coronado pst

[MBJ]

I purchased a Coronado pst from rothervalleyoptics yesterday and thought I might share my thoughts on the build quality of these scopes and wonder if its just me or do any other pst owners agree.

I had the chance to look through it before I bought it as it was already set up on a tripod in the shop when I went in,it was carried outside and the sky was cloudy with a few breaks inbetween .the guy at the shop put a 9mm eyepiece in and focused and aligned it to the sun and I looked through it and was instantly blown away by what I saw.

a huge prominence at about 3 o clock and some smaller ones round the limb.a few sun spots and lots of granulation as I moved the etaon tuner.i told the guy to box it up and I was buying it there and then.

today the sun was out in a semi cloudy sky so I thought all day I will be on the back garden with my new pst.

I opened the box and took it out of the foam protector complete with blocking filter attached and protective cap.

out of curiosity I unscrewed the blocking filter to have a look at it before I used it.

to my horror I saw what I can only describe as very bad workmanship in the blocking filter housing, a huge blob of what looks like clear silicone was staring me in the face. this silicone looks like its encroached onto the glass where the blocking filter sits.

my concern is if I buy the 15mm blocking filter will I be able to see this silicone when looking through the scope.

upon further investigation I looked on the back of the blocking filter and saw more silicone holding the filter cell in place albeit not even level.

the other concern I have is the etalon tuning ring feels lose and when I look through the scope and turn it it doesn't make proninences appear gradually as you tune it,they flicker on and off as it moves loosely.

I am thinking about returning it to the shop and getting a refund as im seriously unhappy with these defects.

here are some photos of my findings and I look forward to any thoughts people have.

[astrofox]

Thats just poor assembly and quality control. Not acceptable in any scientific kit. Return it.

[keithatrochdale]

Hi

Don't be worried by the spots of silicon, they are there to make sure it cannot unscrew.

You will find that you do not need to adjust the etalon tuning ring once you find a position you like.

Do get yourself a zoom eyepiece for it, a cheap one will do nicely.

And if you can find one, one of the shields is very nice and not rubbish as I originally thought.

Get out there and enjoy your PST.

PS Do you know about this site; http://solarchat.natca.net/index.php.

[jabeoo1]

Lunt also use silicone between components.   My scope had a tiny small bump of silicone near a threaded section in the filter cell end.   There was no silicone squeezed out between sandwiched surfaces like in your top image.  

 

It should not be there in this excess and certainly no where near overlapping the light path.  Your images show excessive amounts of residue where it just has been lazily put together.  Personally I would not be happy with the condition of the scope and would take it back.  

 

How you describe the loose etalon tuning ring would be enough for me to return it.

 

Sorry to see this. 

[JamesF]

I don't think that either of the silicon blobs you've shown will cause problems with the performance as they shouldn't impinge on the light cone which is actually quite small by the time it reaches these filters.  There does seem to be quite some degree of paranoia involved in the assembly of these in terms of making sure that none of the filters should ever come loose, hence the excessive use of threadlock on many.

It definitely sounds like something is iffy wtih the etalon tuner though.  You could push the rubber grip to one side to check that there is a screw properly engaged with the tuning ring (it's intended that you should be able to change this if required to get the tuning correct), but I would be tempted to return it if you're at all unsure, or at the least contact RVO to discuss the problems.

Generally though I think that quality control on these scopes is astonishingly poor.  That doesn't mean they're all bad -- some of them, probably most, are absolutely fine.  But reports suggest that others can be really pretty skanky.  I have one eyepiece holder that I have completely disassembled to find that the final filter (the last in your set of photos) is not only scratched on the objective side, but also the edges of the eyepiece side are chipped.  Both of these defects must have a negative effect on the view.  Of course by disassembling the OTA I've almost certainly voided any warranty (and it's too old now anyhow), but the only way to have found these problems is to do just that.  I've tried to contact the manufacturer, but not even received an acknowledgement of my email, let alone any meaningful response.

James

[Paul73]

Get the shop to swap it at their expense. They can then have the conversation with the manufacturers, who on the evidence of these pictures, may be getting a little complacent.....

