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More PST mod woes


lukebl

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Hi all.

I've sort of abandoned my PST mod, despite paying a fortune on a 110mm D-ERF filter, but now the sun's getting higher I thought I'd look at it again.

At the moment I've just screwed the eyepiece holder & filter from the original PST focus box into a cheap Skywatcher diagonal (as in this picture). The screw thread of the eyepiece holder on the diagonal is fortunately the same as the PST one. However, I am rather at the mercy of the optical quality (or lack of it) of the cheap diagonal and would rather have a straight tube, avoiding a diagonal altogether.

Any idea where I can get a short tube with the correct thread, either 1.25 or 2" fitting?

I have said this before, but with hindsight, I really don't think the PST mod is worth it. Once you factor in the cost of the filters, donor scope, BF10 filter, etc, you may as well have bought a 60mm SOLARMAX or similar. Ah well. Too late now, but the basic PST unmodded is a fabulous piece of grab-and-go kit which gives lovely views and is best left in its original state!

post-3895-0-42204400-1396283233_thumb.jp

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Hi Luke,

You are right about the price of the mod being close or equal to the purchase price of ~£1300 for the Solarmax 60 but you do get an extra 40mm in aperture and thereby greater resolution. I am sorry you have not "clicked" with the Mod. I am more than happy with it. Maybe you will see the light as it were by persevering for another summer.

Ian

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As an avid PST modder I'm also sorry to hear that you have been disappointed whith what should have been a superb performer. Each one that I have made, using no different techniques to those recommended have been far superior to the original and on a par with bespoke units of similar aperture costing far more. I say this as a visual observer, imaging may well have other parameters to consider. The only downsides, as far as I can see,are that at F10 for best results you have a rather long telescope to mount and regardless of the aperture or the size of the blocking filter, you are still left with the original "sweet spot" afforded by the PST 20mm etalon.   :smiley:

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I'm aware of over a 100 successful PST mods.

The best results are with the Stage 2 mod and a BF10/BF15.

The views and images from a good 100mm mod will beat, hands down, any single stack solar scope less than 90mm aperture.

Bear in mind that the Lunt 60, is just a "different" PST - the internal etalon size is about the same - think of it as a PST Stage 0.5 mod with an 60mm single lens objective.....

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Thanks folks.

That's just it, Merlin, you need to get at least a BF10 filter for the mod to be any good. More expense, and where can you get them anyway? They seem unobtainable here in the UK. And to think I was in the States last year and could have bought one for $500. A lot of dough, but presumably a lot more in the UK. ....if I could find one!

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Thanks folks.

That's just it, Merlin, you need to get at least a BF10 filter for the mod to be any good. More expense, and where can you get them anyway? They seem unobtainable here in the UK. And to think I was in the States last year and could have bought one for $500. A lot of dough, but presumably a lot more in the UK. ....if I could find one!

You can't buy them in the UK at all. I spoke to TH, the importers, and they said Meade don't release any for UK sale. When I spoke to Meade USA they were not happy to sell me one, and were not even happy to repair the "rust" on my one. Even trying to get a secondhand one is difficult because they are all bundled with etalons and nobody wants to split them. It's a hopeless, ridiculous situation.

Lunt BFs are your only reasonable bet, but I still haven't heard for sure if you can use them with a PST mod.

Coronado SolarMax II anyone?

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Hi Luke,

You and the other posters are correct  - you can't get the Coronado BF10s in the UK other than 2nd hand. I do however know a number of people who have bought / imported from Hands on optics.

http://handsonoptics.com/index.php?main_page=product_info&products_id=1059

Even with the taxes/import duty they have ended up paying £360-380. I know that is a significant sum but I had my wifes' cousin bring one over for me from the states in her hand luggage and it cost me £325, so its not a huge hike.

Lunt BFs are your only reasonable bet, but I still haven't heard for sure if you can use them with a PST mod.

Coronado SolarMax II anyone?

I can't remember exactly but I think it is OK to use Coronado BF with a Lunt etalon but not OK to use a Lunt BF with a Coronado Etalon as they are not suitably matched - Merlin66 (Ken) should be able to confirm.

Ian

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I concur Ken and I have successfully used the Lunt B1200 with all my pst mods , and also built large aperture scopes built around the LS60T that work very well indeed.

But to answer luke's original question, JamesF made  a straight through adapter for his 0.5 pst mod.

http://stargazerslounge.com/topic/187570-pst-stage-05-mod/page-2?hl=pst+mod#entry1963409

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What you do have to remember, is that although expensive for the parts you do get a scope that would cost you many, many times more than the cost of parts.

You can save some money by using a D-ERF part way down the tube, a 75mm works well in my Peter Drew converted TAL100 and saves over £190 if you bought the 110mm;

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