Lunt VS Coronado BF

Use this section to discuss "standard" Baader/Coronado/ Lunt SolarView/ Daystar, etc… filters, cameras and scopes. No mods, just questions/ answers and reviews.
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Gingerfish
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Lunt VS Coronado BF

Post by Gingerfish »

Hi all,

First post, so be gentle :lol:

I love my little LS50THa, but I need a bigger blocking filter. Right now I have a B400, which is just about ok for visual, but more or less useless for imaging. As I am planning to mod my scope down the line (most likely the 102ED F7), I want to upgrade my blocking filter first (I have already upgraded the focuser to a MoonLite mini).

I have heard you can use a Coronado BF on a Lunt, but not the other way around. Is this still true? If it is, then I can save quite a bit of money here.

A Lunt B1200 is £924

A Coronado BF10 is £499

A Coronado BF15 is £699

I know both can suffer from "rust", and Lunt seem to have better service. But once they go, most people seem to upgrade the broken bit with a 3rd party one anyway.

What do you guys think?

- Christian


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Chris

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Re: Lunt VS Coronado BF

Post by marktownley »

Hi Christian.

I used my Lunt 50 with a Coronado blocker with no problems.

Welcome to the forum!

Mark


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Re: Lunt VS Coronado BF

Post by Gingerfish »

Thank you Mark,

Is there much difference between the BF10 and the BF15?

- Chris


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Re: Lunt VS Coronado BF

Post by marktownley »

Gingerfish wrote: Tue Nov 03, 2020 8:19 pm Thank you Mark,

Is there much difference between the BF10 and the BF15?

- Chris
None at all, the BF10 is more than adequate.

A larger blocking filter just shows a great field of view that is off band and unusable.

Mark


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Re: Lunt VS Coronado BF

Post by Gingerfish »

Thank you, Mark!


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Re: Lunt VS Coronado BF

Post by RKBerta »

I have a 60mm external Etalon (Coronado....US made and pre Lunt_) on a 80mm APO scope that normally uses a Coronado BF diagonal).
I have another Lunt 60mm Ha scope with pressure tuner so after reading your post I decided to try if I could use the Lunt BF with the Coronado etalon....worked fine. The main issue was making sure you get the correct in/out focus with whatever scope you are using.
By the way the Lunt scope is about 4 years old...the ERF on the BF had rusted so called Lunt. They said that they changed over to a new coating that hasn't had any rust issues in the 1 1/2 years since they switched. That particular scope is used in a Scout observatory I manage so they replaced the filter for free. They sent it to me and I replaced myself....just needs a pin spanner to remove the retaining ring and replace the filter.


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Re: Lunt VS Coronado BF

Post by Gingerfish »

Thank you, good to know!


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Re: Lunt VS Coronado BF

Post by Bob Yoesle »

I have a 60mm external Etalon (Coronado....US made and pre Lunt_) ...the ERF on the BF had rusted so called Lunt.


Just a couple of minor corrections / clarifications:

Typically a US made Coronado filter is not "pre Lunt," it would be pre-Meade. There was a short period of time (~ 1 year) after Meade purchased Coronado when production remained in Tucson. Another short period followed when production moved from Tucson to southern California, which would be "post Lunt." Thereafter, production moved to and currently remains in Tijuana, Mexico.

The first filter in the blocking filter assembly is typically not the "ERF." An ERF is typically a UV or UV/IR blocker on RG630 or BK7 located ahead of the etalon. The filter you are referring to in the blocking filter is typically a longer IR blocking filter which uses silver and dielectric coatings (ITF - induced transmission filter) on a RG630 substrate which can "rust" with moisture invasion (Coronado), or (Lunt) is a BG38 filter glass which reduces image brightness as well as providing reduced long IR transmission. This BG38 soda-lime filter does not rust like the ITF, but has surface deterioration* from moisture exposure, which now is protected by being coated versus uncoated.

* https://www.nature.com/articles/s41529-020-00130-9


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Re: Lunt VS Coronado BF

Post by RKBerta »

Bob,
Thanks for further info re: the filters on the Coronado and Lunt. The 60mm Coronado Etalon, BF10 and BF30 I have was pre-Meade. The Lunt 60mm with pressure tuner was donated for use at our Scout observatory which I manage here in Michigan. The observatory is really first rate with a large roll off roof setup that when opened covers an external patio class room. Has a 14" Celestron SCT HD on a Celestron CG Pro mount, a 13" DOB and another 12" DOB. Normally we get thousands of scouts through each year although Covid shut it down for a couple of years sadly.


80mm f6 Officina Stellare APO triplet, 152mm Officina Stellare f8 APO triplet, TV 85mm f7 ED APO, 8" SCT HD, 11" SCT.
Astro Physics 900 and 1100 mounts, Ioptron MINI Tower Pro ALT/AZ mount, ZWO AM5 mount,
Lunt 60mm Ha single stack, Coronado 60mm Ha single stack with BF 30
Day Star Quark Chromosphere
Player One Neptune mono with 178 chip, 256mm DDR, tilt plane for solar imaging
ASI 071 Pro cooled color for DS imaging
ATIK 490 EX OSC for DS imaging
SBIG STL 6303e mono with RGBL and Ha, SII, OIII filters for DS imaging
ASI AIR Plus

JPL/NASA Solar System Ambassador
Michigan Scout observatory manager
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