ISO Rating <-> Development Times

[Bessa-ist-das]

Hi all,

firstly I'd like to apologize for maybe a rather silly question. I tried the search but couldn't come up with any answers so that's why I'm posting this new thread here.

My question is in regards to the film speed at which it will be exposed vs the development times according to e.g. the specs of the developer or the massive dev chart.

I have exposed and developed my film (Neopan 400) so far at it's nominal ISO 400 value.

Now, if I decide to rate the film slightly less sensitive (e.g. ISO 200 for better shadow details) what implications does that have on the development times?

Do I still develop the film at ISO 400 (e.g. with ID-11 1:1 at 20 °C for 9.5 mins) or do I have to change the devtime? If I have to change the dev time, will that be then the time for pull processing that one stop?

I just can't get my head around that... Your help is very much appreciated.

Greets from Vienna and great forum btw ;-)

Wolfgang

 

[funkaoshi]

If you want to pull a roll of Neopan 400, you would shoot it like it was a roll of ISO 200 film, and you would develop it like it was a roll of ISO 200 film. At the massive dev chart site, they will have the development times for Neopan 400 shot at ISO 200. You would use those times.

If you shot the film like it was ISO 200, but developed like it was ISO 400, you will end up with a roll overexposed by 1 stop. Make sense?

 

[Bessa-ist-das]

If you want to pull a roll of Neopan 400, you would shoot it like it was a roll of ISO 200 film, and you would develop it like it was a roll of ISO 200 film. At the massive dev chart site, they will have the development times for Neopan 400 shot at ISO 200. You would use those times.

If you shot the film like it was ISO 200, but developed like it was ISO 400, you will end up with a roll overexposed by 1 stop. Make sense?

Understood... that means the answer to my question is expose at let's say 200 and keep the dev times as given for 400.

 

[funkaoshi]

Yes, that's right. (So yeah, you actually had everything right. You don't want to pull process you want to overexpose.) Good luck.

 

[Al Kaplan]

"Expose for the shadows, develop for the highlights". Increasing the development time raises contrast, adding little to your shadow density campared to highlight density. Back in the days when Tri-X ruled the news business pushing film was common. The inrease in contrast and the graininess of the image didn't much matter when printed in the newspaper. Getting an image, any image at all, did matter.

Some developers do give you a tad more film speed than others. Diafine is one, but Diafine gives you only one speed with a given film and no way to control contrast. Ansel Adams explains it best in his book "The Negative". Long out of print is "35mm Negs and Prints" by Y. Ernest Satow who goes into great detail about pushing various films with different developers. A lot of those films are no longer made, such as ISO 800 HPS and ISO 1,000 Agfa Isopan Record.

Improvements in optics means that you can now buy some pretty damned sharp fast lenses compared to what was available fifty years ago.

But to get back to your question, no, you can't really change the speed of a film, but you can get a fairly decent printable negative with a higher ISO set on your meter by playing with development time. Take notes.

 

[David William White]

I'd like to add that the massive dev chart lists common starting points for exposure and development, but you may wish to find your own. There are factors that put you outside of the lab testing enviromnent of Fuji or Kodak. Calibration of the meter, shutter speed inaccuracies, pH of your development water, quality of light during the shoot, whether you shoot indoors under incandescent lamps or outdoors with sunlight, etc. etc.

So what you want to find is your personal film speed and personal development times that yield satisfactory negatives -- as judged by your prints. Many portrait photographers I know increase exposure by 2 stops over their meter as a regular thing, which is equivalent to downrating Neopan 400 to ISO 100, and then adjust development times to yield the best printable negatives.

You may get better negatives by providing more exposure, either with the nominal development times or shortened or lengthened times. Depends what you want, what you like, the light conditions present, what kind of auxilliary light, and all that.

We usually drift around, switch filmstock, switch developers, etc. to try to get the look of that other guy, wondering what boat we missed. Instead, you can, within a few rolls, figure out how to get negatives that work for you.

This means you must bracket exposures, and repeat with different rolls processed for different times, then make contact sheets and examine the results. When you make a contact sheet, you expose till the clear film base is as black as the paper around the film, and no more. Lock in your enlarger height, aperture, and exposure time and make all your contact sheets the same way from now on. It will then be obvious if you are consistently over or underexposing or are consistently not carrying your development to its fullest.

It really only takes a day and a 3 or 4 rolls of film to put you right smack in the ballpark you need to be in for the rest of your life. It will be the most informative day you've ever spent.

Not so really tough, but I'll tell you what: As a test, sometime, just bracket by taking the same shot but two stops overexposed. Develop normally. Chances are, you will find a vast improvement. If not, congratulations and my apologies for wasting your time. If so, then go do the contact sheet experiments and find out what your film speed and development times are.

My best regards,

David

 

[Al Kaplan]

David has some good advice. By contact sheets I'm assuming that he means STANDARD traditional contact sheets, printed on photo paper going through developer and fixer, not scanning and making thumbnails.

 

[David William White]

Just to clarify: yes.

 

[John Bragg]

Try this site for some good tips on finding personal film speed and developing time.

http://www.barrythornton.com/

Lots to browse and it is as in depth as you want it to be.

Regards, John.

 

[Bessa-ist-das]

Great input, thanks!

Great input, thanks!

Thanks to you all for the excellent input and hints. I think I've now got some very good starting points to explore further.

It always seems to me that the more you learn the more there is to learn. 🙂

Thanks for your time!

Cheers
Wolfgang