Quote:

---

@ Chris - if I just throw in a .5x focal reducer, that would not improve the maximum field of view? I think I would again see the black corners with the wider eyepieces....

---

Post Extras:

Quote:

---

Watch out for vignetting with a 2" diagonal, I already learned that the F6.3 compressor for the bigger SCTs stops down the aperture. You can check for this by focusing a high powered eyepiece, then look thru the front end and see if the tiny exit pupil disappears off axis before your line of site moves off the edge of the corrector.

---

Post Extras:

Quote:

---

Agreed. The C90 cannot possibly illumimate a 2" ocular. Stick to 1 1/4' and try what suits your needs best: something around 25mm or 32mm, both of which may show some vignetting depending on the particular design of the eyepiece. In most cases, a Plossl or Ortho will work best.

---

Hi Erik,

yes 2" is not possible at all with the C90. (BTW, the russian MTO 10/1000 Maksutovs work fairly well with some 2" eyepieces, there are even some commercial 2" adapters available. The MTO also can be used with a full-size 35mm camera while the C90 will not cover the corners of the 35mm frame.)

My C90 would not 100% illuminate even the TeleVue 25 mm Plössl. And although it's not exactly a "big" eyepiece, even this and the 1 1/4" diagonal already spoil the counterbalance of this small scope.

As I said, I have stopped using any 1 1/4" eyepieces with it anyway and now enjoy it much more with the original 0.96s

CS
Thomas

--------------------
Celestron C90 Astro
Meade 2080 LX3

Post Extras:

Quote:

---

I have come to terms with the fact that I am a nut for small Maks. I've owned four between 70mm and 105mm. My favorite of the lot, and probably my favorite telescope of all time, is my Orion Apex 90. I got it to serve as a grab-n-go and travel scope, and it does, but it also fills a larger and even more important role: it's my no excuses telescope. It is so small and so trivially easy to set up and gives such good views that I don't stop and think about whether I should take it along on a trip or whether I should haul it out to look at the moon on a nice evening. I just do. No excuses!

I have bigger scopes and use them, too. They just don't have the same indefinable appeal. Sounds like you feel something similar for your C90.

---

yes, you sum up everything that I like of my C90. It was a youth's dream anyway. Back in the 80s all these scopes were totally out of reach for me, at the time I had a small (also nice, of course) 60/800 Vixen refractor. I also always liked the Meade 2044 when it came out - but later I learned that the optics have a rather mixed reputation, anyway the C90 is even smaller and more classic in design and operation. I LOVE that C90 fork mount, its a beautiful design and offers very smooth operation, there is really nothing I find to complain about after one year ownershop.

The whole scope just feels like it is a quality scale model of a real big classic observatory. It takes you back to the 70s or even 60s in apperance and operation. This is totally different to the Meade ETX90 that I owned previously. The ETX hat rather better optics (but does that really matter? I'm not using it above 80x or so anyway...) and the ETX worked also much better with 1 1/4" eyepieces as it was designed for that in the first place. But the feel of the whole assembly was - to me - not "quality" at all. I might end up buying another ETX90 when I find a computerised version for a real bargain price at some time - the ETX is then such a different experience to the C90, and in my opinion it is a future 1990s classic in it's own right, that I might give it a second try.

What I now like so much about the old little eyepieces, is their quality feel: It's not the "wow, this is the best you can ever have, cost no object at all" quality of a Nagler. But it's more a "we know it's small, it has limited technical data, but still we want to make it high quality" approach that shines through with these old eyepieces.

Now I have the original (i.e. Vixen or Celestron) 25 mm, 20 mm, 18 mm eyepieces, after some time I now also sourced the 40 mm Celestron, I will then need the 30 and 12 mm, probably the 9 mm as well, to have a complete collection. The even higher magnifications I personally find not so important with this scope. Also, classic feelings aside, the eye relief with say a 6 mm ortho is really not so nice for me. We have a 6 mm and 9 mm Vixen ortho (1 1/4") and I really dislike using the 6 mm, no matter how classic it might be while the 9 mm is still somewhat okay.

The photo attached shows both my 90s, back when I still owned the ETX.

CS
Thomas

Post Extras:

Quote:

---

What kind of eyepieces did yours come with, especially which one is the one where the whole pleiades would fit in?

---

Mine came with a mirror star diagonal and 30mm and 18mm Kellners. I'm pretty sure they were part of the original kit, because all three fit in a box with a styrofoam insert. The whole rig came in a nice foam-lined hardcase...gone are the days when something like that was included gratis!

With the 30mm EP I can just barely get all of the Pleiades in. I like both of the little eyepieces, they are a bit dated by today's standards but like you said, the quality is evident. Time to hunt down some more focal lengths, methinks.

I like the idea of a telescope on the bedside table. With the whole mini-observatory vibe the C90 gives off, I'm sure it looks great. Unfortunately all I can see out my bedroom window is trees. But trees have birds and squirrels, and I'm having fun with the C90 as a daytime spotter, too. Not from the bed, though!

As you might have guessed from my comments above, I have been on a quest to find the smallest, most portable telescope with good optics and mechanics. I like long f/l scopes and I've always been drawn to Maks. I started out with an Orion 102mm, then got the 90mm (as Ed Ting wrote, "because it was there") and decided I liked it better. In exchange for giving up 10% of the aperture I also got rid of 10% of the length and close to 20% of the weight.

For a long time the Apex 90 has been my optimum. I tried a Celestron C70 spotting scope, but the views were too dim and the mechanics were rough (other samples may be better). I tried a Synta MC90, a weird little f/5 Mak also sold by Omcon and Orion, but the views were soft. The C90 was about the only thing smaller (well, shorter, anyway) than the Apex 90 that I hadn't tried.

One of my fellow club members has a fully equipped Questar 3.5 that he brings to public outreach events. It's a sweet scope for sure, but going head-to-head against the Apex 90 I didn't see any differences. Saying so might bring down fire and brimstone from Questar devotees , and I happily admit that other samples of both scopes might have yielded different results. The point is that optically I don't feel like I am giving anything up with the Apex 90. I'll be curious to compare things over the long haul, but so far the C90 seems the equal of the Apex. The shorter f/l gives a wider field but doesn't seem to affect image quality, which I guess makes sense: f/11 is still pretty darn long.

Nice to chat with someone who shares my obsession!

--------------------
Orion XT6 "Shaft"
Little Maks: Orion Apex 90, Celestron orange tube C90, Synta MC90
Edmund Astroscan "Baby Red"
76mm ongoing ATM experiment
Celestron UpClose 10x50
Celestron SkyMaster 15x70

10 Minute Astronomy

Post Extras:

Quote:

---

Mine came with a mirror star diagonal and 30mm and 18mm Kellners. I'm pretty sure they were part of the original kit, because all three fit in a box with a styrofoam insert. The whole rig came in a nice foam-lined hardcase...gone are the days when something like that was included gratis!

---

now you mention it: My C90 also came with a black hardcase. I don't know for sure that it's original.

I am now offered a pair of 18 mm 0.96" Vixen orthoscopic eyepieces. (The Celestron 18 mm that came with my scope is a Kellner.)

As I now could have *two* identical 18 mm Orthos, I'm wondering how the C90 would do with a binoviewer....... ?

--------------------
Celestron C90 Astro
Meade 2080 LX3

Post Extras: