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Author Topic: PST Extension Tube Removal  (Read 18820 times)

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Offline John Winfield

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Re: PST Extension Tube Removal
« Reply #30 on: 22:23:18, 01 July, 2006 »
I thought some of the people on this thread may be interested to know that I am managing to image through my new PST without removing the new extension tube, by using a Meade LPI.
I can just drop it into the stock eyepiece holder and it easily reaches focus, fitting the whole disk onto the chip almost perfectly filling it.

Here's my first image:

http://ukastroimaging.co.uk/forums/index.php?topic=19181.msg181210#msg181210

You can pick up a 2nd hand LPI for little cost, if you want to try it.

John
10" LX200R, Pentax SDHF-75 on AP900
ART11002 + TT Filter wheel, DSI Pro.
WO ZS66SD + PST.
Old kit:
C11 on EQ6 mount. Meade SN8 on LXD75 mount, ART285

Offline michaeloconnell78

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Re: PST Extension Tube Removal
« Reply #31 on: 18:55:12, 18 July, 2006 »
How I take images with the PST and 300d is by using this little thingy:
http://www.telescope-service.com/Cor_Halpha/start/halphastart.html
It's the PST Foto R. Works very well.
Regards,
Michael
www.astroshot.com
Gemini G41 Observatory+ Mount; 16" LX200 SCT, TEC140; Pentax75SDHF; PST CaK, PST Ha.

Offline albertw

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Re: PST Extension Tube Removal
« Reply #32 on: 23:18:47, 18 July, 2006 »
Hi,

It seems I have one of the newer PST also as the extension tube has a filter in it. I've an image of the holder and extention tube at http://www.flickr.com/photos/albertw/192909547/

Unfortunately I havent managed to separate them yet, though I have broken one baby boa constrictor in the process! I think I'll stop playing with this for the moment until the purpose of the new design is worked out.

Offline NickH

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Re: PST Extension Tube Removal
« Reply #33 on: 17:28:37, 19 July, 2006 »
Naughty Coronado, stopping modders...naughty...

Celestron C11: DSI-C/Toucam Pro 2 ICX mod and SC1.5 mod/ Meade LPI/EOS300D/ED80/WO80ZS/Shoestring guider. PST/PST CaK/ART285

No time....always bloomin cloudy...need to build the Obsy..

Offline dwsubc

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Re: PST Extension Tube Removal
« Reply #34 on: 18:46:24, 24 July, 2006 »
How I take images with the PST and 300d is by using this little thingy:
http://www.telescope-service.com/Cor_Halpha/start/halphastart.html
It's the PST Foto R. Works very well.

Mike,

How does this work?  Can you get a full disk image with it?

Thanks, Dave

Offline michaeloconnell78

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Re: PST Extension Tube Removal
« Reply #35 on: 19:05:07, 24 July, 2006 »
Dave,

Here's a link to a thread in Cloudynights.com in which I made a few comments and pictures in relation to it.
http://tinyurl.com/kae9g


In terms of images:

This image is an unprocessed image from the Canon 300d and the Foto R used in the PST. I've only resized the overall image to make it smaller so that I can post it up here without the mods having a heart attack! :) No part of the imaging frame has been cropped.
Hopefully this gives a good indication as to the scale of the image relative to sensor size.

Clear skies,
Michael.
Regards,
Michael
www.astroshot.com
Gemini G41 Observatory+ Mount; 16" LX200 SCT, TEC140; Pentax75SDHF; PST CaK, PST Ha.

Offline dwsubc

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Re: PST Extension Tube Removal
« Reply #36 on: 22:24:22, 24 July, 2006 »
Many thanks Mike,

I already have a 20mm Kelner with a T-adaptor that I use to mount a camcorder to the PST.  It might give similar results to your adapter and I will try it tomorrow on the 300D.  If it doesn't work, I will get the Foto R.  I have a Zigview timer for the 300D and I really would love to use it to capture a few hours worth of full disk activity - say 1 frame every 10sec or so.

thanks again for your help,
Dave

Offline albertw

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Re: PST Extension Tube Removal
« Reply #37 on: 10:38:03, 28 July, 2006 »
I already have a 20mm Kelner with a T-adaptor that I use to mount a camcorder to the PST.  It might give similar results to your adapter and I will try it tomorrow on the 300D.  If it doesn't work, I will get the Foto R.

Thats what I had hoped but my arrangement put the eyepiece too close to the sensor to focus. However rather than buying the 'Foto R' you might be able to just buy a t-ring extension to do the job. Thats what the Telescope-Service.com folks recommended to me anyway.

