Cheap but acceptable diagonal?
Posted 12 September 2013 - 08:04 PM
Any suggestions would be very welcome. Will $50 get me home?
Posted 12 September 2013 - 08:08 PM
Posted 12 September 2013 - 08:21 PM
Posted 12 September 2013 - 10:31 PM
Meade deluxe economy star diagonal
I've actually tested the Meade Deluxe Economy Diagonal and was surprised at how good it was. Collimation was spot on and when star tested at 220X against a much more expensive diagonal ... I couldn't detect any difference! However, the housing is 100% plastic, so I wouldn't want to use it with any heavy eyepieces!
BTW ... Telescope Warehouse is a good company to do business with ... orders are promptly shipped and arrive within a few days after placing them.
Posted 13 September 2013 - 12:49 AM
...I'm worried if those are the diagonals people say to immediately discard upon receiving your new scope.
People who write that about the stock Celestron diagonal are, and not just in my opinion, seriously overstating the alleged flaws in this prism diagonal. I sometime wonder if they understand how a prism works and why it might be accepable for your SCT or my smaller and larger versions. (Remark not applicable to any CN memeber in good standing--only intended for emphasis). ;)We should ask why Celestron hasn't switched to a 1.25" mirror? There are many servicable and cheap versions made in China.
Read this brief report by Gary Hand
Two inch EPs change the game---a two inch prism is expensive. And for what it might be worth, I have a TV diagonal and really don't see much gain when using 1.25" EPs. But I wasn't much good with the difference between tabaco notes and rasberry-earthy notes in wine.
Posted 13 September 2013 - 01:19 AM
As for using them visually, I really like my $40 celestron 1.25 prism, it has a great view through it, just as good if not better than my $189 AT Quartz 2", though sometimes you have to adjust the flat spring to get them aligned properly.
Posted 13 September 2013 - 03:26 AM
The main issue with the cheapo 1.25" prism diagonal supplied with Celestron SCT OTAs (apart from the restriction on the FOV compared with a SCT threaded diagonal, or a 2" refractor diagonal in a 2" fitting visual back) is that the eyepiece retaining screw rapidly wears its thread. Optically it's not great, but it is OK, unless you want to image in the ultra violet, and for imaging you really don't need a diagonal at all.
We should ask why Celestron hasn't switched to a 1.25" mirror?
Personally I don't see why Celestron package a cheap diagonal and a cheap eyepiece when they could package something far more useful instead (active cooling fans, a corrector plate dew heater strap and, most importantly of all, a dew cap) but, as usual, you get what the marketing department wants to dump on you, not what you might find useful.
Posted 13 September 2013 - 09:47 AM
Posted 13 September 2013 - 09:53 AM
People who write that about the stock Celestron diagonal are, and not just in my opinion, seriously overstating the alleged flaws in this prism diagonal.
Optically, the Orion/Celestron 1.25 inch prism diagonals are plenty good, mechanically, they have their issues but are certainly acceptable mechanically. I find the corresponding Orion/Celestron 1.25 inch mirror diagonals are often miscollimated (easily fixed) but the prism diagonals are quite good in this regard.
The diagonal is close to the focal plane, it's flatness is not as critical as an optical component that distant from the focal plane (Newtonian Secondary) since any part of the image only sees a small portion of the diagonal.
Posted 13 September 2013 - 10:21 AM
You can find these good quailty ones with 99% dielectric for like $80 or so, but if you wanna stick to the 1.25" visual back with a 1.25" diagonal get a astro teck used model 99% dielectric you may find them just abit over $50 but will be worth it.
Posted 14 September 2013 - 03:43 AM