feeling stumped by Fuji NPS 160 chart

On a whim I decided to open up the box that contained the canister for Fuji NPS 160 and read the chart... (time on my hands as passenger in car). I was following quite nicely on the exposure guide but after some contemplation could not figure out the circled 1/2 in the chart. What does that mean? In the chart below it shows +1/2 for exposure compensation but it doesn't show a + or - for the one above. Any thoughts? I'm sure I'm going to be completely embarrased by the answer.

What you couldn't make the image any smaller? From squinting it looks like F/16.5 at 1/250 with full sun. It's just sunny 16.

smileyguy said:

On a whim I decided to open up the box that contained the canister for Fuji NPS 160 and read the chart... (time on my hands as passenger in car). I was following quite nicely on the exposure guide but after some contemplation could not figure out the circled 1/2 in the chart. What does that mean? In the chart below it shows +1/2 for exposure compensation but it doesn't show a + or - for the one above. Any thoughts? I'm sure I'm going to be completely embarrased by the answer.

Click to expand...

At first, I thought it was a modification of the "sunny 16" rule: "With the shutter speed set to the reciprocal of the ISO film speed, the aperture should be f/16." ... but ... it is going the wrong way. If the shutter could be set at 1/160th second, the aperture would be f/16 ... but most shutters cannot be set at 1/160th. If the shutter was set to 1/125th second, a slightly smaller aperture would be required ... f/16 1/2; f/16.5 - halfway between f/16 and f/22 - seems to be about right. However, the chart specifies 1/250th. Decreasing the exposure time one stop... and that would therefore require a half stop MORE aperture, or f/11.5 at 1/250th.

Sounds like an error from Fuji (errors happen to the best of them) to me.

I think the first one is "beach" but like I said I can't really read it. Sunny is the second one at F/11.

Let me try again with the size... :embarrassed:

It's just sunny 16 but since cameras don't usually offer 1/160 or 1/320 they adjust the F/stop.

And if your camera doesn't have half stop markings I suppose you can't/shouldn't use this film. Many of my camera/shutters only have 1/3 stop markings so I probably should keep using B&W film. ;-)

BrianShaw said:

And if your camera doesn't have half stop markings I suppose you can't/shouldn't use this film. Many of my camera/shutters only have 1/3 stop markings so I probably should keep using B&W film. ;-)

Click to expand...

Let's see ... the difference between f/ 16 1/2 and f/16 1/3 - is 1/6th of a stop.

One sixth of a stop??? Do you think that anyone can, or needs to be that accura....

Oh, wait a minute - a "smiley". That explains it... you are yanking our chains!!!

Thanks for all the brilliant replies, folks!

So, if I understand this correctly it is a slight alteration of the sunny 16 rule? So the chart is indicating f16 and a 1/2, f11 and a 1/2, etc.?? I must be dense, I don't think I would have figured that out by looking at that chart. Oh well...

One sixth of a stop??? Do you think that anyone can, or needs to be that accura....

In another life, all of the studios doing product photography had their lenses marked in 1/10 of an f stop.

We were doing all of the work using tranny film and as the end product was a printed colour catalogue, really accurate metering was required as the film had to have a highlight to shadow range of 3 stops maximum.

This range resulted in extremely superior colour reproduction in a four or five colour offset printing process.

Trust me when I say if you wish to photograph white or slightly off white fluffy towels, using a white or very light background as requested by the client. Then by keeping the exposure absolutely spot on at the start of the process, you could see the different fluffy white towels clearly in the catalogue.

FWIW All of the Hasselblads were very easy to work with, one metered exactly to a known standard, applied black or white reflectors to kill or lift light, adjusted the lens to the correct 1/10th of a stop then shot.

With the RB/RZ most photographers somewhere along the line forgot to allow for bellows extension. You could see immediately on the lightbox the difference.

The basic idea for this came from an american photographer who preached total control to save money. His name may have been Dean Collins, not sure. However we looked seriously into what he had to say, thought it could be worth it and set up one studio (out of fourteen) this way.

Initially it took about a week to get things going correctly. Going on memory, it was about 20 years ago, there was an immediate savings of film in the vicinity of 20%. With colour stats used for paste ups and layout there was a savings in time and stuffups.

