Lyra 100mm f11 PST Modded refractor - performance

[A McEwan]

Hi all.

Further to recent post about my acquisition of said telescope: http://stargazerslounge.com/topic/177040-musings-on-a-lyra-102mm-f11-achro/ here are some further thoughts about it having put in some time at the eyepiece over the last few days.

First off, H-alpha mode. With the improvements made to the focuser, objective (cleaned) and interior flocking, the image I saw over the last few days appeared to be sharper and brighter. Generally "tighter", and the scope welcomed magnifications of 122x routinely (and 157x at times). Note I have only used this setup visually.

The scope is obviously now working at its best. The "sweet spot" is easily controllable and I found that the tuning of the PST etalon is a lot finer than on my Lunt LS60 PT scope. A small adjustment makes a lot of difference. The sweet spot is not such an issue on this scope, as the long focal length and larger aperture make it ideal for zooming in to observe features in higher power with a smaller resolvable area. Positioning the feature being studied in the sweet spot is a breeze, and then the view really begins to show incredible detail.

There have been some large prominences over the last few days that showed amazingly intricate detail when I used high powers, rerall magazine photograph levels of detail and clarity. Active regions also benefit from the extra aperture. Filaments not so much, but I suspect that is due to the bandwidth of the etalon. Certainly the basic etalon in my Lunt (~0.7A) shows filaments better even with the 60mm aperture)

Anyway, detail, resolution, brightness and sharpness are all totally outstanding. Best I've ever seen with my own eyes through an eyepiece. I do however need a small extension tube to get my eyepieces to focus more easily in the BF eyepiece holder. Focuser travel is all the way out before focus is reached.

White light next. For this I remove the PST etalon with the attached focuser and BF and install a Baader 2" Hershel wedge into the stock focuser on the OTA (and remove the ERF over the objective). With this I found that my eyepieces were only just getting to focus with the drawtube all the way out. Looks like that extension tube will get double duty, being used in this mode too.

Granulation easily evident and loads of detail in the Sunspots. Faculae nice and bright. I use a Solar Continuum filter permanently mounted in the wedge (with the required ND filter obviously) and a single variable polariser in the eyepiece to attune the brightness/contrast of the image for comfort.

Very rewarding views - exactly Ias I already expected though.

I've also managed some observations of Jupiter as a straightforward astro scope and the detail on the disc has been pretty much as I expected. Nice detail within the belts and the moons resolved as tiny tiny discs. Great for open clusters too.

Primarily I bought this as a 100mm PST mod as I'd always been curious about how one of these scopes would perform. Would it outperform the commercially available 60mm scopes - to "that" degree? Would it be reliable? Easy to use?

Performance-wise I'm over the moon. It definately is a step up in performance.

Downsides are that is seems to put a strain on my HEQ-5. Maybe an EQ6 head is needed for ultimate in stability - essential for focusing and tuning in fine detail? Ability to "handle" a sweet spot is required too, but if you've used a PST before you should be used to that. I do get some slight internal reflection from somewhere... I played about with the ERF, angling the fitting over the objective this way and that but couldn't see it making any difference. It's only an issue when the whole disc is shown though. (Any tips on that greatly appreciated please)

Clear (and Sunny) skies,

Ant

[Peter Drew]

Pretty much mirrors my experience with my Tal 100/PST mod, far superior to the standard unit and better than a 60mm commercial solar telescope. Internal reflections are difficult to trace let alone eliminate, there is definitely one small but noticeable one which appears to be a reflection from the eye as it disappears with the eye in different positions. A larger mod produces even better results when seeing conditions permit.

[A McEwan]

Mmmm..... "larger".....

[A McEwan]

Further update: Spent the whole afternoon using this scope yesterday in h-alpha mode, to great effect! Although gusty, the mount handled the scope very well considering. I made sure it was perfectly balanced this time, and used a mount extension for easier viewing. Active regions, prominences and filaments and filaproms all showed incredible detail and clarity! I lost count of the number of "Wow"s that the scope got from people looking through the eyepiece!

I particularly enjoyed watching the developments within active regions, and the ways the structures of proms changed over the afternoon. Best views were at 122x in these conditions.

I also found that there were NO internal reflections on this occasion...

Greatly enjoying this amazing scope!

Ant

[Merlin66]

Ant,

It's a great feeling when it all comes together and your chin drops to the ground, and you look around to find others to share with...a number of times I've gone OMG!!! and pulled my wife outside to see the solar spectaculars - she is suitably impressed...........

[A McEwan]

Indeed - and all the advice I've been offered along the way has been worth its weight in gold (or should that be hydrogen...LOL)

Ant