New Coronado PST issue (yes I bought one now instead of a lunt 40...)

[DaphneVS]

Hi all, I have some issues with my new PST which I have already dismantled and readjusted to no avail, I am hoping you might be able to help me out. Out of the box, I noticed that it could only show some surface detail, a sunspot a n d tiny prominences at a single focus spot which was right at the (left) edge of the tube turn. Anywhere else to the right - nothing but a blank (but vibrant, which seemed to rule out rust issues) red disc. This looked odd because I was expecting to see either (prominence)-or(sunspots and granulation) but not all together, but there it was.  I thought maybe the tube turret had been mounted wrong, so I took the rubber band off and moved the stopping screw five holes to the left. The result is that the focus spot is now at the middle of the tube turn instead of the extreme left, but nothing else seems changed. I still see a blank disc when turning the etalon right or left of that point.

A second issue regards imaging - I'm not set up for ccd imaging and don't use a tracking mount, but merely handhold a digicam to the eyepiece , still unlike my afocal moon captures with other scopes, the images i took through the pst all show the same - the disc at an angle, with a big blank spot, and granulation at the top only. as for prominences, unlike naked eye observing, the digicam captures either the prominence, or the inside of the disc (without moving the etalon though), but maybe that's as it should be (?) attached two sample pics (the second is a stack of nine consecutive captures) . Do these seem normal to you in a pst?

Naturally suspecting filter rust i had a close look at the blocking filter and the itf, and found no edge or center rust on them however, both feature golden specks which I wonder about (phone pics attached!) - oxydation? something else? 

Lastly, the prism  doesn't look all that well aligned to me. I have tried to nudge it a little but it returns to its original place.  However I didn't remove the screw (there is a big blob of glue round the contact area)- was that a prerequisite to successful adjusting of the chips? The misalignement isn't huge, but I wonder if it might be sufficient to produce that angled image I see in the eyepiece (?) - more phone pics of the prism attached

Edited October 16, 2021 by DaphneVS

[Elp]

The PST is notorious for being not so straight forward for imaging (it was never designed for it). Mine performs similar in that ring tuned to the left shows prominences, just after centre starts to show sunspots though I don't really see granulation through mine, the view is similar to your second image but much brighter including annoying bloom/reflection around the inside of any eyepiece I use.

My prism is also similar to yours though I've found the image is focused uniformly across the field so I haven't messed with it too much as it seems very flimsy.

You need to check your itf filter, if your scope has a blue coloured main objective lens (also confirmed with a thereabouts +100000 pst serial number) the ITF is the filter in the lower half of the eyepiece holder which connects directly to the prism box (the red one in your image shows the one side of it), the eyepiece holder may be tight if it's never been removed from the prism box. You can also see the bottom of the itf if you look above the prism at it though will be difficult to see any imperfections. If there's gold or yellow specs, what looks like yellow growth or mold, or clouding or uneven colour the ITF needs replacing. If it's an older pst the main objective lens will be a goldish colour and any breakdown will be visible as a rust like appearance.

The smaller filter in the top half of the eyepiece holder I believe is the ND5 filter which usually doesn't need replacing though your provided photo is blurry.

In terms of imaging a mono astro camera is the best option, I find it difficult achieving focus with my zwo 224mc as the focus point is around 5mm "into" the eyepiece holder from the top edge (being colour also presents further focusing issues), haven't had a clear day yet to try dslr but been told it can be done via the use of a threaded 8-24mm zoom eyepiece which connects directly to the dslr t-ring.

[Merlin66]

Based on my experience with many PST’s.

I think you may have moved the tuning screw a bit too much. One or two holes is sufficient.

The tilt on the prism is not excessive, some tilt is needed to avoid reflections and ghosts.

If the PST is new I would not think failure of the ITF element is likely.

The final smaller (red) filter in the eyepiece tube is actually the very important blocking/ sort filter. This works in conjunction with the etalon to give the narrow band bandwidth required.

I would spend a bit more time at the eyepiece, get used to the PST. It’s not like your average telescope and takes time to come to terms with.

 

Edited October 19, 2021 by Merlin66

[Stu]

If dissatisfied I wonder why you haven’t returned it or contacted your retailer rather than dismantling it?