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How much difference does a good vs great mirror make?

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#26 ccwemyss

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Posted 12 October 2021 - 12:54 PM

Like with so many other things today, computerized production is able to achieve "good enough" for the vast majority of people, at a greatly reduced cost, which pushes truly high quality into an ever smaller and more expensive niche. That, in turn, decreases the number of artisans who keep the knowledge and experience alive, which can lead to a gradual loss of the expertise. Eventually we get homogeneity of quality and cost for all but a few who can afford bespoke articles.

 

When everything still involved hand crafting, there were variations in quality and price. But a maker who took pride in their product would put in the extra effort. Partly because their methods became easier to carry out from practice and experience, and partly because they believed their beautiful work deserved to be in the hands of more users, for just a bit more, average people could get top quality. 

 

Chip W. 


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#27 CHASLX200

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Posted 12 October 2021 - 06:25 PM

I noticed the same things when comparing my 1996 Meade ETX90 to a present day Skywatcher 90mm Mak. The classic U.S.A. made Meade was a bit better than the Skywatcher. Both instruments provided very sharp high power views of the moon and planets but the classic. U.S. made ETX90 showed a darker sky background and better contrast, especially when viewing Jupiter. I immediately attributed this to smoother optical surfaces of the 1996 U.S.A. made ETX 90. As an optical tube assembly, it is an excellent little scope!!! I bought it here on the classifieds for a very reasonable price!!! I replaced the stock finder with a Rigel and I have loads of fun with this scope!!! This fine little Mak is definitely the best used purchase I've ever made!! It really is worth the time and effort to scan the CN classifieds as classic scopes do occasionally pop up for sale here!

My U.S. made 125 ETX was just crazy sharp. I mean that thing would do 60xx on the moon and still was sharp. Dim but sharp.



#28 Bonco2

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Posted 12 October 2021 - 07:41 PM

I noticed the same things when comparing my 1996 Meade ETX90 to a present day Skywatcher 90mm Mak. The classic U.S.A. made Meade was a bit better than the Skywatcher. Both instruments provided very sharp high power views of the moon and planets but the classic. U.S. made ETX90 showed a darker sky background and better contrast, especially when viewing Jupiter. I immediately attributed this to smoother optical surfaces of the 1996 U.S.A. made ETX 90. As an optical tube assembly, it is an excellent little scope!!! I bought it here on the classifieds for a very reasonable price!!! I replaced the stock finder with a Rigel and I have loads of fun with this scope!!! This fine little Mak is definitely the best used purchase I've ever made!! It really is worth the time and effort to scan the CN classifieds as classic scopes do occasionally pop up for sale here!

Barbie,

Planned tonight to continue my comparo of small refractors with the ETX 90....But got clouded out. I don't know the vintage of my ETX. It's not an RA and I don't like having only electrical control. I'd prefer mechanical slow motion controls  combined with electrical tracking.  When I first got it I used the 45 diagonal and I was not impressed. Just not sharp and had bad double star resolving performance. But later I used the regular eyepiece slot. That's when I found out the little ETX is a performer. Looking forward to doing more comparisons as the weather allows.

Bill


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#29 oldmanastro

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Posted 12 October 2021 - 09:06 PM

Barbie,

Planned tonight to continue my comparo of small refractors with the ETX 90....But got clouded out. I don't know the vintage of my ETX. It's not an RA and I don't like having only electrical control. I'd prefer mechanical slow motion controls  combined with electrical tracking.  When I first got it I used the 45 diagonal and I was not impressed. Just not sharp and had bad double star resolving performance. But later I used the regular eyepiece slot. That's when I found out the little ETX is a performer. Looking forward to doing more comparisons as the weather allows.

Bill

Bill,

 

  Maybe that 45 diagonal produced some problems with the collimation. Not an uncommon problem with some diagonals. I tried the 90 degree diagonal and it came out ok even then I continue to use the flip mirror eyepiece port. 

