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Carole's POD and PZT


Carastro

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I bought this in 2010 when I was a bit green about the gills and didn't realise it was going to cause me a problem imaging at or near the Zenith.  But in all other ways I really love it.  Setting up every night was becoming a chore.

So to start with I had this:

 

Links no longer work, so have replaced with actual photos.   Possibly due to me updating my website.  

 

7 POD.jpg

Edited by Carastro
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I live in SE London, so also when I first started I was unaware how bad Light pollution is for imaging, but I ploughed on regardless using a DSLR and a LP filter helped, later changing to a Mono CCD camera as I progressed.   

I started to go to - and still go to (coronavirus permitting) Dark Sky camping sites with others and places like the Kelling Heath Star party to get to darker skies and this has helped a lot, so I do all my learning and experimenting at home.

One of my early rigs inside the POD:

 

Kit inside POD 2010.jpg

Edited by Carastro
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However it soon became very annoying that I was unable to image when targets passed overhead and behind the dome, so I started to investigate a PZT.

What's a PZT you all ask?

It's a POD Zenith Table.  The idea is that you build a platform alongside the POD, unlatch the dome and slide it onto the table.  (Getting it back onto the Walls is quite another matter, but come to that later).  

So I enlisted a good friend who is a retired engineer to help as he had all the tools and a good idea of what would work.  

This is the framework.

 

Framework.jpg

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The dome bolts had to be changed to Quick release brackets, (also not easy to do at night without making a noise and especially when it is freezing cold).

Quick%2Brelease%2Bbracket%2Bcompleted.jpg

 

Edited by Carastro
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Finally I had my table.  Ramps had to be built to enable the Roof to rise up on closing,

 

I can now reach the Zenith.  The obstruction where the dome is is to the North East and mostly houses are in the way anyway, and Targets rising in the East can be imaged without the PZT, until they get too high.

 

 

PZT finished.jpg

Seeing Zenith.jpg

Edited by Carastro
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It has been a godsend throughout the Coronavirus pandemic as I never managed to get to a dark location (campsite) in 2020 until September.

Carole 

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@Carastro Nice one Carole, I can fully understand how invaluable your dome is, just looking forward to finishing the configuration on mine.

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Thanks Geof and John,

Getting the dome back on is quite difficult, as due to another early error when I shifted the POD to try to offset the pier, I made the walls slightly uncircular (only about 1/2 inch difference in diameter, but it makes it REALLY REALLY difficult to get the 3rd dome bracket back on when the dome has been off the walls because it springs back into circular shape, and trying to do battle with a huge and heavy precast HPDE Dome is extremely difficult as it doesn't want to pull itself in, in order to fit the dome bracket on. 

Then one night I decided to give up and make do with just the two dome bolts, and come back in the morning and finish the job, perhaps with hubby to help.  So I rotated the dome on only 2 brackets into the "home position" as it will only close properly and lock in one position (for the same reason), when all of a sudden, I realised the dome was now in closer - in the right position to put the bracket on once is had moved around the walls a bit. 

So that is my routine now.  Took a few years of struggling before I found out.

Carole  

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That's a good write up Carole.  I can't see the photos in the second and third posts, which is a pity.

I'd seen a photo of your pod before, but I thought that it was some sort of table top affair.

Is it easy to get in and out of it?

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Great write up Carole. Just a little idea I had when looking at the side platform, have you ever thought of bolting on some small dolly wheels on L-brackets around the half dome that you have to shove around. I would have thought it would make things easier to move.

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Posted by: @don4l

hat's a good write up Carole.  I can't see the photos in the second and third posts, which is a pity.

I'd seen a photo of your pod before, but I thought that it was some sort of table top affair.

Is it easy to get in and out of it?

So that will be a photo of the kit inside and the framework of the PZT while it is being constructed?

I decided to view the thread today without being logged in, but I can still see all the photos.

It is easy to get in and out of once you get the hang of it = one foot in and one foot out, duck under the top of the opening and then stand up inside.  I have had a few tall visitors try to get in whole don't know the drill and I wish i had taken a video of it, it was hilarious seeing their antics trying to get in and out.

Carole  

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Posted by: @MarkAR

Great write up Carole. Just a little idea I had when looking at the side platform, have you ever thought of bolting on some small dolly wheels on L-brackets around the half dome that you have to shove around. I would have thought it would make things easier to move.

Pushing the dome on the table itself is quite easy, as my Chum who constructed it put some strips of very slippery plastic along the sides and down the middle.  The really difficult thing is getting the dome back onto the walls, as you can slide it to the edge of the wall but it doesn't want to lift back on, especially with the wheels on top of the walls. 

When we first did it it wasn't such a problem due to the ramps he installed, which can't be too close otherwise they obstruct the dome lip when rotating the dome, but after a recent repair (due to erosion of the wood and screws popping out), it doesn't work quite as well now, so I get it as close as I can and then have to use a crowbar (similar) to lift the dome onto the wheels on top of the wall.  Once it is on the wall, I can normally manage to heave it that little bit further to get the dome brackets back on.  However the whole procedure is made more difficult because of trying to do it quietly in the early hours of the morning. 

I avoid taking the dome off if I can get away with it because of the palaver, but definitely glad I have it.  It was the same engineering chum who separated my stuck spacers yesterday.  

Carole  

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I have re-saved the images missing in posts 2 & 3 which Don says are missing and made them small enough to post on here, hope these ones work.

Early kit inside

1361889093_KitinsidePOD2010.jpg.58e1a5ac767b9ea3125de65a926ded53.jpg

Frame of the PZT being constructed.

1782416891_PZTframe.jpg.9afd518d13a23dff2867600059d5bd51.jpg

 

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Here is also a later rig, but still a few years ago.  I have been using a dual rig for some years, but this particular arrangement did not last for too long as I realised I was pushing my luck at the limit of what my mount could carry, so instead of the Gold ED120, I had the Black ED80 as the lower scope with a smaller WO scope on top.  Also changed cameras and filterwheels since then too.

1405655647_ED120dualrig.jpg.13410866f27c57cdcc7503cd7c2a7d88.jpg
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Apparently the Shapes cut out photo wasn't visible either so have re-saved and attached.

1106870483_PZTshapescutout.jpg.5dab17c0c3f34a8b8b19743dc02ae06e.jpg

Carole 

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Posted by: @Carastro

The really difficult thing is getting the dome back onto the walls, as you can slide it to the edge of the wall but it doesn't want to lift back on, especially with the wheels on top of the walls. 

Ahh, so it's just the last up and over to sit it on the wheels which is the problem.

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  • 2 weeks later...

@carastro

OK - I've just found this post and it is most interesting. The PZT seems like a mixed blessing, but it does look like a worthwhile modification.

For a while I had my WO GTF-81 next to the Wave Series 115. I used the '81' for RGB with my Atik 314L+ and the '115' with my new SX Trius-694 Pro for Luminance and narrowband. Amazingly the FOV was almost identical for both so the '81' images were almost exactly 2x2 binning equivalent. The problem was the dome was in the way above a very modest angle so there were often few things to image.

Putting something like your PZT in place would not only resurrect the 2 telescope setup but would make it positively viable. It certainly was hugely useful being able to get approximately 10 hours worth of imaging in one clear night as opposed to spreading it over a few nights in the hope of another clear sky!

Thank you for the write-up, it really was positively inspirational. I've been at this hobby for over 12 years and always seem to be able to learn something. The observatory was beyond a doubt the biggest leap. Setting-up every possible night and then having to dismantle it all in the small hours before work the next day - I can't believe I did that for 8 years! ? 

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