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Celestron Edge HD vs Meade ACF [Optical Properties]

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#26 Eddgie

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Posted 15 July 2019 - 07:52 AM

Again we are back to SCT bashing even though the op is asking something else.

 

There are many logical errors in your argument. Here is one.

 

Some random Russian website tested Meade SCTs of various vintages and found variable quality. But somehow you managed to extrapolate these results to all new SCTs including Celestrons. 

 

Lets be clear, this tells you nothing about consistency of recent vintages of SCTs. Further even if recent vintages of SCTs have variability it tells you nothing about the standard deviation. For example are all at least diffraction limited? If so, that is quite an excellent outcome since that means you are limited by seeing rather optical quality. What’s wrong with that?

 

In my 20+ years of observing I can count on my fingers evenings where seeing was good enough to tell the difference in optical quality better than diffraction limited in apertures > 8”. Even then it was not conclusive.

 

Do you realize the kind of seeing you need to tell optical quality of scopes above and beyond diffraction limited with aperture 8” and above? As an experienced observer you should know this. 

It is relevant to the OPs question.  He asked which would be better, and it would be impossible to answer it in a blanket kind of way because the comparison would depend on the specific two telescopes being compared.    

 

My post then goes on to substantiate my claim that there are some pretty bad telscopes out there and if his comparison included one of these, it would loose not because of the design, but rather because of the quality to which it is made.

 

You can choose to believe that the Russians don't know what they are doing, but I can just as easily point to other tests elsewhere that show some pretty bad SCTs (and the worst ones tend to be Meades). 

 

Ignore the tests though if you like.   I report what I see, but I don't force anyone to do anything with that data and if they choose to discredit that data with only their subjective evaluations to stand on, I am really OK with that.  

 

Lots and lots of tests out there though, and I encourage people to go out and study some on their own.

 

http://r2.astro-fore...astrofotografie

 

http://fidgor.ru/Observers/test.html

 

http://teleskop-spez...-teleskope.html

 

It would unfair to expect Meade and Celestron to produce every scope to the high levels of quality that someone like TEC, AP, or Intes Micro can provide.   The amount of labor that goes into the scopes that these top tier companies make is many multiples of times greater than is allowed for mass market products.  Often, final finishing is done by hand, and many hours of labor can be expended in search of perfection.   Celstron and Meade simply could not exist if they had to make scopes to that level of quality because there is not a large enough market to buy them at the price they would have to charge. On the whole, I would say that they make mostly good scopes, but quality varies considerably. 


Edited by Eddgie, 15 July 2019 - 07:56 AM.

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#27 Eddgie

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Posted 15 July 2019 - 08:24 AM

And if I am going to bash, I would reserve that for US consumers that have no interest in learning to properly evaluate optical quality, won't read a book on it, and content themselves with subjective opinions of others that won't do these things either.

 

In the US, we get "Ed Ting says the C9.25 is special" and for a decade, people believe that the C9.25 they buy is ground and polished with fairy dust, but I can point to numerous tests that show that this is simply urban legend.

 

US Consumers will buy anything if it is cheap enough, and that says it all.   


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#28 Winks

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Posted 15 July 2019 - 09:49 AM

I have both 8" models. The Meade is an early LX200-R 8" and the Edge is, well, the Edge.  Only modifications to either is a Moonlite focuser and Bob's knobs on the Meade and TempEst coolers of the Edge.  The Meade had some image shift. The Moonlite fixed that and is also a joy to use. The Meade wieghs more than the Edge. But, it holds collimation better.  Seems I am always having to tweak the Edge a bit and I never have to touch the Meade.

 

The Meade was the forked LX200.  I had purchased this second hand from Starizona and they said the optics were excellent.  And so they are.  Frankly, I can't tell the Meade and the Edge apart visually.  I did have the Edge with me recently when I was in the Gunnison, Colorado area at 9000 feet elevation.  Incredible views and absolutely flat with no coma across the field (I hate coma). I wish I had also taken the Meade with me to compare.  But only so much room.  On the other hand, I was just out with the Meade the other night here in Arizona and Saturn was fantastic.  So, I call it a wash with the optics.  Both are the best I've used as far as SCTs go. (We are talking back to about 1976)

 

What the downsides of each?  The Meade was originally a full forked LX200.About 5 years after I purchased it, the electronics crapped out.  Meade said there was nothing they could do as the electronics had changed over the intervening years.  All I could do was purchase a new LX200 base and forks - at a very outrageous price. That is why the Meade is now unforked and resides on my iOptron 45 Pro - which it shares with the Edge (although the Edge also sits on a hypertuned AVX with Starsense and works very well on that).  Works fine there.  Never had any mechanical issues with the Meade.  It is very well built.

