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Old 10-10-2021, 01:52 PM
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Stonius (Markus)
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Stonius is offline
Join Date: Mar 2015
Location: Melbourne
Posts: 1,347
Thanks astro744 for attempting to explain it to me. It kind of makes sense, but I still struggle to understand some aspects of this whole field stop malarkey. For example;

Why does the 2.5x powermate have a 1 1/4" barrel, while the 4x is a 2", (even though the field stop on the 4x could easily be accomodated by a 1 1/4" barrel)?

Also, I understand that the field stop will likely get smaller as magnification increases, but it doesn't seem to be a linear relationship. As mentioned, the 2.5x and the 4x are about the same at 10mm or so. I also have an ES telecentric 3x that has a field stop even smaller than the TV 4x (it's around 5mm).

Clearly, there must be something I don't quite understand yet. But I guess life would be boring if you understood everything all at once.


Last edited by Stonius; 10-10-2021 at 04:38 PM.
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