• Battery Mix-Up
• Batteries And Memory Cards
• Resolution: How Much Is Enough?
• Resolution Redux
• DVD Alphabet Soup

Battery Mix-Up

My camera uses four AA batteries. I’ve been careful to buy the NiMH batteries in sets of four, but during moves, some get lost and some corrode, so often I have orphan batteries. Can you mix NiMH with different mAh ratings? How about NiCd with different mAh ratings?

For those not familiar with the terminology, the mAh rating of a battery is essentially its capacity or how much energy it can store. With that in mind, you really shouldn’t mix the mAh rating. The idea is that you want all the batteries at the same level/capacity during operation.

Think of your four AA batteries as legs of a heavy oak table, with the tabletop being your camera. If all of the legs of the table have the same load-bearing capability, then your tabletop is sturdy and should last through dinner. If one of the legs is made of wood such as balsa wood, however, which is less capable of handling a heavy load, then you’ll have problems. As more weight is added to the table, the weak legs will start to give. More of the weight of the table will then have to be supported by the other legs or the table will collapse.

Now, back to batteries. If you have three large mAhs grouped with one small mAh, you could have problems. The single, small-capacity cell could be drained and damaged before the others. This is true for NiCds also.

I’m a film photographer making the transition to digital. I have a Kodak film scanner and would like to scan my slides, potentially for large 13x19 prints. At what dpi should I be scanning?

The easy answer would be to give you a specific dpi for a 13x19 print, but I’d rather give you information that will allow you to calculate the dpi for any size print. (Then you won’t have to write back when you want a different size.)

If you’ve been following my comments about optimal dpi for an inkjet printer, you’ll remember that the printers are looking for a file resolution of somewhere between 240 to 300 dpi; 300 dpi is a safe number that always works for printing, but with most inkjets, 240 gives the same results with a slightly larger print size, for all practical purposes. So you’ll need to scan your film so that the image at the final print size will be at 240 to 300 dpi.

If we assume that a 35mm slide/negative measures 1.5-inches wide by 1-inch high, we can start calculating different file sizes, depending on the print size.

To simplify things, we’ll just concern ourselves with one dimension because normally we don’t change the aspect ratio of the photo—no stretching, no squeezing. And since one of our dimensions is one inch, I’ll use that to make it easier.

In your case, you’re looking for a 13-inch-high print from a 1-inch-high original, so you need to scan at 13 times the final resolution or 13 x 300 dpi, which equals 3900 dpi. If you have good results with your printer at 250 dpi, then 13 x 250 dpi would result in a scanning resolution of 3250 dpi. Your scanner won’t have these exact numbers, so you’ll scan at a higher resolution to reach them.

Okay, class, time for a pop quiz! You’re on a train that leaves Philadelphia traveling at 80 mph, and are scanning a slide to produce a print that’s 11x14 at 250 dpi. At what resolution will you have to scan the original? And, for extra credit, where is the train going? The answer can be found at the end of this column.

When I try to print a photo from Adobe Photoshop Elements, I get a window that states, “The image is larger than the paper’s printable area. Some clipping will occur.” When I give the go-ahead, it prints a small magnified section of the photo. What can I do to print a photo straight from the program?

This message comes up two times. One is when people have the resolution and size correct, but they’re trying (inadvertently) to print a horizontal on a vertical page or vice versa. You need to tell the program that the printer is expecting a certain orientation of the image. The message also comes up when there’s a resolution issue with your image as a result of trying to send too big a file to your printer. You need to change the resolution of the image to a printing resolution of 240 to 300 ppi (dpi).

You do this in the Image menu, under Resize>Image Size. In the dialogue box that appears, change the resolution to 240 to 300 dpi and be sure that the “Resample Image” box at the bottom is not checked. If you need a different image size than what’s then indicated by the Width and Height boxes, check Resample and type in a new number in either Width or Height.

Remember, if you end up resampling the image to change your image size, your image quality will change. If you’re enlarging your image, then the resampling will create new pixels by interpolating the spaces between your original pixels. While this interpolation is very sophisticated, it’s still an educated guess as to what the pixels should look like. Image quality will suffer.

One other box to be aware of is Constrain Proportions. Make sure this is checked. If it is, when you type a number into the height box, the width will change by a proportionate number, and vice versa. If Constrain Proportions isn’t checked, when you change the image size in the width or height boxes, you might end up squeezing or expanding the image.

If you need to change just the width or just the height once your image has been resized, simply crop it.

Please explain the difference between DVD-R, DVD+R, DVD-RW and DVD+RW.

DVD came about as manufacturers searched for a higher-capacity CD. The DVD specification was written in 1995, with delivery of actual products starting in 1997, and the format has been growing by leaps and bounds. At first, the discs were only available as a replicated product. In other words, the disc and the data on the disc were manufactured at the same time.

After a time, and following the path of CD-ROMs, the industry developed DVD-R or DVD-recordable. This DVD-R is a blank disc that can be written to only once. It can be read in most DVD players and DVD drive-equipped computers, provided the disc has been laid out and recorded according to the DVD spec. It requires special software to create the proper formatting of the disc. When introduced, the drives required to burn these discs cost over $40,000, but now can be found for under $600!

Continuing on the CD path, manufacturers soon began development of a re-recordable DVD disc similar to the now-common CD-RW or CD-rewriteable. Unfortunately, due to competing standards promoted by different manufacturing standards, there are two different DVD rewriteable standards, DVD-RW and DVD+RW (sometimes referred to as DVD “minus” RW and DVD “plus” RW).

DVD-RW is supported by the original DVD consortium that set the DVD standard, so it’s said to be more compatible with current DVD drives and set-top players.

DVD+RW is supported by several manufacturers and is said to have some advantages over DVD-RW. One of those is the ability to erase a disc quickly. The DVD+RW people also have come out with a version of the write-once technology and have named it DVD+R.

This battle of standards is ongoing (reminding me of the early days of the VHS vs. Betamax war), so we’ll have to wait to see who comes out on top.

To learn more about the rewriteable discs, check out www.dvdforum.org or www.dvdrw.com.

Pop Quiz Answer: It’s 2750 dpi. And the train is going to Boston since every word-problem train goes from Phila-delphia to Boston.