PST question

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Robert Henry 1355
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PST question

Post by Robert Henry 1355 » Sun Jan 08, 2017 3:52 pm

Hello-
I just purchase PST DS scope and would like to know if there is a way to make the field of view larger in the PST. I know that the PST has a 5mm blocking filter but was wondering if you could make it a 10mm blocking filter PST with some kind of modification? Does the 400mm focus length limit how big a blocking filter that would be useful/practical? Mark Townley are you there(lol)!
Thanks
Robert

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marktownley
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Re: PST question

Post by marktownley » Sun Jan 08, 2017 4:52 pm

Yes, I've swapped out the BF5 in my PST for a BF10, just a straight swap. Unscrew top half of ep holder from PST (this is the bit with the 5mm blocker in), unscrew Bf10 ep holder from the bf10 diagonal and screw it onto the PST - simples!
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Robert Henry 1355
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Re: PST question

Post by Robert Henry 1355 » Sun Jan 08, 2017 7:27 pm

Thanks,Mark,I knew you would have the answer! In the visual view with the 10mm BF in the PST,do you have a significant improvement over the 5mm stock BF? Is the view more comfortable? I just purchased the PST DS . Do you know if the ep holder top half is cemented in so that it can be unscrewed? I don't want to force it if so.
Thank you much!
Robert

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marktownley
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Re: PST question

Post by marktownley » Sun Jan 08, 2017 8:25 pm

Hi Robert, there was a bit of thread lock on it, but that comes undone quite easily. I just found by BF10 gave a better view than the BF5. All blockers are different so your mileage may vary.
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Robert Henry 1355
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Re: PST question

Post by Robert Henry 1355 » Sun Jan 08, 2017 9:30 pm

Thanks,Mark.
Robert

Robert Henry 1355
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Re: PST question

Post by Robert Henry 1355 » Mon Jan 16, 2017 3:36 am

Hi,again,Mark-
I e-mailed a tech specialist at Meade-Coronado and he stated that changing the bf5 with a bf10 would not change the image scale.He says because of the PST focus length,only the bf5 would work.Your thoughts on this,please.
Thanks,
Robert

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Re: PST question

Post by GUS » Mon Jan 16, 2017 9:13 am

I replaced my BF5 with a BF10 and it worked fine. It doesn't change image scale, just gives you more black sky around the sun, ie, stays in view longer before you have to move the scope.

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Re: PST question

Post by Robert Henry 1355 » Mon Jan 16, 2017 3:17 pm

Thanks,Gus-
I think from what you and Mark have helped me with,I will see if Meade/Coronado just sells the bf10 and holder without the diagonal. Probably not,but I'll take a shot and cross my fingers they do.
Bob

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Re: PST question

Post by marktownley » Mon Jan 16, 2017 4:21 pm

The meade guy is right in the sense it will not change the image scale (or resolution) that is governed by the 40mm/400mm fl of the PST itself. Like GUS says it just gives you more black space around the sun.

The sweet spot in my PST isn't dead centre, but the bigger fov allows me to (off) centre it on the camera chip so the disk ends up evenly on band.

All the BF filters behave subtly different, I have 4 bf5s, 2 bf10s and a bf15, and one of the bf10s gives a more contrasty image with the PST. With the SM40 scope the bf15 was best, each situation is different!
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Re: PST question

Post by marktownley » Mon Jan 16, 2017 4:24 pm

Robert Henry 1355 wrote:Thanks,Gus-
I think from what you and Mark have helped me with,I will see if Meade/Coronado just sells the bf10 and holder without the diagonal. Probably not,but I'll take a shot and cross my fingers they do.
Bob
You could buy a bf10 blocker and remove the 10mm blocker nose, put this on the PST, put the 5mm blocker from the PST back on the diagonal and resell it as a BF5 diagonal, get a bit of your $$$ back ;)
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Re: PST question

Post by Robert Henry 1355 » Mon Jan 16, 2017 5:56 pm

Thanks,Mark-
Just got e-mail from Meade: they don't sell the blockers separately,as I figured would be the answer.Oh,well,I tried.Would you be willing to part with your good bf10,and if so,how much to US? If not,I will probably look for used one on the internet.
Thanks much,Mark,
Robert

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Re: PST question

Post by marktownley » Mon Jan 16, 2017 10:09 pm

Sorry, I want to keep my blockers.
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Re: PST question

Post by Robert Henry 1355 » Mon Jan 16, 2017 11:13 pm

No problem

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