61 replies to this topic

[Daniel Mounsey]

Companies who market their mount often claim they hold more than double what they actually can. As a person who works in floor sales, I can honestly say this tacky marketing approach has caused more harm than good and I'm amazed it's still in use today. I have a message to manufactures. STOP including the counter weights as part of the load capacity. You're not doing anyone a favor. If you spent some time doing floor sales, you'd understand. it's like claiming 60mm refractors have 500x power.  

 

 

[John P]

Without industry standards, this is what you get.  At the same time, I've noticed many manufacturers/retailers have started to make an effort to be more specific about their mount capacity. Vague and confusing or even absent claims are present with much of our equipment, including optical quality, tracking accuracy, etc.

[Mitrovarr]

Can those mounts really not hold that much at all? I was under the impression that those mounts were unable to hold that much well, as in steadily for astrophotography, but you could go somewhat above the 1/2 quoted weight limit visually although the scope would feel quite undermounted as you approached the limit.

[wargrafix]

Its like the memory debacle that hit HDD manufacturers. Its misleading claims that makes the customer suffer.

[michael_m]

Thank you Daniel for bringing this subject up. I know for me this is a very serious question as I investigate which "ultimate" mount to get as I prepare for getting into astrophotography in a more serious mannor. Some mfg's do list the max load not including the counter weights. As for me, I don't take seriously the max load claim unless it also specifically mentions the max weight without the CW's.

For the record, Astro-Physics does a good job of giving the prospective buyer an honest assessment of what kind of load their mounts can carry. And as they say, it is also relevant to the length of the tube assembly and/or nature of the balancing needs of the equipment being used on the mount.

It helps a lot when fellow CN folks know their weight load and mention it in reference to the mount being used.

Thanks Daniel, Michael

Edited by michael_m, 29 June 2015 - 10:26 AM.

[bobzeq25]

1/2 is just a very rough rule of thumb.  The relationship between claimed capacity and actual varies wildly.  It depends on many things, the specific mount, how well it's setup and operated, the length of the OTA...  Paul can put 20 pounds or more on his 27 pound rated ZEQ25, and get better tracking than most people here ever see. 

 

Given that, plus any seller's natural tendency to exaggerate, it's hard to see how any advertising claim could ever be more than a rough guide.  You're better off looking at what people actually put on their mount, and their experiences.  "The wisdom of crowds" is a very important concept in AP, in many arenas.

 

Using that wisdom, it appears to me that the quality of mounts is very strongly related to their price.  There really don't seem to be many bargains, or many mounts that qualify as AP that are poor, for their price.  Your best decision tool may simply be to decide how much you can afford.  It also appears to me that almost no one thinks they bought too much mount.

 

Here's a great compilation of available data.  Note especially the enormous range of reported PE for the G-11.  That's what you're up against.

 

http://lambermont.dy...g/astro/pe.html

Edited by bobzeq25, 29 June 2015 - 10:54 AM.

[jrbarnett]

Companies who market their mount often claim they hold more than double what they actually can. As a person who works in floor sales, I can honestly say this tacky marketing approach has caused more harm than good and I'm amazed it's still in use today. I have a message to manufactures. STOP including the counter weights as part of the load capacity. You're not doing anyone a favor. If you spent some time doing floor sales, you'd understand. it's like claiming 60mm refractors have 500x power.  

I concur.

 

But it's not unique to astronomy mounts.

 

The problem is that there is no standardized way of rating mount capacity.  It's a lot like full sized truck towing capacity rating.  Different manufacturers use different methods for calculating capacity so their results, even if expressed in the same units or ratios, are in actuality apples and oranges when it comes to comparing vehicles.

 

This in turn opens the door for marketing abuse by gaming the lack of standardization.

 

With mounts the issue is compounded somewhat by the nature of use.  Visual observing can successfully be conducted at load levels that are challenging for imaging with any given mount.

 

Unless and until the industry itself gets off its duff and cooks up some standardized method for rating capacity, it's up to us consumers to alert our fellows when a given mount really doesn't live up to its marketed capacity.

 

- Jim

[Richard Whalen]

I think a better way to judge what a mount will handle is shaft size and bearing spacing along with gear size.

[rmollise]

Companies who market their mount often claim they hold more than double what they actually can. As a person who works in floor sales, I can honestly say this tacky marketing approach has caused more harm than good and I'm amazed it's still in use today. I have a message to manufactures. STOP including the counter weights as part of the load capacity. You're not doing anyone a favor. If you spent some time doing floor sales, you'd understand. it's like claiming 60mm refractors have 500x power.  

 

Who are you speaking of? The makers I am aware of DON'T include the counterweights in the load capacity. The stated payload is IN ADDITION TO the counterweights. Now, that may sometimes be overoptimistic, especially for imaging. But I don't know of too many who include the counterweights in total (Vixen has at times).

