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Doesn't this depend on whether the scope is balanced for a certain weight at a certain point? With my lightest eyepiece and the scope pointed near zenith, I have to dangle a counterweight from the UTA of my scope.
With a 31 nagler at the horizon, I have to add a 5lb counterweight to the mirror box.
There is NO weight that would be perfectly balanced near the zenith AND the horizon, so some form of counterweight will always be necessary unless the scope is so large the weight of the eyepiece is insignificant, or so "sticky" that the difference in the weight of eyepieces causes no noticeable balance changes.

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Actually you raise another good point...why isn't there a predefined weight that all eyepieces are designed to?

If there was ONE weight, all scope assemblies could be set to balance on that one value and using a scope would be much simpler.

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Because size/weight/shape of telescope/mount etc are vastly different as primary eyepiece design parameters (focal length, AFOV, eye relief, glass, cost, ...) are vastly different.

If you demand optical engineers "one size fits all or telescope balancing issue by eyepiece" type requirement as mandatory design parameter, I suspect you will be disappointing result of product in terms of optical quality, mechanical robustness, price etc.

I believe free to design anyway you want is much better solution so that we consumers can choose whatever our liking

If you sort my weight measurement in eyepiece focal length, it tells something: Some eyepiece weight is more than 10x than other with the same focal length.

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Partial list where it is interesting:
 grams   F/L model name
 237.0  16.0 WO-UWAN
  84.0  16.0 ZAO2
 722.0  17.0 TV-Ethos
 179.0  19.0 TV-Panoptic
 358.0  20.0 Pentax-XW
 678.0  22.0 TV-Nagler
  68.0  23.0 SV-Plossl
 298.0  24.0 Hyperion
  81.0  25.0 Zeiss-Ortho
  75.0  28.0 Siebert-UW
 958.0  28.0 WO-UWAN
 771.0  30.0 BW-Optik/Zeiss
 291.0  30.0 TMB-Paragon
 160.0  30.0 Tak-LE
 354.0  31.0 Hyperion
 308.0  32.0 Edmunds-RKE
 175.0  32.0 TV-Plossl

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Tammy

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Thanks for the data...it just supports what I am saying.

A 10x weight range is a sign of poor design in the industry.

A standardized weight would make for a better product.

A lighter weight would make for a better product.

And if they would design a doughnut that cause you to lose weight, life would be perfect. ;<)

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Doesn't this depend on whether the scope is balanced for a certain weight at a certain point? With my lightest eyepiece and the scope pointed near zenith, I have to dangle a counterweight from the UTA of my scope.
With a 31 nagler at the horizon, I have to add a 5lb counterweight to the mirror box.
There is NO weight that would be perfectly balanced near the zenith AND the horizon, so some form of counterweight will always be necessary unless the scope is so large the weight of the eyepiece is insignificant, or so "sticky" that the difference in the weight of eyepieces causes no noticeable balance changes.

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What would be interesting to know for each eyepiece available out there is how much of the weight comes from the glass and how much from the housing - particularly for the really heavy eyepieces. Perhaps design of the housing and materials used could be adjusted to reduce the weights of some of these really heavy pieces.

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Doesn't this depend on whether the scope is balanced for a certain weight at a certain point? With my lightest eyepiece and the scope pointed near zenith, I have to dangle a counterweight from the UTA of my scope.
With a 31 nagler at the horizon, I have to add a 5lb counterweight to the mirror box.
There is NO weight that would be perfectly balanced near the zenith AND the horizon, so some form of counterweight will always be necessary unless the scope is so large the weight of the eyepiece is insignificant, or so "sticky" that the difference in the weight of eyepieces causes no noticeable balance changes.

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I imagine it varies for mount type too. I use a williams optical EZ mount for my refractor. So all I have to do to balance the scope is adjust the position of the OTA in the rings so that with the altitude unlocked the tube assembly does not rotate up or down because of gravity. Once I've done that I am good to go.

The problem arises if I position the OTA with a really heavy or really light eyepiece and then I try to use one at the other extreme. That is why any of the 18+oz eyepieces won't work for me. If I bought one of them then I would have to re-adjust the tube in the rings when I switched to lighter eyepieces.

So every time I look at a possible eyepiece purchase I check the weight and the eyerelief because I wear eyeglasses. Those two criteria eliminate quite a few eyepieces for me.

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Agreed.

And if all your eyepieces were of the same weight, you would only have to adjust balance once.

And the lighter the eyepiece, the less impact it has on the mount and scope.

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And if all your eyepieces were of the same weight, you would only have to adjust balance once.

