M42 lens

<p>What is the diference between the m42 yashica 50mm f1.4 DS and the m42 yashica 50mm f1.4 DX?<br>

Thanks to all</p>

<p>Here's what I think I know:</p>

<p>The DX has a barrel holding the glass elements that extends further back into the camera than we see for most M42 lenses. This was OK for the early Yashica SLR designs, but the rear of the barrel could block the path of the reflex mirror in later Yashica SLR's and in non-Yashica M42 mount SLR's or digital SLR's. The newer DS optical design kept that barrel clear of all M42 mount camera mirrors.<br>

In addition, the DS lens has enough radioactive thorium oxide in some of its glass elements to yellow the glass over time. It's like a similar situation with the Asahi Super (and Super Multi-Coated) Takumar 50mm/1.4 lens. There are forms of UV exposure that remove the yellow.</p>

<p>Also, the DX has a tab to switch between manual and automatic aperture operation, while the DS does not.</p>

<p>I don't really know. I suspect the coatings are different. I've read the DS coatings were Tomioka before Yashica made the Zeiss C/Y lenses under contract . So The DS lenses were quasi Tomioka lenses in C/Y mount as sopposed to the ML lenses. Where exactly the DX lenses fit I suspect is an improved coating and may represent either the same lenses or those made after Tomioka was consumed by Yashica, which itself was consumed by Kyocera</p>

<p>Note that Tomioka made lenses for Yashica since the '50s, so in fact every Yashica lens is a Tomioka lens.</p>

<p>Tomioka is a sleeper of a manufacturer -- made great lenses!</p>