Aries/Lunt Etalon Modification

[Valery]

Hi all!

Let me explain the fault (not a full success) of this modification.

1. The Lunt 80 was designed (optics) as a straight through system. It has a singlet objective, singlet collimator lens and single focusing objective. All three elements work in harmony and produce aberrations free flat field images.

2. The Synta's 150mm F/8 objective has another design than singlet objective in the 80mm Lunt scope, it has another F/D and so, another light cone.
This mean that probably not full aperture of the etalon works in this modification or may be full aperture of the etalon works, but not full aperture of the telescope.
Also, here MUST be present spherical aberration in any case and, almost for 100% sure coma too (like in SCT or Newtonians).

3. This modification need a special 3, 4 or better 5 lens system which will collimate the light from the main objective, will eliminate all aberrations like spherical (which already present for red light in the 150mm objective itself), coma, astigmatism and field curvature.

4. The DS-II module can be used after the proper modification-1 as a step 2. However it will probably suffer from field curvature. But still work.
Now the DS-II work not in the light cone it was designed for, not with the aberrations it must address.
Hence the results which less than expected.



My present "ARIES solar conversion kit" is designed for modification of the SW 150mm F/5 scope in to the solar telescope with adding this kit, LS50F Ha and B1200 or B1800 blocking filter. The recommended option is 2" WO focuser which is much better than native Synta one.

This kit can be used also with SW150mm F/5 telescope and PT 50mm etalon from Lunt 80mm telescope. It will work even better than now it work with LS50F H-a.

It is easy for us to design and produce the kit for CR6 telescope or similar SW 150mm F/8.


The very best modification will be if to use not the DS-II module, but the second PT 50mm etalon from the Lunt 80mm telescope. This will offer less pronounced sweet spot and larger field where one will have truly 0,5A band.


I have experimented with my present conversion kit in SS and DS modes.
The results are mixtured .

1. My first LS50F Ha is circa 2008. Two more etalons I have for experiments are 2009 and 2013 years of production.

2. The first, 2008 year, etalon has a bit wider band pass, but require a minimal tuning to come to the band. It has wide enough "in band" field - a full sun disk in H-a.
After I add more tilt, I get more pronounced curved band with narrower band pass and better surface contrast within this band.

3. Two other etalons require more tilt, has narrower band pass and higher contrast within the band. However there is no central sweet spot. When I make some adjustments, I can reach the position when the picture becomes symmetrical and the edges of the full sun disk is in band, but the 75% of the disk is out of band.

4. I make the conclusion that post 2008 etalons are not good for this type of modification.


5. When I use (for DS) my first 2008 etalon and one of these two etalon, I get a curved band across the disk where the band pass is very narrow and details are extremely contrasty. But much dimmer, of cousre.
I was able to make pictures only with high magnification (4x balow, at about F/20).


6. I tested this SS (with 2008 etalon) and DS (with added other etalons) on a SW 120mm F/5 telescope. All is significantly better if to mean uniformity. But the resolution is lower and prominences are significantly more difficult to photograph because of higher photon noise, than in 150mm scope.


If this mod (in my case) is interested for peoples, let create the topic about it and I ask moderator to do this, if possible.


If you have any questions, don't hesitate to ask.


Valery Deryuzhin
ARIES.

[etatsolarchat]

Hi Valery,

Your mods sound interesting but have a little trouble following, can you post some pictures of it, or start a new thread about it?

thanks

[MapleRidge]

Hi Valery...

I have been happy with the mod with the SS setup using the Lunt DSII and most recently the primary etalon from the LS80...realizing of course there are limitations of performance when we start changing the primary objective. I would be very interested to see more details on your system to remove the deficiencies...and perhaps allow the DS setup to work much better.

I am most confused with reference to the LS50FHa used in some of your setups (I see this as a front mount etalon, but please tell us more), and also reference to a PT50mm etalon (which I believe refers to the primary PT etalon in the LS80T). Any additional information/photos of the configuration would be very helpful.

As mentioned in an earlier post, lets move the modded Lunt system to a new thread.

Thanks,
Brian

[solarchat]

Im happy to make a new thread for you guys but I dont know which post to start it with. I dont follow all this mod stuff. if you want me to make a new thread, I can choose a post and move it and everything below it to a new one. I will need to know wich post and the title for the new thread.

[MapleRidge]

Hi Stephen...

Sounds like a great plan.

Based on the thread history, can you start a new thread with Valery's first post and we can carry on from there? As for a title, I'd suggest 'Aries/Lunt Etalon Modification'.

Brian

[solarchat]

done