8 Inch Dob Vs 10 Inch Dob

[Refractordude]

From your experience is it worth getting a ten inch dob rather than an eight inch dob? Here is an article covering the topic.

https://jgroub.wordpress.com/2018/08/11 ... explained/

I like to know what you think of the writers opinion between to two sizes. The article is long so I snipped three important parts. Left click the images. Thanks all.

[notFritzArgelander]

I think it's a silly argument. I went from an 8" to a 10" and was very happy. I got happier still when I went to a 12" and a 14".

In terms of resolution 10" gets down to 0.5 seconds of arc, which is the maximum resolution the atmosphere permits on great nights.

[Bigzmey]

If you are going for the aperture you should get as large scope as you can handle comfortably. IMO every inch counts. I am happy I went from 8" to 9.25", but 11" was to large and heavy for me to handle comfortably.

[Ylem]

I have had both, IME at my location, the 10 was a lot brighter!
It didn't seem to go much deeper, but the light grab was worth it.

Physically both tubes were 48", where by a 12" the tube is 60" long.
That was the deciding factor for me to go with the 10.

[notFritzArgelander]

On DSOs I think that GCs show the biggest differences. Many places advise that 6" is the minimum for globs. I've had nice views of globs with the 6". Globs start to become impressive at 8" and more so going to 10" and 12".

Planetary nebulae are another thing. The yellow in the Ring Nebula start to become discernible at 12".

Also for planetary views, more aperture (as the atmosphere permits) is always better.

Magnitude is not the only metric. It's just the easiest to discuss.

[JayTee]

You go with the biggest scope you can afford and transport. It's that easy.

[DeanD]

The article quoted implies that 1/2 a magnitude (ie: 8" to 10") isn't much, and 1 magnitude is so much better (8" to 12"). Well yeah, obviously the bigger the better, but 1/2 magnitude improvement is still not to be sneezed at.

Have a look at this chart for visible stars by magnitude: http://www.stargazing.net/david/constel ... stars.html
- one magnitude gives approximately 300% more stars, so 1/2 magnitude would give approx 150-200% more (yeah, I know it is a log scale but I am approximating: in fact 1/2 magnitude equates to ~ 1.6x brighter, while 1 magnitude is ~2.5x brighter). So 1/2 magnitude is still quite a jump!

My first scope was a 10" (I ground it myself), and I remember taking it to a (very) dark sky (SQM ~ 21.8-22) and seeing the Horsehead easily. Not so easy with an 8" though...

So, if you can easily carry a 10", I reckon go for it!

-Dean

[mikemarotta]

From your experience is it worth getting a ten inch dob rather than an eight inch dob? Here is an article covering the topic.

You got some good advice. Obviously, more is better if you can lug it around and set it up. Myself, I am saving my pennies so that I can pay Jeff Bezos to take me to the James Webb so that I can plug my brain right in to its computers.

In the meantime, I tried a ten and it was too heavy and I bought an eight and gave it away because it was too heavy. I do push-ups and sit-ups. I walk kilometers with 10kg of deadweight in my backpack just for fun. But while I could LIFT the scopes and carry them around, SETTING THEM DOWN SAFELY was harder.

But if you are up to the workload, go for whatever you can afford.

[jrkirkham]

I agree with others. For observational astronomy get the biggest you can handle and afford. I started with a 6" dob . I liked it, but wanted more and traded for an 8". There was a lot of difference between the 6 and 8, but aperture fever struck again and I upgraded to a 10". The 10" was the perfect sweet spot for me. I could transport it in my SUV. It was rugged. It was easy to set up for others to use when I gave talks. The view was brighter. It is still one of my favorite scopes. It is about as big as I can easily transport.

[Refractordude]

Thanks all

[DeanD]

BTW, I currently have a 12" dob, and it takes up less room than my 4" refractor in the car. I redesigned my 10" dob to be a truss-type rather than the original "cannon" (Yes, I did get questioned about it by a policeman when I was having a breathalyser test! ). When it was stolen I built a 12" truss dob which packs down to a small esky-sized box and takes about 5 minutes to set up... I don't have any real issues in carrying it or setting it down as I have made it as light-weight as possible.

(Current project is a 14" binocular scope, but that is another story!)

- Dean