The perfect imaging trinity?

[rocketandroll]

Hi all

Ok, sorry for a lot of threads on similar topics.... but I am trying to come up with a coherent plan to start my second year of astrophotography with a pretty optimum set of gear to cover all the things I want to image but have not really been able to do justice to this year due to not having the right equipment at the right time :-)

So...

My criteria are: I want to have an imaging set up that is portable as I will, at best, need to lug it outside into the garden to start imaging, at worst, have to take it to star parties and on a holiday to the south of France next summer.

I have the HEQ5-Pro, I am thinking that if I possibly can I will keep that when I upgrade and get a NEQ6 next spring as well to cover all possibilities.

I am happy with my Eos500D for now. Ultimately I'll be upgrading to a dedicated CCD, but not for another year or so until I have a perpetual observatory.

Likewise, now it's working, I'm happy with the guiding set up I have with the ST80, Lodestar and PHD/EQMod.

I want to have scopes that cover all possible DSO imaging needs in terms of focal length. All need to be at least f6 or faster given the limitations of the DSLR for taking long subs and can't be too huge.

I want three scopes:

One in the 350 - 500mm fl range to cover large nebulae and widefield shots (got this, the Meg72 with FRII reducer).

One in the 550mm - 800mm fl range to cover smaller nebulae and larger galaxies, clusters etc. For this, I am currently veering towards the Ikharus 102 from Ian King, in leu of being able to afford a triplet in that range.

One in the 1m to 1.5m fl range for galaxies, smaller globulars and planetary nebulae. This is the controversial one. I currently have the RC6 but to be honest, colimating an RC seems to be a pain and at f9 it's just too slow for what I want to do with it. My current leaning is towards one of these: Orion Optics SPX 200 f6 Newtonian Telescope [ORI_SPX200_f6] - £600.00 : 365Astronomy: Discovery for every day!

It's f6 so colimating it won't be as much of a headache as an f4 Newt. It is however fast enough for my needs, matching the focal ratio of my refractors. It is 1.2m fl which is about bang on what I need. I have a thing for supporting British companies and get a far warmer fuzzier feeling about these. It's also not TOO massive and not TOO heavy. It just seems non viable to get a refractor above 1m fl without compromising massively on speed or spending many, many thousands of pounds on a 6"+ one which needs two people to lift, so I think this the one that I need a reflector for.

Anyone think this all sounds mental? Is there a better option to look at for the long fl scope?

Thoughts in general on the plan?

Thanks all!

Ben

[ollypenrice]

You don't need two people to lift a 6 inch refractor! Our TEC140 (a bit under 6 inches) is built like a tank but only weighs 8 Kg. However, you are right about speed and price with big refractors. You do at least save weight by emptying your pockets to buy them!

I'd say your thinking was sound, though I might wonder whether the 800 to 1200mm FL step is large enough. The TEC has 980mm and this isn't enough for more than a small number of galaxies. Adding 200mm FL wouldn't get me into the next class of object. I feel that you need to jump to around 1.6 metres for that, and then you need to be doing some serious guiding. An EQ6 can do it but might not choose to do so, if you see what I mean.

For a good value doublet giving around 800mm I'd look at the ED120 and reducer-flattener. For more dosh there's the Altair Astro 115 triplet.

Olly

[rocketandroll]

Thanks for the sound advice Olly

I think you're right, for small galaxies, 1.6m or so would indeed be better.... but realistically, as I can't break the bank at the moment, and still need something portable and which will hopefully not kill my HEQ5 until I upgrade.... an 8" Newt seems the only viable option.

Ultimately, once I have an obsy to stick it all in, I'd like to start looking at one of the CT range, or, even an AG if funds allow. Thats a year or so off for now.... 1.2m is fine for a semi-portable set up and will still give me much better sized images of things like M51, M27, M20 etc than a 800mm or so refractor.

With the two small refractors stopping at 600mm fl or so... I am somewhat lacking in the 700 - 900mm range, but as you say, an ED120 or one of the lovely Altair 115's next year may be the answer on that one.

For now... I'm trying to cover specific objects I want to image in the next few months... and most of them are either very big (Rosette, Horsehead/flame, M45, cone nebula area, M31, M33 etc) or very small (M27, M16 (possibly a bit low now), M1, NGC891 and a few others I want to have a stab at.

I think I'm about covered with those three for now.

Order going in with Orion shortly.... for a VX8L with 1/10 focuser upgrade and 1/10PV optics upgrade.

I'm told colimation on the f6 VX8 is 'easy'... I'm keeping my fingers crossed :-)

Ben

[RobH]

My scopes are a pair of 80mm refractors with FL's of 480 and 555mm....these are my widefield scopes. My mid field scope, which is great for things like M27 and a few larger galaxies, is a 152mm refractor with a FL of 1200mm, and currently, the scope I have for the tiny objects, small galaxies and planetaries etc, is an Edge 11 SCT with a focal length of 2800mm, which, if I can get my reducer spacings correct, most of the time will be used at F7, giving a FL of 1960mm.

This is just a bit too long, and at some stage I may change to a 12 inch F8 RC and use a focal reducer to get down F6 (1800mmFL) which is the ideal FL for many of the smaller objects IMHO, the other alternative being something like an F5 14 inch newtonian.

Olly is correct about mounts however, and imaging at long FL's is tricky, even with the mount I have, which is an AP1200 and the most expensive single item I've ever bought apart from my house!

Cheers

Rob

[rocketandroll]

Thanks for the thoughts Rob!

Yours sounds like a fairly good range :-)

The long fl guiding issue is why I wasn't trying to push it too far... I managed 10 minutes at 1.4m focal length on my HEQ5 (polar aligned in about 2 minutes flat) the other day when I did my first guided images... so I am fairly confident I can get some good stuff at 1.2m or so.

I know that won't really do justice to the really small stuff... but that can wait till I have an observatory and a load of spare cash for a meaty mount :-)

The Orion VX8L is now on order... expected delivery in about 4wks...

to be honest between 200mm and 1200mm I think I'm covered for 90% of what I want to image... there's pleanty of time to get into the teensy stuff later.

Cheers!

Ben