Once the trannies were to be scanned we found that as they were so close in density, saturation, etc, etc, we could get the scanning done with far fewer problems.

The printers had a ball as the highlight to shadow dot didn't blow out or bog down, the client was over the moon as their main competitors catalogue looked pretty ordinary compared to theirs.

The total savings amounted to about 15% in actual costs and throughput increased dramatically once the film had been shot.

We were so impressed with this that we started looking at other ways to improve accuracy in exposure. Sinar had their meter probe for the GG on our 4x5 cameras. We tried them but it didn't really work out as hoped. Apart from that they were hopelessly overpriced and we just couldn't justify them. We did teach the Sinar rep how to use the probes a treat though!

Mick.

Mick Fagan said:

One sixth of a stop??? Do you think that anyone can, or needs to be that accura....

In another life, all of the studios doing product photography had their lenses marked in 1/10 of an f stop.
Trust me when I say ... Then by keeping the exposure absolutely spot on at the start of the process, you could see the different fluffy white towels clearly in the catalogue...
We were so impressed with this that we started looking at other ways to improve accuracy in exposure. Sinar had their meter probe for the GG on our 4x5 cameras. We tried them but it didn't really work out as hoped. Apart from that they were hopelessly overpriced and we just couldn't justify them...

Click to expand...

Interesting!!

I had been immersed in "Light meter" calibration and accuracy ... and establishing "Accuracy Evaluations" for them. Our targets were the top of the State of the Art equipment available ... using Standard Lamps - Intralaboratory Standards cycled though the NBS.

Our efforts were mainly directed at equipment using Cascade Photomultipliers ... you haven't lived until you take a jolt from the primary energy supply from one of those; ~ 1800 volts or so. Unforgettable.

But, I digress. I'll avoid a discussion of the various problems inherent in measuring anything to determine "exposure" and merely ask about the equipment used that would be accurate enough to determine the amount of light accurately enough to enable confidence in an exposure to +/- one tenth (1/10th) of a stop. What was used?

Also ... "f/stops"? Weren't most of the really accurate lenses calibrated and marked with "t/stops"?

Ed, The basic idea was to calibrate the whole studio.

Firstly, the two lenses for each camera were colimated by a scientific optical works. Once the lenses had been re-assembled they had their effective apertures measured at (I think) three focusing settings, infinity being one of the settings.

Each lens had lines engraved on a non moving part and a corresponding set on the aperture ring. There was a printed chart for each lens that was permanently attached to each camera stand.

The idea sounds complex but in fact it was extremely simple. The photographer arranged the product, set and focused the camera, decided on the f stop required, checked the focusing distance off the lens, consulted the chart and moved the aperture ring the required amount to get a true aperture.

The photographer also used a flash spot meter which had a specially made black tube attached to the end. This was to ensure that flare didn't play any part in getting a false reading.

Once our test studio was set-up and running it took about three days to get what we wanted. The film was sent off for scanning, colour seps done, then 4 colour chemical proofs were made.

The results were pretty stunning. I can remember standing in front of the colour corrected reflected light box, viewing the proof prints. Pretty much everyone there asked the same question:- "how much does it cost to get a set of lenses calibrated"?

The photographers all liked the system, once they got into the habit of doing things one step at a time, life was a bit easier for them.

Mick.

Mick Fagan said:

Ed, The basic idea was to calibrate the whole studio.

Firstly, the two lenses for each camera were colimated ...

Click to expand...

I understand all that, but my question was directed toward measuring the amount of light ... accurately enough to make concern about one-tenth of a "stop" reasonable. What brand/ model Flash Meter was used / is supposed to be that accurate?
My Gossen Ultra-Pro has a resolution of 1/10th stop; Gossen only claims an accuracy of +/- 1/3 "stop".

My next question would be directed to Photo Engineer: What are the design parameters / manufacturing tolerances of ISO film speed, for either negative or "reversal" film? It is difficult enough to "worm" exposure meter tolerances out of the manufacturers ... I can only imagine how tight-lipped they are about film speed.