Going H-alpha: Replacement ITF from Maier.

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WARNING: SOLAR OBSERVATION REQUIRES GREAT CARE AND SAFE FILTRATION.
INSTANT PERMANENT BLINDNESS CAN EASILY RESULT FROM SIMPLE MISTAKES.
NEVER LOOK AT THE SUN THROUGH ANY LENS, MIRROR OR INSTRUMENT UNLESS IT HAS BEEN FULLY TESTED AND APPROVED FOR SUCH USE. YOU FOLLOW MY EXAMPLE ENTIRELY AT YOUR OWN PERIL!

Whoopee! My Maier ITF replacement arrived in the post. Excellent service from Both Maier and the international postal services. It came with an O-ring which was not part of the Coronado ITF construction.

I have sought advice on whether to fit the O-ring first or the filter. I know the shiny green side of the filter points towards the objective/sun. With the deep red towards the eyepiece. The O-ring has me stumped. I have no useful data to make a valid choice for its position.

The images here show the new filter in the PST housing.  Only the glass filter is supplied by Maier.

I'm thinking of putting the O-ring in first to help to seal the exposed filter face and to push it further out of harm's way. Looking at it logically, as a regular PST spare part, it would be better protected inside the black casing. But still subject to changing atmospheric humidity. While the red, backside, of the filter is much better sealed inside the ITF/BF tubular housings.

Maier tell me that the filter surfaces are fragile and that I should only handle it by the edges. Which I duly did after having removed the screw-in filter housing and its locking ring. I used a small pair of engineer's, screw-adjusting dividers without any effort. No thread locking medium thank goodness!

Had I known what to do with the O-ring it would have been no more than a 5 minute job. Provided of course I had previously separated both filter housings from the PST.  ITF replacement can still be done provided the pentaprism has been removed from the black PST housing. I'm not sure it is possible with the prism simply backed as far away as it will go via the focusing knob.

The clarity of view through the Maier filter is truly remarkable compared with the almost opaque [rusty] Coronado original. I can see the darkened room quite clearly and read newsprint easily through the Maier ITF. The view is cast in deep red with only a table lamp for lighting.

The view through the new Maier ITF filter on an overcast day with snow on the ground:

Via the original Coronado ITF it is so dark that I can barely make out anything at all. The [white] computer screen is almost invisible at 2' and the lit lampshade, at a similar distance, only dim. This is not a function of the colour density of the old and rusty filter. It is quite simply, almost opaque. It seems sensible to replace an old ITF filter if it shows a rusty complexion despite immaculate outer coatings. Otherwise, you won't know what you're missing.

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