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Meade lx65 8" (ACF) vs Celestron 8se
#1
Meade lx65 8" (ACF) vs Celestron 8se
We are thinking about getting a telescope again. I've pretty much got it narrowed down to either a Meade lx65 8 ACF or a Celestron 8se. Anyone with experience with both have a preference one way or the other? I'm leaning towards the Meade because of the Advanced Coma-Free (ACF) catadioptric-variant optical path.
Save a life. Adopt a greyhound.
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#2
RE: Meade lx65 8" (ACF) vs Celestron 8se
(November 20, 2020 at 1:50 pm)popeyespappy Wrote: We are thinking about getting a telescope again. I've pretty much got it narrowed down to either a Meade lx65 8 ACF or a Celestron 8se. Anyone with experience with both have a preference one way or the other? I'm leaning towards the Meade because of the Advanced Coma-Free (ACF) catadioptric-variant optical path.

I don't know a damn thing about telescopes but I think Coma-Free has to be a selling point.   Cool
 “Two things are infinite: the universe and human stupidity; and I’m not sure about the universe.” ~Albert Einstein                                                 
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#3
RE: Meade lx65 8" (ACF) vs Celestron 8se
It just means you can't get Fox News.
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#4
RE: Meade lx65 8" (ACF) vs Celestron 8se
If I spend money on optics it has to have a set of crosshairs....


Smile
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#5
RE: Meade lx65 8" (ACF) vs Celestron 8se
(November 20, 2020 at 1:50 pm)popeyespappy Wrote: We are thinking about getting a telescope again. I've pretty much got it narrowed down to either a Meade lx65 8 ACF or a Celestron 8se. Anyone with experience with both have a preference one way or the other? I'm leaning towards the Meade because of the Advanced Coma-Free (ACF) catadioptric-variant optical path.

First, I don't think you would go wrong with either. Both are reputable brands that give good quality. The Coma-free aspect of the Meade is very similar to the optical coatings of the Celestron, so again, that isn't as big of a deal as you might think.

So, the optics are almost identical. That means we turn to the mount. Too many people forget this as a critical part of a telescope.

Again, both seem to be essentially the same. The Celestron has holes for eyepieces, which is a nice thing. The mount on the Celestron does look somewhat flimsier. Again, i am sure it is sufficient, but that is a consideration.

Another question is what you intend to use your scope to do. The focal length on these points to looking at small objects like planets or planetary nebula as opposed to galaxies or the broader nebula like Orion or Eagle. Make sure this is what you want from your scope.
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#6
RE: Meade lx65 8" (ACF) vs Celestron 8se
(November 20, 2020 at 2:19 pm)polymath257 Wrote: Another question is what you intend to use your scope to do. The focal length on these points to looking at small objects like planets or planetary nebula as opposed to galaxies or the broader nebula like Orion or Eagle. Make sure this is what you want from your scope.

I was looking at these two because they were the biggest mirrors in my price range. The thought process there was more light = more desirable. I wanted to us it for both planets and larger objects, but this sounds like neither of these are good solution for that.
Save a life. Adopt a greyhound.
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#7
RE: Meade lx65 8" (ACF) vs Celestron 8se
(November 20, 2020 at 3:34 pm)popeyespappy Wrote:
(November 20, 2020 at 2:19 pm)polymath257 Wrote: Another question is what you intend to use your scope to do. The focal length on these points to looking at small objects like planets or planetary nebula as opposed to galaxies or the broader nebula like Orion or Eagle. Make sure this is what you want from your scope.

I was looking at these two because they were the biggest mirrors in my price range. The thought process there was more light = more desirable. I wanted to us it for both planets and larger objects, but this sounds like neither of these are good solution for that.

Yes, larger objective=better is true all other things being equal. But there are trade offs. The larger focal length will produce higher magnification for a given lens. This has good aspects and bad aspect.

Planets and planetary nebula are small in angular size. Close by galaxies, like most of those in the Messier catalog, tend to be *large* in angular size. But, while planets tend to be pretty bright, galaxies tend to be dim and 'cloudlike'.

If you magnify a planet, you get a larger image which *often* means you see more detail (see below). if you magnify a galaxy, you get a larger area of haziness that s just as dim. If the galaxy in question is already large (like Andromeda or the Whirlpool), this is NOT an advantage. You will generally see more at lower magnifications, which have a wider field of view.

