Help with my first scope

[mansunz]

Hi all. I would like some advice on my first proper scope. Currently, i am viewing via a SW 114 / 1000 Newtonian Telescope in a suburban environment. I have bought a set of Meade series 4000 EP kit that is currently on its way which hopefully would last me a few years. I had my mind set on a 10" DOB. However, I would like to explore all options before i commit to it. I am entertaining the idea of getting a CAT. At this stage, i am fascinated by DSO. From my point of view these are pros and cons:

Pros:
- Potentially one less upgrade cycle
- Easier to store the scope, if i were to go with the DOB i would have to leave it in the garage which gets scorching hot during summer.
- Potentially higher height clearance
- Less obvious to the missus (oh trust me this is important)

Cons:
- Cooling time seems longer?
- Higher upfront cost (by quite a bit .....)

Unfortunately, it is difficult for me to try it out with the local astronomy club (I have young family....) and would likely resort to just backyard viewing. A second hand CAT (say 8") would still cost more than a brand new 10" dob but I would consider it if the versatility and performance gains are worth the extra $$. Once again, appreciate any assistance to get a newbie on the right track. Cheers

[Baurice]

An 8" cat is very expensive. I have a 5" Maksutov and LOVE it. The 10" Dob would show more deep sky objects, though.

[Refractordude]

Is there really a big wow difference in like grasp between a 8" and 10" dob. The 10" dob/f5 will require expensive eyepieces. Until more play money funds become available, you can barlow all your eyepieces for better edge correction. Collapsible dobs save a lot of space and may cool down quicker. Amazon pays for return shipping.

[Star Dad]

Pi * R^2 is the answer.
so - given that Pi is the same - the difference is 4^2 vs 5^2 or 16 versus 25 or about a 150% more light gathering ability for the 10 over the 8. Personally I find my 8" Newtonian easy to transport. I'd like to move to a 10" Newt. But a 12" is out of the question - it gets too big/awkward/heavy. The theoretical limit of an 8" Newt is 13 Mag in my Bortle 5 skies using a 40mm eyepiece. A 10" brings it down to 13.2. See this calculator: http://www.cruxis.com/scope/limitingmagnitude.htm. Not a lot of extra bang for the buck.

Good luck!

[JayTee]

Let's get the general wisdom out there for all the newbies to absorb. When it comes to upgrading your mirror, typically, 4" is what is required for the human eye to see a noticeable difference. So from an 8" reflector you would need to go up to a 12" reflector to see a significant visual difference. When it comes to refractors the general wisdom is 2 to 2.5 inch increase will show you a significantly better view. So 80mm to a 102mm will not give you as much of a difference as 80mm to a 127mm refractor.

Hope this helps.

Cheers,
JT

[Thefatkitty]

Let's get the general wisdom out there for all the newbies to absorb. When it comes to upgrading your mirror, typically, 4" is what is required for the human eye to see a noticeable difference. So from an 8" reflector you would need to go up to a 12" reflector to see a significant visual difference. When it comes to refractors the general wisdom is 2 to 2.5 inch increase will show you a significantly better view. So 80mm to a 102mm will not give you as much of a difference as 80mm to a 127mm refractor.

Hope this helps.

Cheers,
JT

Exactly. I went from an 8" to a 12", and there was a huge "wow" factor for the magnification. However, there was also a huge Wow factor in increased weight and less portability. I traded for a 10", and really, the 10" is just a wider field of view with a few things more apparent than my old 8". And a little heavier.

As for refractors, not to knock JT's advice; but I have three fracs at f/11; a 60mm, 80mm and a recently acquired 102mm. The difference 20mm's makes for me is another Wow factor. That could also be due to my light pollution; it might not make as much of a difference under dark skies. Could also be my old eyes

At any rate, an 8" dob would be a lot less obvious/intrusive to the significant other. And as for cooling times, I leave my Skywatcher 10" in the shed all year with temps ranging from -40C to +40C; this way it's always acclimatized. Yours should be fine

Hope this helps and all the best,

[JayTee]

Hi Mark,

I profess the 2 to 2.5 inch (~50mm) increase based on the fact that a 20mm jump just did not give my old eyes the wow factor. Plus I have read that number range on other sites.

From my own experience I have a 70mm, two 80mm and two 102mm refractors and yes there's a difference between the 80 and the 102 but not what I would call wow. I have viewed through a 127 next to my 80, at a dark site, from that I got a WOW.

Anyway, it's all subjective.

Cheers,
JT

[GONKO]

I went from a 114 celestron to an orion 8 inch dob. The amount of stuff the dob can pick up compared to my 114 is off the chart. Not to mention a much more stable base if comparing to the alt az mount.
The 8 inch also fits in the car boot once off the base, and the base can go in bedside it, do transporting is doable. This was a big one for me. A larger scope would not fit.
But if you plan on not transporting or have a large truck/ wagon car, then a 10inch come into play....but more awkward to move and handle.

[Lowjiber]

Good advice and comments above. However, I'd like to address your storage concern...

... if i were to go with the DOB i would have to leave it in the garage which gets scorching hot during summer.

I live in the Mojave Desert where summer time temps regularly reach 115 deg (F). My garage temps usually run in the high 120's. I've stored my 10" Dob in the garage for a decade... no issues at all.

Orion sells a padded carry/storage bag that protects the tube from insects that like to climb inside. The bag has a serious carrying strap that allows me to easily transport the tube by carrying it over my shoulder.

[helicon]

Storage for a Dob is quite easy as John points out. Neither high or low temperatures effect it. The only concern I would have is exposure to moisture, so be sure to store in a dry environment.