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First Impressions of the Orion 90mm f/10 Explorer

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#1 Refractor Geek

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Posted 31 December 2006 - 08:54 PM

Hi All,
First impressions of the Orion 90mm f/10 Explorer with the altazimuth mount. This scope is the replacement for the Celestron 90mm f/11 FirstScope with the altazimuth mount, that had a bad objective lens among other problems. Along with my impressions of the Orion scope, I will attempt to describe the differences between the Orion and Celestron as they are very similar models. I should also add that I have no affiliation with Celestron or Orion. The Celestron was purchased from an online vender, and the Orion scope was purchased from Orion directly, I don’t know if this makes any difference, but I figured I would mention it. The reason for purchasing this scope was to have a good grab-n-go scope; as well as a scope the kids could use. I went with an achromat, because I am not rich. I chose the 90mm as it can see the brighter DSOs, and the planets, but is still portable; and I wanted a long focal length to control CA.

The Orion is a 90mm f/10 achromatic refractor mounted on an altazimuth mount, and the Celestron is a 90mm f/11 achromatic refractor mounted on an altazimuth mount. There were some interesting differences between the Celestron and the Orion. The Celestron comes with a zero power red dot finder; the Orion has a 6 x 26 erect image finder. I tried the red dot finder and found I didn’t like it much. This may have been due to the fact that the red dot finder requires you to use both eyes; which for me means using my glasses. The mounts were similar except for the accessory tray. The Celestron has a circular tray with eyepiece holes, and the Orion has a large triangular tray no holes. I like the Orion tray better, because it is larger and I can never hit those eyepiece holes in the dark. Though the mounts were similar, the Orion seemed to have smoother motions and a little better build quality. The eyepieces were quite different; the Celestron comes with 20mm and 10mm Kelners, and the Orion comes with their 25mm and 10mm Sirius Plossls. I think the Orion eyepieces are the better match for a scope of this type. The OTAs are metal, and the lens cells are plastic on both the Celestron and the Orion; however the Orion dew shield is metal while the Celestron dew shield is plastic. I am unsure if this difference would effect how long the scope stays dew free. Both scopes come with a 45 degree erecting prism diagonal. The prism in the Celestron diagonal was loose and could be heard moving inside. The Orion diagonal was heavier, and had no loose parts. I didn’t check the collimation of the Celestron; with all the rattling around I didn’t see the point. The Orion diagonal was in collimation. Both scopes come with the standard Synta rack and pinion focuser. Lastly, the Celestron comes with the standard black paint with orange logo. The Orion is White with black logo; makes me feel like I am looking at a Meade. This is where the comparison ends; as the Celestron had a bad objective, and was sent back.

Setup of the Orion and first light. The scope arrived in one piece; thanks to it being well packed, and double boxed. Putting things together was very straight forward. I put in my Cheshire eyepiece, and found the collimation to be fair. I haven’t had much time with it outside, as the new scope curse is in full swing. I did get a chance to look at Luna. I used my Orion dielectric diagonal and UO Orthos for astronomical viewing. The image was sharp and clear, CA only showed up at higher powers and only on the lunar limb. Stars focused down to fairly sharp points, but this is where the only fair collimation reared its ugly head. The star was offset into the first diffraction ring, not a problem at low power, but when splitting double stars this would be a real pain. I found after some testing with an artificial star, that the errors were on both ends of the OTA. While there are no collimation adjustment screws, I found that some thin shims on the focuser and objective cell seemed to correct the problem. The only thing I have been able to do since the last adjustments is to use my solar filter and view the sun. The view was sharp and some sunspots were visible; now all I can do is wait for the clouds to part and test it again under some real stars. I should mention that I did try the 25mm plossl, and found it to be sharp, but not as contrasty as the Orthos.

The best part though was looking at the sunspots with my kids. They had a great time and are excited about using the new scope. I think this easy to use scope will really cultivate their interest in astronomy, as well as being a great grab-n-go scope.

Let me know what you think of this review. Should I submit it to the CN reviews?

Thanks and Clear Skies

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#2 KWB

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Posted 31 December 2006 - 09:35 PM

Hello Jim,
I thought it was a pretty good review. These type scope setups make really decent,inexpensive grab and go rigs.
I have owned a vitual clone to yours,the only difference
being it's black and badged Tasco,vintage 1988. It served
me pretty well over the years as my favorite double star
scope because it was real handy. Since your kids are going
to be the primary users,the problems with viewing near the
zenith shouldn't be that big a factor. I'd say you could
have done far worse for your kids 1st scope-wish mine would
have been this useable. Enjoy it.

Kenny

#3 Refractor Geek

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Posted 31 December 2006 - 09:56 PM

Thanks Ken,
I made a couple of changes to the scope; one you can see in the photo. I added brass focus knobs; not only do they look good, they allow the scope to be slid up in the rings a little. I also had the original legs to my CG5 mount, that I put on in place of the legs that came with the altazimuth mount. I found them to be steadier than the originals. I have wooden legs on the CG5. I will update the performance info when clouds finally clear.

