158 replies to this topic

[VA3DSO]

It's not bad, I have one I grabbed for 50$ unopened. For wide field views it's okay, but the optics are so so and the CA is a bit too much for me.

Wow! This thread has legs! It's almost 10 years old...

 

Anyway, I just recently picked up one of the Celestron Omni AZ 102's (the Costco special) and overall I'm impressed with the OTA. It's really well built, the star test is actually excellent (inner and outer focus images are nearly identical), the collimation is spot on, and the CA is there but it's not horrendous. I added a colour correction filter to my diagonal to tame what CA is there - overall I find the views very pleasing. It's not high power APO scope, but as a general rugged and transportable scope, I think it's a great deal.

 

The mount is a bit flimsy but can do the job in a pinch. I prefer my scope on my AZ4 mount which is much more stable. I picked up a padded carrying case meant for camera tripod equipment but it fits the AZ 102 OTA like a glove:

 

 

Overall I'm really happy with the scope, and it's a wonderful compliment to my 8" SCT.

 

 

Edited by Rick-T137, 16 October 2024 - 10:28 AM.

[tony_spina]

 

Wow! This thread has legs! It's almost 10 years old...

 

Anyway, I just recently picked up one of the Celestron Omni AZ 102's (the Costco special) and overall I'm impressed with the OTA. It's really well built, the star test is actually excellent (inner and outer focus images are nearly identical), the collimation is spot on, and the CA is there but it's not horrendous. I added a colour correction filter to my diagonal to tame what CA is there - overall I find the views very pleasing. It's not high power APO scope, but as a general rugged and transportable scope, I think it's a great deal.

 

The mount is a bit flimsy but can do the job in a pinch. I prefer my scope on my AZ4 mount which is much more stable. I picked up a padded carrying case meant for camera tripod equipment but it fits the AZ 102 OTA like a glove:

 

 

 

Overall I'm really happy with the scope, and it's a wonderful compliment to my 8" SCT.

 

 

 

 

What case are you using? 

[VA3DSO]

What case are you using? 

It's a 27-inch long padded carrying bag I bought of Amazon...

 

https://www.amazon.ca/dp/B0D3228CH1

[tony_spina]

It's a 27-inch long padded carrying bag I bought of Amazon...

 

https://www.amazon.ca/dp/B0D3228CH1

Nice 

[VA3DSO]

Oh wow! Oh wow! Oh wow!

 

I took my Omni AZ 102 out tonight to a nearby darkish sky site to have a look at Comet C/2023 A3 (Tsuchinshan-ATLAS). I knew I had a small window between sunset, when the comet would be visible, and when the full Moon would wash everything out. I was right! About 7:30PM I spotted the comet through my 7x50 binocs, and then I got it in my 32mm eyepiece through the AZ 102. The nucleus was very distinct, and the tail was visible and it seemed there was a well-defined halo around the nucleus. The halo had a very sharp, defined edge - at least to my view. The 32mm which gave me about 2.5° could basically fit the whole comet including the tail in the 50° field of view. It was awesome!

 

Then I got aggravated as I felt like someone had just turned on a streetlight behind me - I turned around to squint at the 97% full Moon. I decided to try the AZ 102 on the Moon. WOW! What a surprise! I already had an svbony color corrector filter on my diagonal  and I also had a 3D printed a 66mm aperture mask for my AZ 102 giving me a 66mm f/10 scope with it in place. The combo of the aperture mask and the color corrector filter gave absolutely beautiful views of the Moon. It was so SHARP! And no visible false colour. I pulled the mask off and yep - there was some CA. Not tons of it, but it was noticeable. But with the mask on, it was gone.

 

The best view came with my 6mm Ortho plus my 2x Barlow yielding around 220x. The image was still amazingly sharp - even though I could see the atmosphere's impact on the view, that was still super crisp!  I didn't view the Moon long - maybe 20 minutes. It was just so sharp! And finding focus was a snap (pardon the pun!). I'm really impressed with this AZ 102. I'm looking forward to some detailed lunar exploration when the Moon's phase is more favourable. As it was I spent most of my time surfing the terminator beyond Mare Crisium. I am pretty sure I got a view of Mare Smythii which actually appeared to be detached from the Moon's surface due to the atmospheric disturbance and the way the shadows were playing. It was quite a sight! To my amazement, I was able to simulate what I saw using Stellarium:

 

 

I also looked at the Moon's full disk at 44x with the 15mm eyepiece. It looked just like a photograph! So crisp!

