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markclaire50

Does a good quality Star Diagonal matter?

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Has anyone ever really noticed a tangible improvement from changing their diagonal? Or is it all just a big myth? 

That's it! ? 

Thanks 

Mark

 

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A poor one will certainly affect the views so it is definitely worth making sure you are at a decent level. I have a Baader Zeiss T2 prism which I am sure provided a better view at high power than a another basic diagonal.

I suspect these articles may be right up your street.

https://www.cloudynights.com/articles/cat/articles/mirror-vs-dielectric-vs-prism-diagonal-comparison-r2877

https://www.cloudynights.com/articles/cat/user-reviews/the-baader-bbhs-sitall-silver-diagonal-r3038

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I agree with Stu.

Some years ago I did a side by side comparison of a Skywatcher startravel refractor vs William Optics at 3x the price. Using the supplied eyepieces and diagonals.

The view (terrestrial) was like a foggy day to a clear day.

Swapping parts individually between scopes, I tried to see if any particular part of each package was the strong, or weak, link.
In every respect the WO parts were better and contributed to the overall performance.

With the diagonals I could easily see that the WO part well outperformed the SW part.

So yes it can be worth paying for the better diagonals and eyepieces.

You can of course hang on to the 'quality' diagonal if you change scopes.

Hope this helps, David.

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I've noticed a difference moving from a stock diagonal to a decent quality one such as the William Optics or Revelation ones. The differences between those and the next step up again get somewhat harder to spot and sometimes are more about overall build quality and finish than tangible optical differences. Nevertheless I've tended to get the very best that I can in any optical componant so, like Stu I use the Baader Zeiss T2 plus, in the 2 inch sizes, Tele Vue Everbright and Astro Physics Maxbright.

 

 

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I have tested the Skywatcher diagonal that is supplied with the Esprit 120ED and my new APM amici diagonal and you can tell the difference. It's more brighter and the contrast is better in the APM diagonal.

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Try looking through the scope normally and then look through it without the diagonal-just the eyepiece. Obviously it's hard to look through the scope without a diagonal when it's pointed up high in the sky. The difference between the two images is the maximum possible improvement. A new diagonal can't improve on that. Then you'll know if you would like to get a better diagonal or if it isn't worth it for you.

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If you have any doubts about collimation and rotate the diagonal for convenient viewing for example with an SCT in alt/az mode, if the mirror in the diagonal is not aligned then the error can become more apparent.

Bob.

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Thank you all for some very interesting (and I was secretly hoping) stories that make me think it would be worth upgrading to improve my current views. Currently I have the stock 2" diagonal with the sw80ed and 1.25"diagonal with the 127mak. I like the suggestion of taking it out and looking directly through w/wo diagonal. I will need to avoid zenith objects, as I already have neck problems! ? I have a particular test target in mind that isn't too high or low and I think would provide a good test - orion nebula and trapezium. I'm slightly suspicious of the mak diagonal's performance in particular. So it will be first on my list if I see a clear difference and especially if the E star pops into view without diagonal but disappears with it!

Thanks

Mark

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Massive improvements in contrast, definition and scatter can be had if you use an optically top class diagonal. A telescope is only as good as its weakest link, and that link is often the diagonal. 

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Pay once for a quality star-diagonal... or buy more for inferior ones...! 

The stock 1.25" star-diagonal that is attached to my TeleVue Ranger, (refractor), and I own two of them, (i.e. the star-diagonal), and is/are better than the 'cheap' plastic & mirror one that I had supplied when I purchased my ETX105 before the 're-mod', (sorry, no image), and an improvement of the one attached to my C6, (SCT), (see image below). 

IMG_0511.JPG.4afa2a03bbdadb3dae203f773423288b.JPG

 

If you you have a 2" focusser then this Altair Astro one(, see image below attached to my ETX105 're-mod'), is damn good value IMHO. It is available as SCT or as 2" push fit, complete with a 2" to 1.25 reducer.

PIC021.JPG.317e3ab5bc2a32848d576782c9caf3ab.JPG

 

Edited by Philip R
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