Adapters for Front-mounted Solarmax Etalons

Use this section to discuss "standard" Baader/Coronado/ Lunt SolarView/ Daystar, etc… filters, cameras and scopes. No mods, just questions/ answers and reviews.
Post Reply
pmlogg
The Sun?
The Sun?
Posts: 15
Joined: Thu May 19, 2016 11:13 am

Adapters for Front-mounted Solarmax Etalons

Post by pmlogg » Thu May 19, 2016 1:16 pm

When I switched from a PST to a pair of SM40 etalons on my FS60CB I didn’t have an adapter so I made one that slid on over the fixed, screw-on dew shield. That worked fine but I then upgraded to SM60 and found issues with sag, which needed careful positioning of the slide-on adapter and etalon to avoid/minimise.

In the expectation that the problem would be worse with two SM60s double-stacked I bought a screw-on adapter which replaces the dewshield, using the threads for it. That is very secure but so far I’ve been underwhelmed by the views. I presume that is more a tuning issue than anything to do with the adapter?

With my second hand TMB100/8 came an adapter for an SM40 which slides onto the front element once the dewshield is removed. My thoughts are to get that adapter bored-out and threaded for the SM60 (I have an SM40 to SM60 adapter that would still allow the modified slide-on adapter to be used with SM40s). However, still concerned about security and sag with two, heavy SM60s on a slide-on adapter I wonder whether a screw-on one might be better?

I had at one point considered buying a TV-76 as its dewshield has the same thread as the SM60 but one of the reasons I went off the idea was because of the potential of sag, particularly with a pair of SM60s.

I do have a screw-on SM60 adapter but not for the TMB, which doesn’t have a fixed, screw on shield; it slides and is attached by 3 screws. The only available thread is on the lens cell itself so I thought it might be possible to use a step-down ring to attach the screw-on cell that I have to the lens cell threads. When I asked for the specifications of the thread on the lens cell, APM, who made the TMB, advised against attaching the etalons in that way. They think that the front cell could be damaged.

Am I being paranoid about using slide-on adapters for doublestacked SM60s?
Attachments
TMBfront.jpg
TMBfront.jpg (28.78 KiB) Viewed 693 times

User avatar
Merlin66
Librarian
Librarian
Posts: 3167
Joined: Tue Dec 13, 2011 1:23 pm
Location: St Leonards, Australia
Contact:

Re: Adapters for Front-mounted Solarmax Etalons

Post by Merlin66 » Thu May 19, 2016 2:16 pm

I used for many years a pair of external SM60 etalons mounted with a large CNC slip fit with nylon screws aluminum cell.
Providing it's a neat fit, no issues, no drama.
You will need the special adaptor and a T Max tilt tuner between the etalons.
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

pmlogg
The Sun?
The Sun?
Posts: 15
Joined: Thu May 19, 2016 11:13 am

Re: Adapters for Front-mounted Solarmax Etalons

Post by pmlogg » Fri May 20, 2016 8:24 am

Thanks for that. The adapter is a very tight fit. Hopefully I'll be able to find someone to machine it to accept SM60 at a sensible price.

The etalons are actually SM60 IIs so the adapter isn't needed (although I do have one) and luckily both have T Max tuners. I'm needing though to work on the tuning; perhaps moving the Richfield tuner pin(s) as I've noted on some posts. I'm also thinking of how I might achieve the 'clocking' some have referred to without incurring a very big machining bill.

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests