SingAstro

Are mirrors or prism diagonal recommended for short focal length scopes ?

i did some research and found that mirrors are used, however, are mirror diagonal performance good ? as in collimination etc

thanks

If you want peak performance, both mirrors and 90 deg prisms need collimation. 45 deg Amci prisms are OK for terrestrial use, bu not suitable for astro use.

Hi,
Check on this article: http://www.cloudynights.com/item.php?item_id=82

What's your scope f-ratio?? Base on the above article, a "fast" scope is better to use a mirror diagonal.

Have a nice day.

my scope have a f-ratio of 6.0

for my case it would be preferable for me to get a dielectric mirror ?

Hi,
My suggestion is that if you got limited budget and your scope isn't those high end scope, get a normal mirror diagonal will do.

Have a nice day.

weixing wrote:Hi,
My suggestion is that if you got limited budget and your scope isn't those high end scope, get a normal mirror diagonal will do.

Have a nice day.

I've discussed with a lecturer on the advantages between normal and dielectric diagonals. He mentioned that that in Singapore, the adv of dielectric over normal diagonals is minimal. But if we are in places with very good seeing conditions, then the dielectric diagonal has significant advantages.

Of course, if got budget, get a dielectric diagonal.

Cheers.

you can get budget dielectric diagonal ( made in china ) from luiming...search his name in singastro forum....

it is as good as any other dielectric coated diagonal....

The prices of dielectric diagonals are dropping. If you can afford it get it.

looking for one which can last a very long time, a dielectric is on my mind.

is GSO brand recommended ?