Whats the best telescope for looking at DSOs ??

[legoalan]

Hi everyone I need you guys' help again. I really want to be able to see DSOs (galaxies, nubulae, clusters etc) but apparently my 1400mm focal length, 150mm aperture (f/9) telescope isn't 'fast' enough to look at decent observations of them.

I am thinking about getting a Skywatcher 200P dob as an upgrade but I thought I'd consult you geniuses before purchasing Should I go for the 200p dob or are there better alternatives?

(My budget is £200 - £350)

[brantuk]

Grab a copy of "Turn Left at Orion" or "Illustrated Guide to Astronomical Wonders" first for an idea of what you're likely to see. It may be the best investment you ever made between £16-£20 from amazon.

If you still want a dob after that then go for the largest aperture within budget. A 200P is very nice but dso's still appear as smudges with little or no visible structure. Don't be fooled by the glossy pics you see on tv and in magazines.

If you can visit a local astro soc on an observing night would be a good idea. Look through one or two dobs to get an idea of what you'll see

[JamesM]

Agree with brantuck about going along to a local observation night to establish your own benchmark of what might meet your expectations. A dobsonian will offer you the best value for money regarding aperture but then there is the portability question, cool down times etc that weigh against a big dob. If I had the money I would start my dribbling with an 'obsession' brand of dobsonian for some amazing views whilst looking through a certain green eyepiece!

James

[Ad Astra]

My students see plenty of DSO's with f/8 150mm dobs. Just a matter of dark skies, and correct pointing.

A good low power (32-40mm) eyepiece also helps.

Dan

[sgazer]

hi,

for observing, the speed of the telescope is not important, it's only important for prime focus imaging. For observing, you can get any magnification or FOV depending on what eyepiece you put in. A fast scope will require better eyepieces. A longer focal length eyepiece eg. 35mm, will give you a wide field of view and a brighter image than a 10mm eyepiece. Aperture is king for observing, the more aperture, the more light collected and you'll be able to see more. An 8" scope will gather nearly double the light of a 6" scope and is a good starting point. A Skywatcher dob is about the best value for performance. Don't expect too much though, even in a 10" dob, I found the Orion nebula (relatively bright) to still be a grey object, with only the occasional hint of green. All other nebulas were just grey smudges (to me), star clusters were a bit more interesting. That's really why I got into imaging. I don't want to put you off, but just be realistic with what you expect to see with the upgrade. Lots of people find observing with an 8" to be great (ahem!). Certainly dark skies would help and perhaps a mild skywatcher LP filter.

[legoalan]

Thanks guys, I knew you wouldn't let me down. I guess I will go down to a local astro society on an observing night and have a look around before the upgrade.

[legoalan]

By the way can anyone explain to me what right angle finders do better than just a normal finder scope and is a telrad worth the money?

Thanks

[brantuk]

Right angled finders mean you don't have to bend in awkward positions to see through a "straight through" finder. Does my back the world of good lol.

Telrads are great vfm and very effective - you can match the view in the sky to that on a star map cos the reticle is the same scale

[MartinB]

As Brantuk says re right angled finders but they do have the disadvantage of not being able to see the sky as you line up your finder. I much prefer the ordinary sort. In most circumstances I prefer a Telrad although I prefer to use both!

[ollypenrice]

If your area is appropriate (not on a busy flight path or surrounded by other observatories) much neck strain can be removed by firing a green laser pointer through the finder to see roughly where you are. I have cervical arthritis and love this trick...

Olly

[Capricorn]

You don't need a fast scope for looking at DSO's, you need a fast scope for imaging DSO's, but not observing them.

For DSO's you need reasonable aperture and if you have 150mm them get out and use the thing, it should be adaquate.

Only proviso is start with a lowish magnification and don't try for high magnification. The things are generally dim and a high magnification just make the image dim.

[rory]

hubble is pretty good. might be a little over budget mind. only kiddin, im also after a telrad to replace my excuse of a finder.

[Moonshane]

my summary would be :

• get a Telrad, definitely
  
• a right angle correct image finder (preferably 9x50 but 6x30 is OK too) will really help - I also use both - Telrad for initial placement, fine tune with the finder
  
• darker sky is cheaper than a bigger scope but not as convenient
  
• larger aperture (e.g the 8" or even more) will give you a far better chance of seeing galaxies and nebulae even at home but especially at a darker site. 6" scope has 28" square of light gathering and an 8" has 50".
  
• you may find the scope you have will be better on planets, moon and doubles than an 8" dob (but maybe not) and therefore keeping them both might be a good idea initially at least.
  

In good conditions I can see lots of DSOs from home (I live within 10 miles of Manchester and 4 miles of Stockport) with both my 6" f11 and my 12" f5.3. With the 6" I even managed to just see M51 and companion recently when the moon was just out of sight.

[legoalan]

Thanks for all the info, I'm tempted to go and get a telrad finder now =P