Is this a rusted PST objective?

[cathalferris]

Does this look like an oxidised PST ERF filter between the objective elements? The striations are in the lens, not a reflection. This pic was taken in direct sunlight.

If it is a victim of the "rust", does anyone have a non-rusted spare objective from a modded PST lying around for sale?

[John]

I'd say that was a rusted one from the pics I've seen of others with this issue. I would you put your "wanted" advert on the UK Astro Buy & Sell website as we don't buy & sell on the forum at the moment.

Thanks

[Merlin66]

Definately failure of the energy rejection coating. If the PST is less than five years old you can get this repaired under warranty.

If you can't find a replacement gold tube, then you could consider a Stage 1 mod.