Next, magnification has its own issues. The problem is that we look through an atmosphere and that atmosphere often has a lot of turbulence in it. This is known as 'seeing'. A high magnification only magnifies that turbulence and you don't actually get to see more.

In general, don't expect to use a magnification above 350x except *very* rarely. The seeing just usually doesn't allow such to be useful. Oh, but when it does!

When I go out to observe, I generally stay in the 100x to 200x range of magnification, only pushing above that if the conditions are excellent.

In practice, this means that, unless you have been to a star party and seen what a telescope can do, you are likely to be disappointed at first in your views of planets. Jupiter is easy and fun. Saturn's rings are easy. But getting details in the clouds of Jupiter takes very good seeing. Seeing the Cassinni division in Saturn's rings is usually going to be possible, but don't expect detail in the clouds of Saturn.

Mars is HARD. Period. You can see a polar cap and maybe some vague dark markings. Don't expect anything else. Even in professional telescopes, it is hard.

Next, are you planning to do photography? if so, make sure your mount is absolutely stable and you have a quality camera that can take time exposures. Without photography you are very unlikely to get many colors from nebulae (other than a blue-green). i was able to see color in the Orion nebula using a 'yard scope' (36" mirror), but that was what it takes visually.

Finally, and this is a*very* important, what are you spending on your lenses? I would plan to spend as much on them as the scope itself. The wider the field of view, the better (but you will pay for 82 degrees!). Don't do anything under a Plossl. Get a variety of sizes and watch what the magnification will be from each.

To find magnification from a lens, take the focal length of your scope (2300 in the cases you are considering) and divide it by the focal length of the eyepiece. So, if you have a 25mm eyepiece, and a 2300mm focal length, the magnification will be 2300/25=92x.

Eyepieces below 5mm are usually difficult to use: they are narrow. A *very* high quality eyepiece can overcome this to some extent by having a wider field of view. Expect to pay for this luxury.

Sorry to make this a book. There are a lot of variable and beginners make a lot of mistakes. If you can (and I know COVID may not allow this), find a star party and look through some scopes. That is the best way to find out what is possible and what you want to see.
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#8
RE: Meade lx65 8" (ACF) vs Celestron 8se
(November 20, 2020 at 4:41 pm)polymath257 Wrote: Sorry to make this a book. There are a lot of variable and beginners make a lot of mistakes. If you can (and I know COVID may not allow this), find a star party and look through some scopes. That is the best way to find out what is possible and what you want to see.

Thank you for taking the time to write the book. I really do appreciate it.

I already understood some of what you wrote like how to calculate magnification. Even the part about to much magnification being a bad thing. What I don't understand is how that applies to real world viewing. For example what is too much for one of these scopes for different objects the moon, Saturn, Jupiter, and Andromeda?

As far as photography goes I have a decent FX format Nikon, but I was also looking at one of the Celestron 5MP imagers. I think they are limited to like a 30 second exposure though so I'm not sure which way I want to go yet.

I was also looking at one of the Celestron Eyepiece and filter kits. They run about $170 retail and come with:

32mm Plossl Eyepiece - 1.25”
17mm Plossl Eyepiece - 1.25”
13mm Plossl Eyepiece - 1.25”
8mm Plossl Eyepiece - 1.25”
6mm Plossl Eyepiece - 1.25”
2X Barlow Lens - 1.25”
#80A Blue Filter - 1.25”
#58 Green Filter - 1.25”
#56 Light Green Filter - 1.25”
#25 Red Filter - 1.25”
#21 Orange Filter - 1.25”
#12 Yellow Filter - 1.25”
Moon Filter - 1.25”

on top of the eyepieces that come with the telescopes. From what you said I'll probably want to upgrade later, but I'm hoping that will be enough to get us started.
Save a life. Adopt a greyhound.
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#9
RE: Meade lx65 8" (ACF) vs Celestron 8se
(November 20, 2020 at 5:40 pm)popeyespappy Wrote:
(November 20, 2020 at 4:41 pm)polymath257 Wrote: Sorry to make this a book. There are a lot of variable and beginners make a lot of mistakes. If you can (and I know COVID may not allow this), find a star party and look through some scopes. That is the best way to find out what is possible and what you want to see.

Thank you for taking the time to write the book. I really do appreciate it.

