No Auto-ISO(? or !)
May 4th, 2011“The last thing you want to do is to let the camera decide what ISO setting to use”
Heard/read this already? I am pretty sure. With one exception (see the end of this post) I (naturally disagree.
First thing: It is not true that Auto-ISO (in a Nikon) silently jacks up your ISO. When Auto-ISO wants the camera to leave the base ISO you dialed in the Auto ISO mark will blink in the viewfinder. It is something that moves in the viewfinder - hard to ignore, much harder at least than forgetting the settings from last night’s binging:
So I just got my *** lens this week and I was super excited to break it in today at an outing to the California Academy of Science, which was a lot of fun and presented a handful of photography opportunities. Unfortunately I made a grave error…. I forgot to check my settings and my ISO was set to 1250 the entire day!! it was definitely unnecessary to have that setting so high and it ruined my pictures quality!
Outch.
What is wrong with Auto-ISO: It is in its current implementation too static (Ken Rockwell figured this out years ago *)
- the AS-mode is of very limited use, you have to switch Auto ISO to shoot manual (luckily it gets ignored when using a flash)
- It ignores the focal length - idiotic to enforce 1/250s shutter speed at 18mm
- It ignores VR
What controls do we need
- Max exp. time (default 1/60)
- Max exp. adjust: absolute, relative (default relative)
- VR exp. adjust (default 3)
- Disable in manual (default on)
- Max ISO (default 1600)
- Allow underexposure (default off)
Max exp. adjust absolute is what we have now, relative means that the Max exp. time will be computed relative to a 50mm lense. So the 24mm lens will use a Max exp. time of 1/30 and a 200mm lens will not go below 1/250
VR adjust - dial in 1 (options should be 1,2,3,4,6,8,12,16,24,32) to not prolong the Max exp.time when VR is activated, otherwise the factor is appled- in the default example a 50mmVR lens would let you go down to 1/20. Perhaps a stops scale would be easier to read
Disable in manual - hard to imagine when you want to turn this on…
Max ISO - I think almost dispensable - when we have good control over the exposure time it is really the only remaing variable that decides about getting or not getting the picture
Allow underexposure: Allows the camera to underexpose instead of going over the computed Max exp. time (= better too dark than blurry)
* I usually disagree with Ken Rockwell, but nobody can be wrong all the time
