Can't Decide 8SE or CPC 800 GPS SCT

[Flyhigh7]

I understand the advantage of the twin fork stability of the CPC 800 but I'm trying to determine if the optics inside the CPC800 are better than the 8SE to merit the additional expense. And if so, by how much better.

Also, I like the recommendation to get 2" eye pieces but wonder if getting a 2" diagonal and 2" eye Pieces gives a true 2" throughput or is there something in the system that is less than 2" and I'm just adapting it larger.

Also, read where the focus adjustment on the 8SE is not very accurate as far as fine tuning and wondering if the focus on the CPC 800 might be better.

I'm looking for the scope in this range that will yield the brightest deepest objects and I can even afford the CPC 9.25 but I'm concerned about the additional weight. I do like that Celestron says the 9.25 collects 33% more light than a 8" Scope.

I used to have a 6" Reflector so I wonder how much more light will an 8" collect than the 6". Wonder if there is a formula for that.

I recently purchased the Celestron Giant 15*40mm Binoculars and was surprised that they were able to see 4 of Jupiter's moons 2 nights ago. They were just little dots to the sides of the bigger Jupiter dot but it was neat how they were lined up. Couldn't see the orion nebula or anything that looked like a nebula in orion though I saw a review that said you can see nebulas with these binoculars.

I thank you in advance for any 'light' you can give me on these issues.

Regards!

[West83]

I was looking at 8" SCTs and from what I gathered all tubes are pretty much identical (talking about Celestron) apart from Edge HD ones.

What you are paying more for is the mount, which is substantially beefier (and bulkier!) on the CPC. More stability but a heavier setup to move around.

If you go for the SE, keep in mind that many claim it's undermounted in that setup. An acquaintance of mine used it with a motorfocuser (apparently its a good upgrade right after dew shield) and he enjoyed it quite much.

Hopefully other can provide more info about the 2" EPs.

Good luck!

[JayTee]

They both use the same OTA.

[Lady Fraktor]

West83 is correct, the standard SC are all the same but the Edge SC are better corrected optics.

[Ylem]

I currently run a 6 on my SE mount, the 8 was a bit shaky for my liking.

Have you looked at this; https://www.highpointscientific.com/cel ... on-8-12091

[Flyhigh7]

Thanks Guys, Maybe I should look at the Edge or the Evolution. Anyone using or have any experience with these. Looks like the Evolution has a better mount but I'm not sure.

[Bigzmey]

I have both Edge HD and standard SCTs from Celestron. The difference in image quality is noticeable. It sort of like difference between achro and APO refractors. Does it worth extra cost? In my opinion yes, if one can afford it. It does not mean that image quality of plain SCTs are bad, they went a long way since the classic orange tubes. From my experience the image quality of plain SCTs are at least as good as similar size (and well collimated) DOB. But the image from the Edge is more refined. Sharper stars, better contrast, a bit more details in DSOs.

As for the mounts my biggest concern about fork mounts is that you are paying a big chunk of money for SCT/mount combo and you stuck with it. If you decide to upgrade the scope or mount you would have to sell both the scope and the mount. If you invest the same money in a stand alone mount and SCT OTA separately, you could own multiple scopes and use them on the same mount, or replace your scope with something different, or upgrade your mount and keep the scope.

Another scenario, you crack your SCT corrector plate. If you have the fork combo, that's it. The whole thing is total loss. If you have stand alone mount you could look for a used OTA or buy brand new OTA to replace the damaged one.

[gregl]

I have an 8SE. The advantages are that it breaks down into components that are easy to transport, and it's light weight and easy to set up. The disadvantage is that it's driven by spur gears which are subject to more backlash than worm gears. When focusing there is at times annoying wiggle. If I was going to buy again I'd seriously look at the Evolution which I believe has worm gears. I did once look at a CPC but the larger overall unit was quite heavy and after being put into a packing case, was just too big for me to transport conveniently. Another option is the Meade, the dual-fork mount seeming to be a smaller package than the Celestron. But, as Bigzmey wrote above, the OTA and mount are a dedicated package, and it is a heavier unit than a separate OTA and mount. If you ever wanted to use an equatorial mount your OTA will not be easily, if at all, removable from the fork mount.

