Reciprocity Effect on NPS

[doug_brightwell1]

I sometimes shoot landscapes right at sunset and dusk, and

have needed exposures of 4, 15, even 30 seconds particularly

with a polarizing filter cutting down the light.

 

 

Fuji says that exposures over 2 seconds are not recommended.

How does NPS handle reciprocity at longer exposures? What

effects would I notice that make it "not recommended?" Is it

simply a matter of a color shift that's easily corrected in

PhotoShop?

 

 

Any idea what the reciprocity factor would be at those longer

exposure times?

[edward_c._nemergut]

Hmmmm.... I don't know.

 

I'm not exactly sure why you would choose a film designed for weddings

and portraits for sunset landscapes (with a polarizer!) I've heard of

people using NPS to shoot snow and sand landscapes (where the film's

lower contrast can be helpful) but not the situation you've

described. Personally, I'd choose Provia 100F or Velvia for such and

application--maybe Supra 100 if I need a CN-41 film. All those films

have better reciprocity characteristics.

 

Sorry to be so blunt, but it sounds to me like you are trying to force

a square peg into a round hole...

[jdc]

I have never used NPS so I can't comment on what to expect. <p>but..<p>I'm not sure why

anyone would would suggest Velvia for a long exposure -- green sunsets? For print film

you might try Portra 160/400vc they have good reciprocity characteristics, NPL or 100T

(test NPL first It works best around 80-100iso IMHO) are very good on long exposures

and are also pretty saturated. I don't know what to suggest for chrome, the color bias is

such a personal thing.

[doug_brightwell1]

The main criteria was a color negative film that�s available in 4x5

single sheet readyloads that has a long exposure range and can

handle high contrast subjects. Portra 160vc, which I normally

shoot in standard film holders, is not yet available in single

sheet readyloads. I thought since NPS is used a lot for

weddings, and weddings are typically shot in MF, that someone

on this forum might have some experience with longer

exposures.

[pete_andrews]

The 'S' in NPS stands for short (exposure time). NPL is designed for longer exposures, but it's also tungsten balanced. Maybe NPL with the appropriate filter would be a better choice for long exposure times.<br>I've never tested these two films in such a situation, but the general effect of reciprocity failure is that exposures need to be extended beyond that which a straightforward lightmeter reading suggests, and a colour cast.<br>The colour cast might be of a type that's easily correctible in printing, or may be of the 'crossed curves' type, which isn't fully correctible.

[edward_c._nemergut]

J D C, I'm suprised that you haven't used Velvia for long exposures:

I've used it up to 20 seconds to photograph sunsets *without* a CC

filter for years. In fact, John Shaw reports using Velvia up

to 1 minute (!) in his books without any CC filters (he does add 1 1/3

stop,

however). I don't deny that it goes a little green; however, I've

always been able to overcome that by adding some time (I add 1/2 stop

for 8 seconds; and 1 stop for 16 seconds).

 

Back to the original question, I guess Porta 160 (NC or VC) is a

reasonable choice given your situation and desire to use a color

negative film. I still think Velvia or ProviaF are better choices.

To bad Kodak discontinued Ektar 25...

[wayne_crider3]

Ah yes; The problem of 4x5 color neg film. I ran into it, but never have had anything give me what I want. Now I use a 6x9 back giving me a decently large neg and more choices. In 4x5 I'd go Provia F or Astia @200. Too bad Gold 100 isn't available in 4x5 or 120 for that matter.

[jdc]

<i>J D C, I'm suprised that you haven't used Velvia for long exposures:</i><p>

I have but not of sunsets. I took 20 ready/quick loads to the northwest last fall. I was very

disappointed. In all honesty though I did not test the film before hand (I shot it at 50iso) I

used it mostly in the dense forests of Washington and at night in Portland. I got much better

results from 100sw and 100vs (also untested and shot as rated). 20 sheets, if you bracket,

might cover 6 or 7 different setups, I think I shot 5 or 6 -- so I am in no position to judge

the film.<p>

My comment above was overstated and I apologize.