Rear Mounted Lunt 60 Modular Mod (HA) | Complete

[OlegLviv]

Hello friends am not alone=)
Yes yes single lens that I sad collimation lens also works as a Barlow 1.89 x and the objective is F4.2
Can Do It this modification!
After two months of work, such a miracle turned out!
In my mind its very good modification with my 127/9 refractor!
Better PST 2 modification!
Such a larger sweet spot in the 35mm standard than in the PST 20mm
I will show a comparison later

Refractor Achromat 127/F9 + Lunt 60mm + Coronado BF15
Camera:Apollo MAX M 432
Barlow Lens: Televue Powermate 2.5x/Televue Powermate 4X
Baader UV/IR CUT + Astronomik 6nm Ha

[OlegLviv]

A few photos my stack modification!

[OlegLviv]

Such a larger sweet spot in the 35mm standard than in the PST 20mm

[pupak]

Hi Oleg,
many thanks for the samples. The photos are very nice. Am I to take it that you used the LS60THa with that collimating lens for a simple 60/F4.2 objective and got such beautiful results?
Can you share the exact setting of the etalon position in relation to the focal point your 127/F9 ?
This is a very important value and your result is really a small miracle.

[MalVeauX]

Did the double stack version succeed?

Hi,

Yes, the first iteration with a Siebert Optic telecentric worked, however it had a sweet spot so it was determined that it was not a true telecentric. I replaced it with a Baader TZ4 4x telecentric and the sweet spot was gone and it worked very well. I also had to change the location of the ITF and blocking filter, for vignette reducing purposes. It is no longer near the camera and is instead before the telecentric. This system is a collimated system with air spaced etalon followed by a telecentric system with air spaced etalon (I used my pre-meade PST etalon which is excellent contrast). Together when tuned, they do quite well in this configuration on the 150mm refractor with no electronics needed to tune. This also works on my Lunt 60 stock instrument as a double stack as well for full discs.

LuntPST_DS_TZ4_IMX174_Reducer_ImagingTrain_01.jpg (133.9 KiB) Viewed 2516 times

SolarSetup_LuntPSTDS_06032022.jpg (78.42 KiB) Viewed 2516 times

Here's the real world view in FireCapture, the double limb gone and a nice wide FOV:

FC_LuntPST_DS_BaaderTZ4_IMX174_Reducer_06032022.jpg (135.57 KiB) Viewed 2516 times

Here's the same imaging train back in the stock Lunt 60 OTA, as it's totally modular and reversible and can be used in either system. It just inserts. The spacing and focus is the same.

FullDisc_Solar_Lunt60DS_07152022.jpg (238.39 KiB) Viewed 2516 times

Here are my latest double stack results with this system (some of these are mosaics, huge):






















And the full discs (mosaics, but only 3~4 slices to make them, easy). Same imaging train, same camera, etc as above. Just in the Lunt 60 OTA as seen in the image above.






Very best,

[OlegLviv]

Hi Oleg,
many thanks for the samples. The photos are very nice. Am I to take it that you used the LS60THa with that collimating lens for a simple 60/F4.2 objective and got such beautiful results?
Can you share the exact setting of the etalon position in relation to the focal point your 127/F9 ?
This is a very important value and your result is really a small miracle.

Yes I use the LS60THa with that collimating lens for a simple 60/F4.2 .
The collimator lens needs to be at -264mm back focus. Don't use focal ratio to place the colliator, use a measured back focus value.
MalVeauX told me.

[pupak]

I tried this etalon with -264mm back focus on AR90/F10 and the results were unusable. You are a lucky man.

[OlegLviv]

I tried this etalon with -264mm back focus on AR90/F10 and the results were unusable. You are a lucky man.

Man wats wrong you have Lunt 80mm Duble stack with 150mm refractor you are lucky =))))

[MalVeauX]

I tried this etalon with -264mm back focus on AR90/F10 and the results were unusable. You are a lucky man.

Hi,

So the collimator in the previous Lunt 60 LS60THA vs the latest modular Lunt 60 LS60MT are different, I've had two people try to use their older Lunt and found the positioning to not work. The focal length of the singlet is different, but also the collimator is also differently positioned.

Finding the correct position for the collimator is the same process. Take the etalon chamber out of the singlet based OTA of the LS60THA and point the lens at the sun. Using a black piece of metal and a measuring instrument, find where the disc is at focus behind the lens. It should be equal the lens's actual focal length. Note that position. Measure from that point back into the light cone to the location where the collimator lens would be if it were reinserted into the OTA. That back focus distance is constant and that's where the collimator needs to be on any other lens and OTA. On the LS60MT it's around -264mm. The LS60THA is probably different, but again, measured the same way.

Very best,

[OlegLviv]

I tried this etalon with -264mm back focus on AR90/F10 and the results were unusable. You are a lucky man.

Sorry for not correct answer my friend told me how we are doing (-264mm back focus without 1.86 lens barlow which is not MalVeauX on his telescope)
You and I have 1.86 lens and the distance will be different than have MalVeauX Lunt 60.
You can see the correct distance on my drawing.

[pupak]

I tried both variants. Back focus -264 and then focus location identical to your image. Neither option yielded a usable result.
Probably 90/F10 is already beyond the limit of usability for collimation at F4.2.

[OlegLviv]

I tried both variants. Back focus -264 and then focus location identical to your image. Neither option yielded a usable result.
Probably 90/F10 is already beyond the limit of usability for collimation at F4.2.

Ohhh you can see your result us? Your sweet spot!

[pupak]

The sweet spot didn't happen. I couldn't even focus.

[OlegLviv]

The sweet spot didn't happen. I couldn't even focus.

Perhaps you need to install a 30mm or 50mm or 80mm extension adapter or shorten the telescope, I cut mine OTA minus 70MM+-

[Alto]

Fascinating article and result.

Way beyond my capability but nonetheless impressive!

[lsp1998218]

I tried this etalon with -264mm back focus on AR90/F10 and the results were unusable. You are a lucky man.

Sorry for not correct answer my friend told me how we are doing (-264mm back focus without 1.86 lens barlow which is not MalVeauX on his telescope)
You and I have 1.86 lens and the distance will be different than have MalVeauX Lunt 60.
You can see the correct distance on my drawing.

Hi Oleg, thank you very much for the important information. Can I just simply understand that you only fit the distance from etalon to focus plane(148mm) to the new scope and become successful?

Best

Su

[LLichter]

Thanks you marty for this post.

i did get this to work with a Meade Messier AR152L/1200.

Still have some tilt problems but it worka great.

haveing a lot of fun with this.

Dominik

[OlegLviv]

Nice hear you!