 

Downside on the Edge? Well, it you look up previous posts by me, you'll find a big thread where I had an extremely odd problem with the Edge.  All the star images were literally donuts.  Well focused donusts, but donuts nonetheless.  Countless hours on the phone with Celestron yielded no help whatsoever. Clueless.  After many nights of trying to isolate the cause, I finally figured it out.  It was the vibrations through the ground from my pool pump which were causing the tube with the corrective lenses in the Edge to wobble in a circular manner. It was an almost perfect torus.  The whole process, while frustrating at first, actually became a fun and interesting exercise in isolating a variable. Took me back to my college physics days. So, it turns out the Edge is very susceptible to vibrations - I don't know it it is a particular resonance vibration or a high frequency vibration or what. But, certain vibrations will cause the internal lense holding tube in the Edge to wobble.  Now, when I want to use the Edge I have to make sure the pool pump is off.  By the by, I view from a concrete pad about 15 feet from my pool pump which also sits on a small concrete pad. The only common ground for both is the ground.  The Meade is totally unaffected by vibrations.

 

That all stems from the different ways Meade and Celestron correct coma in their designs.  Meade corrects at the front end and Celestron corrects at the back end. Meade uses a different secondary and corrective plate design than a regular SCT and Celestron uses corrective lenses (if memory serves, Richard Buchroeder had an article for this way back in the 80s or early 90s in Gleanings for ATMs in S&T).  Both work. The Celestron does correct better for a flat field but my eyes cannot see it and I presume it has a more pronounced effect when imaging.

 

I am a visual observer. Don't do imaging and no plans to begin.  Frankly, though, if forced to pick between one or the other, I would keep the Meade. I love the Moonlite focuser. I like the solid collimation.  But, those are small edges over the Edge. Visually, no difference. The real kicker for me which puts the Meade over the Edge is the vibration issue. I do worry that at some point the tube with the lenses in the Edge may start to wobble even more and I have to make sure to turn my pool pump off when using the Edge. 


Edited by Winks, 15 July 2019 - 09:52 AM.

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#29 Astrojedi

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Posted 15 July 2019 - 11:04 AM

It is relevant to the OPs question.  He asked which would be better, and it would be impossible to answer it in a blanket kind of way because the comparison would depend on the specific two telescopes being compared.    

 

My post then goes on to substantiate my claim that there are some pretty bad telscopes out there and if his comparison included one of these, it would loose not because of the design, but rather because of the quality to which it is made.

 

You can choose to believe that the Russians don't know what they are doing, but I can just as easily point to other tests elsewhere that show some pretty bad SCTs (and the worst ones tend to be Meades). 

 

Ignore the tests though if you like.   I report what I see, but I don't force anyone to do anything with that data and if they choose to discredit that data with only their subjective evaluations to stand on, I am really OK with that.  

 

Lots and lots of tests out there though, and I encourage people to go out and study some on their own.

 

http://r2.astro-fore...astrofotografie

 

http://fidgor.ru/Observers/test.html

 

http://teleskop-spez...-teleskope.html

 

It would unfair to expect Meade and Celestron to produce every scope to the high levels of quality that someone like TEC, AP, or Intes Micro can provide.   The amount of labor that goes into the scopes that these top tier companies make is many multiples of times greater than is allowed for mass market products.  Often, final finishing is done by hand, and many hours of labor can be expended in search of perfection.   Celstron and Meade simply could not exist if they had to make scopes to that level of quality because there is not a large enough market to buy them at the price they would have to charge. On the whole, I would say that they make mostly good scopes, but quality varies considerably. 

My point which you repeatedly keep ignoring is that you cannot use a 20 or 30 yr old OTA to evaluate the current gen products or make such broad generalizations.

 

What I would like to see is someone test 20+ 50+ EdgeHDs (to be statistically significant - assuming 1000+ OTAs, 85% confidence level, 10% margin of error) and then come up with a bell curve. I don’t really care about every SCT that has existed. When I buy a new car I don’t evaluate its performance based on a 20 yr old model.