I already understood some of what you wrote like how to calculate magnification. Even the part about to much magnification being a bad thing. What I don't understand is how that applies to real world viewing. For example what is too much for one of these scopes for different objects the moon, Saturn, Jupiter, and Andromeda?

As far as photography goes I have a decent FX format Nikon, but I was also looking at one of the Celestron 5MP imagers. I think they are limited to like a 30 second exposure though so I'm not sure which way I want to go yet.

I was also looking at one of the Celestron Eyepiece and filter kits. They run about $170 retail and come with:

32mm Plossl Eyepiece - 1.25”
17mm Plossl Eyepiece - 1.25”
13mm Plossl Eyepiece - 1.25”
8mm Plossl Eyepiece - 1.25”
6mm Plossl Eyepiece - 1.25”
2X Barlow Lens - 1.25”
#80A Blue Filter - 1.25”
#58 Green Filter - 1.25”
#56 Light Green Filter - 1.25”
#25 Red Filter - 1.25”
#21 Orange Filter - 1.25”
#12 Yellow Filter - 1.25”
Moon Filter - 1.25”

on top of the eyepieces that come with the telescopes. From what you said I'll probably want to upgrade later, but I'm hoping that will be enough to get us started.

For the moon and planets, the issue with magnification isn't the object you are looking at as much as the atmosphere of the Earth. It is rare that you can push above the 300-350x level and see anything. If the Earth's atmosphere allows it, though, go for it. Use the moon filter on the moon to reduce brightness: there is a LOT to see there and it changes from day to day as the terminator moves.

Galaxies are another thing. What they can tolerate depends on the specific galaxy (going above 200x for Andromeda is likely to be counter-productive). And, for example, M101 is *big*. But good luck finding it except on a dark night, especially if you have magnification too high. Some galaxies are actually easier with binoculars. By the way, have you considered a good pair of binocs? Fully multicoated, not too heavy; probably 7x50 or 10x50?

With a 2300mm focal length, that 6mm lens won't get much use. Furthermore, you can just use the 13mm and the Barlow lens and get just about the same result. You will *never* use the Barlow with the 6mm except to verify that you can't see anything. The same can be said for the 8mm; the 17mm and the Barlow will do just as well. So, if you can (and you may not be able to), I would drop those two lenses.

In their place, I would go for a 25mm and a 20mm. You will find that these will be your workhorses, along with the 17mm.

One of the joys of this hobby is learning what all this means in real world viewing.

Do you know the trick for checking how good the seeing is? Turn your scope on a nice, bright star. Focus on it until it is as close to a pinpoint as you can get. Then turn a bit out of focus. You will get a white disk of light, but on closer observation, you will see a series of rings in that disk. You will actually be able to see how good the atmosphere is by how sharp those diffraction lines are. The scopes you are looking at aren't subject to tube currents, but those show up as little swirls floating across those rings.

My experience with photography is rusty, so I don't have anything to say about your choices. I did most of mine with film (just to show how old I am).
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#10
RE: Meade lx65 8" (ACF) vs Celestron 8se
(November 20, 2020 at 1:50 pm)popeyespappy Wrote: We are thinking about getting a telescope again. I've pretty much got it narrowed down to either a Meade lx65 8 ACF or a Celestron 8se. Anyone with experience with both have a preference one way or the other? I'm leaning towards the Meade because of the Advanced Coma-Free (ACF) catadioptric-variant optical path.

Here is a good discussion about them Cloudy Nights

I'm not an expert on either of these, but yes I would go for the ACF.  Celestron has their Evolution HD or Edge HD, but they are more expensive (but I understand that they are very good!)

For the price, I would go with the Meade.  If you are willing to pay more, you have more options.

Also realize that you are going to need eyepieces, and good ones are expensive. Also, consider what you are going to do about dew (heaters, tube extension, 12V hair dryer).

BTW, I've never owned a catadioptric telescope. I currently own a large refractor and a large Dobsonian.

(November 20, 2020 at 5:40 pm)popeyespappy Wrote:
(November 20, 2020 at 4:41 pm)polymath257 Wrote: Sorry to make this a book. There are a lot of variable and beginners make a lot of mistakes. If you can (and I know COVID may not allow this), find a star party and look through some scopes. That is the best way to find out what is possible and what you want to see.

Thank you for taking the time to write the book. I really do appreciate it.

