Tal PST mod - first pics

[hunterknox]

Hi All,

My Tal-based PST mod is now complete and I've had just enough time this evening to grab a couple of quick pics. I haven't quite got the hang of the colouring in yet (these are only my 3rd and 4th astro pics respectively), so any tips on colouring and other processing would be very welcome.

Massive thanks to Merlin66 for providing the instructions and inspiration. I think I owe you more than one pint!

Here's the finished product if anyone's interested. Apologies for the poor quality - my phone doesn't have the best camera but apparently it does do pleasingly weird colour rendition...

If anyone else fancies butchering a Tal for a PST mod then let me know. I made a few mistakes along the way so you don't have to!

[johninderby]

Looks very promising and those images are really good. My project's a couple of months from completion so it's nice to see how someone else's project has turned out.

John

[Carbon60]

Just finished butchering my Vixen 80MF and fitting the back end of my PST with an adapter ring. Waiting for a DMK41 to complete the project. Thanks also go from me to Merlin66 for his help and advice.

Early shots with a webcam look pomising. Refinement and the DMK should make it all worthwhile.

Your shots look great.

Stu

[Merlin66]

Good to see you guys are having success. The images look pretty good.

You have to develop your own "style" when it comes to colourising the image.....

The PST mod is certainly a cost effective way of achieving hi-res Ha imaging.

Onwards and upwards!

[step_hen]

Both scopes looking good and nice results too! where did you get the adapter ring stu? I know the 80mm F11 is the scope of choice for modding, but can it be done with a c100ed at F9? does the scope become unusable for normal viewing once its modified, or can it be reverted to its previous state quickly?

Stephen

[Carbon60]

Thanks Ken, style still under development.......

Stephen, the adapter was custom made by a local machine shop. I also have a second adaper (spacer) in progress so that I can replace the PST 'black box' and cut out the pentaprism.

Sorry, I can't comment on the C100ed (Maybe someone else can). I've effectively sacrificed the Vixen specifically for H-a.

Stu.

[Merlin66]

If you can position the etalon from the PST 200mm inside focus then it would make a good donor. The effective aperture will end up about 80mm - the etalon acts as an aperture stop and only gives an f10 beam - so the final aperture will always be 1/10 the focal length.

If you have a suitable spacer then yes you can still use the scope for other things - don't know why you'd want to - when you see the results ;-)

[step_hen]

"The effective aperture will end up about 80mm - the etalon acts as an aperture stop and only gives an f10 beam - so the final aperture will always be 1/10 the focal length."

So the 80mm F11 Vixen would give the same effective aperture as the stopped down C100ED?

Can i have a copy of your PSTmod guide please ken? I'll PM you my email.

Stephen

[Merlin66]

Yes.

Just PM and email address and I'll send a copy of the PST mods (6Mb)

[hunterknox]

Stephen - my first choice was the C100ED and I know there's someone on another forum who's converted one, but I had problems getting a focuser to fit mine, so it got sold on.

Carbon60 - that adapter looks ace. Did you make that? Any plans to make more? I know a couple of guys who might be interested in those.

RE: the Vixen scope - does that still need to be chopped down or is it good to go with the adapter?

[johninderby]

Hi Ken

Could you send me a copy as well. I meant to ask you before.

PM sent

John

[Carbon60]

Hi Hunterknox,

The adapter was made for me at a local workshop. I got the guy to chop the Vixen (yes this needs to be done) by 85mm off the back end and then had him re-thread (a bit of a challenge) to refit the focuser. He then made the adapter to fit the threads on the (approx) 2" focusing tube and the front of the etalon. Given the need to have the OTA cut down and re-threaded, it is not much more work to get the adapter made at the same time. At least you'll be assured that it will fit!

Stu.

[hunterknox]

Thanks Stu, very neat. I might pester you for their contact details if these folks are genuinely interested. I've got half a mind to get the spare Tal sorted properly!

[Merlin66]

Re the Vixen donor - you can either cut the OTA about 85mm and add a 2" TS focuser and use a 2" to M50 nosepiece or remove the existing focuser and cut a few mm to add a fixed "adaptor"; needs to have a M50 x 1 thread to suit the PST etalon.

I'll send out copies of the write-up as requested.

[kev 102 42]

PST to 2" nosepiece £25 on astroboot.

[Carbon60]

FYI for inspiration on what can be achieved with a PST etalon check out this web site: AstroPage Cai-Uso Wohler

Herr Wohler's H-alpha work is awesome!!

Stu.

[Merlin66]

For a 100mm effective aperture an a "humble" PST etalon it just shows what the others are missing.

[JonH]

Can anyone tell me if the Astroboot PST to 2" nosepiece is suitable for a stage 2 mod? It looks a little shorter than the Teleskop version though quite a bit cheaper.

BTW, thanks Kev for the heads up.

[Merlin66]

Jon,

I've used both types. Either is OK.

[JonH]

Thanks Ken.

[AstroManDan]

Can you all specify how much your mods cost in total including the scopes, but not including the Coronado. As SnS do a pack and they quoted about £600 for doing the mod for me - £375 for the mod kit and then probably £225 for a Z80 clone.

[Macavity]

So, this is down to the increased resolution (going from 40mm -> 80mm) and image scale? I must admit, I've yet to even try Barlow-ing my PST. Pretty amazing stuff, and doubtless very pleasing...

[Merlin66]

AstroManDan,

Caution with that mod. All you are really buying is an ERF and a nosepiece adaptor.

The Z80 is overkill for the job and unfortuantely is not an optimum solution.

I believe it is an f6 scope; f10 is the way to go.

[carldr]

Wow, I had no idea you can either mod the PST in this way, or that the results would be so great. The more I read this forum, the more in awe I am of you guys.