 

And based on my experience of using / collimating ~25+ EdgeHDs is that all of them were diffraction limited or better. So as far as I am concerned this variable quality argument for newer SCTs is a complete myth. But if you show me scientific data otherwise then I will agree with you.

 

The mistake you are making is generalizing the results of these websites (which are not scientifically relevant at all) to any and all SCTs.


Edited by Astrojedi, 15 July 2019 - 12:13 PM.

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#30 rkelley8493

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Posted 15 July 2019 - 11:09 AM

I have both 8" models. The Meade is an early LX200-R 8" and the Edge is, well, the Edge.  Only modifications to either is a Moonlite focuser and Bob's knobs on the Meade and TempEst coolers of the Edge.  The Meade had some image shift. The Moonlite fixed that and is also a joy to use. The Meade wieghs more than the Edge. But, it holds collimation better.  Seems I am always having to tweak the Edge a bit and I never have to touch the Meade.

 

The Meade was the forked LX200.  I had purchased this second hand from Starizona and they said the optics were excellent.  And so they are.  Frankly, I can't tell the Meade and the Edge apart visually.  I did have the Edge with me recently when I was in the Gunnison, Colorado area at 9000 feet elevation.  Incredible views and absolutely flat with no coma across the field (I hate coma). I wish I had also taken the Meade with me to compare.  But only so much room.  On the other hand, I was just out with the Meade the other night here in Arizona and Saturn was fantastic.  So, I call it a wash with the optics.  Both are the best I've used as far as SCTs go. (We are talking back to about 1976)

 

What the downsides of each?  The Meade was originally a full forked LX200.About 5 years after I purchased it, the electronics crapped out.  Meade said there was nothing they could do as the electronics had changed over the intervening years.  All I could do was purchase a new LX200 base and forks - at a very outrageous price. That is why the Meade is now unforked and resides on my iOptron 45 Pro - which it shares with the Edge (although the Edge also sits on a hypertuned AVX with Starsense and works very well on that).  Works fine there.  Never had any mechanical issues with the Meade.  It is very well built.

 

Downside on the Edge? Well, it you look up previous posts by me, you'll find a big thread where I had an extremely odd problem with the Edge.  All the star images were literally donuts.  Well focused donusts, but donuts nonetheless.  Countless hours on the phone with Celestron yielded no help whatsoever. Clueless.  After many nights of trying to isolate the cause, I finally figured it out.  It was the vibrations through the ground from my pool pump which were causing the tube with the corrective lenses in the Edge to wobble in a circular manner. It was an almost perfect torus.  The whole process, while frustrating at first, actually became a fun and interesting exercise in isolating a variable. Took me back to my college physics days. So, it turns out the Edge is very susceptible to vibrations - I don't know it it is a particular resonance vibration or a high frequency vibration or what. But, certain vibrations will cause the internal lense holding tube in the Edge to wobble.  Now, when I want to use the Edge I have to make sure the pool pump is off.  By the by, I view from a concrete pad about 15 feet from my pool pump which also sits on a small concrete pad. The only common ground for both is the ground.  The Meade is totally unaffected by vibrations.

 

That all stems from the different ways Meade and Celestron correct coma in their designs.  Meade corrects at the front end and Celestron corrects at the back end. Meade uses a different secondary and corrective plate design than a regular SCT and Celestron uses corrective lenses (if memory serves, Richard Buchroeder had an article for this way back in the 80s or early 90s in Gleanings for ATMs in S&T).  Both work. The Celestron does correct better for a flat field but my eyes cannot see it and I presume it has a more pronounced effect when imaging.

 

I am a visual observer. Don't do imaging and no plans to begin.  Frankly, though, if forced to pick between one or the other, I would keep the Meade. I love the Moonlite focuser. I like the solid collimation.  But, those are small edges over the Edge. Visually, no difference. The real kicker for me which puts the Meade over the Edge is the vibration issue. I do worry that at some point the tube with the lenses in the Edge may start to wobble even more and I have to make sure to turn my pool pump off when using the Edge. 

Great answer waytogo.gif

I will also comment that I deforked my LX90 due to some issues with the Audiostar system. I had the same issues with my ETX125, the Audiostar is just too picky on how to work it. Example, if you choose "Galaxies & Nebulae" from the menu and select a target [let's say Bode's Galaxy], it will either slew in the wrong direction or do absolutely nothing. However, if you choose "Messier Objects" from the menu and select M81, it will point and center Bode's Galaxy without any issues. Another example, the initial alignment. If you slew too far in either direction while centering a star, alignment will fail. If you wait too long to center the target, alignment will fail. Too many variables can cause the alignment to fail or misalign.

