g__day
17-06-2007, 01:24 PM
I'm kinda surprised that there is no well established methodology to review (and even advertise mounts) - particularly german equatorial mounts with Goto ability.
To me a mounts three key capabilities are carrying capacity, tracking ability and pointing ability. Carrying capacity is almost always discoverable, yet nowhere in most reviews do we see any scientific or engineering based comment on tracking and only the most general comments on pointing.
Last week I asked Kevin at Astro Optical for instance about the Vixen Sphinx SXD
1) What was the true carrying capacity 15kg vs 23kg reported in the USA (and was this visual or astrophotography usage limits)
2) What was the maximum periodic error in tracking before and after PEC?
3) What was the maximum pointing error?
4) Was PEC remembered after scope power down or must it be re-set each and every time its used?
The answers after about five e-mails were
1) 15 Kg of scope - uncertain if usage was visual rated or astrophotography rated
2) Wouldn't comment other than it varies
3) Not commented on!
4) Must be re-learned on each and every power down, no plans to add this essential feature!
* * *
So there is someone in the business for 2 decades who can't easily comment on the key aspects of their mounts. But go to Peter Ward at Advanced Telescope Supplies or BinTel or Astronomy Online to mention just three of many - say you look at Losmandy mounts - see if tracking or pointing ability is mentioned - answer no!
* * *
Then last week I discover a service that a third party performs - Dr Clay - Arkansas University emeritus astronomy professor - that improves many mounts PE by 3 to 4 times!!!! So it leaves me really pondering how bad are manufacturers like Celestrons final assemble quality control!
And why don't reviewers speak of these issues?
* * *
How hard would it be for say this site to recommend a code of review, a methodology, for all major manufacturers to abide by - then ask distributors to all advertise there wares by this codes practices?
If we were to suggest a methodology for reviewing a GE mount in a standard fashion what would its ten commandments be - so to speak?
May I suggest:
1. List a mounts maximum carrying capacity - in ideal (windless and well balanced set-up) conditions - for both visual and astrophotography applications
2. List its guaranteed worst case raw PE and corrected PE and average PE and corrected PE (say using Tpoint or Pempro to confirm).
3. List its guaranted worst case pointing ability on ten well dispersed stars
4. Describe the quality of its gears and bearings in standard, comparable terms.
5. Confirm that it is tested and quality assured at completion - and that an external service provider doing their own quality assurance can't improve performance 200% - 300% by simple checks and adjustments that the factory itself should always be doing!
6. Confirm whether its ASCOM compliant.
7. List its faults and limits (e.g. if you don't supply 3A it will be wonky - Celestron CGE, if you don't balance the scope well the motors tend to burn out - Losmandy)
8. Describe its hibernate functions.
9. Confirms its abilities are consistent across all sky positions (it shouldn't vary depending where it points on the sky shoudl it?)
10. Describe the warranty and replacement details in more detail (e.g. Zane at Magellan observatory told me he had a horrible time with the Australian supplier of his G11 who disputed the errors and suggested all kinds of tests until it was out of warranty and then told him it was at his cost to get it repaired)! So describe how serious a failure has to be before it can be serviced or replaced. If it fails twice can it be totally replaced within warranty? If it doesn't perform to its rated minimum levels - can it be serviced, tested and if it still fails replaced?
* * *
Maybe this is too ambitious - but if a site like this one framed a should comply with methodology for selling and reviewing all mounts - what would you suggest the benchmarks should be? If all amateur astronomy sites distributed this and sent it to the manufacturers and reviewers - do you think they might come one day alot closer to applying this standard?
At present without this being done the risk is all on us!
PS
I'm ashamed astronomy magazines don't already have this sorted. If we can get a benchmark agreed - lets send it to all reviewers and manufacturers and see if they can adopt this this year. If we can benchmark cars, PCs and their individual components, TVs, cameras and other electrical devices - why can't we do it with the most important component of an imaging platform?
/end_rant
To me a mounts three key capabilities are carrying capacity, tracking ability and pointing ability. Carrying capacity is almost always discoverable, yet nowhere in most reviews do we see any scientific or engineering based comment on tracking and only the most general comments on pointing.
Last week I asked Kevin at Astro Optical for instance about the Vixen Sphinx SXD
1) What was the true carrying capacity 15kg vs 23kg reported in the USA (and was this visual or astrophotography usage limits)
2) What was the maximum periodic error in tracking before and after PEC?
3) What was the maximum pointing error?
4) Was PEC remembered after scope power down or must it be re-set each and every time its used?
The answers after about five e-mails were
1) 15 Kg of scope - uncertain if usage was visual rated or astrophotography rated
2) Wouldn't comment other than it varies
3) Not commented on!
4) Must be re-learned on each and every power down, no plans to add this essential feature!
* * *
So there is someone in the business for 2 decades who can't easily comment on the key aspects of their mounts. But go to Peter Ward at Advanced Telescope Supplies or BinTel or Astronomy Online to mention just three of many - say you look at Losmandy mounts - see if tracking or pointing ability is mentioned - answer no!
* * *
Then last week I discover a service that a third party performs - Dr Clay - Arkansas University emeritus astronomy professor - that improves many mounts PE by 3 to 4 times!!!! So it leaves me really pondering how bad are manufacturers like Celestrons final assemble quality control!
And why don't reviewers speak of these issues?
* * *
How hard would it be for say this site to recommend a code of review, a methodology, for all major manufacturers to abide by - then ask distributors to all advertise there wares by this codes practices?
If we were to suggest a methodology for reviewing a GE mount in a standard fashion what would its ten commandments be - so to speak?
May I suggest:
1. List a mounts maximum carrying capacity - in ideal (windless and well balanced set-up) conditions - for both visual and astrophotography applications
2. List its guaranteed worst case raw PE and corrected PE and average PE and corrected PE (say using Tpoint or Pempro to confirm).
3. List its guaranted worst case pointing ability on ten well dispersed stars
4. Describe the quality of its gears and bearings in standard, comparable terms.
5. Confirm that it is tested and quality assured at completion - and that an external service provider doing their own quality assurance can't improve performance 200% - 300% by simple checks and adjustments that the factory itself should always be doing!
6. Confirm whether its ASCOM compliant.
7. List its faults and limits (e.g. if you don't supply 3A it will be wonky - Celestron CGE, if you don't balance the scope well the motors tend to burn out - Losmandy)
8. Describe its hibernate functions.
9. Confirms its abilities are consistent across all sky positions (it shouldn't vary depending where it points on the sky shoudl it?)
10. Describe the warranty and replacement details in more detail (e.g. Zane at Magellan observatory told me he had a horrible time with the Australian supplier of his G11 who disputed the errors and suggested all kinds of tests until it was out of warranty and then told him it was at his cost to get it repaired)! So describe how serious a failure has to be before it can be serviced or replaced. If it fails twice can it be totally replaced within warranty? If it doesn't perform to its rated minimum levels - can it be serviced, tested and if it still fails replaced?
* * *
Maybe this is too ambitious - but if a site like this one framed a should comply with methodology for selling and reviewing all mounts - what would you suggest the benchmarks should be? If all amateur astronomy sites distributed this and sent it to the manufacturers and reviewers - do you think they might come one day alot closer to applying this standard?
At present without this being done the risk is all on us!
PS
I'm ashamed astronomy magazines don't already have this sorted. If we can get a benchmark agreed - lets send it to all reviewers and manufacturers and see if they can adopt this this year. If we can benchmark cars, PCs and their individual components, TVs, cameras and other electrical devices - why can't we do it with the most important component of an imaging platform?
/end_rant