I already understood some of what you wrote like how to calculate magnification. Even the part about to much magnification being a bad thing. What I don't understand is how that applies to real world viewing. For example what is too much for one of these scopes for different objects the moon, Saturn, Jupiter, and Andromeda?

As far as photography goes I have a decent FX format Nikon, but I was also looking at one of the Celestron 5MP imagers. I think they are limited to like a 30 second exposure though so I'm not sure which way I want to go yet.

I was also looking at one of the Celestron Eyepiece and filter kits. They run about $170 retail and come with:

32mm Plossl Eyepiece - 1.25”
17mm Plossl Eyepiece - 1.25”
13mm Plossl Eyepiece - 1.25”
8mm Plossl Eyepiece - 1.25”
6mm Plossl Eyepiece - 1.25”
2X Barlow Lens - 1.25”
#80A Blue Filter - 1.25”
#58 Green Filter - 1.25”
#56 Light Green Filter - 1.25”
#25 Red Filter - 1.25”
#21 Orange Filter - 1.25”
#12 Yellow Filter - 1.25”
Moon Filter - 1.25”

on top of the eyepieces that come with the telescopes. From what you said I'll probably want to upgrade later, but I'm hoping that will be enough to get us started.

If you stay with the hobby, you will probably sell that eyepiece kit and get something better.  You might want to go into an astronomy shop and ask about eyepieces.

Honestly, you only need 3 eyepieces to start.  A 30mm to 40mm for low power.  Then something in the 17-22mm range for medium power.  Then something smaller like 10 or 13 for planets and perhaps globular clusters.  You will use the low-power when finding object, and then bump up to the medium power to do most observations. 

A planetary eyepiece is really only good for planets and sometimes a tight globular or planetary nebula.  You could use even more magnification on planets -- like that 6 or 8mm, but most nights it will just look like a fuzzy mess because of atmospheric seeing (or your telescope not being cooled down yet).

Eyepieces come with different apparent field of view (AFOV).  This is where the expense comes in.  Wide AFOV eyepieces let you see more of the sky at the same magnification.  I am an AFOV junkie, but my eyepiece collection costs a few ounces of gold.  Large AFOV can be a bad thing if the eyepiece is an old cheap design.  You will probably want to go with something in the 55 to 70 degree range.  Smaller is just too small.  Larger and good quality may cost too much (unless you limit yourself to just a few eyepieces).

Some colored filters can help with planetary detail, but if they are poor quality, they will be useless.  These filters serve no other purpose (well, a moon filter can be useful, but I've never bothered).  I wouldn't bother with them.

Here is some telescope math.

Exit-Pupil = eyepiece-focal-length / f-ratio.  Your f-ratio is 10.  So,

Exit-Pupil = eyepiece-focal-length / 10
Eyepiece-Focal-Length = 10 * Exit-Pupil


Low Power Exit Pupil = 3.5 -> 6 mm .   That means 35 to 60 mm eyepiece.  In reality, choose 30 to 40.  Anything that has a large field-stop and is over 30 mm is good.

Medium Power Exit Pupil = 1.8 -> 3.5 mm.  That means 18 to 35 mm eyepiece.

High Power Exit Pupil = 0.5 to 1.8 mm .  That means 5 to 18 mm eyepiece.  Something like 5 to 8mm is only for planets. Really, 5 is too high a power on anything but the best optics with excellent nights of seeing.  A compromise of 10 to 13 mm might be slightly low for planets but still nice, but could be useful on some star clusters.

(November 20, 2020 at 3:34 pm)popeyespappy Wrote:
(November 20, 2020 at 2:19 pm)polymath257 Wrote: Another question is what you intend to use your scope to do. The focal length on these points to looking at small objects like planets or planetary nebula as opposed to galaxies or the broader nebula like Orion or Eagle. Make sure this is what you want from your scope.

I was looking at these two because they were the biggest mirrors in my price range. The thought process there was more light = more desirable. I wanted to us it for both planets and larger objects, but this sounds like neither of these are good solution for that.

If you haven't done astronomy before, I would join a local astronomy club, or go a star party (wrong time of year for that, though).  Most new telescopes don't get used more than a few times, because the owners can't find anything in the sky, or the telescope doesn't give them the views they hoped for.

These are fine entry-level scopes.  You should be able to see a lot with them.  But I hope you have realistic expectations, and want to explore.  These can connect you to the universe when you get to know what is up there.
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