Mary Harboe
07.01.08

Digital Cameras and the Computer

Digital Cameras:

Digital cameras do not use film to capture images. Instead images are saved on an internal storage media or memory card. These memory cards come in capacities measured in bytes. They can range from 32 megabytes up to 6 or 8 gigabytes. I’m sure we will see even larger sizes soon.  A new digital camera will usually come with a small memory card, possibly only 32 Mgbs.  Therefore one must buy a memory card if you want to be able to take more than 7 or 8 photos at a time.  Memory cards are expensive. Buying the largest capacity card you can afford as the price per Mgb will drop significantly compared to the lower capacity cards is more economical but then if something happens to that one card, lost or damaged, you have lost everything. If you have two or three cards each at less capacity and something happens to one you still have the photos that are on the other cards. Do shop around as prices are competitive.

Do not leave memory cards in direct sunlight and keep them in their protective cases when not in the camera and away from magnetic fields.  Never touch the electrical contacts to avoid failure or loss of image data.

There are different types of cards.  The one you use depends on your camera.  And as in every aspect of the digital world there are advances constantly being made to improve size, capacity and quality.  We have Compact Flash, xD-Picturecard (Olympus), Smart Media, Sony Memory Stick and more. The two used most in digital cameras are Compact Flash and Smart Media. We can put up on the web page a chart to give a comparison of the cards.
 

Connectivity:

Connectivity is how a digital camera is connected to your PC or printer for image transfer. 

The most common way is by using a USB 2.0 connection.  After installing the software which comes on a CD with the camera, (the first step to take with a new digital camera), the computer will be able to recognise your camera as a separate drive.  You then can upload the images as files on your PC.  To do this we use a USB cable which is also provided with your camera.
 
Another way to transfer the images is with the use of a card reader. A card reader is a piece of hardware you attach to your computer via a USB cable.  You place the memory card from your camera directly into the reader.  It will recognise it and then you can transfer the images.   The newer printers now come with integrated card readers.  This means you can print directly from the memory card without uploading the images to the computer.

Digital Images:

Digital images are composed of pixels.  If you enlarge a digital photo beyond its best size you will actually see the dots.  These are called pixels per inch (ppi). This is also called the display resolution of the image.

Dpi (dots per inch) is not the resolution of images it is the printer’s resolution. The number of ink dots a printer uses to print text or images.  The more dots per inch the more detail your image will show.

A required image resolution (ppi) can be calculated by multiplying print size by print resolution.  An 8 by 10 image at 300dpi requires a resolution of 2400 x 3000 ppi. or a 7 Mg pixel camera.

Graphic File Types:

All digital images are bitmaps.  All bitmaps are composed of pixels. It is the number of pixels that determine the size at which and image can be printed or displayed.

Because saved bitmap files are quite large in size other graphic formats are used to store images in compressed form. The most well known are JPEG and TIFF. 

JPEG are compressed images and the best to send by email.  The negative aspect of a JPEG is that each time you save a JPEG you are losing quality.  Not a lot but some. So it is best to do all the editing of the image before you save it as a JPEG.

Mega Pixels;

When we buy a digital camera the one spec we always see are mega pixels of the camera.  We tend to think the more mega pixels the better.  True enough.  But if you do not want to print photos larger than an 6”x 4” prints (15 cm x 10 cm)   than 2 to 3 mega pixels are sufficient.  What you can not do is crop the photo and then expect to be able to enlarge the cropped part of the photo. Then you will see the pixels.  So in this way the higher the mega pixels of the camera the more ability you have to work and edit your photos because the initial photo will be of a higher resolution. Of course the higher the resolution of a photo the less photos on the card.

Mg. Pixels needed in camera to print:
 6" X 4" = 2 to 3 Mg pixels;  8" x 10" = 7 Mg pixels;  A4 = 8 Mg pixels;  A3 = 10 Mg pixels;  A2 = 12 Mg pixels .

 

Printing and Printing Services

Photo Paper :  over 40 different types of photo paper available from different manufacturers, ranging from standard glossy to photo quality, canvas effect, some printers even let you use postcard size paper and t shirt transfers. Photo paper has adequate thickness and a glossy surface which holds the ink.

On normal ink jet paper the ink tends to bleed into the rough surface areas and the image becomes flat and muddy and colours are not vivid. Use normal paper only for making test prints.  If you are going to use your printer ink, which is also expensive, then you should also use good quality photo paper. 

If you have to print quite a few photos you can also use a printing service. There are a number here on the coast one in Myramar shopping centre in Fuengirola. Just bring in either the photos on a CD or your chip from your camera or put the photos on your flash drive. You can also send the photos to a digital print service on line via the internet. They will print them and mail them on to you. This enables you to edit your photos first then send them to be printed, so you get exactly what you want.  This is definitely cheaper than printing yourself.  A good site for this is: www. photobox.com

If you don’t want to print the photos you can still let your family see the Christmas snaps by uploading them to a web site. There are many sites now where you register and receive your personal area on the site, password protected, so only the people you want to share your photos can enter and see your digital gallery.  Picasa has this service built into the program.  And photobox.com offers free storage space with an emailing facility; storage can be private or public.

This year the electronic picture frame was one of the most popular gifts.  Their built in memory can store several images to be shown one after the other at predetermined intervals, the capacity dependent on the size of the memory card used. They come with easy to use software.

Back up your Irreplaceable Photos:

We know that everything important on your computer should be backed up either on an external hard drive, CDs, DVDs or flash drives and this of course applies to your photos.  A tip though is not to use rewritable discs as their life span is much shorter due to the dye used in the manufacturing process.  Make two copies of each CD or DVD and store them in different places out of sunlight and heat.  There is a debate as to how long they will last from 5 to 100 years!!  A great difference!

Television Screen: 

There are cables to connect your digital camera  to your Televison to view your photos.  You can produce a digital slide show complete with music and text to be played in synch with the photo presentation.  Viewing time per photo can be predetermined.    My colleague is conducting a comprehensive photography course starting on the 14th of January at St Andrews Church in Los Boliches. It will include all areas of digital photography including cloning; layers, cropping etc. please call me for more info. 637 091 130.

Batteries:

Digital cameras need a lot of electrical power to perform their multiple functions. You can use AA alkaline batteries but the best batteries to use of course are rechargeable batteries.  There are Nickel Cadmium (NiCd) and Nikel Metal Hydride (NiMH) rechargeable batteries. You want to use Nickel Metal Hydride which are the most powerful.  They will last through hundreds of recharges.  They do lose their charge slowly if not in use though. so always have a spare set recharging.

If your camera will not be used for a long time remove alkaline batteries as they may leak caustic chemicals and ruin your camera.  Rechargeable Lithium and NiMH batteries do not leak and can safely be left in place.  Recharge NiMH batteries about once month during long periods of non-use. They say the NiCds should be fully discharged before charging as they remember their last state of charge and will hold less power after time.  Others argue this memory effect is negligible.

Never mix rechargeable with alkaline.  It is better to fully charge batteries and then store them in a cold place like the refrigerator but in a sealed bag to protect from moisture. They will hold their charge for quite a few months but let them adjust to room temperature first before use. Over charging batteries is the most common cause of premature battery failure.  Most chargers are not smart chargers. They monitor temperature, time and current to ensure batteries are not overcharged.
The one feature on a digicam that drains the most battery power is the LCD. This feature, which lets you preview images or set different camera functions, accounts for most of the power used. Switching the LCD screen off while taking pictures will let you capture up to 5 times more images on a single charge. Only use it for reviewing images later to extend battery life.