DSI, ETX70 and M42

Dave (Lillis) - I had a lash the other night at M42 (another trapezium shot :oops: ). The idea was to judge the FOV using the DSI on the ETX70. Consequently, and since the clouds were rolling in and Orion was setting, I didn't bother with darks or flats. Oh, and it was freezing :shock:

Below is an image based on 47 stacked frames (Registax 3). I know my focus wasn't very good - the ETX70 is tough to focus onto the DSI, even with a Hartman mask. Funnily enough, it doesn't really show that much in the image. What does show is the lack of darks.

I also tried a shot at colour. The DSI seems a bit quirky on colour - I've yet to get to grips with it... I would have preferred a longer exposure time (4 secs plus) but tracking on the ETX would not allow it. Roll on the AP1200...

I estimate (via Starry Night Pro) that the image covers approx 45 mins by 52 mins - roughly a little less than half a degree square. No barlow or other optics in the path. This is close to what CCD calc from Ron Wodaski calculates - 45.9 x 54.8 mins. The image below is also cropped by about 10% top and bottom.

So there you go - nowhere near the FOV of your setup. I'd prefer a wider view like yours but that'll mean a top-of-the-range SBIG and a 4" APO...

Enjoy

Cheers

Dave McD

Dave,
Thats not a half bad image.
Its wider then I thought, and I can imaging that focusing would be a pain, since you can "look through" the DSI like with the DSLR.
One trick I found with the ETX70 tracking is to try taking photographs when the object is very near the meridian, but make sure it doesnt cross it during the exposure, this is the best place for minimal declination motor usage, thus 1 less drive to worry about going wrong.

I'm going to built a cheap wooden wedge so I can get images further north then M42 in Orion, M42 is not far from the limit where the camera would hit the base of the scope.
you dont need to use mega expensive SBIG cameras, the canon will give you the big field of views, and given the newer models out, its only getting cheaper!

I thought it wasn't bad either - especially without darks. I need to nail the focusing though. I'll try and get my hands on the flexible focuser that came up here a while back. Trying to focus on the laptop is a pain. I've avoided a parfocal eyepiece because I suspect that would only give me rough focus and I would still need to fine focus.

Funnily enough, the C8 is dead easy to focus.

I've a wooden equatorial wedge 'under construction' at the moment and hope to finish it 'real soon now'... But that's a good tip on the meridian.

As for a DSLR, I am well impressed by all the shots I've seen on this board. They really are first rate. But (isn't there always a but?) I already have a digital camera and I really want to get into photometry - so a non anti blooming CCD is the way I'm considering going. I've seen enough images to know that there's very stiff competition out there. One of the SBIG group members got his onto APOD today! And they regularly adorn the US mags, calendars and so on. These guys are miles ahead - it would take me two years or more to catch up with where thay are today - and of course they'll be two years ahead then...

When my trusty Olympus digital camera gives up though, I will definatley be looking closely at DSLR's as a dual purpose tool.

In the meantime, if and when we get clear skies, I'll soldier on with the DSI and M42. But guiding will hopefully not be an issue in April as the 1200GTO will be on the way! The ETX70 would look a bit stupid on it though :lol:

Cheers

Dave McD

1200GTO very nice,
I think the ETX70 is well within its weight limits.
Maybe you could consider selling the olympus on astromart so you can fund getting a different DSLR ??, just a thought.

Some of they guys you're referring to regarding imaging are practically professional astrophotographers, they're on a level so far up there, with equipment so expensive, I'll never be there, atleast not without remortgaging the house first :lol: :lol:

I got a lumicon giant easy guider which is an off axis guider, so I might give it a go this weekend and see how it pans out, I want to get the perfectly tracked 5 minute image

As regards the 1200GTO, its a lovely mount that gets rave reviews. I chose it because the key piece of equipment in imaging is the mount (well, you could argue that clear skies are more of a priority ). The Paramount ME was just too much. About another $3k.

That said, by the time I've added the pier, counterweights, mounting plate, Import Duty and VAT, its a costly piece of kit. Then I need to fund a 160 Starfire in the next two years (or similar - maybe a TMB). Oh, and a camera - Finger Lakes do a nice $40,000 one... :shock: Then there's the observatory to budget for :shock: :shock: And I need a case for the 1200... This can be such an expensive hobby... Oh, forgot the focuser ($1K), and dewheater...

However, I look forward to showing the beast off at Cosmos (if I can carry it!!) I'm not aware of anyone else in Ireland with a 1200 but I know Eamonn Ansbro has at least one Paramount ME.

The Olympus is about 3 years old. Its a great camera - 10x optical zoom and 2 mpixel. I love it. But its probably not worth much with prices always coming down. Still, A DSLR *would* give me another weapon in the armoury. But until the bank balance recovers, I'll have to wait.

You're right about the CCD guys - they have aton of money invested in their hobby - and fair play to them. They have some serious kit there which can certainly rival images I've seen from Hublle - and I'm not bulling. However, it seems that they are seriously into producing pretty images - which they do admirably. I'd rather get into a bit more science. Asateroid hunting, supernovas, variables etc. I think that's what Eamonn concentrates on. If you're watching Eamonn, I *will* come over to you at some point and have a chinwag!

I've heard on the boards that the Lumicon is very good - I'd be interested to know how you get on. A five minute shot would be cool! I assume your going for something real deep?

Cheers

Dave McD