Sunday, January 30, 2011

Vertical Grip? One battery or two?

I recently had a conversation about using battery grips. I have them for my cameras, but don't always use them. I do like them. A lot. I usually find it more comfortable to do vertical images with the grip. But it does add weight. And the camera can look more intimidating. But that isn't what I'm here to write about.

The other part of the discussion was about using two batteries in the grip. Isn't that reason enough to use the grip? I use one battery. No, it isn't for weight. I have two batteries. I figure that if I have one in the camera, when it runs down I can take it out, put in the other one, and put the first one in the charger. That way I can keep working. If I used both batteries in the grip they would run down together, and then I'd have to wait to charge them (one at a time). By using one at a time I can keep going.

Sure, I can purchase another 2 batteries. But, until then, I'll use one at a time. Battery life has been such that I haven't had the overwhelming need to get an extra pair.

Friday, January 28, 2011

More about DPI and the web and printing

This is a followup to Tuesday's post about the relevance of the DPI setting in an image file. In the first part, we were dealing primarily with images on the web. There, the dpi in an image file doesn't matter. If the image is 72 dpi or 300 dpi, it is just going to display on the screen at its pixel dimensions. So if we have an image that is 1800 x 1200 pixels that is what you get on the screen.

Does that make the DPI irrelevant? No.

DPI comes into play when we take our images and place them into a page layout program, like Adobe InDesign. In the page layout program the file that is marked as 72 dpi will come in at a very large size (25" x 16.7") and will look pixelated. The file that is marked as 300 dpi will come in small (4" x 6") and be of a finer quality. Here is an illustration of how they would look when placed into a standard 8.5x11 landscape page in InDesign:

Here the 8.5x11 page is indicated by the red line. Both of the images on the page are the same size (1800x1200 pixels). But you see the large difference in how they look. The 300 dpi image (green outline around it) fits well within the 8.5x11 page, while the 72 dpi image is four times the size of the 8.5x11 page.

The sad part about all this is that many people will find the quality of the 72dpi image acceptable enough to print. That is why setting your image files to 72 dpi on its own is not enough to deter their being swiped from the web. They also need to downsampled to a smaller pixel dimension. For places like Facebook and Flickr I usually downsize to around 600 pixels on the long side, and also add in a watermark.

Even that is not really enough. Here is the same 8.5x11 page in InDesign, but this time the image files are 600x400 pixels (but still 72 and 300 dpi). Again, the red line shows the 8.5x11 page, the yellow line is around the 72 dpi version and the green line indicates th 300 dpi version:

As you can see, even here these 600 pixel wide images are still printable at an acceptable quality for many people. If you printed out of Photoshop without changing anything in the files you would see a similar situation. The 600 pixel wide image at 300 dpi will print at 2 inches wide, while the version marked as 72 dpi will print at 8.3 inches wide.

Based on the above, my personal advice on setting resolution is to set your DPI HIGHER rather than lower if you want to want to make it more difficult for your images to be "borrowed" and printed. If the person borrowing the image doesn't know what they are doing, the higher DPI image will print smaller (at better quality). The lower DPI image will print larger; probably at a quality good enough for the person using your image.

Of course, if the image is just being borrowed to be used on a web site there is little you can do to prevent that other than not share any of your images. If the image can appear on someone else's screen, they can take it. Best advice I can give here is to develop a recognizable style and a watermark (even though that can be cloned cropped out).

To reiterate again, the important numbers when distributing your files are the pixel dimensions, NOT the DPI setting. Keep the dimensions small for proofs, Facebook, Flickr, etc. And find out exactly what your clients need if they are going to be printing your images.

Tuesday, January 25, 2011

What do you do when someone asks for a 300 dpi file?

So you thought that file size was confusing... Wait until you get into a discussion about resolution.

Did you ever get a call or an email from a client asking for a 300 dpi image? What does that mean? Here's how it typically goes, "Hey John, we saw this great image on your web site. We'd like to use it in an article in our magazine. Can you send us a 300 dpi version of it?"

If it is early in the morning and the above question is followed by the typical, "oh, by the way, we have no budget, but we'll send you a copy of the magazine" I will probably just say, "sure," and send them a 300 dpi version that will be just what they asked for, but possibly nothing like what they wanted.

If I'm in a good mood and it looks like they may actually have a budget I will ask them for more information. First question might be what is the usage and the budget. But this isn't a business discussion here, so we'll jump to the technical question... "300 dpi at what print size?" is the big question that needs to be asked.

300 dpi on its own doesn't mean all that much. Here are some sample images. One of them is 300 dpi. Another is 72 dpi. And the other one is 1 dpi. Can you tell the difference?

I didn't think so (or at least not without looking at the filenames).

Basically we have three images that are 400 pixels wide by 400 pixels tall. On the web the resolution setting for them is meaningless. They display one pixel to one pixel. Where the difference comes in is in the printing. What would happen if I sent the 300 dpi version of the above image to the client? It would be just what they asked for (300 dpi), but nothing like they wanted. It would print at about 1.3x1.3 inches, not the full double-page spread that it should be printed at.

Anway, here is what happens if we bring the 72dpi and 300 dpi versions of the image into a page layout application like InDesign. The file tagged at 72 dpi comes in at around 5.5x5.5 inches at 72 dpi. The 300 dpi version comes in, as stated above, at 1.3x1.5 at 300 dpi--much smaller. Can you scale the 300 dpi version up to 5.5x6.5 inches? Sure thing! But then the resolution goes down to 72 dpi. Similarly, we can change the 72dpi version to 300 dpi. But then the print size shrinks. Both files have the same pixel count. The resolution number is telling the layout program how much space to stretch those pixels out over.

Another place this gets confusing is in the images coming straight out of a digital camera. For example, take a file from the Canon 5D mkII that is 5616x3744 pixels. What is the resolution?

The answer is 72 dpi. Or 100 dpi. Or 240 dpi. Or 300 dpi. Or whatever resolution you want it to be. The DPI by itself means nothing until we go to print.

That 5616x3744 pixel image will (approximately) be:
at 72 dpi = 78 x 52 inches
at 240 dpi = 23.4 x 15.5 inches
at 300 dpi = 18.75 x 12.55 inches
That's all from the same file with no changes to it.

Some camera files claim to be 72 dpi. Others claim to be 180 dpi. Others might claim some other resolution. This resolution number is not important. The actual pixel dimensions are the important numbers. You can change the resolution at any time without affecting the file size/quality. In Photoshop, go to Image > Image Size and UNCHECK the RESAMPLE box. Then you can type in whatever resolution you want. The document size will change, but the pixel dimensions will not. In Photoshop Lightroom you get to select the pixel dimensions and dpi when you export your image. While working on your image those numbers don't come into play.

So, when someone asks for a 300 dpi image you need to go back to them and ask them for more information. Is this for web or print? What will the printed size be? Then you can work backwards and come up with the pixel dimensions you need to provide.


Model in the sample photos is Courtnee Fallon (Zita the Aerialist).