Paul

[laudropb]

I was thinking of purchasing one of these, but your post has me thinking again.

[John]

I had a PST for a short while. It worked well and mine was luckily not one of the ones affected by the "rusted" objective / front filter. I think those are the older ones now. Mine worked quite well but I did think the overall build rather poor for a £500+ instrument. I guess most of the cost is the Etalon filter which contains platinum I believe and the other filters involved are rather specialised too. Focussing was really very basic. It did work however and I got some nice views of H-Beta visible features while I had it, once I learned how the "sweet spot" worked

The Lunt 35's look better put together at least externally although I've never used one.

[spaceboy]

I find it interesting that people still buy PST's at their current prices (£450-£500 a couple years ago was a more competitive price). Given the LS50Tha can be had for £200 more that the PST and offers 10mm more aperture, lower bandpass, arguably a better focuser with compression ring diagonal and pressure tuning, I would rather wait the extra months saving up but that's just me.

As for your example MBJ I doubt very much that the silicone will cause you any issues as most dedicated Ha scopes have a sweet spot which is often in the centre of view. My dealings with RVO has always been positive so for the tuning ring issue I am sure if you popped back to RVO they will take a look at it for you and no doubt if need be replace the unit.

[axle01]

I've got a PST and was unhappy with the black box and the Penta Prism for focusing so I removed the black box had a adapter made to connect a non rotating helical focuser to the etalon then purchased a BF10 to replace the original blocking filter.

You can unscrew the blocking filter from the black box and get a cheap Skywatcher or Celestron diagonal and unscrew the eyepiece and screw the original BF in, it has the same thread, instead of going to the extra expense of getting a BF10.

The end result is so much better than the original and much better visual and easier to focus.

Why Meade doesn't flick the black box and instal a helical focuser and diagonal with the BF in it don't know.

I will endeavour to post some photos tomorrow.

Alan

[keithatrochdale]

I was thinking of purchasing one of these, but your post has me thinking again.

Don't be put off, they are great fun.

And if you want to do a conversion later with a bigger scope you are half way there.

.

[keithatrochdale]

Do you know that you can ream out the 5mm hole in the BF5 to 6mm - does not seem much but is a 44% increase in area! (if my maths are correct)

.

[jkwhinfrey]

I bought one a couple of years ago and found the etalon ring was loose much as you describe. I checked the locking screw under the rubber to find that it was stripped.

It went back to Telescope House for them to sort out... which they did

I'm quite happy using it now, and the detail it shows is better than others I've looked through. Coronado/Meade's QA isn't up to much IMO. I'd send it back.

I'd probably go for the Lunt 50 if I was buying now. I'd like a Lunt 60.

[Gazabone]

I have to say I'm delighted with mine. I had the opportunity last week to try it side by side with a Lunt 60 (not the pressure Tuned version) and I have to say the my little PST compared quite favourably; I was thinking of upgrading but now I'm not so sure.

In your case, yes, the silicon blobs are undesirable but I think your first comment is very telling; that you were blown away the first time you looked through it.

Whatever you choose to do, hope you get lots of rewarding solar views.

[MBJ]

thanks for all the feedback guys,i really appreciate it and have taken all your comments on board.

I went with my gut instinct and returned the unit to rvo this morning and told them about my concerns.

on the way I thought about the pst build quality spoiling my experience and not really wanting to replace it with another pst so I asked ian and the guys what they thought about me swapping the pst with extra cash and upgrading to a solarmax 2 60mm.

as usual they came out on top form with no questions asked and let me swap the unit for a new solarmax 2 with the bf10 .

big thumbs up to RVO for the no quibble after sales service and as usual I will always shop there for any of my astro gear.

[axle01]

Here's my .5 PST mod

[JamesF]

Here's my .5 PST mod

That's looking very nice.  I like the addition of the finder on the dovetail.  Very neat.

James

[axle01]

That's looking very nice.  I like the addition of the finder on the dovetail.  Very neat.

James

Thanks James