Re: Here is why; and confusing conclusions about tubelength

Theo Griep writes:

So, both objectives and eyepieces are missing the essential data about
the intermediary image distance. Instead, objectives have a nonsense
tubelength value on them.

You're quite right.

That said, you do not need to change the tubes to get the intermediate
image where you want it. This can be done simply by normal focusing.
Since 1/f = 1/v + 1/v', when v changes slightly, you just change v'
slightly to compensate.
.

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