About good optics vs excellent optics I can say that the ETX 90 (USA made) has very good optics and the Questar has excellent optics that can be pushed a bit over 300x magnification. The ETX 90 stops at about 225x which is excellent too (about 60x per inch). To be honest it is very difficult to distinguish between the two until you reach the higher powers. The Questar also provides a brighter image. This tells us that the difference between a good to very good optic and an excellent or great one is difficult to discern until you reach the higher magnifications that the telescopes are capable of.


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#30 barbie

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Posted 12 October 2021 - 09:42 PM

When I pushed my Etx90 to 258x this past summer, I also viewed the planets at the same power through multiple Questars and couldn't tell any differences between my ETX90 and the Questars both in terms of image brightness and overall quality. The one thing the Questars had was the refined mechanical craftsmanship but I'm quite content with the appearance and mechanical quality of the ETX90 and have found my little slice of Questar optical performance for far less investment. Consequently, I'm quite happy and content and will no longer be pursuing a Questar. My skies even on my best nights here in Ne. Ohio never support 300x so I'll never get to compare a Q3.5 to my ETX90 at that kind of magnification anyway. Both myself and the Q3.5 owners were shocked when we made the side by side comparisons back on August 20th 2021!!


Edited by barbie, 12 October 2021 - 09:46 PM.

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#31 kansas skies

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Posted 12 October 2021 - 11:35 PM

My ETX90 is the more recent version (foreign), and its optics really are quite nice. Its go-to mount can be a bit of a pain, but it is usable (and very noisy). I have set it up on a couple of occasions side by side with my BB Questar, and have to say that I do notice a considerably brighter image in the Questar. That being said, I really didn't notice much difference in image quality on those occasions. I do suspect that if I were to continue the comparisons over a period of time, and under a wider variety of seeing conditions and magnification, the Questar would most-likely produce more consistent results, but I could be wrong. Then again, I'm not really interested in comparing them any further, as I've already promised the ETX90 to my granddaughter whenever she feels as though she's ready for it. The thing I really like about the ETX is that by loosening one thumbscrew, the OTA can be easily removed and mounted to a Vixen dovetail on my Polaris mount. This combination then produces a telescope that's very rugged and super-easy to use. Either way, it's a scope my granddaughter can be proud to own.

 

Bill


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#32 CHASLX200

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Posted 13 October 2021 - 06:02 AM

Barbie,

Planned tonight to continue my comparo of small refractors with the ETX 90....But got clouded out. I don't know the vintage of my ETX. It's not an RA and I don't like having only electrical control. I'd prefer mechanical slow motion controls  combined with electrical tracking.  When I first got it I used the 45 diagonal and I was not impressed. Just not sharp and had bad double star resolving performance. But later I used the regular eyepiece slot. That's when I found out the little ETX is a performer. Looking forward to doing more comparisons as the weather allows.

Bill

Many of the 45 degree diagonals are bad. Mine was on a 90mm Achro.



#33 Tom Stock

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Posted 13 October 2021 - 08:10 AM

Transparency.  Humidity has dropped here in norh fl (recent cold front) and there is less moisture in the air so less scatter and better contrast.


Edited by Tom Stock, 13 October 2021 - 08:10 AM.


#34 barbie

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Posted 13 October 2021 - 01:19 PM

Back on August 20th of this year, I immediately knew I was going to have a night of abnormally excellent seeing and my intuition was to push the ETX90 to absurdly high magnification of 74x/inch of aperture and the effort was well rewarded!! In all the years I've been observing(just over 5 decades), I've never had any scope perform like the ETX 90 did that night, not even my high end Japanese refractors or Russian Maks, of which I have had many!!

Bill- I've only had limited experience with 45 degree diagonals but was not impressed by the few I did try. The 90 degree flip mirror on my ETX90 is fantastic!! I hope you get another chance to use your ETX90 soon!! Your granddaughter will be getting a wonderful little scope!!


Edited by barbie, 13 October 2021 - 01:22 PM.

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