Getting Started with DSOs

[Stub Mandrel]

I'm still enjoying imaging the moon and planets, but last night I found the beehive cluster and it wouldn't all fit in my 20mm eyepiece.

I'm thinking of getting a s/h Canon DSLR body but it's obvious that the bigger (and therefore easier) DSOs are going to be way too big for using one with the 150/1200mm scope.

I have a number of other options, which would be likely to be the best for starting out with deep sky objects? they all have the advantage of being light and therefore better suited to the EQ3 tripod.

• My cheap 76mm Bresser refractor
• A very old Prinzgalaxy 3-element 62mm x 400mm telephoto, f6.3
• A very old Centon 72mm x 500mm f8 multi-element mirror lens - I suspect this is better quality than  the plain lens.

Both the lenses are t-mount. I have a 2x/3x teleconverter (a barlow, I suppose) but this would need a pentax screwmount to canon converter and I may not be able to focus at infinity.

[Dom1961]

It isn't exactly 'too big' for your scope, try getting a 25mm eyepiece or a wide angle eyepiece

[Stub Mandrel]

The problem is not viewing, it's imaging ... won't I struggle to get bigger DSOs to fit the frame using the 150PL?

[Dom1961]

Ahh right sorry I misread your post, in that case I have no idea!! Sorry I don't do AP

[Owmuchonomy]

Hi. For DSO imaging you don't use an eyepiece. You attach your DSLR at prime focus. M44 is a big target though and it will just about fit on a Canon crop sensor at 1200mm fl. please refer to this excellent website below to see what your scope can image satisfactorily.

http://www.12dstring.me.uk/fovcalc.php

[Stub Mandrel]

Ah! That's a really useful link. I hadn't realised how much bigger (huger!) a DSLR sensor was compared to a webcam sensor!