Reciprocity failure with fast shutter speeds/Kodak Portra films

[fju]

Does anyone know if I need to compensate for failure of reciprocity when shooting at shutter speeds of

1/4000 sec?

 

I'm referring specifically to Kodak Portra films. In one part of their website, they say that failure of

reciprocity can occur at shutter speeeds of 1/1000 sec. and faster. But in a different part of their site

they seem to say you can shoot up to 1/10,000 sec. without need for compensation.

[larrydressler]

I have noticed no problems when I use a lens wide open on the n90s at 4000th of a second to get shallow DOF.

[randrew1]

Kodak needs to update their tech pubs. I searched kodak.com for "Portra reciprocity" and didn't find anything describing the new products.

 

I left Kodak before the new Portra films were introduced, but I know good reciprocity was always a design goal for this product line. I also know that high intensity failure was seldom a big problem. Since there is plenty of latitude in these films, I wouldn't worry about exposure compensation.

[helenbach]

Here is what Kodak say in the current Portra film data sheet on their website:<P>

 

"No filter correction or exposure compensation is required for

PORTRA 160NC, 160VC, 400NC, 400VC, or 800 Films for

exposures from 1⁄10,000 second to 1 second."<P>

 

This tech pub (E-4040) is dated September 2006. I am not aware of any changes to Portra films since then that make this data obsolete.<P>

 

Where is the reference to 1/1000th second?

 

Best,

Helen

[discpad]

Francisco, if you shoot the Portra films +1/3 EV -- which you should be doing anyway, to "clean up" any manufacturing tolerances in the toe -- you'll also compensate for any reciprocity failure at the same time.

 

The key to successfully shooting any color neg film is to NOT underexpose, as you'll gain ugly grain in the shadows. By the same token, you can easily overexpose by a full stop with no harm whatsoever. Take a look at "Fuji Pro800Z shot at 100asa" at:

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00Lgq2

for a discussion of color neg film accidentally overexposed by three full stops.

[fju]

Thank you all for your responses.

 

Helen, my comment was regarding E-4040 as well. I don't recall where it was on the

website that they mention 1/1000 sec., but I believe that page was referring to all of their

films. It included information on reversal films as well as B&W.

 

Dan, I'm new to Kodak Portra films but in the past I always shot Fuji NPH rated at 320. I

did this as a precaution for that specific film, and I always shot NPZ 800 at 800.

 

In my brief experience with Portra 160NC I cannot not see any difference between the

frames shot at 100, 125, and 160.