Getting ready for DSO season

[astromerlin]

Hi, I've had a great time imaging Jupiter this summer and learned a fair bit along the way.

I now want to start imaging DSO's but the trouble is the SPC900 and my 10" ota doesn't give a good fov.

So, I was thinking of getting a lens to fit on the SPC900 instead, something like this one Canon Zoom Lens EF 28-90mm 1.4-5.6 USM

but just before I spend my money I'd thought I'd ask if anyone else has done this.

[dmahon]

I don't think that the SPC900 is able to take the long exposures necessary for DSOs.

[astromerlin]

Hi, Thanks for your reply, I should have mentioned that my SPC900 has already been modded for long exposure, What I really need to know if there are any pitfalls in using lenses.

I recently discovered CCD Calc and playing with the settings I realised that using a zoom lense I could frame my DSO'S for a decent field of view.

Any advice will be helpful.

Cheers

John

[dmahon]

I like this site to get an idea of what you'll capture:

http://www.12dstring.me.uk/fov.htm

Canon lenses probably aren't on there as defaults (it's mainly scopes), but you can just plug in the aperture and focal length of any scope/lens.

[GrantEb]

Hi

I have an old Tamron lense that I am not using. I could send you to try out before spending your money if you like.

It is a 300mm , that has been modded to fit a 1.25" eyepiece (camera).

Let me know if you would like me to send it to you.

Cheers

[Photosbykev]

You can make an adaptor to fit on the rear of a Canon lens and will take the SPC900 camera with a 1.25" nosepiece. This is the one I made using a Canon rear dust cap to use on a 600mm f4L prime lens but it will fit any Canon mount lens

PhotosbyKev SPC880 webcam and the moon

[lukebl]

Images of DSOs with an SPC900 won't be much good. Why not use a DSLR with the 250 and use the SPC900 as a guide cam (as I do). I get a field of view of about 1.25 degrees at prime focus with my 250PDS . (see my first attempt at the Witches Broom neb here)

[astromerlin]

Hi

I have an old Tamron lense that I am not using. I could send you to try out before spending your money if you like.

It is a 300mm , that has been modded to fit a 1.25" eyepiece (camera).

Let me know if you would like me to send it to you.

Cheers

Thanks that's a very generous offer and well appreciated. Since playing with CCD-Calc and getting confused with aperture and focal length for a while I have discovered that I should be looking for 135mm with a small focal ratio. That should get me almost all of the Witches Broom, I've seen a couple of lenses on ebay and just biding my time for a cheap one.

I wish I could afford a Canon but not presently so the SPC900 will have to do. What I'm looking for is to hone my skills with the processing side of things with DSO's and invest in a better camera later.

[GrantEb]

The lense i have is adjustable from 60mm to 300mm f3.8 - f32.

Shout if you want to play with it for a while.

Cheers

[astromerlin]

Hi GrantEb, I've PM'd you. That'll be great thanks. Lens size and type seem to be a learning curve all of their own.

Forgot to ask, you are in the UK I hope?