The good old days

[xtreemchaos]

thanks Den, yes she should start waking up soon mate "fingers crossed".

[MarsG76]

Awesome images.... memories....

Good news is that we're only a few years away from another solar maximum.. but the bad news is that the maximum is expected to be a fizzle not a BOOM!!!!

[johninderby]

I want to see some proper activity. 😁

[Rusted]

3 hours ago, johninderby said:

I want to see some proper activity. 😁

And, preferably, live to tell the tale! 

[Pete Presland]

I naively thought the Sun was always on going to look like that when I firsted Solar imaging. Its going to be so good when it does kick back in to life.

[sophiecentaur]

This thread seems a good one to hitch a lift on because there is bound to be someone with experience of the Coronado PST. I'd really love to get some information about using them. I just got one on eBay (I know: caveat emptor etc.) and the sky has really never been crystal clear since it arrived. Hence I haven't had an opportunity to test it properly. I am aware that the image looks dim and that getting features requires some subtle twiddling of the filter control.

So far, I have used it with a couple of eyepieces and with a X2 barlow  (also with my DSLR) but never managed to get a crisp focus. I can go through a 'best' condition so I don't think I am at any end-stop of focus. The PST has a non-standard focus control so I don't know what to expect but is it normal to find the image moves from side to side as the focus knob is turned? I could take off the side panel and that may give me a clue about how the focus actually works but I am reluctant to because I may need to return it.

The absence of sunspots at the moment really doesn't help. My DSLR images have dark spots but they are dust!! I blew them away, ready for my next sunny day session.

[Rusted]

21 minutes ago, sophiecentaur said:

This thread seems a good one to hitch a lift on because there is bound to be someone with experience of the Coronado PST. I'd really love to get some information about using them. I just got one on eBay (I know: caveat emptor etc.) and the sky has really never been crystal clear since it arrived. Hence I haven't had an opportunity to test it properly. I am aware that the image looks dim and that getting features requires some subtle twiddling of the filter control.

So far, I have used it with a couple of eyepieces and with a X2 barlow  (also with my DSLR) but never managed to get a crisp focus. I can go through a 'best' condition so I don't think I am at any end-stop of focus. The PST has a non-standard focus control so I don't know what to expect but is it normal to find the image moves from side to side as the focus knob is turned? I could take off the side panel and that may give me a clue about how the focus actually works but I am reluctant to because I may need to return it.

The absence of sunspots at the moment really doesn't help. My DSLR images have dark spots but they are dust!! I blew them away, ready for my next sunny day session.

Hi Sophie,

I have some images on my blog from back when I dismantled my secondhand PST for the internal parts.

https://fullerscopes.blogspot.com/2018/02/pst-dismantling-images-of-parts.html

Try clicking on Newer and Older Posts at the bottom of my blog page for more blog posts with more pictures.

For focusing, the PST relies on a prism which slides diagonally on rails inside the black box.
Unfortunately the prism can become rotated on its mounting blocks which doesn't help.

Removing the black box cover is essential to examining the situation inside.
With luck you won't have stripped screw heads like my secondhand PST had on arrival.

If your views are very dim then you might have a rusted ITF filter. This is a filter inside the black box.
I had exactly the same problem of dim images and had to buy a new ITF filter. I bought a new one from Maier in the US.
From memory it cost about £90 equivalent with postage. Possible customs charges too?
Beloptik of Europe also offers replacement ITF filters but they are rather more expensive.

Fitting the new filter is probably for those with some DIY and/or optical experience.
An experienced member of a local astro society might be able to help if the job is beyond your practical skills.
You don't want to damage anything.

[sophiecentaur]

Hi @Rusted

That's an interesting link and the arrangement for focussing, using the prism is what I suspected but I was assuming a normal 45 degree prism . I think something must be mis-aligned to cause that sideways drift.

I contacted Meade and they offer a $150 repair (for virtually anything including replacement) plus $20 carriage (@Mexico !!) but that may not apply to UK, which is where I am located. I shall have to approach the vendor when I have more info from Meade. We may need to modify the price on the basis of spares or repair, if he wants to. I enjoy a challenge; if that filter has actually burned out, it would make the scope not very interesting but the mis-aligned focuser could be solved, I'm sure. 

[Edit: I will take off the side plate and see if I can re-align the prism, which your blog seems to suggest is no problem.]

Edited February 4, 2020 by sophiecentaur

[Rusted]

Here are some better images of the PST interior if you can get the covering plate off despite the pink thread locker.

The prism slides in a track with two pins for alignment.
While the fibrous pad is supposed to keep the prism in contact with the greasy track but obviously fails to do so quite regularly.
So that the prism is no longer parallel to the top of the black box. Which is the ideal set-up.

I used a small mirror to capture my rusty ITF with the camera. The angle is too oblique otherwise while it is still in place in the black box.

In theory you can unscrew the eyepiece holder with its mounted ITF and IBF filters. Overcoming the thread locker will be your challenge.
I fixed the [empty] black box down on the bench with two sturdy, padded F-clamps.
While I used a 2' pipe on the arm of a brand new Python rubber strap wrench and nearly broke the strap!

Hope this helps.

Edited February 9, 2020 by Rusted
Image added.

[Merlin66]

Sophie,

First question to ask....is the front objective lens of the PST a “blue” colour or does it look “golden brown”

If it’s not blue then it’s an older version which has NO ITF filter in the eyepiece holder.