Film speed

umdah · Oct 4, 2009

what is the end result difference between rating a 400 xp2 super at 200 and
setting film speed at 400 and exposure compensation of +1. don't both settings overexpose by 1 stop?

Thank you.

Ian Grant · Oct 4, 2009

Both give the same exposure yes. Two ways to skin a cat

Ian

umdah · Oct 4, 2009

Ian, thank you.

RalphLambrecht · Oct 4, 2009

umdah said:
what is the end result difference between rating a 400 xp2 super at 200 and
setting film speed at 400 and exposure compensation of +1. don't both settings overexpose by 1 stop?

Thank you.

My way of exposing XP2.

2F/2F · Oct 4, 2009

umdah said:
what is the end result difference between rating a 400 xp2 super at 200 and
setting film speed at 400 and exposure compensation of +1. don't both settings overexpose by 1 stop?

Thank you.

Both settings overexpose the metered exposure equally (by one stop).

However, this does not mean that they always overexpose the ideal exposure. Depending on what and on how you meter, you could be over, right on, or under the ideal exposure at *any* EI setting. Learning how to see what your light meter is recommending, and then knowing whether to follow it or adjust off of it is key in getting good exposure far more than is re rating your film.

umdah · Oct 5, 2009

Ralph, 2F/2F...

Thanks for your replies. If the amount of light hitting the film is the same in both cases, why is it that a lot of users downrate their film speed to 200/250/320. Is there a hidden secret here?

Thanks.

RalphLambrecht · Oct 5, 2009

umdah said:
Ralph, 2F/2F...

Thanks for your replies. If the amount of light hitting the film is the same in both cases, why is it that a lot of users downrate their film speed to 200/250/320. Is there a hidden secret here?

Thanks.

The simple answer is:

The standard to measure film speeds may not based on the same criteria as the consumer's development setup and quality expectations. Manufacturers may use different developers and agitation methods than the end customer, and you may prefer more shadow detail than you get from box-speed exposures. Every user has his or her personal exposure index (EI) and it may differ from the ISO speed on the box.

JBrunner · Oct 5, 2009

Most photographers will have a personal exposure for a given emulsion that depends on developing. You will find this much more often with true black and white emulsions that a photographer is developing themselves. Less so for a C41 process that is sent out. Most C41 emulsions I rate at box speed because I send it out for standard processing, although I may vary an exposure from the meter for various reasons. IMO there isn't a standard reason to overexpose XP2 than by more than a third to half of a stop or so (pushing aside), if you are having it processed by a lab. I might give it a third to a half to have a little more detail at the bottom, because its latitude is on the top (if I was the one printing).

steven_e007 · Oct 5, 2009

It depends on the camera, too. I often uprate or downrate to compensate for slow tired shutters in my vintage cameras, or the flare and light loss of an ancient uncoated lens - although sometimes maybe the two effects cancel each other out

umdah · Oct 6, 2009

Ralph, Jbrunner and Steve,

Thank you kind people for your help.

Regards,

Anscojohn · Oct 6, 2009

umdah said:
what is the end result difference between rating a 400 xp2 super at 200 and
setting film speed at 400 and exposure compensation of +1. don't both settings overexpose by 1 stop?

Thank you.

******
Yes.

Film speed

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