On the other hand, the LX90 optical tube is very nice and produces great images. Jovian eclipses, Saturn's north pole hexagon vortex, dust lanes on Andromeda are all visible in this scope. I can also handle it very easily as it is not super heavy. I did put on some muscle since I first purchased it though sumo.gif

Anyways.. what I was really wanting to know was how the contrast, brightness, design of the Celestron Edge HD compares to the Meade ACF optics. I am not looking to purchase either anytime soon, just curious about the performance. Thanks for all the replies so far, great feedback applause.gif



#31 Astrojedi

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Posted 15 July 2019 - 11:23 AM

And if I am going to bash, I would reserve that for US consumers that have no interest in learning to properly evaluate optical quality, won't read a book on it, and content themselves with subjective opinions of others that won't do these things either.

 

In the US, we get "Ed Ting says the C9.25 is special" and for a decade, people believe that the C9.25 they buy is ground and polished with fairy dust, but I can point to numerous tests that show that this is simply urban legend.

 

US Consumers will buy anything if it is cheap enough, and that says it all.   

Again incorrect. Another bad generalization. Price based market subsegments exist in every country not just the US. Ironically the SCTs are actually very expensive in Europe / outside US due to the market structure. If they were priced similar to the US I feel the market would be a lot bigger.

 

I am a US consumer and I have read Suiter’s book which you keep regurgitating here. While very informative it does not have modeled diffraction patterns for newer SCTs.

 

Second, the C9.25 does have a better looking field due to lower  Spherochromatism than other SCT models. 

 

And scientific testing would reveal that the C9.25 also has a much smaller spot size in green due to the design vs. say the C8. The eye picks this up immediately. I think this is also why it appears to have less coma.

 

I notice quite a difference when using my 82deg 30mm with the C9.25 vs the C8. And I noticed this even before I understood the difference in design.


Edited by Astrojedi, 15 July 2019 - 12:15 PM.

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#32 rkelley8493

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Posted 15 July 2019 - 11:39 AM

And if I am going to bash, I would reserve that for US consumers that have no interest in learning to properly evaluate optical quality, won't read a book on it, and content themselves with subjective opinions of others that won't do these things either.

 

In the US, we get "Ed Ting says the C9.25 is special" and for a decade, people believe that the C9.25 they buy is ground and polished with fairy dust, but I can point to numerous tests that show that this is simply urban legend.

 

US Consumers will buy anything if it is cheap enough, and that says it all.   

 

Again incorrect. Another bad generalization. Price based market subsegments exist in every country not just the US. Ironically the SCTs are actually very expensive in Europe due to the market structure. If they were priced similar to the US I feel the market would be a lot bigger.

 

I am a US consumer and I have read Suiter’s book which you keep regurgitating here. While very informative it does not have modeled diffraction patterns for newer SCTs.

 

Second, the C9.25 does have a flatter field and less  Spherochromatism than other SCT models. I notice quite a difference when using my 82deg 30mm with the C9.25 vs the C8. And I noticed this even before I understood the difference in design. 

It's not that big of a deal.. Let's keep it friendly flowerred.gif

I think what Eddgie is trying to say is that an "assembly line" product isn't going to have the same consistency as a "hand crafted" product. Therefore it would be tough to judge two products equally based on a single observer's opinion, especially if there is a chance that some assembled products may be of better quality than others of the same product line. 



#33 TG

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Posted 15 July 2019 - 11:49 AM

I hear this about Celestron and Meade, but the bench tests I am seeing suggest that both still vary considerably in quality.


Maybe there are fewer real lemons though, and as long as it is decent optically the diffraction of the aperture and secondary will be the main limits to performance. At the price point though, no one should expect Meade or Celetron to produce every scope with a Strehl of .9 or higher.

My never ending search for bench tests has led me to the opinion that the bell curve for Celestron probably peeks around .92 which is nothing to sneeze at (and I would say absolutely in the "Good" category) so most will likely be somewhere in the .85 to .95 range, but until I go a few years without seeing a poor sample, I am going to make a guess that Meade and Celestron put together sets of optics that are diffraction limited, puts them in tubes, and sells them, with no particular effort made to ensure that they are any specific place on the quality bell curve. My bet is that by chance, some sets are excellent and some are poor, but most are Good. That is the way mass production works.

