Double Stack Evaluation Requested

[pdmphoton]

Hello All,
I double stacked the 130MT Lunt with a front mounted Coronado 90mm DS etalon.
(Still getting use to tuning it as it is so different from a pressure tuned etalon.)
Seeing conditions were awful today with significant turbulence. Nonetheless I wanted to get some feedback from the group on a quick initial test.
First two images were captured with a ZWO 183mm and a 1.6X Barlow. Closeup of sunspot was captured with a 174mm and 2.5X Powermate.
Any helpful observations would be appreciated.

I will do a comparison test with the internal double stack vs. the front mounted Coronado in the next day or two when there are decent seeing conditions.

I will say, from just a quick visual comparison the front mounted setup appeared to have the edge.

130MT + 90mmDSII 1.6X Barlow 183mm copy.jpg (12.26 MiB) Viewed 988 times

130MT + 90mmDSII 1.6X Barlow 183mm INV BW copy.jpg (11.46 MiB) Viewed 988 times

130MT + 90mmDSII 174mm 2.5X PMT copy.jpg (983.1 KiB) Viewed 988 times

Thank you,
Paulm

[DeepSolar64]

Paul,
I think these look good. You appear to be on band. Your top disc looks to be evenly tuned and illuminated. Something that troubles me to no end in doublestack. I think your test is successful.

James

[pdmphoton]

Paul,
I think these look good. You appear to be on band. Your top disc looks to be evenly tuned and illuminated. Something that troubles me to no end in doublestack. I think your test is successful.

James

James,
Thank you for your helpful response. I find that double stacking with the Lunt internal etalons, while convenient, presents challenges with reflections.
While there are methods to deal with the reflections the "solutions" reduce light throughput too much for my taste. I am hoping I will be able to dial in the Coronado DS unit to obtain full discs with the Lunt 130MT.

[DeepSolar64]

Paul,
I think these look good. You appear to be on band. Your top disc looks to be evenly tuned and illuminated. Something that troubles me to no end in doublestack. I think your test is successful.

James

James,
Thank you for your helpful response. I find that double stacking with the Lunt internal etalons, while convenient, presents challenges with reflections.
While there are methods to deal with the reflections the "solutions" reduce light throughput too much for my taste. I am hoping I will be able to dial in the Coronado DS unit to obtain full discs with the Lunt 130MT.

Good luck Paul. I think you are on your way to achieving your goal with the 130MT and Coronado etalon.

James

[pupak]

The most challenging thing about the DSII is to tune them so that there is a contrasting surface and at the same time the prominences are clearly visible. I got the best results with the LS40 and Quark combo. Full discs are a demanding discipline if you want high resolution. Your photos are very good.

[marktownley]

Looks good Paul

[Carbon60]

Looking great, Paul. You'll refine with practice.

Stu.

[MAURITS]

Well done Paul.