Rule of thumb for DoF in S16 compared to S35

[Sune Bang Ingemann]

Hey, 

So if focus is determined by Front pupil diameter (Should we say film/sensor plane for practical purposes) and distance to subject,  what is the rule of thumb for DoF on S16 compared to S35? This of course assumes that i'm 1-to-1 just using 2x wider lenses to achieve the same FoV. 

The context is that I'm shooting a short on S16 with B-speeds, and wanna keep them at 1.3 T-stop to avoid the triangular nature of the bokeh. That made me wonder, how much of a task i'm asking of my 1st AC, compared to shooting 1.3 T-stop on a S35 sensor. I'm not really interested in getting sucked into the whole scientific part of it,  more if old timers had some rule of thumbs from back in the day.

Best regards

 

Edited January 30 by Sune Bang Ingemann

[Giray Izcan]

You will find those lenses to be pretty soft wide open unfortunately...

[Robin Phillips]

you gain 2 stops of depth of field in super 16 for a given field of view vs that same field of view on s35. so a 16mm at T1.3 will look like a 32mm T2.8 s35 equivalent. 

But, on the B speeds going truly wide open can cause some significant softness. if you need to basically be wide open, I'd try to split between 1.3 and 2.

edit: spelling

Edited January 30 by Robin Phillips

[Sune Bang Ingemann]

Are they really that soft compared to MK II/ MK III ? 

I actually wanted Ultra Primes, but the rental house couldn't give a student discount deal on those. Oh well, I'll do some testing. 

In regards to DoF, 2 stops more, was what I came to as well. 

Thanks for the answers

Edited January 30 by Sune Bang Ingemann

[Albion Hockney]

super speeds are all really soft wide open. you are using only the the center of the lens though.

If your ok with a softer more halated look then your fine, but if you want it to be tack sharp you want something more modern.

you can use anything....even something like the Sigmas or Tokina's would work well. the 16mm will give the picture enough interest that totally clean sharp modern glass will still look great.

[Jon O'Brien]

3 hours ago, Albion Hockney said:

....even something like the Sigmas or Tokina's would work well. the 16mm will give the picture enough interest that totally clean sharp modern glass will still look great.

My thoughts exactly.