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Need advice for a decent diagonal, but not top end

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#1 Telaeus

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Posted 04 February 2013 - 01:08 PM

Hey folks. I just picked up a used Vixen ED103S that came with a cheap 2" diagonal and one 21mm Baader Hyperion eyepiece. I think I've settled on the Celestron AVX mount (it came with a Vixen porta) as a decent not too expensive mount (I do plan on starting AP). And I'm looking at maybe the Meade 4000 eyepiece kit to give me something to start with that's ok.

However, it seems to be much harder to find info on diagonals. I don't want to get a cheap diagonal. However, I am trying to keep costs reasonable. What's a decent diagonal for this setup? Thanks!

Matt

#2 csrlice12

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Posted 04 February 2013 - 01:17 PM

Most any GSO Dielectric or clone.

#3 MikeBOKC

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Posted 04 February 2013 - 01:59 PM

I have been quite happy with this one from our sponsor. You also get a small Cloudy Nights discount!

http://www.astronomi...ity-dielectr...

#4 Telaeus

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Posted 04 February 2013 - 05:22 PM

Ok, well that makes it easy. Thanks for the advice!

Matt

#5 Jon Isaacs

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Posted 04 February 2013 - 07:06 PM

Hey folks. I just picked up a used Vixen ED103S that came with a cheap 2" diagonal



How "cheap" is cheap? Unless the current diagonal is plastic, whatever you buy, don't expect a lot of difference.

Jon

#6 Paco_Grande

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Posted 04 February 2013 - 07:44 PM

99% dielectric. Orion has theirs on sale right now, under $120. The 2" Williams Optics Carbon dielectric is $135 from AgenaAstro.

That AstroTech is a nice one. But try to find one...

Also, the GSO's are real nice, too.

#7 Bart

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Posted 04 February 2013 - 08:13 PM

I second the Orion Dielectric . Very well built. The one linked here is the 2", they make a 1.25" as well.

#8 johntrob

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Posted 05 February 2013 - 06:12 AM

I have bought two here on CN swap shop and classifieds. Watch the ads, some goods one show up at decent prices occasionally.

John

#9 csrlice12

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Posted 05 February 2013 - 08:22 AM

Good Point John. You can save in the classifieds. Jon (different guy, different spelling)also made a good point: What about the diagonal that came with the Vixen. Vixen usually has pretty good quality stuff, and if the diagonal is metal, you're probably good to go. Is it possible they sent you a terrestrial diagonal (look at a tree, does it appear right side up and does left to right match (ie. you see thru the diagonal/eyepiece what you would see without one), if it does, its a terrestrial diagonal and you will need to replace it for astronomy use. (Note: at 103mm, it is doubtful it is a terrestrial diagonal, but hey, strange things happen in this hobby. Like Jon said, if its not plastic, its doubful you'll see much difference. I'd ask to try someone else's first, just to get an idea. It is also possible your diagonal's mirror isn't aligned properly (Do you have any "chopped off views" or where one side of the FOV is in focus and the other side not?)

#10 Telaeus

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Posted 05 February 2013 - 02:29 PM

Jon - I say cheap because while it's a nice scope, he sent it with non-Vixen parts the rest of the way. I got him to add in one Baader Hyperion eyepiece when I bought it for a price. But the finder scope was in bad shape (arrived with a snapped thumbscrew and only one wire in the finder eyepiece (the other was hanging out). Don't remember the brand, but it was close to a no-name - couldn't even buy one anymore.

I don't think the 2" diagonal is what came with it. I could be wrong, having never seen a new one. However, since I was looking at getting 1.25" eyepieces, I figured I'd need an adaptor or new diagonal anyway. Then I figured I might as well get a decent one.

Other John - I have been watching the classifieds. Thanks!

CSR - It's not a terrestrial diagonal. As far as testing how well it focuses, I got it last week, and the weather has been awful. Best I've been able to do is put it together and stare at it. And look at trees in the distance (upside-down trees). I don't remember noticing any chopped off trees though.

Matt

#11 Jon Isaacs

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Posted 05 February 2013 - 03:08 PM

I don't think the 2" diagonal is what came with it. I could be wrong, having never seen a new one. However, since I was looking at getting 1.25" eyepieces, I figured I'd need an adaptor or new diagonal anyway. Then I figured I might as well get a decent one.



Matt:

"No-name" diagonals can still be good diagonals. The job of the refractor diagonal is pretty easy because it so close to focal plane.

I have four 2 inch diagonals, two are dielectric TeleVue Everbrights which are of the highest quality, the bodies are machined from a single piece of aluminum, no threaded nose piece. I also have a Meade Dielectric diagonal and I have a no-name diagonal with what I assume to be standard coatings.

At the eyepiece, they all look about the same.

The advantage of the dielectric diagonals is the surface is much harder than the standard and therefore more durable, easier to clean without damage.

I suspect your current diagonal would do a good job for you. Post a photo and someone will probably recognize it.

Jon

#12 Telaeus

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Posted 05 February 2013 - 03:38 PM

Jon,

I'll have to take a closer look when I get home. Would be nice to only have to buy an adapter...

Matt

#13 Telaeus

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Posted 05 February 2013 - 09:23 PM

Here's a pic of the diagonal I have. Any good?

Thanks!

Matt

Attached Files



#14 Paco_Grande

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Posted 05 February 2013 - 09:54 PM

I'd think any diagonal with a compression ring is going to be just fine, unless it's damaged. And that has a compression ring. :D So, if the image looks proper-good, then buying something else won't make any diff.

#15 Midnight Dan

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Posted 06 February 2013 - 07:28 AM

Hi Taleus:

Chances are, that diagonal is as good as the next. There's probably no need to buy a new one.

On the other hand, there's something to be said for a pretty face! :grin: I have a William Optics 2" and a GSO clone. Through the eyepiece, they views are identical. But I always find myself reaching for the WO and it's sleek, sexy good looks instead of the clone's blocky design.

-Dan

#16 Telaeus

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Posted 06 February 2013 - 12:45 PM

Ok, thanks for the look-see. I can appreciate a pretty face, but I probably won't worry about such things until after all the other necessities are bought. Until then, I'll go with this.

Thanks! I had no idea there wasn't a bigger difference... figured if it was any kind of glass between you and the image, there would be major quality differences between stock and upgraded.

Matt

#17 Jon Isaacs

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Posted 06 February 2013 - 01:57 PM

Ok, thanks for the look-see. I can appreciate a pretty face, but I probably won't worry about such things until after all the other necessities are bought. Until then, I'll go with this.

Thanks! I had no idea there wasn't a bigger difference... figured if it was any kind of glass between you and the image, there would be major quality differences between stock and upgraded.

Matt


Matt:

The fact that diagonal is so close to the focal plane means that overall flatness is not so important. Each part of the image is reflected off a small area of the diagonal. A Newtonian or SCT/Mak secondary mirror is quite different because the entire mirror contributes to every part of the image.

I think you are taking the wise course, take care of the necessities first and then if you want a new diagonal, take your time and buy one.

Jon

#18 Telaeus

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Posted 06 February 2013 - 05:45 PM

Interesting. I have much to learn. This was a hobby of my father's when I was a kid. Used to observe together... and then I moved out, and haven't had a scope since. Just my Astronomy magazine for 20 years. So I have many fond memories, but little technical know-how. Thanks for the info!

Matt






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