Example.. EdgeHD, which people somehow believe will have better optics than the standard SCT. Here is one with .934 Streal, which by the way, is pretty much right at where I estimate the bell curve to peak. Now this is a good scope but as I said, people think that the EdgeHDs are supposed to have better quality, and this one is pretty much in the middle of the quality range.... http://fidgor.ru/Obs...2/test_369.html


Just a little nit: coma should have been subtracted before calculating the final result. I suspect doing this would have pushed up the Strehl from decent to very good.
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#34 Astrojedi

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Posted 15 July 2019 - 11:50 AM

It's not that big of a deal.. Let's keep it friendly flowerred.gif

I think what Eddgie is trying to say is that an "assembly line" product isn't going to have the same consistency as a "hand crafted" product. Therefore it would be tough to judge two products equally based on a single observer's opinion, especially if there is a chance that some assembled products may be of better quality than others of the same product line. 

Sure. I have no hard feelings. Just trying to have an unbiased discussion here which is a bit more scientific in nature. There are many flaws and biases in Ed’s argument that I am pointing out. I think it is very important to understand these nuances lest folks draw incorrect conclusions. 


Edited by Astrojedi, 15 July 2019 - 11:51 AM.

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#35 rkelley8493

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Posted 15 July 2019 - 12:00 PM

Just a little nit: coma should have been subtracted before calculating the final result. I suspect doing this would have pushed up the Strehl from decent to very good.

 

Sure. I have no hard feelings. Just trying to have an unbiased discussion here which is a bit more scientific in nature. There are many flaws and biases in Ed’s argument that I am pointing out. I think it is very important to understand these nuances lest folks draw incorrect conclusions. 

I always thought that the Strehl Ratio of a scope with a Central Obstruction would be significantly lower than a scope without a CO, i.e. an Apo refractor. Is that correct, or does Strehl Ratio measure something totally different?


Edited by rkelley8493, 15 July 2019 - 12:51 PM.


#36 rkelley8493

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Posted 15 July 2019 - 12:50 PM

Any afocal shot, or even a single shot at prime focus, is going to fall far short of what the optics are capable of.  And indeed, these images are very, very soft.  This says nothing poor about your scope, or your skills as a photographer.  It's just an artifact of the method that you used to obtain them.

 

To really see how good the optics are photographically, you would either need to do a proper star test of the scope or do a video run and sort through a few thousand frames and stack the best, the way that high resolution planetary imaging is done.

True, smart phone images aren't going to be anywhere close to real astrophotography. Like you said, the method used to obtain these photos wasn't "ideal" for showing the scope's potential. What I saw visually was actually very sharp with excellent contrast. I was trying to show that I got some really good views thru this scope. I'd never seen the Copernicus Crater in such detail, and the mountain ranges on the moon were very beautiful as well. Something I never really noticed before until I got this scope. 

I haven't gotten into astrophotography just yet. I know it's an expensive rabbit hole to go thru and tedious work. Maybe sometime down the road, but I'm lucky if I have a clear night to do some stargazing as it is. It's been a very wet & cloudy year in the southeast USA. 



#37 Richard Whalen

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Posted 15 July 2019 - 01:18 PM

I always thought that the Strehl Ratio of a scope with a Central Obstruction would be significantly lower than a scope without a CO, i.e. an Apo refractor. Is that correct, or does Strehl Ratio measure something totally different?

Strehl ratio does Not take CO into account.  It is a measurement that assumes a perfect scope optically for its design and goes down from there with abberations etc. So you can have a SCT with say a .95 strehl and a Apo with the same. Optical quality will be near the same, but the view may not as the Apo has no obstruction. Also some scope designs

/manufacturers measure only the primary mirror, not the complete system, or what is getting to your eyepiece.

 

As far as Meade verses Celestron, I still think its luck of the draw on new ones as it has been for 40 years.  


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#38 TG

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Posted 15 July 2019 - 01:47 PM

I always thought that the Strehl Ratio of a scope with a Central Obstruction would be significantly lower than a scope without a CO, i.e. an Apo refractor. Is that correct, or does Strehl Ratio measure something totally different?