Offline dwsubc

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Re: PST Extension Tube Removal
« Reply #38 on: 08:57:37, 31 July, 2006 »
Albertw,
I tried what you suggested with an extension tube I had and it worked fine.  The nice thing is the sun's disk is just smaller than the image size so I guess the tube is just the perfect length (lucky).  One thing I had to do to get focus was to pull the eyepiece about 3mm out of the holder from the fully home position.
thanks for the tip
Dave

Offline NickH

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Re: PST Extension Tube Removal
« Reply #39 on: 11:11:59, 23 August, 2006 »
Hmm, now that filter in the new PST's is an ERF, not dissimilar to the Baader Cool ERF (in mini) by the look of it.

Does this mean that the need for the Baader Cool ERF is negated (or have they got two in the tube now, one pre, and one post etalon?)

If it is the former, then modding the PST to larger aperture with the newer models will be a walk in the park, if the latter, then...hmmm...

Why place an ERF at the back end as well? The idea is to stablise the etalon temperate and reduce UV/IR incoming to that. If they have removed that need, then I am confused..

What we need is a tube comparison of the new and old ones. The old one is a front lens, (added rust on request...) and the ERF located behind that. The new tube? Anyone want to have a look?

Also, just picked up this interesting post from CN forums, which beggars belief if it is true. This is from a UK based poster

"I was told by a Meade sales rep at a previous Astro event in reply to my question about the "rust" problem that the problem did not exist and that people were deliberatly making up the fault so that they could get their PSTs replaced by the new updated version.
All very strange! "

Coronado US admit there is an issue and are handling warranty (up to 5 years) replacements for all US customers... Can this story from the UK be true?





Celestron C11: DSI-C/Toucam Pro 2 ICX mod and SC1.5 mod/ Meade LPI/EOS300D/ED80/WO80ZS/Shoestring guider. PST/PST CaK/ART285

No time....always bloomin cloudy...need to build the Obsy..

Offline michaeloconnell78

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Re: PST Extension Tube Removal
« Reply #40 on: 20:45:02, 26 August, 2006 »
Can this story from the UK be true?

Short answer...No! Whatever dealer said that has absolutely no idea what they're talking about.

I've seen images of PSTs with the problem. Very obvious!

Michael.
Regards,
Michael
www.astroshot.com
Gemini G41 Observatory+ Mount; 16" LX200 SCT, TEC140; Pentax75SDHF; PST CaK, PST Ha.

Offline NickH

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Re: PST Extension Tube Removal
« Reply #41 on: 20:48:55, 26 August, 2006 »
Oh the question was more "could a rep really have said this". I know it is true, I have seen it on 3 scopes our club members own!

Celestron C11: DSI-C/Toucam Pro 2 ICX mod and SC1.5 mod/ Meade LPI/EOS300D/ED80/WO80ZS/Shoestring guider. PST/PST CaK/ART285

No time....always bloomin cloudy...need to build the Obsy..

Offline NickH

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Re: PST Extension Tube Removal
« Reply #42 on: 11:36:29, 02 September, 2006 »
And here is the proof from Coronado!

Post from another forum, from a user reply (someone who had the problem)

The "breakdown" or rust colored appearance that has been seen on front objectives of some PSTs is a result of degradation of the ITF coating. Our ITF's are being supplied by an outside source. Upon arrival at Coronado they were cemented and assembled into the PST objective. Unfortunately, when improperly handled, meaning too much time before cementing whether at the vendor, Coronado or both degradation began. This degradation could not be seen during the assembly process or in our field testing prior to shipment. The coating started to visibly degrade a few months after assembly. Because this problem does not affect safety (only performance) and does not affect all PSTs, Coronado is repairing the affected units rather than issuing a general recall.

Our current procedure is to use another style of the ITF and locate it further down in the optical tube. These units will look different as the front objective will be clear, but neither safety nor performance are adversely affected by this change.

Best regards,

Russ Tanton

Coronado Instruments

Celestron C11: DSI-C/Toucam Pro 2 ICX mod and SC1.5 mod/ Meade LPI/EOS300D/ED80/WO80ZS/Shoestring guider. PST/PST CaK/ART285

No time....always bloomin cloudy...need to build the Obsy..

Offline John Winfield

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Re: PST Extension Tube Removal
« Reply #43 on: 17:19:06, 02 September, 2006 »
What does "ITF" stand for?
10" LX200R, Pentax SDHF-75 on AP900
ART11002 + TT Filter wheel, DSI Pro.
WO ZS66SD + PST.
Old kit:
C11 on EQ6 mount. Meade SN8 on LXD75 mount, ART285

Offline NickH

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  • It aint just the weather that's CaK
    • The Cherhill Observatory
Re: PST Extension Tube Removal
« Reply #44 on: 09:03:08, 03 September, 2006 »
I guess ITF is the "Infrared Telescope Filter" but I could be wrong

Celestron C11: DSI-C/Toucam Pro 2 ICX mod and SC1.5 mod/ Meade LPI/EOS300D/ED80/WO80ZS/Shoestring guider. PST/PST CaK/ART285

No time....always bloomin cloudy...need to build the Obsy..

 

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