One of the issues with the 8SE is the tripod, which is not all that sturdy. Someone gave me a much heavier tripod and I adapted the base of the SE mount to fit and it makes a big difference. Someone once suggested hanging a gallon jug of water under the stock tripod to help steady it.

As to the focusing, I put an oversize knob on mine, about 2 inches in diameter or so, and that helps a lot. Scopestuff sells them (http://scopestuff.com/#Machined%20Things) but I also seem to remember someone made one from a plastic jar lid or something like that. (I have machine tools so I make one from aluminum.)

So in the end, I'm keeping the SE; the issues with the mount aren't severe enough to upgrade and the focusing knob and heavy tripod make a significant difference.

As to eyepieces, you don't buy based on barrel diameter; you buy the eyepiece based on the focal length and the field of view, which, in turn, determines the barrel diameter.

Finally, for lots of good info on the NexStar scopes, see this site: https://www.nexstarsite.com

[Flyhigh7]

Bigzmey makes some excellent points that I need to consider as did gregl. The idea of a water jug to stabilize the 8SE mount is excellent. Just don't bump the jug or it will oscillate till you steady it.

I was leaning toward the CPC 800 until reading the points made by Bigzmey. I have also been looking at the
EQ mounting Advanced VX 8" EdgeHD and I do like the Evolution Series Scopes also. My 6 inch Reflector had an EQ mount and it was pretty stable though it didn't track perfectly over long periods.

I almost talked myself into going 9.25 but I ran a few tests at the gym this morning to determine how easy lifting the extra weight will be and though I can lift it a few of you have made excellent points about why lighter is better as the heavier weight to lug around might keep the thing in storage.

I read a review of the Evolution that said it is not a good scope for astro-photography though it didn't say why so i find that hard to believe and though my primary use is NOT for photography though I eventually dabbled in it with the 6". I saw a UTUBE video of the Evolution 8 and it is very light and I love the build in battery.

So many options. And then there are the Dobsonians! Yikes. By time I pull the Trigger I'll be bald!

[Ylem]

Bigz makes some excellent points about the CPC package, I lived through a "Forkectomy" once, not exactly fun.

My beloved Celestar finally gave up it's last ghost and had to fit it with radius blocks and dovetail.

The Evolution looks decent and has been on the market for a few years, any bugs should be out of it's soul by now

[Bigzmey]

Bigzmey makes some excellent points that I need to consider as did gregl. The idea of a water jug to stabilize the 8SE mount is excellent. Just don't bump the jug or it will oscillate till you steady it.

I was leaning toward the CPC 800 until reading the points made by Bigzmey. I have also been looking at the
EQ mounting Advanced VX 8" EdgeHD and I do like the Evolution Series Scopes also. My 6 inch Reflector had an EQ mount and it was pretty stable though it didn't track perfectly over long periods.

I almost talked myself into going 9.25 but I ran a few tests at the gym this morning to determine how easy lifting the extra weight will be and though I can lift it a few of you have made excellent points about why lighter is better as the heavier weight to lug around might keep the thing in storage.

I read a review of the Evolution that said it is not a good scope for astro-photography though it didn't say why so i find that hard to believe and though my primary use is NOT for photography though I eventually dabbled in it with the 6". I saw a UTUBE video of the Evolution 8 and it is very light and I love the build in battery.

So many options. And then there are the Dobsonians! Yikes. By time I pull the Trigger I'll be bald!

This is paralysis by analysis, we all been there.

It is not just the Evolution but generally AltAz mounts considered not as good for AP as EQ mounts. This is because even though AltAz GoTo track the target they don't correct for sky rotation, which limits the length of photo exposure you can do with AltAz.

I believe there is now software processing to account for that rotation, but still EQ mounts offer simpler solution for AP. On the other hand AltAz mounts are more convenient to use for visual observing.

I have both 8" and 9.25" SCTs. 9.25" is definitely substantially larger and heavier. Still, I can carry and lift either with comfort. One consideration is that because 9.25" is larger and heavier it requires different class of mounts to support it. So, there will be added cost and weight for heavier mount.

As for DOBs they are great for visual observing but even more limited for AP than AltAz mounts. They offer more aperture for the money and stable observing platform, but are larger and heavier than folded optical systems like SCTs.