#4 KWB

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Posted 31 December 2006 - 10:09 PM

Your definately thinking ahead. My AZ3 also has a pretty
stout wooden tripod and replacement focus knobs. If I may
suggest a 90 degree RAF,a must IMO if your going to be
using this scope much,and if your like me,you WILL.

Kenny

#5 Refractor Geek

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Posted 31 December 2006 - 10:19 PM

That sounds like a good idea. A new Orion dielectric diagonal is already in transit for this scope. The finder will be next.

Have a great new year, and clear skies to all.

#6 kent

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Posted 01 January 2007 - 08:25 AM

Wonderful review Jim! Don't see any reason why not to submit to C.N. Review.
Funny you should do a report like this at this particular time. My little boy came to me Christmas eve and asked if Santa could bring him a telescope of his very own for X-mas. I had told him that Santa was already on his way and their was no way he could go back and pick up the scope. I also told him that I could see what I could do to try an get him a scope. So I asked him what kind of scope he would like and he more or less told me that he would like a refractor.
So Jim a few questions; how old are your children? Do you find that they could handle the telescope by themselves? (bring it in and out of the house) And does using your better ep's make a big difference in the views?
I'm looking at more or less the same thing for my young fellow but from Skywatcher(which is pretty much the same).

#7 KWB

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Posted 01 January 2007 - 08:51 AM

An F/10 scope is a very forgiving when it comes to lesser
eyepiece designs,even kellners give useable performance.
Televue plossls are superior to kellners and are noticeably
better performers. Do they make a "big" or significant im-
pact on the view? IMO,I doubt it-the scope is what it is,a
90mm acromat capable of pretty satisfactory views of double
stars,luna,planets.

Kenny

#8 Spyke

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Posted 01 January 2007 - 11:34 AM

I found this pretty useful. I have one coming, and have not found much in the way of user-reports on the Internet. Thanks for posting, Jim. :bow:

#9 SAL

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Posted 01 January 2007 - 12:22 PM

Nice review Jim. About three years ago I purchased the Orion Observer 70EQ (f/10) for a family member as a gift. I was floored by the quality views the little Synta provides on brighter objects. I have considered getting one for myself as a quick grab and go scope for those 15-20 minute moon sessions as it is very light and easy to set up quickly. Achros can provide enjoyable observing on a limited investment budget.

#10 Refractor Geek

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Posted 01 January 2007 - 03:53 PM

Kent,
My son is 8, and my daughter is 9. They haven't had a chance to drive it on their own yet; the new scope curse you know. :cloudy:
I had my daughter try and pick it up assembled; she was able to lift it but she didn’t think she could carry it. My plan was to supervise them with it at first, until they got the hang of using it. I figured I would take it in and out of the house for them until they get a little stronger. I haven’t weighed the scope, but I guesstimate about 20 pounds assembled. I’m sure they could handle the mount and OTA separately, but there is still the issue of fragile optics. Of course this would be true of any telescope, but the refractor design is probably the most rugged for kids.

As far as views; the Sirius Plossls that it comes with are decent eyepieces. They have only 4 lenses so they are fairly bright, which is good at only 90mm aperture. My son had an easier time with the Plossls than my Orthos as the Orthos are a bit more finicky about eye placement. The other thing to keep in mind is; are you going to use it for astronomy only, or do you want to do some terrestrial viewing too? I thought it would be nice to do both. I don’t know about the Skywatcher, but the Celestron and Orion versions on an altazimuth mount come with a 45 degree correct image diagonal; so you will want a good star diagonal for astronomy. That said; for grown up kids the dielectric diagonal and the Orthos make for a brighter sharper image. I would recommend Orthoscopics, Plossls, and Ultrascopics for a 90mm aperture scope to make every photon count.

#11 Refractor Geek

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Posted 01 January 2007 - 03:57 PM

I found this pretty useful. I have one coming, and have not found much in the way of user-reports on the Internet. Thanks for posting, Jim. :bow:


I found the same thing. I was supprised at the lack of reviews for these scopes. I think once my kids and I can use it under the stars a bit; I will add that info to my review and submit it to CN.

#12 LLEEGE

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Posted 01 January 2007 - 04:00 PM

Are those vibration pads illuminated or is that stick on reflectors?

#13 Refractor Geek

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Posted 01 January 2007 - 04:08 PM

Are those vibration pads illuminated or is that stick on reflectors?


Thats the reflectors in the camera flash. Wow they really work! :bigshock:

#14 LLEEGE

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Posted 01 January 2007 - 04:12 PM

Yes,they do!

#15 Refractor Geek

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Posted 02 January 2007 - 10:38 PM

The clouds have finally parted, unfortunately it is also a full moon, but I did get to see how my collimation adjustments worked out. The stars focused down to much sharper points. Even awash in moon glow, the little refractor split the Polaris double nicely. The full moon showed quite a bit of detail, and the ray patterns around several craters were fantastic. I ramped it up to 240X with my Orion Ultrascopic 3.8mm eyepiece; the image was just beginning to degrade, but Luna still showed good detail. I think it’s a keeper! :jump:


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