Diagonals...more questions!!

[technofan]

Hi guys....My ever going quest to increase my knowledge base continues!!

Many scopes are supplied with a diagonal but....

Is it better to purchase a 'non kit issue' diagonal instead??

Is it considered a good idea to get one with an erecting prism built in??

Reason for asking is I want to identify any 'weak links' in the chain of optics that would mean I wasn't getting 100% from my scope or eye pieces.

Pete.

Jeeze, I'm gonna drive you guys NUTS with questions....

[NGC 1502]

Is it considered a good idea to get one with an erecting prism built in??

I've tried two erecting prisms, one for my ST90 refractor, and a

Meade 45 degree one for my ETX. Whilst they do the job and

provide a "correct" image for terrestrial use, they do degrade the

image, especially for astronomy use, but maybe ok for low power.

Best regards, Ed.

Edit : we don't mind questions, it's what SGL is for !

[John]

Your are right to look for "weak links" but upgrading diagonals tends to provide less noticeable performance gain than other components.

The erecting prism type can introduce more flaws into the optical train. While they won't be noticeable for daytime viewing they will be unwelcome for astro purposes.

[technofan]

Lovely...sorted that out:D

I'll just open my book of 'A Gazillion Questions' and pick another.....

Pete.