Street Lamp, Night
I'm getting close to picking up the Canon 20D. The only thing now is -
of course - there is a new DREBEL on the way, and probably a
replacement already for the 20D - not to mention that I'd better figure
my taxes first. But I am missing some shots due to the slow
writing of RAW with the 300D and it is pretty wretched at focusing in
low light. Most of these night shots were pre-focused manually.
The extra number of pixels is not a deciding factor; on the other hand,
better low-noise at say 800 ASA is important and quicker focusing - yes.
I was in the optomotrists office to get my contact lens prescription
renewed and during a long eye-exam the optomotrist was asking me how
about digital photography. How many megapixels do you need, he
wanted to know.
What size do you want to print?
He says, oh, say 4 x 6 inches.
I tell him that for 4 x 6 inches, you could get by with 3.x
megapixels. He thought this sounded strange since he had seen a
bunch of prints from a 3 megapixel camera and they didn't look very
How were they printed, I asked.
He wasn't sure.
Well, if you do a little math it goes like this: 240 pixels per inch is fine. That's what I usually print at.
So you have 240 x 6 inches = 1440
And 4 x 240 = 960
And 960 x 1440 = 1,382,400 or 1.4 megapixels.
That would mean printing edge to edge. Anyway, gives you some
idea. So an hour later I was talking with another friend who was
doing some printing and I heard him tell me over the phone that he was
making corrections in the jpg and saving it.
I tell him - wait, wait - don't do that. You lose stuff when you save a jpg.
You do? What do you mean? The jpg is what the camera produces.
Okay, I'm not going into a whole long thing here but some instructions
should be given with these cameras such as: if you are going to make
any corrections, don't make them in the jpg. Save it as tif file,
or some lossless format - and make changes to your heart's
content. Actually, even that's not true, since you do lose data
as you make various adjustments - unless you are using adjustment
layers, but let's try and keep it simple.
LET'S PUT TOGETHER FIVE RULES TO REMEMBER for the digital consumer:
1) Don't get many more megapixels than you are going to use. (I'd
better remember that myself) And sure you can get some more in
case of cropping, but don't go nuts. It only costs you more in
time and storage.
2) If your camera is producing jpg files, COPY the jpg someplace safe as a backup. Then save a copy as a tif file.