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DOES RUST ON PST OBJECTIVES ALWAYS KEEP GETTING WORSE?


paulastro
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I have a PST on loan from a good friend as I currently have no HA facility myself.  I have used many over the years as well as larger DS scopes and mods.

Observed with this one yesterday and it showed all the proms and most of the surface features, in only average conditions at best.  The background is very black and it was sharp on the 8mm setting on my zoom.

It has a very rusty objective, two pics below from different angles.  It's an early example, SN 94116.

If I had not looked at the rust, I would have thought the objective was in good condition.

What I'd like to know is if it is inevitable the rusting will keep deteriorating until it is unuseable, or does it only deteriorate so far?

Many thanks.

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From a photo, it is difficult to assess the degree of rust. I used to own a PST that was definitely very brown. Yours is still reflecting some blue.
Mine was much worse. Even then it still worked, but gave a very dim image.

I didn't keep mine long enough to carry out a time/extent measurement.
I found a dead PST with broken etalon so made one good scope from the two.

 

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4 hours ago, Mark at Beaufort said:

I bought my PST in 2005 and only really noticed the rust a few years later. Since that time the views have not changed in fact I often use a double stack.

I did try to get it fixed under warranty but the supplier has ceased trading and my emails were ignored.

 

Thank you Mark, that's really interesting.   It gives me more hope that the one I have on loan will not deteriorate further.  It's certainly better than some other PSTs Ive used over the years which have had an unblemished lens!

Out of interest Mark, what is the serial number of yours? The one I have is 94116, which may be about that age.

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Just now, paulastro said:

Thank you Mark, that's really interesting.   It gives me more hope that the one I have on loan will not deteriorate further.  It's certainly better than some other PSTs Ive used over the years which have had an unblemished lens!

Out of interest Mark, what is the serial number of yours? The one I have is 94116, which may be about that age.

Hello Paul - my PST is 97155 and I remember getting it in the summer of 2005. I took it to Spain for the Annular Eclipse in October 2005. I also took it to the USA for the Venus Transit in 2012 and many observers remarked that the image was one of the best seen through a PST. That statement went downhill when a member of staff from NASA had a 6" Lunt with binoviewers + TelevVue EPs. 

 

annular.eclipse.with lat.long.jpg

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1 hour ago, Mark at Beaufort said:

Hello Paul - my PST is 97155 and I remember getting it in the summer of 2005. I took it to Spain for the Annular Eclipse in October 2005. I also took it to the USA for the Venus Transit in 2012 and many observers remarked that the image was one of the best seen through a PST. That statement went downhill when a member of staff from NASA had a 6" Lunt with binoviewers + TelevVue EPs. 

 

annular.eclipse.with lat.long.jpg

Many thanks Mark.  I guess  the two scopes must be of a similiar age.  I ordered my PST from Astrofest when it first debuted. and took delivery a few weeks later.  It may have been 2005. Yours has certainly been put to good use!  🙂.

 

 

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