax or Avistack. DSO imaging requires longer single exposures to capture as much light as possible from the feint objects.

Peter

[Glider]

NexImage camera for £59! Bargain!... Indeed, well won I think.

I find that actually I'm always turning down the camera gain and shortening the exposures to stop the avi saturating on the planets!!

I think you will be pleasently surprised by just playing with the unmodified camera.

I also got all fired up for making all sorts of modifications but after a while never bothered.

I take 90s of avi at 5 frames per second and import into Registax and let it do its stuff. That's 450 images so I'm hard with setting the limits on which images get stacked and afford to throw a lot away. You are trying to just stack the fleeting images that coincided with a steady atmosphere.

90s is not going to have let surface features you are imaging move appreciably over the duration of the capture.

Go to higher than 5 frames per second and a compression algorithm kicks in on the camera to allow it to keep pumping the increased frame rate down the USB to the computer. This means you (can?) loose information.

Also, the codec that you choose can introduce more or less compression of data.

I'm not trying to be definative in my comments here, just giving some keyword suggestions for you to search SGL or generally Goggle on, it's all out there in far more detail.

I have LX modified a Philips SPC900N webcam to play with DSO but find that after 30 to 60s of exposure I start to see all sorts of amp glows and noisy pixels appearing.

Of course you can do the amp off modification and start playing with cooling modifications. However, Philips webcams are going for anything up to £90 on eBay and by the time you've done all the modifications I worked out I could have spent another £100's. To me it made sense to just buy a CCD 'designed' for DSO work. You can pick up a Meade DSI IIc like mine for £200 to £250.

Enjoy.

[parallaxerr]

Glider,

Thanks for your input. I totally agree on the cost of modding a cam not being worth it. I've seen mods using peltier cooling that look great but cost a lot and never turn out as neat as a unit originally designed for DSO imaging, plus you have to butcher the cam and do some quite fine soldering. I think I'm a long way off DSO yet anyway, I'm going to stick with the NexImage and the planets...

Which video capturing program do you use? I downloaded AmCap from the Celestron site and have come across a few problems. Firstly, there seems to be two ways to set the frame rate from the drop down menus, I can't recall which menus right now. Problem is one of the menus seems to default back to 30fps as soon as you exit it. Also I can only find one type of encoding, YUY2 I think it was. With RAW files I've read I need to set 5fps and IYUV or 1420 encoding. I'm thinking I may just bite the bullet and purchase K3CCD3 as it has all the proper encoding options and extra features such as a reticle.

[riklaunim]

A webcam or NexImage (whis is a webcam) have basic electronics and doesnt give us all the options more advanced cameras have. For capture software try also firecapture:

* FireCapture

It's free, and it works quite nice for me (but in needs "color=true" to be added in the ini file for color webcams).

As for deep space objects - you can play with a webcam/nexImage but it will be quite hard to get good results (you need to get still a lot of frames made on few sec exposures and NexImage isn't modded for long exposures!).

Here is M3 image from DMK21 - dedicated planetary camera:

This is more than 100 frames done at 1,4 sec expositions with a f/5 Newtonian. Stacked in registax and processed in photoshop (levels to bring up fain starts). Raw stack looks like this. For comparison my first light M3 from DSI III Pro looks like this (stack of 30 frames at 4 sec... longer exposition and processing needed).

[parallaxerr]

OK so I received the NexImage and have already carried out the RAW mod. I have captured Saturn and processed in AVIRAW & stacked the images in AVIStack and I'm relatively pleased with the results. It's obvious I need an IR filter and a bit more practice though. The main thing I've realised is that, as good as it is for lunar imaging, my 90mm Refractor isn't up to the planets. I grossly over magnified Saturn (X400) and got an image although it was fuzzy. at X200 the image is sharper but really too small to see any detail. Time for a new scope..........? Watch this space