Today’s question comes from a freelance producer/shooter from LA, who read my Sony SAL1650 16-50 f/2.8 on Sony FS100 blog post and is asking for some advice.
Video Production Question
Hey great article,
2 quick questions, the 16-50 does sound like an excellent choice for FS100, but 2.8 is really faster than I need in doc shooting (can’t hold a subject in focus reliably past f/4 at the very most!) so do you know of any lens similar in quality and ideally par-focal nature to the 16-50 but longer? Like a 16-80 f/4 kind of thing?
Also, for using the 16-50, what adapter would you recommend for smooth physical iris adjustment?
Thanks for your expertise,
Video Production Response
Thanks for commenting on my Sony 16-50mm f/2.8 blog post. I agree that f/2.8 can be too fast (and hence the depth of field is too shallow) for doc shooting. The simple solution is to simply stop-down the lens to f/4.0 or f/5.6 to increase the depth of field so more is in focus and compensate with additional gain to adjust the exposure if needed. The lens will remain parfocal and the cost of the SAL1650, considering its build and image quality makes it a great value at around $800 USD.
Is there an alternative parfocal 16-80 f/4.0 lens that I am aware of? Unfortunately no. Sony has the Zeiss 16-80mm f/3.5-4.5 lens in their line-up but it is neither parfocal nor has a constant aperture. I have read rumours of an E-mount Zeiss 16-70mm but if I had to guess if it would have a constant aperture I would say no but I might guess it would be parfocal, as many e-mount zoom lenses are.
In general there are few zoom lenses that have a constant aperture (needed to prevent lens ramping – a closing of the iris) when zooming. Most are 3x zoom lenses (16-50, 28-75, 70-210) but there is one notable exception: The Canon 24-105 f/4.0 lens can maintain a constant aperture through its entire zoom range and I found it to me very close to parfocal. The copy I tested was a bit soft fully wide but for most of the range it held focus. This lens is actually on my personal wish-list as sometimes I am willing to trade-off an f/2.8 3x lens for a f/4.0 4x zoom lens.
I haven’t looked into lens adapters in a while so can’t give you a definitive answer but I currently use the Sony LA-EA2 adapters and while they don’t have a smooth iris adjustment, at least the iris doesn’t go full wide open like it does on the LA-EA1 adapter. I would imagine the lens adapters with a manual iris ring would be much smoother and can only speak to the Fotodiox Sony A to E adapter that I bought. It was smooth once you started adjusting but unfortunately clicked-in when the iris was fully open and closing again required a bit of force to unclick.
For the Canon lens, a lot of FS100 & FS700 users are going with the Metabones/Conrus EF to E-mount adapter. Sony is now bundling their MarkII adapter with new FS100 purchases. I have not tested this adapter so can’t comment on how smooth the iris changes are but I believe it is an electronic iris change and the increments are something like a 1/3 stop. Matabones is now shipping their MarkIII adapter and if you need a wider lens than the Canon 24-105 f/4.0 lens, consider pairing it with the Speedbooster.