6 vs. 8 inch

[danteexplorer]

Hello,

I'm ready to move up from my 4.5" reflector into something larger.  Are there significant noticeable/practical differences between a 6 and 8 inch dobs? Specifically Jupiter, Saturn, Orion Nebula?  What about size/weight?

On a related issue I'm 6 feet tall, how do folks here elevate a scope of that size to viewing height?

cheers!

[michael.h.f.wilkinson]

I moved from a 6" Newtonian to an 8" SCT 19 years ago. The difference was clearly noticeable, especially on M13 that first night. M42 was also clearly better.

I am 5'11", so am similar in height. My old scope was similar to an 8" Dob in size and viewing angle. I would now use my observing chair which can be adjusted to a large range of heights.

[Pig]

If I were you I would go to at least the 8" if I was stepping up from 4 1/2", although the difference will be noticeable at 6" you might not see enough difference to be delighted  

[ollypenrice]

If I were you I would go to at least the 8" if I was stepping up from 4 1/2", although the difference will be noticeable at 6" you might not see enough difference to be delighted

Agreed. Make a decent jump and make it once. 10 inch!! 

Olly

[RichM63]

One of each of course!

I think that you would find the 8" more comfortable on your back.

I use mine roughly 50/50 mainly dependant on wind speed and whether I'm likely to use a camera.

For purely visual I have to say the 8" has it over the 6" although both telescopes are a joy to use, and both hold collimation very well.

If I could only have one, then it would be the 8" together with after market EPs.

[Bart]

I'd have to agree with Olly. Go for a 10". I went from 6 to 10" and I loved the difference, and believe me, there is a difference. If you're feeling undecided or budget hampers, definitely go for the 8"

Good luck

Barry

[ghostdance]

I too went from a 4.5 to a 6. There is a definite step up, but.....Because of my, er, situation it'll be some time before I can move up in aperture, if ever. If you have the space for storage (altho the 200p does not appear to need too much) or are not limited by other circumstances, I'd go for the biggest aperture you can manage. As Olly says, you may as well spring for a major improvement in your view. My 6" is great and I'm *very* happy to stay with it, but if I could afford/store a bigger scope I certainly would. And keep the 6 for my grab n go widefield

[danteexplorer]

Thank you all, my budget is stretching it at an 8, can't justify spending more (famous last words).

[russ.will]

If it's planets you're after, I'd stay with the 8" for several reasons - I am assuming it's one of the Orion/Skywatcher (Synta) clones at this point.

One, 8" is a decent jump in aperture from where you are currently. You'll notice one heck of a lot more and M42 will have noticeable colour, although it's about the only DSO that will. 10" won't add much.

Two, the 8" is an F6 scope which is less fussy on collimation and a lot easier on the quality of EPs at the edge. The 10" is the opposite.

Three, the 10" is F4.7 so it's pretty much the same focal length and therefore height. They're equally short.

Four, when you start to jump above 8", the amount of magnification you can bang into a planet really starts to be affected by atmospheric stability. You'll get better views of planets (which don't care about aperture because they're bright) more often in a smaller scope. Plenty of planetary observers don't bother jumping over a 4" refractor which is much the same as a 6" newt in performance.

IMHO, an 8" F6 Newt is a sweet-spot in this class of scope, because it's big enough for DSOs and handles higher magnifications more regularly. It's cheaper too.

It's often parroted that you should always go for the most aperture you can afford. Conventional wisdom if you will. The thing is, that's only good advice IF you have more than one scope. I've had a couple of 12" light buckets, but the scope that got used most, because I had a choice to suit viewing conditions, was a 5" refractor. If it came back to my owning only one scope again, it would be the 8" that went last.

Russell

[ollypenrice]

Good point above that 8 inch F6 Newts are sweet on the planets. They certainly are. I went from 8 to 10 inch SCTs, though, and the planets were significantly better in the 10.

Olly

[bingevader]

Yep, agree with all of the above.

I went from the ETX90 (3.5ish) to an 8" dob!
Had the 2 side by side, even the Mrs. said, "WOW!"

Just smiling again, thinking about it.

[russ.will]

Good point above that 8 inch F6 Newts are sweet on the planets. They certainly are. I went from 8 to 10 inch SCTs, though, and the planets were significantly better in the 10.

Olly

Would having the worst 2000ft of atmosphere below you help there? Spare a thought for those of us who live below sea level! 

Russell

[ollypenrice]

Would having the worst 2000ft of atmosphere below you help there? Spare a thought for those of us who live below sea level! 

Russell

Actually, no, this change went back a long way to when I lived in Derbyshire. 8 to 10 inch Meade. I still have the Meade. In fact we're at 3000 feet here (you've robbed me of a thousand!  ) but I don't know how good the seeing is, really. Like anywhere else it's very variable.

Olly

[daiwelly]

hi I went from SW 130 az goto to 200P skyliner a whole lot of difference, go for the 8inch at least.

[Carina Lass]

8 inches receives 16/9 times the light of 6 inch.

so yes a noticeable difference.

I like my sct. But a dob is a great place to start.