doublet fluorite obsolete?

Hello,

I have a question:

Why Takahashi has changed yours renombred doublet fluoritr line FS for a new line of triplet ED? marketing,obsolete design,...?

paulo

I would guess that people are demanding better colour correction for astrophotography than the FS doublets could provide, so Tak moved to triplets (TOA, TSA series) and other designs (FSQ series). I would also guess that they saw that they could achieve outstanding correction with ED glasses, saw that the market perception of ED glasses was fine, and went with it.

Philip

My guess is that demand for shorter, faster & imaging optimized apos are the force behind this trend, doublets flourites are ideal for somewhat slower visual instruments but that market has taken a back seat to astrographic triplets.

Vahe