Originally posted by clickclick
That got me to looking around at the vintage 500mm Takumars and SMC variants. I'm thinking the two are optically the same but it's about different coatings. So, what are folk's thoughts on these lenses? Worth looking for one, or a waste of money since I already have the 150-450? Of course, the LBA is so strong
All three versions of the Pentax 500/4.5 (Super-Takumar, S-M-C Takumar, and Pentax-K) share the same optical formula, so you are correct that the main difference would be coatings, build details and mount support. Whether it makes sense to buy is another matter. Consider:
- The AF with feature of your TC will not work well with that slow a lens (resulting ~f/8 aperture is too slow for PDAF).* Of course, the same is true for that TC with your D FA 150-450mm.
- All versions of the 500/4.5 are "beasts" of size and weight
- Your D FA 150-450mm likely has better optical performance
Steve
* The aperture limitation is not one of image brightness, but a matter of light angle that results in prism "black-out" of the PDAF splitter prism (full explanation (pdf)
HERE).