[bunyon]

Doesn't most of this boil down to:  are you an imager or not?  I'm convinced I could load twice as much on my AVX imaging rig and use it visually.  But with imaging, tolerances are much reduced.

 

So, if they advertise a load for visual use, then, yeah, that won't work for imaging.  The two loads are completely separate. 

 

Are people really so worked up over this that they're leaving the hobby or ditching manufacturers?  I've not seen it, which doesn't mean it isn't true.  But the claims for all the Serious suppliers I've seen are plausible.  And, speaking of someone who deals with salesman all the time, as long as it's plausible, it's claimable. 

[famax]

 

Companies who market their mount often claim they hold more than double what they actually can. As a person who works in floor sales, I can honestly say this tacky marketing approach has caused more harm than good and I'm amazed it's still in use today. I have a message to manufactures. STOP including the counter weights as part of the load capacity. You're not doing anyone a favor. If you spent some time doing floor sales, you'd understand. it's like claiming 60mm refractors have 500x power.  

 

Who are you speaking of? The makers I am aware of DON'T include the counterweights in the load capacity. The stated payload is IN ADDITION TO the counterweights. Now, that may sometimes be overoptimistic, especially for imaging. But I don't know of too many who include the counterweights in total (Vixen has at times).

 

that's right almost every mount manufacturers specify the net load capacity. this is just a misunderstanding.

[Chucke]

I think a better way to judge what a mount will handle is shaft size and bearing spacing along with gear size.

 

I don't think shaft size and bearing spacing are really all that useful for determining load capacity unless you are comparing within a specific design style.  Design is a major factor in load capacity.

 

Look at a Shaefer or a Russell Porter style mount vs. a Cave style mount. The Schaefer/Porter mounts have relatively small RA shafts and closely spaced bearings but can handle huge payloads successfully for imaging.  I think the sizes of the thrust surfaces have a much greater impact than shaft diameter unless a conical shaft is used.  With large thrust surfaces the shaft becomes mostly something that holds the mount together with a small contribution to overall stiffness and the distance from the load to the clutch is very short minimizing shaft wind-up.  With the Schaefer/Porter design the thrust surfaces can be arbitrarily large whereas in the Cave design they are usually the same as the shaft size. The thrust surface is usually slightly smaller than the gear size and is used as part of a clutch. The effect is to simulate are very large conical shaft.  That is why a medium sized Shaefer or Porter mount is vastly stiffer and more compact than a big Cave style mount.  Ed Byers actually uses large conical shafts for his mounts.

 

The downsides to the design are that after a certain thrust surface size is reached (> than about 15" from my experience) the friction gets out of hand unless you can find really large diameter thrust bearings. I have been looking into the Kaydon thin-section bearings for this purpose but they get really expensive in the 14"-16" sizes.  Also, this style mount usually requires machine tools to build.

 

Chuck

[mich_al]

And, speaking of someone who deals with salesman all the time, as long as it's plausible, it's claimable. 

 

ANY time I catch a saleperson BSing me in any manner they are DONE

[WesC]

I kinda agree with Daniel here...

 

A lot of the companies making these claims are purportedly selling imaging mounts... Celestron, iOptron, Meade, Skywatcher. Mostly these mounts are big, monstrously heavy and still not as stable as they should be. They claim payloads that, for the excessive weight of the mounts and tripods, are pretty low. PE is high-to ridiculously high and seldom smooth. Add to that the fact that decent quality imaging can really only be accomplished successfully with shorter focal lengths and with payloads far less than the rated claim (this is where the 1/2 rated capacity rule comes from) ...and you end up with a lot of unsatisfied customers.

 

These forums are filled with complaints about these mounts. And if you notice, the prices are creeping up and up as new models come out trying to solve performance issues. Prices that are quickly approaching that of premium mounts... CEM60 and EQ8 cost more than a G11... the CEM120 will cost nearly as much as an AP Mach One or Paramount MyT.

 

As prices approach premium levels without equivalent performance the thought of having to deal with those issues is even less appealing.

 

Sure there are those who get lucky and get a good (enough) one, or will grudgingly accept so-so images or imaging with very short exposures, or are willing to spend hundreds of dollars extra on aftermarket fixes, or deal with the idiosyncrasies and inconsistent performance.

 

But that doesn't make it acceptable.

[rmollise]

I kinda agree with Daniel here...
 
A lot of the companies making these claims are purportedly selling imaging mounts... Celestron, iOptron, Meade, Skywatcher. Mostly these mounts are big, monstrously heavy

An EQ-6 or CGEM is monstrously heavy? Not even for broken down little old me.