John Hayes can answer this better than any of us here, being an actual optics professional, but it's my understanding that while the Strehl ratio is defined as the ratio of the peak intensity to the actual observed intensity, the optical system for both cases is the same, i.e., it's not a comparison between the obstructed system and an ideal unobstructed one. Moreover, as far as I know, nobody measures intensities to compute the ratio. Rather, interferometry is used to measure the RMS wave error of the system and then a formula is used to compute the Strehl ratio from the RMS value. E.g. I have a 20% obstructed system that has a measured RMS value of 0.02 (1/50 wave). The Strehl is computed as 0.984, i.e., the peak intensity is 98.4% of what an ideal system of the same design would be able to achieve. An ideal unobstructed system would obviously do a bit better.

Generating a ratio of the peak intensity of the optical system vs. an ideal unobstructed system might make sense but that's not what the Strehl ratio is.

Tanveer
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#39 Astrojedi

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Posted 15 July 2019 - 02:32 PM

I think Tanveer explained it really well.

 

Another thing I would add is to be careful comparing different apertures. In smaller apertures quality and high strehl is a lot more important as it is much easier to observe. I can’t even remember the last time I saw the airy disk in my C8.

 

Again not saying that optical quality does not matter in larger apertures but that typically diffraction limited is sufficient. 


Edited by Astrojedi, 15 July 2019 - 02:37 PM.

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#40 Achernar

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Posted 15 July 2019 - 04:57 PM

I think Tanveer explained it really well.

 

Another thing I would add is to be careful comparing different apertures. In smaller apertures quality and high strehl is a lot more important as it is much easier to observe. I can’t even remember the last time I saw the airy disk in my C8.

 

Again not saying that optical quality does not matter in larger apertures but that typically diffraction limited is sufficient. 

In steady seeing, I have seen it clearly though my 8-inch EdgeHD at 300X, and when the seeing is very steady, it came and went through my 15-inch Dob as well. When I did see it though my 8-inch, it was clearly defines and appeared the way it should look.

 

Taras


Edited by Achernar, 15 July 2019 - 05:26 PM.

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#41 Sarkikos

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Posted 20 July 2019 - 02:02 PM

Example.. EdgeHD, which people somehow believe will have better optics than the standard SCT.  Here is one with .934 Streal, which by the way, is pretty much right at where I estimate the bell curve to peak.  Now this is a good scope but as I said, people think that the EdgeHDs are supposed to have better quality, and this one is pretty much in the middle of the quality range.... http://fidgor.ru/Obs...2/test_369.html

The EdgeHD will have better optical performance than the standard SCT in the outer field due to the built-in assembly which flattens the field.  But toward center of field?  I wouldn't get either one for optimal planet viewing.

 

That said, I'm very happy with my EdgeHD 8" for deep sky.  And as long as the optics are acclimated, the stars are sharp enough.

 

Mike


Edited by Sarkikos, 20 July 2019 - 02:05 PM.

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#42 Sarkikos

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Posted 20 July 2019 - 02:12 PM

If memory serves, the Meade ACF's have a focal ratio of F/8, while the Celestron Edge HD are F/10 telescopes, with the exception of the 14-inch model, which is an F/11 telescope. Therefore with the same eyepiece, the Meades will give you a lower magnification and a wider true field of view. I cannot comment on how they perform visually because I never had one nor have I looked through any of them, but I do have an 8-inch Edge HD. The views through it are very impressive, and quite competitive with my 10-inch Dob on the planets. As long as it's collimated properly, you'll find the views very nice through ultra-wide angle eyepieces. I do not regret buying mine at all.

 

Taras

 

I also like the performance of my EdgeHD 8".  But I wouldn't call it competitive when viewing planets compared to my Celestron 10" f/4.8 Newt.  The amount of fine surface detail on Jupiter, for instance, is obviously surpassed by the 10" Newt vs the EdgeHD 8".  

 

Mike


Edited by Sarkikos, 20 July 2019 - 08:03 PM.

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#43 rkelley8493

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Posted 20 July 2019 - 03:05 PM

I also like the performance of my EdgeHD 8".  But I wouldn't call it competitive when viewing planets compared to my Celestron 10" f/4.8 Newt.  The amount of fine surface detail on Jupiter, for instance, is obviously surpassed in the 10" Newt vs the EdgeHD 8".  

 

Mike

Do you think that's primarily due to aperture or design? 

Also, this is kind of off topic, but how does your Baader BBHS mirror diagonal & prism diagonal compare to the ClickLock Mirror diagonal? I've been thinking about adding one of the BBHS's to possibly replace my 2" ClickLock mirror diagonal.

