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[quote=g__day]Is this your understanding of the convention used to classify load capability for a GEM mount - to state only the OTA in the calculation? quote]
The answer to the above question is yes. Counter weight are not included in the calculation. Consider that the whole purpose of balance a EQ mount is to reach equilibrium between the OTA and Counter weight (centred on the polar axis) so that the mount can track smoothly without to much stress on the machanic.
If the EQ mount is equipped with a short counter weight shaft you will need more weight to reach balance if you have a heavy OTA. If the counter weight shaft is much long say 1/2 a meter you will need less weight to reach balance with the same OTA, but this may make the mount unstable.
So generally speaking, you may be able to balance a 41kg OTA using a 1kg counter weight if the counter weight shaft is long enough, but this would be very impractical.
So you should buy the best mount you can afford, ensuring that it has sufficient load carrying capability to carry all your gear with some room to spare. Also consider how this mount will be used in the future, because plans always change.
Final thoughts, this discussion has been about the load carrying capability of the EQ5/CG5, HEQ5 and EQ6. There are many other factor to consider when look at purchasing a mount, price being one but not always the best choice for quality, type of work you plan to use the mount for, type of OTA, autoguiding, ease of use etc.
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