SolarChat!

Looks like Coronado are listening to customers...

http://www.meade.com/solarmax-iii-70mm- ... ilter.html

https://www.optcorp.com/catalog/categor ... olar-Max-3

Well, well, well Looks very much like my early double stacked SM60 on the ED80.
I think the "70mm" is a marketing pitch as the etalons are still 60mm...............
Sorry to say I'm not a convert to the Rich View Tuning, still prefer the original tilt/ T max.
It will be interesting to see what happens in the market with that specification and pricing.

And a bit of a write up with pics...

https://www.cloudynights.com/topic/5872 ... ax-iii-70/

Sounds good, but the internal etalon on the SM60II is/was Rich View Tuned, not tilt adjust.

Five months later......
Has anyone bought one of these?
Any current images?
It would be nice to get an update...........

All very quiet indeed isn't it Ken! I don't know of anyone with one. Coronado are about five years too late with this. Launching into solar minimum is a school boy error...

Mark's linked CN article makes it look promising. The SMIII seems to have better mechanicals (including a better focuser), and a nicer finish. Another poster received one in November and seems quite pleased.

Sorry to say I'm not a convert to the Rich View Tuning, still prefer the original tilt/ T max.

Tilt-tuning, if the etalon CWL is not close to the ideal 656.3 nm (i.e. low tolerance spacer manufacturing - which I have seen in some early Meade front etalons), might produce banding via excessive tilt needed to bring the filter on-band. RichView mechanical pressure tuning would allow the filter to be tuned and theoretically avoid banding due to tilt.

Apparently Meade decided TMax tilt tuning for the etalon closest to the objective is all that was needed, and there appears to be no RichView tuning on that etalon. The second DS etalon appears to have both TMax tilt and RichView tuning:
The RichView front etalon tuning looks to provide edge compression only (as opposed to the internal RichView etalons which have both edge and central spacer compression ability). This theoretically may give the possibility of returning the etalon - once tilted to remove ghost reflections - back to being more precisely on-band. However, tilting the filter too much to remove ghosting might still introduce banding... but the DS image further down the linked post looks pretty uniform, especially given the excessive contrast of the processing.

It would be interesting to know if the front etalons without RV tuning are selected due to their needing less tilt to be on-band, and the secondary DS RV etalons are selected due to needing a bit more native tilt, which makes them better for removing ghost reflections, and then can be RV tuned to be on-band. Coronado used to call this "etalon matching" when double stacking first appeared.