Some PST mod talk, economical?

[thenews24]

Just a few questions about moding the PST, but not the technical 'how to" kind of questions. Merlin has already covered that for a lot of us, which is much appreciated btw.

I'd like to ask though, how economical it is to go from a stock PST, to stage 1 mod, then to a stage 2 mod, instead of just purchasing a solarmax 90 or any other manufactured solar specific scope, for that matter?

I am really interested in attaching a larger donor ota, as well as getiing rid of the black box and adding my own blocking filter, etc.

But ultimately, I woulld basically be buliding my own solar scope at that point, just retaining the PST etalon. Would it be more cost effective to just buy a larger solar scope instead of modding around the PST etalon?

My ulitimate goal is to get rid of the sweet spot. I love the pst, and the possible modifications it can allow, but with the cost of the parts, should I Ultimately buy a better scope? I am good with my hands, and trust my capabilties to do any modification.....but besides the gradification of building something myself, is modding the PST sensical?

[Peter Drew]

My 150mm PST mod cost me under £1500 by purchasing as new secondhand components apart from the OG, so economical compared to any bespoke Ha telescope of similar aperture. However, if the PST sweet spot is a serious issue for you then the expensive route is the answer. My experience has been that front etalons and blocking filters fitted to quality refractors give better views than the bespoke telescopes. The best view I've had so far, devoid of a sweetspot was with a double stacked 90mm etalon on a high end APO and mount totalling the best part of £20K.

[JamesF]

Sorry Peter. OG?

James

[hunterknox]

As someone with a pre-cut donor scope for sale I'd say it's very economical indeed !

Realistically though Peter's right - the only way to avoid a sweet spot is to get a front end filter, which will be far more expensive per unit aperture. It's also worth noting that stage 2 mods are a significant step up in cost from stage 1 due to the cost of the blocking filter.

There are some bargains to be had second hand but you have to be both patient and on the ball when stuff like ERFs and blocking filters come up because they're quite rare and get snapped up quick.

For high res/magnification stuff I think PST mods are the way. Sweet spotting isn't such a big deal for imaging because you can fix up a mosaic easily enough. Full disc imaging is possible with patience but I reckon a front end filter is probably the way to go for that. In an ideal world I'd like both a PST mod and a smaller double stacked scope.

[Peter Drew]

James. OG= Object Glass.

Hunternox. You can still use the original BF5 from the PST on a stage2 mod, the field of view is quite small, like looking at the Moon with a high power eyepiece, but the sweet spot fills the field and is less noticeable than when using a BF10 or BF15.

[thenews24]

As someone with a pre-cut donor scope for sale I'd say it's very economical indeed !

Realistically though Peter's right - the only way to avoid a sweet spot is to get a front end filter, which will be far more expensive per unit aperture. It's also worth noting that stage 2 mods are a significant step up in cost from stage 1 due to the cost of the blocking filter.

There are some bargains to be had second hand but you have to be both patient and on the ball when stuff like ERFs and blocking filters come up because they're quite rare and get snapped up quick.

For high res/magnification stuff I think PST mods are the way. Sweet spotting isn't such a big deal for imaging because you can fix up a mosaic easily enough. Full disc imaging is possible with patience but I reckon a front end filter is probably the way to go for that. In an ideal world I'd like both a PST mod and a smaller double stacked scope.

hmm..yeah, In think I'm going to go ahead and commit to the mod either way, cause I like projects. Haven't dabled with mosaics yet, so seems reasonable enough to cope with the sweet spot. Wondering though, if a front end filter is best to tackle the sweet spot, does the Baader erf on the objective help slightly?

[Merlin66]

The up front ERF in the PST mod only reduces the incoming energy to a safe level. Has no impact on the "sweet spot".