Sunday, January 2, 2011

Base ISO vs. Sync Speed

I decided to get a Nikon D70, one of the few DSLRs that has a sync speed of 1/500 (point and shoots meanwhile don't have much to worry about sync speed, allowing sync at theoretically any shutter speed).

What's so important about sync speed?
As I was choosing the D70, I was reminded that the base ISO was 200.  Did having a 200 ISO (as opposed to 100 ISO) limit erase the ultra-high 1/500 sync speed advantage?  Actually, no it does not.

Here's Neil van Niekerk's explanation of the issue:
http://neilvn.com/tangents/2006/08/24/advantages-of-a-high-flash-sync-speed/

Put another way, at 200 ISO, your flash has 1 stop more range or can shoot at a 1-stop narrower aperture relative to 100 ISO, so that even though you may need to shoot at a narrower aperture at 200 ISO (as opposed to 100 ISO), the relative power of your flash (compared to ambient) won't diminish.

If you're looking for a camera with a very high sync speed, the ones I'm aware of with 1/500 sync speed are:
  • Nikon D70 - has a built-in flash commander for one group.
  • Nikon D70s - has a larger 2-inch LCD screen than the D70.
  • Nikon D50 -  sensor has less noise than the D70 or D70S, but is an entry-level Nikon with no rear dial, no commander mode, and no built-in focus motor.
  • Nikon D40 - also an entry-level Nikon; has an even better (lower noise) sensor than that of the D50.
Some Nikons have a flash mode that can sync at 1/320 (1/3 stop higher than their native 1/250 sync speed) while being more efficient than high speed sync:
Nikon D300, D300S, D7000, D700
Note: I don't know how this higher sync speed works nor do I know what the power loss is.