Diagonal

[Patbloke]

Ok Team,

I'm on the hunt for a diagonal, but before I push the 'buy button' I would like to know a couple of things!

1, Is there any point in buying a 2" if all my EP's are 1.25? 

2, How important is the quality of the diagonal in the overall scope set up?

I guess I may be answering my own question with the quality one when I tell you that I recently bought a Meade HD 60 6-Element EP of a well known second hand site... The quality views through that EP are fantastic (I'm saving for another) However, I was looking through a standard issue diagonal, so will a dielectric improve my pleasure? 

Thank you... 

[rwilkey]

Hi Patbloke, as long as you have a 2" focuser in your telescope I think it is better to buy the 2" to help 'future proof' it.  You may also want to use 2" widefields in the future, many of us have them for DSO's so to have the choice in future is a good idea.  I think a good quality diagonal such as a 'dielectric' is good, better to start as you mean to go on - always try and get the best quality you can afford, the William Optics dielectric diagonal is a quality piece of kit, not just for viewing but the construction oozes quality.

[ronin]

Not sure if the 2" is worth it, going to cost a fair bit move, but allows you to uee either eyepiece.

I would have said yes a good one would improve the image you get.

By rights it should be more reflective, but not enough to stand out - the eye just cannot differentiate that small a change brightness. However it should be flatter and the flatness and better surface should give an improvement.

The surface is after all ground and so is a rough surface and that means it diffuses light to an extent.

I would guess that if you get a good dielectric one you will not be too sure of the better views until you get used to it then go and try the old one again.

Cannot recall anyone complaining of getting a good dielectric diagonal.

[Grotemobile]

http://www.firstlightoptics.com/clearance/opticron-dielectric-diagonal.html

This is what I would go for.You wont notice

a lot of difference, in performance, between the William Optics dielectric,

and the Opticron dielectric.Opticron are very good for the price.

Steve

[John]

If you are going for one with dielectric coatings I'd go for a 2" if possible. Roland Christen of Astro Physics explains why here:

http://geogdata.csun.edu/~voltaire/roland/dielectric.html

The Maxbright diagonals he is referring to are some of the best available.

[RichieP]

I like the beefiness of two inch diagonals. Some 1.25 inch eyepieces can be quite large and small diagonals never look quite sturdy enough to me.

Rich

[kerrylewis]

Go for the best quality 2" that you can afford. It will be future proof as Robin says and you'll never need another one.

[LukeSkywatcher]

Ive often wondered if the 1.25" i got with my Celestron 8SE is any better than the 1.25" i got with my Celestron 90EQ.

Thoughts?

[Peter Drew]

I replaced the stock diagonal on my 8SE with a  1.25" Televue dtelectric one, I can't say that I saw much difference but at least I know that the Televue is a good one. The dielectric coating is also more robust than non dielectric diagonal mirrors.