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Most dobs, even without an eyepiece, cannot be simultaneously balanced at both zenith and horizon.
So you cannot escape some form of dynamic balancing with most dobs. And if you are used to doing it, the weight of the eyepiece isn't important--it only determines the amount of weight.

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True, but this (the spring and pulley system) helps:

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My philosophy, in essence, is the concept of man as a moral being, with his own happiness as the moral purpose of his life, with productive achievement as his noblest activity, and reason as his only absolute.

Ayn Rand (in the appendix to 'Atlas Shrugged')

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And if all your eyepieces were of the same weight, you would only have to adjust balance once.

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Most dobs, even without an eyepiece, cannot be simultaneously balanced at both zenith and horizon.
So you cannot escape some form of dynamic balancing with most dobs. And if you are used to doing it, the weight of the eyepiece isn't important--it only determines the amount of weight.

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Is it not true that the amount of the weight affects the degree of balance?

The heavier the eyepiece, the more the imbalance is.

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There are (at least) two reasons. First, because only high index materials perform "work" on light rays, any optical design code will have a tendency to fill the available working space with glass. It takes a great deal of skill to achieve an equivalent lens design without having nearly solid glass. The second reason is that high index materials are also (typically) high density materials. If plastic worked well, people would use it. It doesn't, and glass is the dominant material. A modern, 80+ degree FOV eyepiece suitable for use at f4 is really working the incoming light cone hard. To achieve good performance across the entire field is, frankly, a miracle. Weight and size are small prices to pay.

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The glass is the only important portion of the eyepiece...the rest is just support.

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And if all your eyepieces were of the same weight, you would only have to adjust balance once.

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Most dobs, even without an eyepiece, cannot be simultaneously balanced at both zenith and horizon.
So you cannot escape some form of dynamic balancing with most dobs. And if you are used to doing it, the weight of the eyepiece isn't important--it only determines the amount of weight.

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Is it not true that the amount of the weight affects the degree of balance?

The heavier the eyepiece, the more the imbalance is.

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The point I was making was that most dobs require some counterweight just to balance themselves. Adding an eyepiece merely changes the weight of the counterweight, not whether or not one is needed.

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Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member

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And if all your eyepieces were of the same weight, you would only have to adjust balance once.

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Most dobs, even without an eyepiece, cannot be simultaneously balanced at both zenith and horizon.
So you cannot escape some form of dynamic balancing with most dobs. And if you are used to doing it, the weight of the eyepiece isn't important--it only determines the amount of weight.

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Is it not true that the amount of the weight affects the degree of balance?

The heavier the eyepiece, the more the imbalance is.

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The point I was making was that most dobs require some counterweight just to balance themselves. Adding an eyepiece merely changes the weight of the counterweight, not whether or not one is needed.

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This is not necessary true.

I have used dobs in the past that did not need counterweights once they were balanced initially.

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The glass is the only important portion of the eyepiece...the rest is just support.

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You don't really mean that, do you?

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Yes I do.

It is true.

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Most dobs, even without an eyepiece, cannot be simultaneously balanced at both zenith and horizon.
So you cannot escape some form of dynamic balancing with most dobs. And if you are used to doing it, the weight of the eyepiece isn't important--it only determines the amount of weight.

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True, but this (the spring and pulley system) helps:

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Lawrence; that "spring & pulley system" looks pretty neat!

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Carol


AstroTech 16" Dob (Thanks ASTRONOMICS!)
Vixen 80MF/AstroTech Voyager
Masuyama's 7.5, 15, 25W, 35mm,
Pentaxes; 5XW, 7XL, 10XW.
14mm Meade 4000 UWA
TV Panoptics; 22, 35

DreamCatcher Dobservatory, #2

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The point I was making was that most dobs require some counterweight just to balance themselves. Adding an eyepiece merely changes the weight of the counterweight, not whether or not one is needed.

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This is not necessarily true.

I have used dobs in the past that did not need counterweights once they were balanced initially.

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As have I.
But most dobs, if balanced perfectly at an altitude of 70-80 degrees will, if pointed at an altitude of 10 degrees, fall toward the ground. Or, if balanced for low altitude, will automatically rise if pointed up at 70-80 degrees.
That is, if the friction in the altitude bearings is very low. Sticky altitude bearings or very large heavy scopes don't react the same.

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Don Pensack
12.5" Truss Dob, 5" Maksutov, Fujinon Binos
Sustaining Lifetime IDA member

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The glass is the only important portion of the eyepiece...the rest is just support.


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You don't really mean that, do you?


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Yes I do.

It is true.

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