Introducing my equipment

[Pedro]

very nice mod. Thanks for sharing

best regards

[marktownley]

A great setup there C-U. Have you shortened the tube on that refractor at all?

[Bill E.]

I love this site for posts like this .Thanks for showing....One Question:The part with the etalon, Is this part of the Pst tube or was it removed then installed in something you fabricated?

[Bill E.]

After looking at your scope and the detail in your pictures, I think you should be working for or competing with Lunt/Coronado.

[swisswalter]

Hi Cai Uso

thank you very much. I'm just on the way to copy it ;-) I'm sure I will ned your help

[Merlin66]

Interesting....
I have an almost identical set up using a Meade 90/990 donor scope, but in my case I find working very close to the optimum -200mm position for the etalon gives best results. Putting the focuser in front of the etalon compromises the design.....

[Bill E.]

Interesting....
I have an almost identical set up using a Meade 90/990 donor scope, but in my case I find working very close to the optimum -200mm position for the etalon gives best results. Putting the focuser in front of the etalon compromises the design.....I would like to see your scope too.please post

[earl]

I always wondered about your setup. Nice job and we know it works due to awesome images you post.

[Merlin66]

I'm still in transit to the way back from Australia.
I'll post a couple of photos when I get home.
I use the Baader Microfocuser #2458125- with an added nylon lock screw, and the Baader (#2956929) Varilock T2 extension to get the distances...

[Merlin66]

The only real problem with the PST etalon is the built-in collimating system and the physical aperture.
With your 120/1000 (f8.3), the size of the solar disk at the etalon will be (200/8.3)=24mm, plus the image size, close to 1/100 the focal length = 10mm. Total size= 34mm.
This is well in excess of the clear aperture of the etalon; the etalon will therefore be acting as an aperture stop.
The system will be stopped down to a 100/1000 (f10), which again is smaller than the CERF...

[Merlin66]

When the etalon is in the "design" position, the back focus, from the rear of the rubber ring is close to 200mm.
I have 120mm between the etalon and the BF15 diagonal on my set-up.....
I'll post some images later...

[Merlin66]

The PST mod is based on a Meade 90mm donor, fitted with a 88mm clear aperture Baader D-ERF.
The spacers behind the etalon add up to 120mm to the front of the BF15 diagonal.
The images show the general layout, but also show a double stacked PST etalon option....works very well, but I found the tuning just too sensitive to be useful.

[Pedro]

PST MOD (Takahashi FS102 + Etalon PST + Coronado BF-10).

Some pictures of the PST mod I made a few years ago (2007). It worked fine until I got other equipment.

On the first image the arrow is pointing to a homemade adaptor and not to the PST etalon (in fact there are two special made adaptors visible in this pic).

More at:

http://astrosurf.com/re/sun.html

best regards

[marktownley]

T Modification (Takahashi FS102 + Etalon PST + Coronado BF-10).

Some pictures of the PST mod I made a few years ago (2007). It worked fine until I got other equipment.

On the first image the arrow is pointing to a a homemade adaptor and not to the PST etalon (in fact there are two special made adaptors visible in this pic).

More at:

http://astrosurf.com/re/sun.html

best regards

What were you using as an ERF in this setup Pedro?

[Pedro]

I used Lumincon H-alpha filter.

http://www.lumicon.com/telescope-access ... a+72mm&hn=

A W25A is also fine.

Take also a look at this link (Sebastien Kersten's PST mod)

http://www.astropixel.org/astropixel_modif_pst.htm

best

[marktownley]

I used Lumincon H-alpha filter.

http://www.lumicon.com/telescope-access ... a+72mm&hn=

Do you have any shots you took with this setup Pedro I could see?

[Pedro]

Hi Mark:

No, I only used it a couple of times for visual observation.

best regards

[marktownley]

[quote]I used Lumincon H-alpha filter.

http://www.lumicon.com/telescope-access ... a+72mm&hn=

Do you have any shots you took with this setup Pedro I could see?

Shame, I was wondering how you found the lumicon as an ERF?

[Pedro]

I worked fine. For imaging it is surely a good option.

best

[Merlin66]

The NIR should be reduced by the finesse of the etalon say by 90% (1:10) and then the Ha blocking filter stops everything anyway.....

[solarchat]

ahhhh the freedom to discuss solar scope modifications.....I finally get to see the amazing scope that has taken such beautiful shots all these months..

[Merlin66]

IMHO the additional energy impact on the etalon is minimal...
the possible problem is the premature failure of the "Mini ERF" or the actual narrowband blocking filter in the Blocking filter assembly.

[Merlin66]

You can also use a sub-diameter Uv-IR filter behind the Wratten red.
Telescop Austria include filter threads for 2" and 1.25" filters in their PST nosepiece.
Etalons are designed to work in a parallel collimated beam. This is achieved at the 200mm spacing with a PST etalon assembly.

[Merlin66]

Hmmmm
The optical arrangement of the PST etalon assembly actually has a -200 mm Barlow at the front side and a 200mm positive lens at the rear.
This really means to get an "optimum" collimated layout, the the barlow lens must be 200mm inside the prime focus, and the final focus is 200mm behind the etalon.
The optical length of a BF diagonal is 80mm, so the spacing would be 120mm to the front of the BF....
On the forty or so mods that I've done to date, this seems to work well.