Converting BW to...um...BW

R

remegius

Well-known
Local time
5:21 AM
Joined
Feb 17, 2008
Messages
293
I'm not sure just what is going on here. I started shooting BW400CN a few days ago, and having it processed with CD at Costco. I noticed when loading the files in Photoshop that they are all RGB files. After doing a little tweaking in PS I printed a couple of files on my 9180 and things just didn't look right. The prints had a bit of a blue color cast, and when I looked carefully at the image on the monitor I could see it there too. On a lark I converted one of the files to grayscale and...voila, I got...grayscale. I'm a little perplexed by all of this. Yes, BW400CN is a C41 film, but even though it has an orange mask like its color cousins, it's still a black and white film. Why should I have to convert the scans that I am getting (good ones, BTW) from Costco to grayscale, when the film itself is black and white to begin with. I'm sure that the answer to all of this is embarrassingly simple but, what the heck, I'm not thin-skinned.

Cheers...

Rem
 
I use the BW400CN much too. And I always tweak them in "real" BW too, cause the Photolab is treating the BW like any other Colorfilm and is pulling it through its C41- Soup. The results are often a little colored, like the film is not really irrigated enough. Once I chose a really BW- Development at the same Lab, and the Film was developed correctly. No Postprocessing needed, but it cost me a lot of bucks. So I postprocess my Scans myself and save the money for the Lab and take the cheap C41.

So, don't worry
 
There may be a couple of reasons. The first is that the developing lab is lazy and scans everything as color to save themselves the bother of having to think. The second is that by saving them as color not grayscale files it may give you more options for how you finalise your processing. (Yes I think you need to post process even from scans). So perhaps its not such a bad thing as it does mean you can tweak the images more than you otherwise might be able to. (e.g. if you wished to apply a color overlay effect you need them in color mode.) BTW if you think things are bad when you get scans from BW400CN boy did I ever get some doozies when I received prints in my days before digital. Unless I found a lab that would print on black and white paper or which really trained its staff, I would get blue, sepia, orange - all kinds of casts depending on how the lab set up (or did not set up) its color channels. Most did not know how to do so with this emulsion and that is why I got such dreadful results.
 
I believe this was discussed a while back. Seeing how BW400CN is a c-41 film and only colour film is processed with c-41 then that makes it a type of colour film so to speak. I could be wrong but I don't think it can be processed correctly using b/w chemicals. Would that not be cross processing? I used BW400CN for a while until I realized that I could scan and convert the cheaper colour films like Kodak 200 and 400 to b/w and get the same results.

Michael
 
My experience is that a minilab operator who knows what he or she is doing will produce neutral prints and neutral scans (always, in my experience, 8-bit RGB JPEGs). Many will produce "more-or-less" neutral scans, but often prints with rather horrid colour casts (I've mostly seen green and magenta). That's one of the reasons I've moved away from C-41 B&W. When I do use it I have the lab develop the film, not cut the negatives, and not bother with scanning or prints. I do that for myself with much better results.

My primary use for C-41 B&W is when I know I'll need to process things quickly and want to be able to scan using Digital ICE. Otherwise I develop "real" B&W myself.

...Mike
 
Dear Rem,

Yup, they're scanning as colour. Why wouldn't they? At their prices they're not a custom lab. Everything goes through the same scanner.

Kodak chromogenics usually wet print better than Ilford on colour paper, and are finer grained, but XP2 Super is sharper and (we find) easier to wet-print on B+W paper. We also prefer Ilford's tonality.

Cheers

R.
 
I'm just in the process of starting to print digital scans from film negs too. One thing I've found in the past is that my local (Fuji) colour lab usually prints B&W with a slight blue cast. Something to do with the colour paper and the chemicals I think. I don't let them print any more but just get the scans on CD (I ask for TIFF not JPEG) which they don't like doing and charge extra but for my part I don't like the amount of compression they apply to the JPEG files.
Then I work them over in Photoshop Elements 6. Now, the TIFF files are quite large compared to the JPEGs, but both come as RGB scans. Previously I've immediately converted the file to Grayscale but I'm beginning to understand that this prevents some options I could use if I kept the RGB channels but desaturated them.
Can anyone elaborate on that?
 
Leigh Youdale said:
I'm just in the process of starting to print digital scans from film negs too. One thing I've found in the past is that my local (Fuji) colour lab usually prints B&W with a slight blue cast. Something to do with the colour paper and the chemicals I think.
Click to expand...

They could equally well print with any other cast, or even (with enough effort) neutral. On my suggestion, one lab I used always went for warm, to the point of sepia.

Something that's worth knowing is that there are no neutral black (and hence grey) chromogenic dyes. These are something of a Holy Grail. Kodak apparently developed one once, but I don't think they've ever used it. Or maybe it didn't work as well as they'd hoped.

Cheers,

R.
 
Roger Hicks said:
Yup, they're scanning as colour. Why wouldn't they? At their prices they're not a custom lab. Everything goes through the same scanner.
Click to expand...

OK...I see what is going on here. I only have Costco develop and scan. No cuts, and no prints. And once I convert to grayscale, no problem. BTW, the scans I am getting from my local Costco are 3087x2048, and are very good. I made an 11x14 print last night on my 9180 and was quite pleased with the result.