 

Overall, it was a super quick but awesome night. I was packed up and driving home by 8PM. I normally would have stayed out longer to look at Saturn, but unfortunately I'm under the weather and really had to push myself out the door even to do this quick outing. But I really wanted to see the comet before its gone. Am I ever glad I did!

[wargrafix]

Man, I regret giving mine away

[VA3DSO]

Man, I regret giving mine away

I think that's the beauty of this particular telescope - it's not really expensive. So, you could likely pick up another one for under $200 if you get lucky. That is if you want another one.

 

For me, it is perfectly scratching that itch for a medium sized refractor. I really prefer to just have two telescopes - a big one and a grab 'n' go one, but this AZ 102 has weaseled its way into my line up and I think it's here to stay!

[VA3DSO]

Just another pic of my Omni sporting it's white tube rings while mounted on the AZ4. This is probably my favourite combination as it allows sliding the OTA forward and giving me a comfortable SCT-like viewing position all the time.

 

 

I really love this scope! What a fantastic value.

[Polyphemos]

Here’s my workhorse AZ 102. Good for an honest 220x magnification.

 

There’s a Baader Semi-Apo filter in there somewhere, though it’s not usually necessary.

 

[VA3DSO]

Here’s my workhorse AZ 102. Good for an honest 220x magnification.

 

There’s a Baader Semi-Apo filter in there somewhere, though it’s not usually necessary.

I've had mine up to 220x as well, and it held up nicely. The CA is really well managed, but I find the SV231 just helps that little bit extra.

 

Is that a GSO two-speed focuser? Is that a drop in replacement? That is sweet looking!

[Polyphemos]

I've had mine up to 220x as well, and it held up nicely. The CA is really well managed, but I find the SV231 just helps that little bit extra.

 

Is that a GSO two-speed focuser? Is that a drop in replacement? That is sweet looking!

The focuser is a GSO two-speed, and it is a direct drop-in replacement if you order the one with the 96.6mm adapter.

 

To reduce the outward movement the draw tube needs to make to bring eyepieces in a 1.25” diagonal to focus I’ve inserted a 2” 35mm “Blue Fireball” (made by GSO) extension into the focuser. A 50mm extension would also work well.

[VA3DSO]

The focuser is a GSO two-speed, and it is a direct drop-in replacement if you order the one with the 96.6mm adapter.

 

To reduce the outward movement the draw tube needs to make to bring eyepieces in a 1.25” diagonal to focus I’ve inserted a 2” 35mm “Blue Fireball” (made by GSO) extension into the focuser. A 50mm extension would also work well.

Thanks!

[John R.]

I was planning on using mine tonight but the weather is not cooperating 

Interesting Jim that you mounted the vixen rail directly on the tube, how has that worked out in practice? I already went to the expense of buying 100mm rings so does not matter I suppose.  

[VA3DSO]

I was planning on using mine tonight but the weather is not cooperating 

Interesting Jim that you mounted the vixen rail directly on the tube, how has that worked out in practice? I already went to the expense of buying 100mm rings so does not matter I suppose.  

My AZ 102 had a small dovetail mounted directly to the tube and it worked fine. I actually bought the rings so I could use this scope with my EQ5 mount, but then I decided it would also work well with the AZ4. The original Omni mount that came with it has been reassigned to be the mount for my little 70mm f/7.1 refractor which is a much more reasonable load for that particular mount.

 

Edited by Rick-T137, 07 November 2024 - 08:01 PM.

[Polyphemos]

I was planning on using mine tonight but the weather is not cooperating 

Interesting Jim that you mounted the vixen rail directly on the tube, how has that worked out in practice? I already went to the expense of buying 100mm rings so does not matter I suppose.  

John, mounting the Vixen rail directly to the OTA works great as long as your mount is flexible enough to accept a scope from either side. The advantages are eliminating the extra weight  and expense of rings, reducing eccentric loads on the mount, and increasing the overall rigidity of the system. In the case of the Omni AZ 102, the direct mounted rail was keeping within the theme of minimal weight and maximum simplicity and utility.

[John R.]

My only refractor mounted like that is my 2 lb. short tube 70/400. It works really well on the the Omni 102 mount which is only marginal for the 102 but works well for a variety of smaller, lightweight scopes. 

 

If I had it to do over it would have been mounted another 15 mm toward the rear, to better balance heavy EP’s. 

[hardwarezone]

I've had good views using 55mm aperture mask to hit the Conrady ratio5 standard on the achromat chart.

Used 9mm expanse clone eyepiece for 73x mag on the Moon at 45 degree altitude.

Without the mask , it's bad CA at 43x mag with 15mm eyepiece. Acceptable at 20x with 32mm plossl.

