12 v 16 inch dobs

[adamsp123]

Out of pure curiosity (at the moment!) how much difference is there between a 12 inch Dob and a 16 inch in terms of the observing experience. I can work out the numbers on each but how does that translate to the eye.

I have heard that you need a 16 to see structure in spiral galaxies like Adromeda or will a 12 do this?

Your input gratefully received

Pete

[Andrew*]

Hi Pete,

While I haven't done a direct comparison between a 16" and 12" dob, I imagine the difference will be quite marked.

As for seeing spiral structure - I've had fantastic views of M51 through a 12" with even the "bridge" visible, and have seen the two main dust lanes in M31 with a 16" (probably more than necessary TBH). But these were under dark skies - the most important factor in getting excellent views of galaxies.

Andrew

[scotastro]

With a 75% larger mirror area a 16" will show a lot more than a 12" assuming the conditions are the same.

You don't necessarily need a big scope to see detail in galaxies. Good transparency, a dark sky and being an experienced observer are probabaly more important.

Mike

[themos]

We had my 12" Skywatcher and a Meade 16" Lightbridge side by side last night. My eyesight is pretty bad and I am not an experienced observer and we did not set out to do a systematic comparison. All in all, I was happy with the views in my 12" and did not feel I was missing much.

[Doc]

I used to have a 10" hardin Dob before I got my 16" Dob and the difference is pretty big between these two. As others have said dark skies will show more in comparison to aperture.

Dark skies and aperture now that is heaven.

[Merlin66]

I regularly used a 13" f4.5 and a 18" f4.5. Under the dark skies of Australia, 110 km north of Melbourne. there WAS no comparison. The 18" everytime.

However, for handling and transporting, cooling down etc etc the 13" was much the better; after seeing some detail in the 18" it was always possible to see it in the 13" - something about "if you know it's there - your brain will see it!!"

[FLO]

I agree with Andrew and Mike, the quality of your sky will have a greater influence on whether you can see dust lanes in Andromeda. Under Greg's dark skies I can see them through an Evostar 120 without difficulty. Although, I have yet to see the spiral and bridge of M51 through anything less than a 12".