[Flyhigh7]

"This is paralysis by analysis, we all been there." oh boy did you peg it Bigzmey! LOL

Kind of leaning now toward the Evolution 8. I like the internal Battery, Weight, simplicity, but I think I won't go for the Edge HD version instead using that money to buy a good 2" Diagonal, a 2 or 2.5X Barlow, and a few 2" eyepieces at each magnification extremes. So it's going to be up to Bigzmey to make a stronger case for the Edge HD optics as he knows the differences. I hate that Celestron's product Specs give the Standard Evolution and the Edge HD Evolution the same tube specs as far as light gathering capabilities. If the optics are better in the HD it should be a little brighter, though I know that the biggy about the Edge HD is the improvement at the edges of the view and that seems more important for AP but not sure about live viewing which is my priority.

So new Question about accessories if I'm going to get the 2" Diagonal, should I go for a 1.25" or 2" Barlow considering I will more than likely purchase 2" eyepieces over the 1.25s. You guys have talked so highly of the 2" over the 1.25" views and I read that going 2" actually delivers more light thus more detail to the wider view. Sucks that Celestron doesn't offer an option that is 2" right out of the back with a few 2" eyepieces.

Soon I'll be looking for eye piece recommendations but I have seen those recommendations already on this great forum.

I hope to plan this out so what ever accessories I decide to purchase, I will purchase them the same day I buy the Scope.

You guys are great. Thanks!

[Bigzmey]

Going with plain 8" SCT is a sensible solution. My plain 8" SCT was my first light bucket and I happily used it for several years before stepping up to 9.25" Edge. But I still use 8" SCT because it is a nice grab and go option.

Evolution will come with 1.25" prism diagonal and a couple of EPs. Before dropping $$ on EPs, diagonal, etc (don't warry you will spend plenty eventually ) I suggest to start observing with starter EPs and see what you like and don't like. This will help you to make better decision for the upgrades.

Once you get to the point of selecting 2" diagonal don't go for SCT diagonals. The adapter they use for SCT attachment has aperture smaller than full 2" EP aperture so you will introduce more vignetting to the system. Instead you should pick a good quality 2" visual back and good quality diagonal with 2" nosepiece.

[JayTee]

If you do buy the 8-in OTA regular or hd. Please reconsider the AVX mount. You are putting a scope on a mount that will take it right to its limit of what it can handle. This is only important if you plan on doing AP. When the mount is under this kind of load you wind up throwing away a lot of images because the mount typically can't track smoothly enough all the time. I know this to be true because I own an AVX mount.

Look for the class of mount like the Celestron CGX, or the iOptron HEQ45 or other similar mounts whose payload capacity is in the 40 pound category.

[Flyhigh7]

Now i'm a bit confused. I said I was leaning toward the Evolution 8". Is that what Bigzmey is referring to when he says "8 SCT"? Probably but I'm still learning the lingo. And is this what Jaytee is referring to when he says "8-In OTA"? If so it is my understanding that the mount for the Evolution 8 is very good and is the same as the evolution 9.5 but it is the 9.25 that almost exceeds the mount capabilities. So I'm thinking I would have some room for addons with the Evolution 8 and I like that mount cuz of the built in battery.

The Diagonals I considering is the 2" Baader BBAS Star Diagonal or the less expensive Celestron 93573 Dialectic 2" Diagonal as I believe both of these with fit directly into the back of the EV 8 though I'm just not sure yet if I'll have clearance with the mount if the tube is pointing straight up.

Good advice to wait and see what I like in eyepieces but I've done that about 40 years ago with a 6" Reflector and a big investment in good eyepieces. This time I was planning on going with the recommendations of you guys who have a ton more experience than I do with an 8" tube f10. I really just figure I need a good quality eyepieces with 1 for lowest mag, one for high mag as the EV comes with intermediate mags. Then get the same with wide angle and maybe a little different focal lengths. Then slowly decide on what others I may want to use.

So what do I want to use the scope for: Mostly visual. I won't get into AP for a few years if I do. I'd like to look at the planets again, deep stuff like star clusters (love those tight Closed clusters looking like a giant glittering diamond in the sky), Nebulas, Galaxies, and double stars. I've seen some of this with the 6" before I sold it when I got married. I expect the 8" will show enough more detail than the 6" to make this investment worth it plus there is a lot of stuff I couldn't find with the 6" so there is so much I'll be seeing for the first time with the 8".

