Digital photo printing + TIFF file question.

Factual Questions
1

I recently purchased a new digital camera and have a couple of questions about the various quality settings it offers. There is a chart in the manual (which I don’t have with me at this time so can’t look up exact numbers) that lists how many photos can be stored at each of the different quality levels. There are 4 different dimensions ranging from 640480 to around 30002000 and three different quality settings for each resolution, however, for the highest resolution it lists a fourth quality option called “TIFF”. The number of photos that can be stored on the 1GB card in “TIFF mode” is in single figures (IIRC) compared to about 80 pictures in the highest of the other three quality settings. So, first question, what is so great about TIFF (Tagged Image File Format) that causes pictures taken using that setting to use up so much more space than the next highest?

Question two relates to printing out digital photos at a local shop (not using a home printer). If I were to print out all my photos in 6x4 inch format which resolution would be the best to use? I assume that the printers the shop uses have a maximum dpi for giving a maximum number of dots on a 6x4 inch printout, and therefore it may be a waste of storage space on the camera to take pictures at very high resolution if it is going to effectively be compressed during the printing process. So, what sort of resolution is going to offer me the greatest number of pictures stored without loss of quality on a printed photo?

2

Part A:

TIFF is a lossless format, while JPEG is a lossy format. When your camera creates a JPEG it uses a compression formula to reduce the amount of information in the file. On high quality JPEG settings, the reduction in actual image quality is sometimes so small as to be unnoticeable, but on lower quality settings you can often see artifacts, which are small areas that appear blurry or unsharp as a result of the removal of information during the compression process.

I’d be very surprised if you could only fit a single-digit number of TIFFs on a 1 gig memory card. The size of TIFF images on my 5 megapixel camera is about 10-12 Mb, so i could fit 80-100 on a 1 gig card.

The fact that your highest resolution setting is 3000x2000 suggests to me that you have a digital SLR, perhaps a Nikon D50 or something similar. Is this the case? If so, then i would strongly recommend shooting in RAW rather than in TIFF. RAW mode records exactly what the sensor sees, with (AFAIK) no in-camera processing. This gives you a lossless, high-quality image that, with some tweaking in Photoshop, will give the best quality results.

But, for 99% of shooting situations, you will probably get perfectly good results shooting in the highest-quality JPEG mode. Unless you’re planning on making very large blow-ups of your pictures, JPEG mode should give exxcellent results. Also, getting the best out of RAW images often takes more experience with digital imaging software such as Photoshop, whereas the in-camera processing that takes place in JPEG mode often makes post-processing quicker and easier. Also, you can get more pictures on a card with JPEG than with RAW.

Part B

I think it’s always best to shoot in the highest resolution possible; in your case, 3000x2000. This gives you more pixels (in the printing process, dots) per inch, and allows for better quality from the printing process. For example, if you take pictures at 640x480, and want to make a 6x4 inch print, you’re only getting about 100 pixels per inch, which isn’t enough for a good quality print. You want at least 200, and preferably 300.

I always shoot at the highest possible resolution. Not only does this give you the best possible quality for prints, but it also gives you some leeway to crop the picture later and still have sufficient resolution for a decent print.

3

I am slightly confused by the specifications of printers on the internet. With reference to the dpi of the printers they give two values, for example:

Max H-Resolution Colour: 2400 dpi 
Max V-Resolution Colour: 1200 dpi

Does this mean that in a square inch of the printout there are 2400 pixels horizontally and 1200 pixels vertically (i.e. 2400*1200 = 2880000 pixels in the square inch)?

I figure that if I know the dpi of the printer being used I can figure out the dots in a 6x4 inch photograph and so make an educated guess at which resolution most closely matches the end product. Though having said this I take on board your point about cropped images.