These companies are selling general purpose GEMs. Is it best to stay under the payload rating when you are imaging with a 1500 dollar mount vice a 9 thousand dollar one? Sure. Is 1/2 the limit? Maybe, maybe not. It depends on your scope, your setup, your conditions and a lot of other things. A lot of generalizations and other things get repeated on this and other amateur astronomy BBSes until they begin to be taken as GOSPEL.

Edited by rmollise, 29 June 2015 - 05:25 PM.

[andysea]

That is true but it would be nice if more manufacturers elaborated a little more on their payload claims. There are many variables i.e. moment arm, focal length, tripod stability etc...

I know it's all marketing driven but wish companies tried do educate potential customers as well rather than just sell their product. This would benefit beginners who are getting into the hobby.

[wrz0170]

That is true but it would be nice if more manufacturers elaborated a little more on their payload claims. There are many variables i.e. moment arm, focal length, tripod stability etc...

I know it's all marketing driven but wish companies tried do educate potential customers as well rather than just sell their product. This would benefit beginners who are getting into the hobby.

 

Great topic!  You make a good point here about elaborating more on their payload claims.   I was told in the begninng and I see this advice passed along to those who want to get into imaging:  Take a mount's rated weight capacity and divide by 2.   That is your imaging capacity.

 

CGEM - Stated Payload is 40 lbs.  Now is that visual?  Imaging?  I have a C9.25 Edge  and i'm not done building it up as an imaging rig.  Right now it's at 28 llbs.  Is that pushing the "half" axiom? 

 

Visual or imgaing and pushing it to max?

 

CGEM DX - 50lbs.  

 

Orion Atlas - 40 lbs.  

 

Losmandy G11  and Ioptron CEM60, both rated 60lbs.

 

Paramount MyT - 50 lbs.

 

Mach 1 - 45lb.  

 

It is said that "premium" mounts do not follow the "half" axiom.  Now what critera delineates the premium mounts and those mounts that must follow the "Half" axiom??    Which mounts need to be coaxed, prodded, hypertuned and have absolutely perfect conditions to acheieve the rated capacity?

 

All this can be confusing for newcomers I think.  

 

William

[orlyandico]

Now what critera delineates the premium mounts and those mounts that must follow the "Half" axiom??    Which mounts need to be coaxed, prodded, hypertuned and have absolutely perfect conditions to acheieve the rated capacity?

 

This question is answered by tribal knowledge.  

 

The rule of thumb is nothing more than a rule of thumb. Say your CGEM at 28lb... doable, if it's a fast newtonian or a Takahashi Epsilon, because of the short focal length. A C9.25 EDGE? not even if it weighed 15lb. The focal length is too long.

 

(I had a CGEM.. and a C9.25.. I speak from experience - so unless you're using that C9.25 EDGE with a 0.5X reducer or Hyperstar.. prepare for hair loss)

[Jon Isaacs]

That is true but it would be nice if more manufacturers elaborated a little more on their payload claims. There are many variables i.e. moment arm, focal length, tripod stability etc...

I know it's all marketing driven but wish companies tried do educate potential customers as well rather than just sell their product. This would benefit beginners who are getting into the hobby.

 

How about this:  

 

The manufacturers could provide a model of the structural response of the mount and tripod. The perspective buyer could then plug that model along with the models for the OTA, rings, camera etc into a dynamic finite element code and produce an accurate simulation of the static and dynamic response of the system.  One would want to do several different scenarios, looking at the effect of wind velocity at several orientations. And it would be important to look at the system response to drives at various orientations.. And then too, one would want to investigate the effect of the tripod leg extension..  One could do a full scale simulations of a long exposures and actually produce a simulated images taken with the system that included a wide variety of conditions and possible scenarios..  

 

The persective buyer could then look at the various images and make an informed decision about purchase.  

 

Otherwise..  there are so many variables to consider.. You're pretty much stuck with the someone taking a rough guess, "Yeah, about 40 pounds."  and then the buyer needs to kind of know that Roland Christen's "about 40 pounds" is probably someone else's "about 80 pounds."

 

Just sayin'

 

Jon

[wrz0170]

 

Now what critera delineates the premium mounts and those mounts that must follow the "Half" axiom??    Which mounts need to be coaxed, prodded, hypertuned and have absolutely perfect conditions to acheieve the rated capacity?

 

This question is answered by tribal knowledge.  

 

The rule of thumb is nothing more than a rule of thumb. Say your CGEM at 28lb... doable, if it's a fast newtonian or a Takahashi Epsilon, because of the short focal length. A C9.25 EDGE? not even if it weighed 15lb. The focal length is too long.

 

(I had a CGEM.. and a C9.25.. I speak from experience - so unless you're using that C9.25 EDGE with a 0.5X reducer or Hyperstar.. prepare for hair loss)

 

 

Nope!  I don't need a bigger, permanent Sunroof.    My CGEM has since departed and i'm impatiently waiting for the delivery of a MyT.  I am thinking that when I'm done getting all the stuff for my 9.25, I would be pushing over 30lbs and you stated no way at 15lbs!!