Even with the CA at 73x mag , there are smaller lunar details to be seen than a more pleasing view with 55mm mask.

[Gonariu]

They say "diameter always wins". I have an achromatic 120/600, I prefer to use it wide open on the moon & planets, if necessary I put some filters on it, its chromatism does not bother me. I must say that, while it gave me beautiful views of the moon and Mars (opposition of October 2020), on Jupiter I got very little out of it.

[VA3DSO]

My personal experience is that diameter doesn't always win. See endless threads of folks claiming their 4" APO's beat the pants of 9.25" SCT's in mediocre seeing.

 

Jon Isaacs was talking in another thread about observing Venus through his Tele Vue Ranger and noting the bad CA at only 100x. Through an 80mm ED, it was fine at 100x, and even at 300x it was mild and he could see more detail on Venus because of it.

 

Were I doing the same thing with my AZ 102, I'm sure unmasked it would be as messy or worse than the Ranger. But stopping it down to 66mm (for f/10) and using an SV231 filter will likely give me views more akin to the ED scope.

 

EDIT: To that I'll add that I've seen with my own eyes that there is more detail to be gleaned from a smaller aperture if it has less or no CA - I did this experiment on the Moon using my AZ 102 and I saw more detail with the scope stopped down than wide open. Likely it is a narrow range of objects that would benefit from this - the majority would take more aperture all the time. YMMV.

Edited by Rick-T137, 08 November 2024 - 01:06 PM.

[VA3DSO]

And to follow up on this... I just had my own personal experience where my AZ 102 "outperformed" my 8" SCT.

 

I had the AZ 102 stopped down to 66mm (for f/10) and a SV231 color correction filter on my diagonal, and my AZ 102 was giving me essentially color free images on the Moon and Saturn. I did most of my observing with my 8mm Plössl and a 2x Barlow good for about 165x. I tried with and without the mask, and the level of detail looked the same to me regardless. I did the same with the SV231 on and off - again not difference in detail was visible. But with the mask and filter on, the views were much more pleasing.

 

Switching to my 8" SCT, I could see more detail - however I couldn't really get above 133x before the view started to break down and it became difficult to get critical focus (using my 15mm Plössl). Going to 182x with the 11mm didn't give any additional detail, and just made it even harder to focus.

 

The real difference was on Saturn. The AZ 102 (even stopped down and filtered up) gave a MUCH sharper view of Saturn and it was much easier to get it into focus. The SCT was hunting all over and I never really landed on a satisfactory view at anything over 100x. What really blew me away was that the AZ 102 showed the yellowish color of Saturn's disc and the rings appeared mildly blueish. This could have been due to the SV231 filter, but overall the view was really nice. Some yellow color was visible in the 8" SCT but I simply couldn't get it to give me decent focus at anything above low power (32mm Plössl good for 63x).

 

So, as I said, I'm sure the 8" SCT was showing more detail when it would focus... but I saw more in the refractor because it was easier to focus and actually would do so at higher power than my poor SCT. Now, the local seeing tonight appears to be pretty bad at least from my backyard in the 'burbs. Under steady skies, the SCT does pull way ahead but not tonight. And this is against a lowly achromat!

[Sk240]

Appreciate your comparison and review and I think I've read an article on CN maybe a year ago where the author said under some scenarios, seeing being the primary factor, a 5" APO could beat out an 8" reflector for planetary observations.  I think it has something to do with the 8" seeing more air columns being a larger scope but I wonder if that article described the situation you just experienced.

 

I too have an Omni 102 I got from Costco in 2022 and had it out last night on Jupiter, primarily because I also just scored a used ST120. The comparison was done at roughly 100x on both scopes and the Omni 102 had less noticeable CA than the ST120 but at the same time, the ST120 was sharper and showed more detail on the planet.  Just as a double check, I had my 13 year old son with young/pristine eyes take a look at both scopes and within seconds he said that the ST120 showed more details.

 

I also tried both scopes with the aperture mask on/off and I also have a Sirius MV-20 CA reduction filter.  The aperture mask cleaned up the CA more than the MV-20 but at the same time, I preferred the filtered view at full aperture as it was a bit brighter and appeared to show a tad more detail.  For the Omni 102, at 100x, to my eyes, the CA doesn't bother me at all and I'd just prefer observing it at full aperture, no filter.  For the ST120, the CA was starting to be distracting at 100x.  YMMV.

 

My conclusion is that while I love the Omni 102, I think the ST120 is just a bit better in all areas except CA, which could be partially mitigated with a CA filter or aperture mask.  I'm now thinking of selling the Omni 102, hopefully to a beginner as I think the Omni 102 with the default alt-az tripod makes for a very good beginner package.  I'd recommend buying a new diagonal ASAP though as the default correct image prism has a hard cutoff disk that clips the 1-1/4" barrel significantly.

