Pst stage 1 mod, focus

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Sol seeker uk
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Pst stage 1 mod, focus

Post by Sol seeker uk »

Hi all, I'm going to stage 1 mod my pst pretty soon with my 10mm tal donor frac.. As it is at the moment with just the pst I'm using a x2 Barlow to achieve focus , so when it comes to modding and cutting the tube do I factor this in or is it more the case of the etalon being 200mm from the point of focus.. is there a way of maybe doing away with the Barlow or again is that beneficial to the sweet spot of f20( or is it f30?) As you can see this scrambles my brain, pretty easily.. thanks in advance..
Ps anyone that's done a pst mod with a tal care to share a rough amount they had to cut off please ?
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MalVeauX
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Re: Pst stage 1 mod, focus

Post by MalVeauX »

Heya,

If the scope is F10, you just need the collimating lens to land at -200mm into the tube. You can measure this by letting a light source focus on a card and where it's at focus, measure 200mm into the OTA and that's where the collimating lens needs to be.

Alternatively, instead of cutting your OTA, you can just use extensions to push the collimating lens foward so that it sits at the -200mm spot in the tube.

Lots of info here as I recently went through the process too: viewtopic.php?f=9&t=26560

Very best,


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