Cheers...

Rem
 
Some say that scanning black and white negs into RGB colorspace will give greater tonality.
I suggest listening to Stephen Shaub's audio post at Figital revolution, HERE.
It's very interesting.
 
I'm with Roger on this one and have found the same. You can convert your b&w RGB scans to greyscale if you want, but recently I have found that some applications (like the offset printing process offered at blurb.com) prefer an RGB file, even if the output is supposed to be monochrome. I have many scanned b&w chromogenic digital negs for which I have discarded the color information. For many of them I want it back and my only option is to re-scan. Moral: easier to keep as much information as you can in your "digital negative" -- you can always discard RGB color information in a working copy, but once you have deleted it that information is either gone or will be a pain to restore. With the astounding drop in the price of storage media over time, you are not likely to be punished for saving larger digital negative files now.

Ben Marks
 
I could be wrong but I don't think it can be processed correctly using b/w chemicals.
Click to expand...
It can be processed with B&W chemicals, but that would only produce the initial silver image.

To get the final chromogenic dye image (and bleach the original silver image), you need the full C-41 process.
 
Benjamin Marks said:
I'm with Roger on this one and have found the same. You can convert your b&w RGB scans to greyscale if you want, but recently I have found that some applications (like the offset printing process offered at blurb.com) prefer an RGB file, even if the output is supposed to be monochrome. I have many scanned b&w chromogenic digital negs for which I have discarded the color information. For many of them I want it back and my only option is to re-scan. Moral: easier to keep as much information as you can in your "digital negative" -- you can always discard RGB color information in a working copy, but once you have deleted it that information is either gone or will be a pain to restore. With the astounding drop in the price of storage media over time, you are not likely to be punished for saving larger digital negative files now.

Ben Marks
Click to expand...

I think that there is some confusion here. There is no color information with BW400CN. It's a black and white film. However, Costco processes as RGB, and this leads to files that, at least on my computer, have a color cast. Once I convert the files in question to grayscale all is well. Today I picked up some 120 BW400CN that I had developed at my local camera shop (Costco doesn't do 120) and, guess what, this stuff was developed correctly, which is to say it was developed as grayscale, not RGB, thus saving me the initial step of having to do a conversion.

Cheers...

Rem
 
IIRC, Kodak BW400CN has an amber film base mask, which is intended for printing on color process machines. This, I believe, leads to color casts when scanning that need correction. On the other hand, Ilford XP2 Super has a clear film base, which makes it suitable for printing in a traditional black & white wet darkroom. This makes for a more neutral scan.

::Ari
 
I shoot XP2 and have it developed at Walmart. May not produce super-high quality pictures, but they are good enough that nobody on the internet notices. But, I do have the same problem you do...

I always go into PhotoShop and auto level, auto contrast, then hit the "Black & White" effect to actually make them black and white. Otherwise, the XP2 processed from Walmart is purple-ish and grey, not black and white :)
 
ElectroWNED said:
I always go into PhotoShop and auto level, auto contrast, then hit the "Black & White" effect to actually make them black and white.
Click to expand...

"hitting the 'Black & White effect' " does not make them grayscale, they ares still RGB. You need to convert in Image/Mode if you want real grayscale.
 
you have to tell the operator to hit the b&w button. then all the data will be converted to b&w without a cast. yes, it will be saved as a RGB jpeg, but what do you care? in compression you don't even get much difference in file size.
 
ElectroWNED said:
I shoot XP2 and have it developed at Walmart. May not produce super-high quality pictures, but they are good enough that nobody on the internet notices. But, I do have the same problem you do...

I always go into PhotoShop and auto level, auto contrast, then hit the "Black & White" effect to actually make them black and white. Otherwise, the XP2 processed from Walmart is purple-ish and grey, not black and white :)
Click to expand...

I've been using XP2 exclusively for a while now. When I get the uncut negs (+CD of Jpegs) from the local camera shop, I scan (Nikon 4000ED), in RGB mode, the frames I want to print and then open them in PS/CS3. I then convert the RGB file to Lab, discard the a & b channels and change the mode to Grayscale. Seems to work quite well.

Harry
 
Most color labs do not know how to process this stuff - or to put it more precisely cannot be stuffed doing it right. As I understand it, every film has to have the color bias set in the processing machine to account for the films own bias towards producing a color cast. And they are all different. And while its nominally a black and white film its being processed like a color film. So if the machine's color channels are not set correctly bingo you get a color cast. Sepia is common but when they really screw up you can even get pink or blue! If you are printing to a print you should ask if they can print on black and white stock - this avoids the problem. But few labs will do this for you. If not and you are processing to digital as it sounds like then you have to reconcile to doing what you have done. For me, I now prefer to shoot color then post process to black and white. Saves the hassle.
 
Pablito said:
"hitting the 'Black & White effect' " does not make them grayscale, they ares still RGB. You need to convert in Image/Mode if you want real grayscale.
Click to expand...

doesn't really matter much for my purposes. I'm not printing images that I have developed/scanned at Walmart. Plus, they look exactly the same.
 
You must log in or register to reply here.
Back
Top Bottom