 

Thanks! waytogo.gif

 

- Ryan



#44 Astrojedi

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Posted 20 July 2019 - 03:20 PM

My EdgeHD 8 is my most used scope but I also have C9.25 and 10” solid tube and 14” truss dobs. I used to have an 8” dob years ago.

 

A 10” solid tube dob will definitely better a 8” SCT on both planets and deep sky. It is a superb all round instrument.  A 9.25” SCT will also better a 8” SCT and actually comes close to a 10” dob. The difference in my opinion (based on a few years of observing experience) is primarily driven by aperture and other factors such as proper baffling, good EPs etc. 


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#45 Sarkikos

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Posted 20 July 2019 - 08:14 PM

Do you think that's primarily due to aperture or design? 

Also, this is kind of off topic, but how does your Baader BBHS mirror diagonal & prism diagonal compare to the ClickLock Mirror diagonal? I've been thinking about adding one of the BBHS's to possibly replace my 2" ClickLock mirror diagonal.

 

Thanks! waytogo.gif

 

- Ryan

Definitely aperture.  If the optics are decent in both scopes, both scopes are well-collimated and acclimated to ambient, a 10" f/5 Dob is going to show finer planet surface detail than an 8" EdgeHD or any other kind of 8" Cat.  The 10" will also show a brighter disk, with more color range.  Now, if you compare an 8" f/6 Dob to an 8" Cat, then of course the view is going to be closer.  Maybe an 8" Mak would beat the 8" Dob.  

 

I think the BBHS mirror diagonal is worth the extra money if you want to optimize the view.  The image seemed a bit brighter and colors were more "alive" in my NP-101 with the BBHS mirror compared to the ClickLock mirror.  

 

Mike


Edited by Sarkikos, 21 July 2019 - 09:03 AM.

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#46 rkelley8493

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Posted 20 July 2019 - 11:26 PM

Definitely aperture.  If the optics are decent in both scopes, both scopes are well-collimated and acclimated to ambient, a 10" f/5 Dob is going to show finer planet surface detail than an 8" EdgeHD or any other kind of Cat.  The 10" will also show a brighter disk, with more color range.  Now, if you compare an 8" f/6 Dob to an 8" Cat, then of course the view is going to be closer.  Maybe an 8" Mak would beat the 8" Dob.  

 

I think the BBHS mirror diagonal is worth the extra money if you want to optimize the view.  The image seemed a bit brighter and colors were more "alive" in my NP-101 with the BBHS mirror compared to the ClickLock mirror.  

 

Mike

Nice! I've been wanting to invest in a good accessory other than another eyepiece.. I think I've got all the EPs covered based on my personal preferences, primary scopes, and OCD lol.gif  A premium diagonal or prism is next on my wish list. Thanks for the info!

 

R. Kelley


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#47 Whichwayisnorth

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Posted 19 August 2019 - 06:01 PM

I have had examples of both that were amazing but the only bad examples I've ever had were Meade.

 

I'd stick with the EdgeHD if those are your only two choices.  


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#48 aa6ww

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Posted 20 August 2019 - 12:29 AM

I've never seen a bad scope from either company that was new. The exception was I've never seen good optics on a Meade LX-200 16" no mater how precisely it was collimated

Once someone add's bobs knobs to either scope or starts playing with the collimation, all bets are off on both scope and the bad reputations start coming into play.  

 

New scopes right off the showroom have always been excellent, again, with the exception of the 16" LX-200's.

 

...Ralph


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#49 fred1871

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Posted 20 August 2019 - 03:53 AM

Ralph, you've had more luck than I have. I've seen poor examples of C and M brand-new; the difference was that the worst Celestron example was not as bad as the several pretty unusable Meades. Also I've seen fewer really good Meades (percentage-wise) than Celestrons over the last 40 years.

 

Obviously YMMV applies here. The luck of the particular samples of each we encounter, and how many in total. But variability of quality is a given with scopes built to a (saleable) price rather than to a standard in the way Questar always claimed.

 

My strong impression is that the typical quality for both C and M is better these days than it used to be. And good-plus optics is more frequent in recent scopes, though again the upper echelon I've encountered more often from C than M.


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#50 rkelley8493

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Posted 20 August 2019 - 09:11 AM

Wow, I wish I would've known this 5 years ago.. When I was getting started, I always had the impression that Meade was a top notch company. I mean I knew they weren't the absolute best there was in the industry, but I thought they were one of the best for mass production. 




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