PST - Anyone know how they work?

[iwatkins]

Hi All,

Received my PST today and as it was cloudy, thought I would at least get a mini-dovetail fitted ready for use.

I noticed the eyepiece holder, which screws into the main block was loose. No worries, might as well clean the threads and get a little bit of boot polish on them.

So the whole tube unscrews from the block. This in turn unscrews to give two parts, the second being the actual eye piece holder. Both of these parts have a filter in them. Incidentally they were both filthy and all need cleaning. Haven't done it yet until I've had first light to see if necessary.

Are they both blocking filters of some sort? Or is one a blocker and the other for something else?

Just interested how it works really.

Cheers

Ian

[Merlin66]

Ian,

I have a PST Mod document available which explains all...just drop me an email for a copy.

In the eyepiece holder, the filter closest to the black box is a "mini ERF" to reduce the energy loading on the sensitive, smaller blocking narrowband filter at the eyepiece. These two filters work in conjunction with the tunable etalon at the front.

Hope this helps.

[Peter Drew]

I wouldn't attempt to clean the filters without advice from a higher authority. Ken?

[Merlin66]

Peter,

yes!

The mini ERF and the blocking filter should be pretty clear - they are protected by their location in the black box....

Is this a new PST??

Unfortunately on some of the mini ERF filters thay suffer from deterioration which may appear as "being dirty" - they are not dirty. This deterioration cannot be removed! and any cleaning will only make matters worse!

On the smaller BF filter the external surface can be blown clean...no more.

Hope this helps.

[iwatkins]

Thanks Ken.

No, would never dream of cleaning anything without checking first. Yes, brand new from FLO this morning. It looks to be mainly fine dust that will blow off I would think. I'll get first light before doing anything.

And thanks for the offer Ken. I'll PM you my email address for Mod doc.

Cheers

Ian

[FLO]

Incidentally they were both filthy and all need cleaning.

That doesn't sound good!

I think we had better have it back please. Please let us know which week-day is best, we'll arrange collection/replacemat.

Was the box sealed when you recieved it? And does it have one layer of tape or two?

Coronado's UK importer/distributer have their own retail outlet, my concern is they might have sent us one of their customer returns or demo model by mistake...

Steve

[iwatkins]

Hi Steve,

Ahhh, that would make sense.

Checked the boxes. The outer plain cardboard box was sealed, single layer of tape. The inner printed Cornado box was single taped but was already cut open. I just assumed you guys had opened it to check it contained what the little checkboxes on the exterior indicated before you sent it out?

The etalon tuning ring is also lightly marked in one spot, so you may be right as to what has happened.

No worries, happy to do a swap Steve. I'll repackage it in the morning and I'll be ready whenever you can do it. I'm working from home the next two weeks so whenever you can fit it in, no rush. I know you guys are snowed.

Cheers

Ian

[iwatkins]

Got your mail Ken.

What a fascinating subject. I'll admit here I'm terrified of modding optical instruments, I just leave them alone and try to look after them from afar (my 8 year old dob is so dusty I really should man up and clean it, but Boris, the spider has lived there the past two seasons, so I'm reluctant).

Even so, great to see how the PST works, so thanks again.

Cheers

Ian