 

Another case in point of this topic;  The MyT is said to be a premium mount and the rated capacity is a true 50lbs of imaging gear.  The rule of thumb does not apply.  I'm not complaining!  Just funny that the capacities of mounts is all over the place.  

[orlyandico]

The rule of thumb really should be "you get what you pay for"  

Edited by orlyandico, 30 June 2015 - 08:26 AM.

[TestnDoc]

 

 

(I had a CGEM.. and a C9.25.. I speak from experience - so unless you're using that C9.25 EDGE with a 0.5X reducer or Hyperstar.. prepare for hair loss)

LOL...could not agree more!! I had one of these mounts a few years ago, and mounted my scope, camera, etc, all under the "load capacity", and it was not pretty. The mount could not take the weight. Sold it and bought an AP1200...wow what a difference. I wish I had never sold my 1200.

[bilgebay]

Well, I will not complain about my mount but here is my story...

 

5 years ago, I was looking for a sturdier mount than my CG5-GT... after considering a lot of factors and eliminating lots of candidates only two mounts were on the table; a CGE-Pro and a Vixen New Atlux. IIRC CGE-Pro was rated for 95 pounds and Atlux was rated for 75 pounds.

 

At that time, some were very happy with their CGE-Pro's but some others were losing a lot of hair ( thank you Orly). Atlux on the other hand, looked to be a more consistent mount according to the reports of all its users. 

 

After days of deliberation I opted for consistency and a smooth PEC curve thus, I went with the Atlux mount.

 

As soon as I received the product and started reading the manual, I realized that it was rated for only 48.5 pounds. Can you imagine the shock I went through? I ran to my computer and checked the web page of the US dealer from whom I purchased the mount and it was still showing 75 pounds and there was no mention of counterweights. I went to the US distributor's website, it was the same. Then I checked the European and Japanese sites....the payload capacity was stated as 48.5 pounds in both

 

You may not find this product on US distributors page anymore but Orion is still listing the product with the same specs which led to my purchase. This was the same wording on the dealer's web page and Vixen Optics USA's page at that time.

 

It took me a while to digest this actually. There was no other mount manufacturer at that time who were including the counterweights when they quoted the payload capacity of their mounts. How would I guess that that would be the case with the Atlux ? There was no way.

 

Have I regretted my purchase ? No, not a bit! It proved to be a premium mount especially after I switched to the NexAtlux board. I imaged with this mount even at its maximum capacity and it produced acceptable results.... but I never forgot that I was cheated... the sour taste is still there...

 

I hope they stopped this practice since then. 

[orlyandico]

This "weight including counterweights" seems to be a practice unique to the North American distributor of Vixen at the time.

 

The Europe dealers and Vixen Japan have never made such claims. In fact Vixen Japan even quotes the moment arm (distance from payload COG to RA axis) at which the payload is quoted, which is more information than mount manufacturers normally give.

[EFT]

To start with, some of these comments have nothing to do with payload capacity (e.g., the ability to imaging with long focal lengths has little, if anything, to do with payload capacity and everything to do with mount accuracy).  It's very important to keep in mind the difference.

 

The list of premium mounts is well know to most people and includes 10Micron, Astro-Physics and Software Bisque as well as a number of truly astronomically priced mounts.  These manufacturers will generally list the equipment payload capacity of their mounts and these numbers can be depended on.  However, the problem is (other than a lack of standards) that the rated instrument capacity cannot account for the size and shape of the OTA used.  A six-foot long refractor weighing 50 pounds is going to handle very different than another scope with the same weight but half the weight.  A huge wind-sail of an SCT is going to handle much different than a refractor of equal weight but less surface area to catch the wind.  An f/15 scope and a f/5 scope of the same weight will need to be handled very differently on almost any mount (except perhaps where either scope is extremely over-mounted).  While there may be ways to present engineering data to better quantify how the size and shape of an OTA will impact the capability of a particular mount to handle the OTA, the information would be far over the head of the average consumer and lead to even more confusion (not to mention wasted effort by the manufacturer).

 

The problem comes down to not just a lack of standards (which would really only be rated imaging capacity vs. visual capacity), but the huge variety of scopes and configurations that people use on mounts.  It is simply not realistic, if even possible, for the manufacturers to characterize all of the possible configurations that people might use on their mounts and how environmental factors like wind will impact these configurations and then provide that information to consumers.  If you are buying a premium mount, then the best thing to do is talk to the manufacturer about your planned imaging configuration to see what they think.  If you are buying a mass-produced non-premium mount, then all you can do is research what others have found out and posted about these products.  Even the "you get what you pay for" rule of thumb is of little use when compared to simply doing your research rather than just buying based on an add in a magazine.