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I have found a camera filter adapter that will thread into scope etalon and allow adding my early ? max40 filter to my clubs solarmax 40 scope; I think the used filter is early as it does have a Tmax but no threads on front of etalon. What I get visually is 1 bright disk with 6? other dimmer disks lined up.With the front tmax I can move the disks closer to center but not in both directions, I tried shimming with masking tape 90 degrees from tmax and got closer but not spot on. Is this nessisary or just move ghosts from field of view with Tmax; by doing this I got great improvement in surface detail over single etalon but lost the proms that I wanted.
Thanks Ric

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Hi Gene,
looks like proms would show up on webcam better with the single setup?
Ric

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I may be mistaken but don't SolarMax scopes have to be sent back to Coronado to be double stacked? I think the filters have to be matched.

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Well, sort of...

First, solar 'scopes with internal etlons such as the PST, SolarMax, and internal etalon Lunts generally don't require any sort of "matching' - just put another etalon on the front to double stack, tilt out the ghosts, and away you go.

Second, I and many others have double stacked using second off-the-shelf etalons. The essential part of the "matching" process seems to involve determining which etalon requires the least amount of tilt to bring it "on-band." This is the etalon that is then mounted closest to the objective (lets call it the "primary" etalon.) The secondary etalon (which reqired more tilt to be on-band), is then mounted on the primary etalon, and rotated to a position where the multiple reflections it creates are removed with the least amount of additional tilt. You are now "matched."

Ideally, one would like to have etalons matched identically every time. The reality is that construction tolerances come into play, and the materials holding the etalons in their cells have some elasticity, and may require periodic adjustment of the tilts and rotations, and possibly even switching the primary and secondary etalon designations.

The new Lunt pressure-tuned etalons would seem to be ideal for double stacking from the tuning point of view, but the front etalon, it seems to me, would still require some sort of tilting to get rid of the secondary reflected images. Hopefully someone with experience with these particular filters will chime in...

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Bob Yoesle

You are a child of the universe,
no less than the trees and the stars...
And whether or not it is clear to you,
no doubt the universe is unfolding as it should.

Desiderata

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The essential part of the "matching" process seems to involve determining which etalon requires the least amount of tilt to bring it "on-band." This is the etalon that is then mounted closest to the objective (lets call it the "primary" etalon.)

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