Film speed vs. digital camera ISO

[blacklight]

Hi,

I wonder, does ISO setting on my digital camera (350D) equal coresponding film speed? E.g., when I set ISO 400, is it the same sensitivity as if I used 400 ISO film?

The reason Im asking is that Id like to practice sunny 16 exposure metering, while my first film camera arrives, but dont know if this rule applies also to digital cameras.

Thanx

 

[ffttklackdedeng]

Hi! The short answer is: yes it does!

But: Sunny 16 is practiced with negative film which has a wide exposure latitude, i.e. you can over- or underexposure by 1 or 2 stops and still get a decent result. With a digital sensor, especially overexposure might look bad

 

[markinlondon]

Yes, but we should really talk about EI (exposure index) and not "ISO speed". ISO speeds relate to a density on film under controlled exposure and development conditions. EI is the everyday equivalent we use.

 

[lZr]

But there must be relationship between ISO and EI. As far as I checked the ISO between my KM 7D and film ISO, I can say that Digital ISO coresponds to slide film ISO. EI is better to use with pushable film, one like TRI-X 400 and TMAX 400.
I mean, with digital camera better to think, you use slide film

 

[Hiyawaan]

For all intent purposes yes, ISO on film and Digi-Cam are the same, but on Digital its like your shooting chrome where you must protect your highlights and remember that the latitude is considerably smaller.

 

[Abbazz]

Be careful with Canon digital cameras, their ISO rating is 1/2 to 2/3 stop higher than usual. ISO 1600 on a Canon SLR is the same as ISO 1000 on another brand digital or film camera.

Cheers,

Abbazz

 

[blacklight]

thanx for replies. Actually, its not a big deal, I can test it without any costs with digital.

But now Ive read the replies, I would like to hear little more about ISO - EI relationship. AFAIK, ISO is sensitivity according to producer, EI is what we set on camera, right?

 

[Socke]

Be careful with Canon digital cameras, their ISO rating is 1/2 to 2/3 stop higher than usual. ISO 1600 on a Canon SLR is the same as ISO 1000 on another brand digital or film camera.

Cheers,

Abbazz

It's the other way around, Canons ISO 1600 is more like 2000.

 

[yarinkel]

I own 2 canons DSLR and their sensitivity is a bit higher than film at equal ISO.
It got me when I tried to use my DSLR to find the optimal manual exposure for some landscapes and then shoot my film camera with the same manual settings.
The slide shots (fuji velvia 100) came a bit underexposed compared to my Canon which was set at 100 ISO and had properly exposed shots.

 

[RObert Budding]

Be careful with Canon digital cameras, their ISO rating is 1/2 to 2/3 stop higher than usual. ISO 1600 on a Canon SLR is the same as ISO 1000 on another brand digital or film camera.

Cheers,

Abbazz

That helps Canon convince everyone that their cameras have superior low light performance. (It is actually quite good.)

 

[Abbazz]

It's the other way around, Canons ISO 1600 is more like 2000.

Ooops, my slip has tongued. Thanks for the correction.

Abbazz

 

[Kin Lau]

Dpreview makes it a point of verifying a camera's ISO/EI settings against what it should be, so if in doubt, just check their reviews.

Canon's DSLR sensor sensitivity is consistently 1/3 stop higher than the meter. Nikon is dead on.

BTW, Canon's digicam (not dslr) sensitivity is consistenty 1 full stop higher, so ISO 50 on my A70 digicam is actually ISO 100.

 

[Finder]

ISO is an exposure index (EI). So they are one in the same. The difference between film and digital is that a digital camera does not actually use the index to determine the exposure - it simply uses the signal from the sensor. Naturally, film does not make a "signal" the camera could use and so you need to tell the camera the relative sensitivity of the media.

Also ISO is not an exact number - ever see ISO 130 or 98? It is simply what a determined response is within a specified range. This range/scale is made by the same organization for both film and digital - the International Standards Organization (ISO).

Also there can be variations, so an ISO from one sample may not be an indication of every product sample. Natually, how you can tell a camera or a separate meter is giving the "right" reading would depend on many factors starting with knowing one of them is actually accurate. But this has been a problem with film as well. Simply stating, each photographer should determine their systemic EI for themselves which would include the entire process from metering though optics, shutter efficency, sensor response, to processing.