Does megapixel matter for black and white photography?

January 27, 2005 3:29 PM

If I'm planning on taking only simple black and white, or perhaps sepia, pictures, does the number of megapixels in a camera matter all that much? I'm not planning on being the next Ansel Adams, btw.
posted by icontemplate to media & arts (19 comments total)

Whether you want to shoot b&w or color doesn't really matter - in general, more megapixels = more detail. (Of course, a cheaply made camera with a bad lens will do worse than a good camera with fewer megapixels, up to a point.)

What do you want to do with your shots - just view them onscreen? print them at 5"x7"? or make large prints?
posted by stonerose at 3:46 PM on January 27, 2005

My impression is that black and white is one of the few areas where film really trumps digital. If I was going to do B&W, I'd probably avoid digital all together.
posted by willnot at 3:50 PM on January 27, 2005

It all comes down to how big you want to print it.

Good photo printing would be ~180 to 300 pixels an inch (the more ppi, the more quality).

So if you have a 3.2 megapixel photo, you're looking at a maximum print size of 8x10, with really high quality only going up to 5x6 or so. If you have a 6 megapixel, you could go up to 11x16 on decent quality, or ~8x10 on really high quality. For printing just 4x6s, I would recommend least 3 megapixels.

Also: cropping. If you take a picture of a storefront from across the street, with a lower resolution camera you might not be able to make the text. With 6 megapixels, though, you could crop down to a fifth of the image and have a nice 640x480 close-up for putting on the web.
posted by rafter at 3:50 PM on January 27, 2005

It matters more how large you expect to make your prints (if at all). Whether color or b&w, if you need to make a photo larger than its maximum size out of the camera, you'll essentially be creating pixels that don't exist. The more you have to start off with, the less you'll need to invent, and thus, the more detail you'll preserve.
posted by Hankins at 3:50 PM on January 27, 2005

My impression is that black and white is one of the few areas where film really trumps digital.

How so? Dynamic range?
posted by mr_roboto at 3:53 PM on January 27, 2005

The more gritty and the more dirty the better, as my school of B&W goes. With that in mind, I'd say if you're over about 2 megapixels you'll probably be okay. I usually add noise if it isnt there in the first place, I also jump up the contrast, and twist the curves. I have a lot of fun with my compact when I don't have my 20D with me.

Mainly, go out there and shoot, don't worry so much with what. You can waste a lot of time being a technical expert.
posted by sled at 4:01 PM on January 27, 2005

I'm just shooting 'em for a simple photoblog with no intention to sell the prints like others do. I've got a point and shoot 2MP already, I was just wondering whether or not these cheapo -$20 cameras would work well with just B&W shots.
posted by icontemplate at 4:06 PM on January 27, 2005

There's no difference in requirements for a color vs. b/w shot. There's no special element about b/w that requires more or less MP. If a photo person wanted to get all persnickety, they might delve into a comparison of the dynamic ("brightness") range of various mediums, slide/film/digital. But that seems to be beyond the scope of this discussion.

I would say the most important thing is the process by which you get the color images the camera makes into b/w. Using the desaturate command is simple, and crummy. Using the built in "Custom RGB to greyscale" action prepackaged with photoshop is better. There are other options, I don't do much oh that stuff, but a search should turn up more than you'd like. I'm not sure if they have a b/w tutorial, but I've found this site to have good tutorials.
posted by Jack Karaoke at 5:06 PM on January 27, 2005

Your 2MP should be able to take B&W's just fine.
posted by fenriq at 5:08 PM on January 27, 2005

Why don't you use the 2MP camera and desaturate the images in photo editing software? Heck even picasa will desaturate and do sepia toned images or you could get, The GIMP* is you wanted more control over the digital image. As others have pointed out, colour or black and white it doesn't matter the quality of the lens and amount of data the camera uses to form an image does. I have a cheap .31 megapixel camera someone gave to me and it takes crappy pictures and wouldn't use it for a photoblog.

*was thinking of free programs if you don't want or have photoshop.

My impression is that black and white is one of the few areas where film really trumps digital.

How so? Dynamic range?

I would say the same thing, that film trumps digital, but I am severely biased - I shoot in B&W and have a darkroom.

Type of film is the biggest difference, XP2 isn't the same as Delta for instance and have completely different characteristics and there differences in grain depending on the ISO rating of the film an there are also the characteristics of the paper used. Sled's pointed out you can use "noise" in imaging software but it just isn't the same in my mind.
posted by squeak at 5:14 PM on January 27, 2005

The GIMP* is you

*if you (should use spell check more often.)
posted by squeak at 5:16 PM on January 27, 2005

Digital noise is nowhere as good-looking as film grain, so digital severely limits the way you can take artsy B&W shots. That being said, you can still make purty B&W shots (self-link to my fav B&W shot with a Canon Digital Rebel and tweaked in PS).

It really behooves you, though, to learn up on different methods of creating B&W shots than plain old desaturation. In PS, my preferred method is to go to the Channel Mixer, set it to Monochrome, and then tweak the different levels of red, green, and blue, making sure that the values of all three add up to 100%.
posted by alidarbac at 7:55 PM on January 27, 2005

alidarbac,

Those were gorgeous pictures and thanks for the tips in ps.

I take photo's with a digital camera that does black and white. I use a Pentax Optio MX which is a middle-of-the-road-hybrid-camera. I mainly got it because I had a gift certificate and it looks like a Star Wars Gun! It got bad reviews, but I still like it well enough (for what I need it for). I took many sepia/bw pictures while in mexico a while back. Here is a self link to what I took (many pics are bw but some are color). It's no where NEAR the calibur of alidarbac's stellar and beautiful work (no ps filters were used in mine however if I knew what to do, I'd like to have tried it)
posted by Hands of Manos at 8:16 PM on January 27, 2005

I'll throw my 2 cents in.

Digital only permits 256 shades of grey.

Film? Well, way more than that.
posted by filmgeek at 8:55 PM on January 27, 2005

Digital only permits 256 shades of grey

If you shoot in raw mode, it's usually 12-bit or 4096 levels, converted to 16-bit (64K levels) when you dump to tiff. 256 is a JPEG limitation, not a camera limitation.
posted by ROU_Xenophobe at 9:18 PM on January 27, 2005

The effects of the RGBG color filter on the CCD will be made more visible by conversion to black and white (I'm guessing here), so you might have to halve the resolution in both dimensions to average it out, giving you an effective 1/4 of the number of pixels.
posted by cillit bang at 11:59 PM on January 27, 2005

Just a quick comment, If you're good at framing your photos with the viewfinder then just stick with the lower number of pixels.

If you find yourself wanting to crop down to certain areas of the scene most of the time, or pull out details on smaller object or things in the distance, then you'll want to go for a higher number of pixels.

That's my rule of thumb
posted by ModestyBCatt at 1:30 AM on January 28, 2005

In PS, my preferred method is to go to the Channel Mixer, set it to Monochrome, and then tweak the different levels of red, green, and blue, making sure that the values of all three add up to 100%.

I just wanted to repeat this, because it really is the best way to turn color into B&W. Mainly because it lets you replicate the effect of the color filters (particularly red) that are often used in traditional B&W photography.
posted by smackfu at 6:37 AM on January 28, 2005

Here's an alternate way to convert an RGB or CMYK color image to B&W:

1. change to Lab color mode
   
2. open the channels pane
   
3. delete the "a" and "b" channels
   
4. change mode to grayscale
   

posted by omnidrew at 8:38 AM on January 28, 2005