 

I also noticed that Costco is now selling the Celestron Starsense DX 100 that has I believe has the same optics as the Omni 102, along with the Starsense phone dock.  I think the Starsense phone dock is a wonderful tool for a beginner starting out, it makes finding objects so much easier.  

 

 

And to follow up on this... I just had my own personal experience where my AZ 102 "outperformed" my 8" SCT.

 

I had the AZ 102 stopped down to 66mm (for f/10) and a SV231 color correction filter on my diagonal, and my AZ 102 was giving me essentially color free images on the Moon and Saturn. I did most of my observing with my 8mm Plössl and a 2x Barlow good for about 165x. I tried with and without the mask, and the level of detail looked the same to me regardless. I did the same with the SV231 on and off - again not difference in detail was visible. But with the mask and filter on, the views were much more pleasing.

 

Switching to my 8" SCT, I could see more detail - however I couldn't really get above 133x before the view started to break down and it became difficult to get critical focus (using my 15mm Plössl). Going to 182x with the 11mm didn't give any additional detail, and just made it even harder to focus.

 

The real difference was on Saturn. The AZ 102 (even stopped down and filtered up) gave a MUCH sharper view of Saturn and it was much easier to get it into focus. The SCT was hunting all over and I never really landed on a satisfactory view at anything over 100x. What really blew me away was that the AZ 102 showed the yellowish color of Saturn's disc and the rings appeared mildly blueish. This could have been due to the SV231 filter, but overall the view was really nice. Some yellow color was visible in the 8" SCT but I simply couldn't get it to give me decent focus at anything above low power (32mm Plössl good for 63x).

 

So, as I said, I'm sure the 8" SCT was showing more detail when it would focus... but I saw more in the refractor because it was easier to focus and actually would do so at higher power than my poor SCT. Now, the local seeing tonight appears to be pretty bad at least from my backyard in the 'burbs. Under steady skies, the SCT does pull way ahead but not tonight. And this is against a lowly achromat!

Edited by Sk240, 14 November 2024 - 08:13 PM.

[Sk240]

Here is the article, I stand corrected, it was about a 4" APO vs 8" SCT, which I think is similar to your situation, granted your 4" is not APO. 

 

https://www.cloudyni...es-and-no-r3387

Edited by Sk240, 14 November 2024 - 08:47 PM.

[VA3DSO]

I just recieved my 8" dovetail from Svbony which is twice as long as the original dovetail supplied with the AZ 102. I did have to drill out the middle hole a bit (tapped for 1/4-20) as that hole is the perfect spot to mount the dovetail as far back on the OTA as I want it. It worked out perfectly! It holds the AZ 102 very firmly and allows me to back off my AZ4 clutches to the point where pointing the scope is buttery smooth. Really looking forward to getting this out under the night sky ASAP!

 

EDIT: I did this because although I prefer the tube rings that I previously got for my AZ 102, they don't fit in the carry bag when attached to the OTA. So I'm going to try this setup for a while, and if it does prove more unstable (as @Jon Isaacs advised me) then I'll switch back to the tube rings.

 

 

Here's a link to the dovetail in case any other AZ 102 owners are looking for something similar:

 

https://www.amazon.ca/dp/B07LGMW1YP

Edited by Rick-T137, 13 December 2024 - 04:28 PM.

[SteveFour86]

Good read all.  This thread does have legs. Still have the AZ102 in my lineup. 

[vtornado]

So Rick,  Have you tried rings vs. long dovetail?

 

I just picked up one of the costco scopes for $100  from craig's list.  For that price it just can't be beat.  Everything is metal except for the focuser wheels (maybe the lens cell is plastic too).  I haven't really put it through stringent tests but it did fine on Mars with 7mm zoom.  The tripod/mount seems a bit wiggly.  A breeze made it only possible to view Mars after the scope settled down, and I was using it with the legs all the way down.

 

I have not tried the included eyepieces.   I think the dovetail is a bit short, and the scope may not be balanced.  Although I did use a better diagonal and svbony 7-21 zoom, which weighs a bit more than the included diagonal and eyepiece

 

This is not an AT ED on an sterllarvue M2c, but look at the price!!!  A functional telescope that a single parent family can afford.  At our star parties, I have moms with daughters interested in astronomy, and when they ask what the price for a starting telescope is and I say $800 (dob + accessories) i see a look of astonishment on their face.

Edited by vtornado, 01 February 2025 - 06:51 PM.