Which 2" Diagonal - Advice

[Pig]

Hiya,

I want to get a 2" diagonal to suit my scope and I don't really want to spend more than £120

Is it worth getting one if I only have 1.25" eyepieces ?

If so I would appreciate advice on what you feel is the best make to get ?

[rowan46]

Only if you intend upgrading to 2" eyepices. diagonals are much of a muchness performance wise no matter what the adverts say. Yes some are built better but most dielectrics give about 99% so how about this one http://www.teleskop-express.de/shop/product_info.php/info/p84_TS-SC-2--Star-Diagonal---99----Compression-Ring---SCT-Thread.html

[Pig]

Thank you Rowan, that looks great What is Lambda a measure of ?

[DirkSteele]

Looks like Rowan46 has made a good recommendation there. Has a very high surface accuracy and has a dielectric coating for 99% reflectivity across the visible spectrum. And it allows you to retain the option for 2" EPs in the future.

EDIT: Lambda is a measure of the surface accuracy in terms of a wavelength of light. In this case 1/12 lambda is very good.

[Pig]

Thank you Matthew - looks like that is the one to go for.

What about this one ?

http://www.365astronomy.com/william-optics-2inch-dielectric-coated-diagonal-cf-body-p-56.html?gclid=CMjWq9_Nr7cCFWLHtAod5xkA1g

[DirkSteele]

Also an excellent choice. I use one with my APM 105 triplet refractor. It is my travelscope so I keep the weight to a minimum and that one is a touch lighter than many of the competing products. The Televue diagonal for example weighs a far amount, but it was machined from a single block of aluminium so understandable. But it is also about £250.

EDIT: Turns out it is now £270. I own one which I use with my TMB 115. I just held both in my hands and there is quite a noticeable difference in the weight,

[Pig]

So they get quite expensive then Quite heavy too. I do like the look of the carbon fiber

[John]

I have 2" dielectric diagonals by William Optics, Tele Vue and Revelation. They vary in build quality from superb (Tele Vue) to pretty good (Revelation) and their prices new vary from £250 (Tele Vue) to £98 (Revelation). They all have compression ring fittings on both the 2" and 1.25" apertures. In terms of optical performance I really can't tell them apart at all

[John]

So they get quite expensive then Quite heavy too. I do like the look of the carbon fiber

The carbon fibre bits are just decorative side panels. The rest of the WO diagonal is made from alloy.

[Pig]

I have 2" dielectric diagonals by William Optics, Tele Vue and Revelation. They vary in build quality from superb (Tele Vue) to pretty good (Revelation) and their prices new vary from £250 (Tele Vue) to £98 (Revelation). They all have compression ring fittings on both the 2" and 1.25" apertures. In terms of optical performance I really can't tell them apart at all

LOL well I might as well get one for a £5er

[Pig]

The carbon fibre bits are just decorative side panels. The rest of the WO diagonal is made from alloy.

The description reads like it is has a carbon fiber body- sneaky or what

[John]

LOL well I might as well get one for a £5er

If the £5 one has that same spec then, yes

More realistically I've seen good Dielectric diagonals go secondhand for around £50 reasonably frequently.

[Pig]

I prefer to buy new John as I intend to keep it for as long as it will last. I sometimes wish there wasn't so much choice

[Teslar]

I've got the standard skywatcher, revelation and a WO carbon sided. Have to say the standard one is pants and the WO is the one I pick up every time. The difference between them is very noticeable for me

[Pig]

I've got the standard skywatcher, revelation and a WO carbon sided. Have to say the standard one is pants and the WO is the one I pick up every time. The difference between them is very noticeable for me

That's interesting, The WO does seem to get a lot of good reviews, is the one yu have the same one as in my link above ?

[emadmoussa]

I have the Teleskop Service one and I think it's brilliant for under a £100

[Pig]

I have the Teleskop Service one and I think it's brilliant for under a £100

Imad can you post the a link to it please, do you get a 1.25" adaptor included ?

[Teslar]

The link isn't working for me but here's mine:

http://www.williamoptics.com/diagonalPrism/dielectricCF_features.php

[Pig]

The link isn't working for me but here's mine:

http://www.williamop...CF_features.php

I must admit, I too am leaning toward this one

[rowan46]

Imad can you post the a link to it please, do you get a 1.25" adaptor included ?

I think that's the link i put up and yes it does come with an adaptor

[Pig]

I think that's the link i put up

Ok thank you Rowan

[emadmoussa]

Yes, 2 inch and 1.25 inch in one

http://www.teleskop-express.de/shop/product_info.php/info/p89_TS-2--Star-Diagonal---99--Dielectric---Compression-Ring---2-.html

[Pig]

Yes, 2 inch and 1.25 inch in one

http://www.teleskop-...-Ring---2-.html

Thank you, it does appear a flick of the coin between the two of them

[emadmoussa]

Thank you, it does appear a flick of the coin between the two of them

Frankly, I didnt seeuch difference between the 99% reflectivity and the 91% one which is almost half the price. I use both interchangeably

[Pig]

Frankly, I didnt seeuch difference between the 99% reflectivity and the 91% one which is almost half the price. I use both interchangeably

How do they compare to the one that came with the scope ?