Quick question about diagonals

[SmokeyJoe]

I'm looking for a cheap diagonal for my SW ED 80.  Usually it is supplied with a 2" diagonal (i bought just the OTA). Given that all my EPs are 1.25" and I only want to have a quick squint when star aligning or a quick look at the moon can I get away with a 1.25" diagonal?  What difference will there be over a 2".

[LDW1]

If you buy a 1.25” diagonal and all of a sudden you decide you want to start using 2” eps you will be right back into the diagonals but if you buy a 2” diagonal now with a 1.25” adapter you will be that much farther ahead in the future ! It boils down to do I spend the additional $ now or in the future ? Don’t say the 2” bug will never hit you, lol !

[joe aguiar]

I have the sw 80 app and I have the 2 inch diagonal  as he said it's a medium focal ratio scope so there are times I use a 2 inch ep to view low power wide extended objects.

Plus as guy above says it has the adptor to use 1.25 size too.

If your in a tight budget u can do 1.25 and get 2 inch later.

Also look at the used market they pop up.

U can also get them in regular reflective or enhanced it doesnt have to get 99% dielectric. 

I have seen brand new in box 92% diagonal for $50 cdn that about 30uk

Joejaguar 

[SmokeyJoe]

Thanks both, as I say it will not be used often,  so a 1.25 will probably do, still might go for a dielectric, not sure what the  practical difference is between 92% and 99%.  

One further connected question. I have seen finder scopes with diagonals, are the diagonals available on their own or do I need a new finder.?

[johninderby]

Right angle finders and  straight through finders have different tube lengths so it’s not so simple as sticking a diagonal on a straight finder. Won’t work. You would have to shorten the tube and as most diagonals on a finder screw into the tube you can see the problem.

Easier just to sell your straight finder and buy a right angle one.

Edited January 15, 2020 by johninderby

[joe aguiar]

ya agree then I guess just order any diagonal if you really don't care u can find even brand new ones from the used market

a lot times when u buy a scope if it comes with 1.25" most the people in the hobby for awhile (like me ) just sell it off norm $20 to $25 casue we don't need it and have something better

try astro buy and sell UK

joejaguar