Let’s face it – sometimes we need to crop. However, when you’re faced with a photo in the viewfinder that’s gonna need an appointment with the crop tool, you gotta be careful. Noise is a tricky thing and it’s especially hard on images where cropping is required.
In this video, we’ll take a look at why your personal maximum ISO for your camera may be too high if the image in the viewfinder is destined for the crop tool. A must watch for every photographer!
UPDATES / NOTES
Please note that when I mention dropping your maximum ISO in the video, I don’t mean that you should keep your shutter speed and F/stop the same and allow the camera to underexpose. Underexposing will result in a situation where you need to bring the exposure back up in your RAW processor and your noise will look just like you had shot at the higher ISO. Instead, you’ll need to increase the amount of light hitting the sensor through either a wider F/stop or slower shutter speed.
Auto / Regular ISO Note:
Also, I’ve had people ask if this applies to Auto ISO or regular ISO. It’s both. The max ISO can be the maximum you set in your Auto ISO menu, or it can be the maximum you’re willing to dial in manually.
Lowest ISO Note:
Finally, I’ve had some people ask, “Isn’t everyone always using the lowest possible ISO all the time anyway?” My reply:
Not necessarily – it depends on the subject. For wildlife photographers (and many others I’m sure), we’re often faced with a range of options, not just a single perfect shutter speed, ISO, and F/stop. Here are just a few scenarios that came to mind:
For example, when I’m shooting macaws in flight in Costa Rica, I find that 1/3200th of a second is about the sweet spot – I very seldom have an image ruined by motion blur at that speed. However, if 1/3200th puts me at say ISO 6400 and I know there may be some cropping afterward, I’ll (begrudgingly) drop to 1/1600th and knock my ISO down to 3200. My keeper rate won’t be as high since more images will be ruined by motion blur, but they photo won’t be a complete loss because of noise overwhelming the detail either. Basically, I’m trading a higher keeper rate for the lower ISO.
Another scenario that comes to mind is hand-holding. Maybe you can hand-hold your given lens at 1/1000th (thinking telephotos here), but that puts you at ISO 6400 on an image you’ll know you need to crop. So, you grab a monopod or even a tripod so you can knock your shutter speed down to 1/500th or even 1/250th. In this case, you trade the flexibility of hand-holding for the lower ISO.
It can also happen with F/stop. Many BIF photographers will drop their lens down a stop to a stop and a half from wide open in order to gain a little extra DoF and keep the entire bird in focus (and have a little fudge factor for slight misses in focus). However, if the light is dim, you may be willing to trade that extra DoF for a lower ISO.
Finally, I think it’s good to just put it in people’s heads 🙂 In conducting my workshops, I often find people are so excited about what they are shooting they forget to double-check that they are using the best shutter speed and F/stop – often shooting a far faster shutter speed than they need. If this video reminds them to look at their ISO when they know they need to crop, I’m sure a lot of people will find that useful.
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