Difference between 200 + 300

[popeye85]

I'm just about on the brink of upgrading my dob going from a 8" up to a 12".

 I have bortle 3 skies not far from me so should get decent views aswell as a South facing garden for planetary observing.

What I'm wondering is how much more I will see with the big dog? - obviously the answer is LOTS AND LOTS but I'm after more specific details- what will M31 look like for example in the 12 compared to the 8?

TIA!

Popeye

[Chefgage]

29 minutes ago, popeye85 said:

I'm just about on the brink of upgrading my dob going from a 8" up to a 12".

 I have bortle 3 skies not far from me so should get decent views aswell as a South facing garden for planetary observing.

What I'm wondering is how much more I will see with the big dog? - obviously the answer is LOTS AND LOTS but I'm after more specific details- what will M31 look like for example in the 12 compared to the 8?

TIA!

Popeye

Try one of the online field of view calculators. You can put in your scope details and target and it shows you what it will look like in terms of size in the eye piece. You can have more than one type of scope/eyepiece combination so you can compare.

This one for example.

https://astronomy.tools/calculators/field_of_view/

Edited September 8, 2020 by Chefgage

[Shimrod]

1 hour ago, popeye85 said:

I'm just about on the brink of upgrading my dob going from a 8" up to a 12".

 I have bortle 3 skies not far from me so should get decent views aswell as a South facing garden for planetary observing.

What I'm wondering is how much more I will see with the big dog? - obviously the answer is LOTS AND LOTS but I'm after more specific details- what will M31 look like for example in the 12 compared to the 8?

TIA!

Popeye

 Have you had a look through this (long) thread?  what can I expect to see?

[vlaiv]

That really depends on your observing skills and observing conditions.

I'm inclined to say - not as much difference as one would hope, but enough to justify upgrade

What you can do is to use 8" scope to roughly see what you can expect. Going from 8" to 12" is adding 50% by diameter.  Take a piece of cardboard and make aperture mask to fit over your 8" scope front opening. Make inner hole of aperture mask be 13.5cm in diameter (5.33").

Take a scope with mask and observe some objects, then take mask off and observe same objects (you can go opposite direction - find faint / threshold object in 8" then put aperture mask on to see if you can still see it).

This will roughly give you sense of what to expect when switching from 8" to 12" - it will be like going from "with mask" to "without mask", as mask is just a right diameter to make light increase in % the same (however, host of other factors including low light eye sensitivity won't be the same so this is only rough guide on what to expect).

HTH

[John]

On some targets you will notice quite a difference - globular clusters are an example.

On others, not so much and what you actually see depends on a whole lot of factors other than the scope aperture as @vlaiv says above.

Personally I find the 4 extra inches well worth having but the scope size and weight has increased markedly to get this and this needs to be considered as well:

 

[Guest]

On 08/09/2020 at 08:20, popeye85 said:

I'm just about on the brink of upgrading my dob going from a 8" up to a 12".

 I have bortle 3 skies not far from me so should get decent views aswell as a South facing garden for planetary observing.

What I'm wondering is how much more I will see with the big dog? - obviously the answer is LOTS AND LOTS but I'm after more specific details- what will M31 look like for example in the 12 compared to the 8?

TIA!

Popeye

@Barry-W-Fennershould be the best person to answer this.😉

Edited September 9, 2020 by Guest