Thanks guys!

[Bigzmey]

When we say 8" SCT it means just the telescope itself ( telescope tube no mount). OTA which stand for optical tube assembly means just that.

When I have purchased my 8" SCT I did not buy the package just the telescope OTA. Since than I have used it on several different mounts.

Unfortunately, I don't have hands-on experience with Evolution mount.

2" Baader BBHS Star Diagonal is a great diagonal. I use it on my SCTs. I went through several diagonals on my 8" SCT and the BBHS is the best by far.

To attach it to the telescope I recommend

Baader 2" SCT ClickLock Eyepiece Adapter / Visual Back (with 2" SCT Thread) # CLSC-2 2956220

https://agenaastro.com/baader-2-sct-cli ... hread.html

[Flyhigh7]

Thanks Bigzmey. I read that the Baader BBAS connects directly to the back of the OTA so would I still need the visual back? And just to show you how dumb I can be, exactly what is the visual back? Don't believe I had one on the 6" Reflector.

[OzEclipse]

Hi Flyhigh,

I used to have a 6" Reflector so I wonder how much more light will an 8" collect than the 6". Wonder if there is a formula for that.

It's a simple ratio of the area of each mirror. You don't have to go the full pi R squared, you can just ratio the squares of the two mirror diameters and you'll get the same ratio.

8 * 8 = 64
6* 6 = 36

64 ÷ 36 = 1.77

So the C8 collects 77% more light than your 6" newt. This may seem like a lot but it isn't.
1. One stellar magnitude is 2.512 so this represents less than one stellar magnitude gain.
2. However, you also lose a little bit of light through the front corrector
3. The central obstruction is bigger in an SCT than a newt so you lose some more light.

The formula doesn't take account of the transmission loss and the central obstructions.

So you may not notice much difference between your 6" Newt and the 8" SCT.
If you are looking for a noticeable increase in light grasp over a 6" and you can afford it, and carry the weight, go for a C11 or Meade 10" or a 10" or 12" collapsable Flex dob, and you will really see a big difference in light grasp.

Another important point is that observing under a dark sky is worth more than aperture so don't ignore portability. You can see a lot more with an 8" scope under dark country skies than a 12, 14 or even 16 inch scope under badly light polluted city skies.

Thanks Bigzmey. I read that the Baader BBAS connects directly to the back of the OTA so would I still need the visual back? And just to show you how dumb I can be, exactly what is the visual back? Don't believe I had one on the 6" Reflector

Photographic mode: the reducer screws directly to the rear thread. I believe that visual back on an SCT is basically a screw on eyepiece tube.

Joe

[Bigzmey]

Thanks Bigzmey. I read that the Baader BBAS connects directly to the back of the OTA so would I still need the visual back? And just to show you how dumb I can be, exactly what is the visual back? Don't believe I had one on the 6" Reflector.

SCT baffle (the tube where the light from the scope comes out) is threaded. So, in order to attached diagonal you have two options. Some like Baader BBHS has threads matching the baffle. This results in semipermanent attachment. The disadvantage is that it takes effort to attach and remove the diagonal and you can't adjust diagonal angle easily.

The more common way to attach the diagonal is the visual back. This is adapter which is threaded to connect to the baffle, and has a standard 1.25" or 2" holder on the other end to accommodate nose of diagonal. It makes changing or adjusting diagonal much easier.

I have tried both ways and recommend to use the visual back. SCT typically come with 1.25" visual back as a part of the package.

[Bigzmey]

So you may not notice much difference between your 6" Newt and the 8" SCT.
If you are looking for a noticeable increase in light grasp over a 6" and you can afford it, and carry the weight, go for a C11 or Meade 10" or a 10" or 12" collapsable Flex dob, and you will really see a big difference in light grasp.

I respectively disagree. I typically deploy 6" refractor (which does not have the central obstruction and in theory should collect more light than a 6" newt) and 8" SCT side by side, and the SCT goes noticeably deeper. I can resolve faint DSOs which are not visible in 6" frac, see fainter stars and split tighter doubles. So 8" from 6" is worthy upgrade. Of cause getting larger aperture give you more light grasp but above 8" scopes become large and heavy. 8" SCT is amazingly lightweight and compact for it light grasp.