Posted by Wick Smith on April 16, 2010 at 12:15 PM
I noticed if I change the settings in my Canon 5DII to expanded ISO, I get an "L" setting that represents an ISO of 50. Does anyone use this setting and under what circumstances? Trying to increase exposure time? Less noise when doing long exposures at night?
Posted by David Rogers on April 16, 2010 at 12:33 PM
From Canon:
Question: I understand the difference between ASA (ISO) films 50 vs. 1600, speed vs. grain, but on my Canon EOS 5D, will the ISO 50 setting give me less noise than ISO 100? I do not have noise at 100. I have noticed that you have to use Custom Function 8 to get to ISO 50 and 3200, so is shooting at these speeds not recommended?
Answer: Some customers claim that they see less noise at ISO 50 than ISO 100 on a EOS 5D, but both settings are about equally noiseless. There is approximately a stop less dynamic range in the highlights at ISO 50, which is the reason why this setting is normally locked out.
Posted by David Rogers on April 16, 2010 at 12:36 PM
So if you are shooting low-light then ISO 50 doesn't necessarily help you. If you have some lighter areas then ISO 50 may actually hurt the image some.
ISO 50 with Canon DSLRs is a 'pseudo' low ISO setting. The camera will take the image at ISO 100 and calculate the ISO 50 image from the exposure. I never use it.
Canon media spokesman Chuck Westfall says:
"On the EOS 5D, the ISO 50 setting is only available when the camera's optional ISO Expansion setting is engaged. One reason for this is that ISO 50 is actually captured at roughly ISO 100 and then processed in the camera to achieve an effective sensitivity equivalent to ISO 50. As a result, there is less dynamic range in ISO 50 images compared to ISO 100 images from this camera. Incidentally, this is not "news;" Canon has acknowledged this right from the start. The main benefit of the ISO 50 setting is the flexibility it provides in terms of other camera settings like aperture and shutter speeds. This flexibility can come in handy in studio lighting situations as well as landscape photography. I've personally found that ISO 100 provides the best overall image quality from the EOS 5D in terms of noise and dynamic range. I'm aware of various individuals who feel otherwise, and they're entitled to their opinion, but I haven't seen any pictorial images from the 5D with lower noise or higher dynamic range than ISO 100."
Regardless of what it is "really" doing, I have used this setting on some occasions when it was very light and I needed a slower shutter speed such as moving water or flora blowing in a breeze. The loss of DR was not objectionable and not a problem, nor was there any noise issue.
Discussion
4 repliesQuestion: I understand the difference between ASA (ISO) films 50 vs. 1600, speed vs. grain, but on my Canon EOS 5D, will the ISO 50 setting give me less noise than ISO 100? I do not have noise at 100. I have noticed that you have to use Custom Function 8 to get to ISO 50 and 3200, so is shooting at these speeds not recommended?
Answer: Some customers claim that they see less noise at ISO 50 than ISO 100 on a EOS 5D, but both settings are about equally noiseless. There is approximately a stop less dynamic range in the highlights at ISO 50, which is the reason why this setting is normally locked out.
Canon media spokesman Chuck Westfall says:
"On the EOS 5D, the ISO 50 setting is only available when the camera's optional ISO Expansion setting is engaged. One reason for this is that ISO 50 is actually captured at roughly ISO 100 and then processed in the camera to achieve an effective sensitivity equivalent to ISO 50. As a result, there is less dynamic range in ISO 50 images compared to ISO 100 images from this camera. Incidentally, this is not "news;" Canon has acknowledged this right from the start. The main benefit of the ISO 50 setting is the flexibility it provides in terms of other camera settings like aperture and shutter speeds. This flexibility can come in handy in studio lighting situations as well as landscape photography. I've personally found that ISO 100 provides the best overall image quality from the EOS 5D in terms of noise and dynamic range. I'm aware of various individuals who feel otherwise, and they're entitled to their opinion, but I haven't seen any pictorial images from the 5D with lower noise or higher dynamic range than ISO 100."