digital iso value vs film

[leica1215]

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when film era, I use to use 160, 400, rarely use 800 or above film, now with the M, often found need to use 800 or above, rarely use 400 or 200 to get correct exposure.

 

I start to think is the digital iso in the same level of light sensitivity versus film?

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[chris_tribble]

This doesn't reflect my experience. In digital, ISO has become the third variable (the others being shutter speed and aperture). In bright light I'll use 200 (and sometimes need an ND filter). In low light I'll use higher ISO. These decisions are made in order to control DOF and to stop (or blur) movement etc.

 

Honestly, I don't find any difference in terms of the ISO choices that I make now compared with film - apart from rejoicing in the fact that I can adjust ISO in the middle of a job if I need to (without swapping bodies or backs).

[tomlianza]

The determination of a speed point for film, which determines the ISO film speed has always been the subject of much discussion. In digital photography, there are two methods that are used, one based upon the noise floor of the sensor, the other uses a more traditional method that picks a shadow value and the calculation is performed based upon the illuminance at the sensor plane.

In analog photography, the methodology for slide and negative films is somewhat different. There is a meter constant that is often noted on a standalone light meter. These constants are very different for illuminance meters and spot meters (lumiinance). All in-camera meters are effectively luminance meters, but the ISO speed can be calculated in either fashion, yielding different results.

[luigi bertolotti]

when film era, I use to use 160, 400, rarely use 800 or above film, now with the M, often found need to use 800 or above, rarely use 400 or 200 to get correct exposure.

 

I start to think is the digital iso in the same level of light sensitivity versus film?

 

Is easy to verfy working together with M and an external meter : I did it sometimes with M8, at the start of my digital experience, and didn't notice significant differences... even the old "sunny 16" rule was always a good reference..

 

BUT, I find that the real problem about "ISO attitude" is, speaking of old dumb rules, the old "1/focal" rule for exposure times : definitely, digital is less forgiving on motion blur... or it's too easy to find small evidences of motion blur by pixel-peeping... ; so happens that, after 6 years of digital, consciously or not, in the mean I DO tend to work at least at 1/125 with 35...I DO tend to consider 1/250 not SO safe with a 90 and risky with 135... ... at the end, this results in a sort of "appreciation" of higher ISO values : fact is that when I bought the M8, one of my thoughts was "160 of minimum ASA ? Ok... even too much..." and when took the M I thought "200 of minimum ASA ? Ok... that's a good level"

[pgk]

With digital its more a matter of matching the exposure to post processing and output requirements when shooting RAW files. I very, very rarely bother to move my M9 ISO from its base of 160, relying instead on determining where I want my highlights to sit and accepting that I will have to boost (or amplify) the shadows in post processing. This works for me but I'm sure that others have other equally effective ways of working. I have read up on the digital definitions of ISO, but given that the vast majority of photographs are all about producing 'acceptable' images, which are examined visually and subjectively, the technical specification of digital ISO is usually of less relevance than the workflow (from taking the photograph to outputting it as desired), which may not make use of the ISO as defined.

[leica1215]

Well said. On the M seems can't adjust ISO to 160 which portra I always get 160 even though 200 is not much different .

[earleygallery]

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I generally don't alter the ISO when I'm shooting digital. I try to impose the same techniques that I use when shooting film. I set the camera at 100 or 200 and stick to it, but it is great to have the flexibility should you suddenly find a need for using a higher ISO where with film I have to carry another body/back or reload mid-roll, or just make do.

 

To answer the OP's point, digital ISO should be broadly the same as with film, so I'm not sure why you always need to select 800 or more, which will just be degrading your IQ.

 

Digital is more like slide film than negative though, and requires precise exposure (or otherwise lots of tweaking in PS).

[Paul J]

No it's just because the film era was so much brighter!

[Guest Gilgamesh]

"

often found need to use 800 or above, rarely use 400 or 200 to get correct exposure.

 

Care to explain?

Likewise, I have no idea what you are experiencing.

[MarkP]

I generally don't alter the ISO when I'm shooting digital. I try to impose the same techniques that I use when shooting film. I set the camera at 100 or 200 and stick to it, but it is great to have the flexibility should you suddenly find a need for using a higher ISO where with film I have to carry another body/back or reload mid-roll, or just make do.

 

To answer the OP's point, digital ISO should be broadly the same as with film, so I'm not sure why you always need to select 800 or more, which will just be degrading your IQ.

 

Digital is more like slide film than negative though, and requires precise exposure (or otherwise lots of tweaking in PS).

 

Exactly how I work, excluding more difficult/poor lighting conditions.

[anupmc]

Exactly how I work, excluding more difficult/poor lighting conditions.

 

Ditto. I only move up ISO as a last resort -- force of habit from M9 days