Question about B/W film conversion

Hi to all,

I have already photographed the 35mm B/W negatives with a D800 and an old 55mm Nikon macro. So far so good. My questions how to proceed from here. My workflow until now was something like this:

-Import the nefs into LR.
-Send them to PS for cropping, invert, levels, save and...
-Back to LR for further processing.

But I tried something else and now I am in doubt. Before send the files to PS I first adjusted in LR the exposure in the "negative" nefs (I suppose I underexpose when I shoot the negatives) and then I send them to PS. Doing this I noticed better shadows.Am I right?

What are your thoughts and advice?

Thanks!!

I think the problem is probably the way LR processes the images. Its default settings are designed for positive images, not negatives.

I would suggest that you try setting the LR sliders as follows: Exposure -2.0, then increase Whites to say +65 or more (but not so much as to cause clipping of highlights). That will expand the highlights to show much more detail, which is shadow detail when you invert the image.

Your original shots should be exposed so that the film base (where no exposure has occurred, e.g. between frames) is just on the verge of clipping, but does not clip.

Thank you!

I am experimenting right now and I see a lot of potential in manipulating the nef (negative) in LR before invert it in PS (I use the PS just to invert, noting else). The best results I get is by doing some extreme manipulation in LR on the "negative":
Contrast, Shadows, Blacks: +100
Exposure to the right almost to clipping.
Then invert in PS where I get a very underexposed image.
Then in LR for the final editing.
It works beautifully!

I will re-shoot the negs exposing to the right to see if there is an advantage. Thanks for the suggestion.

I assume that LR won’t do inversion and so this is the reason for ‘round tripping’ the image? PS will do all of your required operations, so why not do all the work in PS and cut out the LR stages (or have I missed something)?

Yes LR doesn't do the inversion. I use it for my convenience. For example I can batch crop all the negatives etc.

You can do a simple inversion in LR using the Tone Curve. Click on the grey circle at the top of the Tone Curve panel and then drag the bottom-left point of the curve to the top-left, and the top-right point to the bottom-right.

After that, the image is inverted (white parts are now black and black parts are now white).

I loaded about 300 images at a time into Adobe Camera Raw, selected all, and inverted them as described above.

Don

Thank you!
I know the trick but I don't like it because it reverses the operation of the sliders in the "Basic" panel.

What is your purpose in deliberately underexposing when you shoot the negatives?

Hi!

I did not deliberately underexposed. It was a mistake. Actually I centered the meter but I could have added two stops of positive exposure without clipping anything. So maybe I should reshoot them.

I also prefer to center the meter, and do not use exposure compensation - I get better copy exposures with center-weighted metering vs spot or matrix.

I use ACR to convert, from a dng file on my Leica CL. I use a Beselar slide duplicator with an 80mm f4 Schneider Componon, this lens I was told was calibrated for 1:1 reproduction. I made a setting in ACR that does the inversion and some minor changes. I then have the positive to work with and it does all right.

If you have nothing (no Photoshop, Lightroom etc) and a lot of photos then you could always knock something up in Python (it sort of works for colour images too if you remove the ".convert('L')" ). The script takes all the ".NEF" files in the current directory, inverts them, does a simple contrast adjustment and writes them out as ".TIF" files. It will overwrite any existing files in the current directory so you may want to run this in a scratch space (or add in error checking).

The original NEF file

Converted in PhotoShop

Converted using the Python script below

from PIL import Image, ImageOps
import glob
import rawpy
import re

for i in glob.glob("*.nef"):
    print (f"Converting {i}")
    raw = rawpy.imread(i)
    rgb = raw.postprocess()
    img = Image.fromarray(rgb) 
    ac=ImageOps.autocontrast(ImageOps.invert(img.convert('L')))
    newnm=re.sub("nef$", "tif", re.sub("NEF$", "TIF", i))
    ac.save(newnm)
    print (f"Written {newnm}")

www.negativelabpro.com/guide/blackwhite/