As Steve hasn't yet replied, I'll try to answer your query, Jimmy.
Unfortunately, the so-called PST 'rust' problem is quite widespread and also affects the blocking filter (BF) component of Coronado's expensive SolarMax gear. The only 'official' word I've seen on the subject was in this factory email response to a Cloudy Nights poster:
The "breakdown" or rust colored appearance that has been seen on front objectives of some PSTs is a result of degradation of the ITF coating. Our ITF's are being supplied by an outside source. Upon arrival at Coronado they were cemented and assembled into the PST objective. Unfortunately, when improperly handled, meaning too much time before cementing whether at the vendor, Coronado or both degradation began. This degradation could not be seen during the assembly process or in our field testing prior to shipment. The coating started to visibly degrade a few months after assembly. Because this problem does not affect safety (only performance) and does not affect all PSTs, Coronado is repairing the affected units rather than issuing a general recall.
Our current procedure is to use another style of the ITF and locate it further down in the optical tube. These units will look different as the front objective will be clear, but neither safety nor performance are adversely affected by this change.
Best regards,
Russ Tanton
Coronado Instruments
Cloudy Nights has a useful collection of posts on the subject here:
http://tinyurl.com/32n9z5
Meade inherited the resultant warranty claims problem along with their takeover of Coronado, but reportedly lost all of the skilled Coronado personnel when they subsequently transferred the operation from Arizona to California. Hence (presumably) the repair delays and shortages of dealer stocks of new Coronado gear in recent months. I've lately read that they'll be re-establishing manufacture of the line in China - it'd be nice if that leads to reduced prices (he said hopefully!)
Incidentally, when they work well, as mine does, the redesigned PSTs work very well indeed. Whether they'll last indefinitely or eventually suffer coating degradation too, remains an open question.
