Digital SLR Photography

Last update: 1/22/05

The following are my notes about digital photography, some are general, other are specific to the Canon Digital Rebel (300d).  If you are going to buy a dSLR, be ready to spend some money.  SLR's are alot of fun, but they are expensive. But the payoff is huge amounts of creativity.  With a SLR you can do almost anything.  Remember, these comments are about dSLRs, not P&S (Point and Shoot) cameras, and almost entirely about the Canon equipment that I have.

Ok, first, some definitions:

Ok, how much does all of this cost (in 2004 dollars)?  I have a Canon Digital Rebel that I bought with the 18-55mm kit lens.  This is what I have bought so far, in the order that I bought them:

Canon Digital Rebel w/18-55mm EF-S lens:      $999.50USD
Canon EF 75-300 f/4-5.6 EF III USM          :      $170.00 (used)
Canon 550EX flash                                         :      $350.00
Canon 28-135/3.5 - 5.6 EF IS USM              :      $420.00
Canon 50/1.8 EF prime                                   :       $80.00  (best value of all Canon lenses)
Canon 420EX flash                                         :      $199.00    (wireless slave to my 550EX)
Canon 10-22mm/3.5 - 4.5 EF-S                   :      $800.00
TOTAL:                                                         :     $3018.50 (not including shipping and taxes; prices in 2004 USD)

"Short", or wide angle lenses are surprisingly expensive.  It seems that they are very hard to make.  This really stinks for digital SLRs because of the "multiplication factor".  My 10-22mm lenses acts like a 16-35mm lenses (in terms of a 35mm film camera).   There is no way to get less than 10mm (16mm)!  Interestingly, my 10-22mm lens is as big as my 28-135mm lens, focal length has nothing to do with len's size!

Note: EF-S (note the "-S") lens can only be used on the the Canon 300D and 20D cameras because their back element goes further into the camera than other EF lenses.  However, any EF lenses will work on any Canon SLR camera (made in the last 20 years, FD lenses will work (sort of) with an adapter and in manual mode).

Aperture (Using my 50/1.8 lens which has the largest range of all of my lenses):
Biggest opening
Most light
Smallest DOF
Fastest shutter
f/1.8 f/2.0 f/2.2 f/2.5 f/2.8 f/3.2 f/3.5 f/4.0 f/4.5 f/5.0 f/5.6 f/6.3 f/7.1 f/8.0 f/9.0 f/10 f/11 f/13 f/14 f/16 f/18 f/20 f/22
Smallest opening
Least light
Greatest DOF
Slowest shutter

Smaller aperture means greater depth of view (the things in the background are in focus).  Portraits are usually taken using a shallow DOV, which means a larger aperture (low f number).  Landscape pictures are usually taken with a large DOV which means a smaller aperture (high f number).  Isn't it crazy how the f numbers are the reverse of what you would think they should be, I guess that it's because they are really a fraction, ie, 1/f number.

Note: For most lenses, around f/8 is the "sweet" spot.  Most lenses work best (best color, sharpest picture, good DOF, etc.) at f/8.  Also, DOF is a big issue (at least for me).  At low (f/1.8 - f/8) big apertures, if I use my 50mm lens at f/1.8 it seems like everything is out of focus except for my subject's face (this could be good or bad depending on what you want).  Of course, at f/1.8 I might not have to use a flash or be able to use a faster shutter, so everything is a trade off and it depends on what you want.


Built in flash:  Never use the built in flash unless you have no other choice.  When using anything other than the 18-55mm or 50mm (or physically shorter) lenses you will get weird shadows.  This is because the lens will block part of the flash and you will get a weird shadow at the bottom of your picture (it's the lens blocking the flash!).  For bigger (physically) lenses, you have to use an external flash.

A picture of my cat, Duffy, using the built in flash and a lens that was too big (my 10-22mm).  See the horrible shadow?!

Flash Guide Number (GN):  The amount of light that a flash can deliver.   Technically, it's f/stop x distance to subject (usually at ISO 100).  To use a flash in manual mode, f/stop =  GN divided by the number of feet to the subject.   For Canon flashes, the GN is the model number divided by 10 (yes, crazy).  So a 550EX has a GN of 55.  However, this is sort of misleading because the 550EX is a zoom flash (it has a lens in it) and the GN is calculated at it's maximum zoom (which gives the best GN number (by the way, for the 550 the GN is calculated at zoom of 105mm)).  A neat thing about "smart" (E-TTL, Electronic  - Thru The Lens) flashes like the 550EX is that it has variable flash power output.  What this means (in theory) is that I can put my camera in manual mode (or aperture priority or speed priority) and the flash will calculate the correct amount of flash/light (by using a pre-flash and metering the light thru the lens).  E-TTL usually works pretty good, and if it doesn't, you can adjust your exposure by using exposure compensation (EV) or FEC (Flash Exposure Compensation) or other tricks.


Canon's best lenses are called "L" (Luxury) lenses.  They are the PRO quality lenses and cost alot, I don't have any of them.  You can tell if a Canon lenses is a "L" because it's name will have a "L" in it (i.e. EF 17-40 mm f/4L).  "L" lenses are also usually white or have a red ring painted on them in the case of a black lens (like the 17-40)(the white lens is a 70-200mm).
The really weird thing about lenses is the fact that their size doesn't really tell you what their focal length is.  Here is my 50mm and 10-22mm (the 10-22mm is much bigger):
The scale for the 50mm, 10-22mm, and 17-40mm is (closely) correct (the white 70-200 is a smaller size/scale).  Strangely, I think that my 10-22mm might be alittle bigger than the 17-40mm (physically).  And alot bigger than my 50mm.

Fast lens: A "fast" lens is one that lets in alot of light, which means that you can use a faster shutter for the same amount of light verses a "slow" lens (or, still get a picture without a flash in low light).  Fast lenses are anything less than f/3, slow lenses are anything over f/5.  My Canon 50mm/f1.8 is a "fast" lens, my 75-300 f/4-5.6 is alittle "slow" (but not bad).  I've seen some telephoto lenses that where f/8 or f/11  (that's really  slow!  You had better be in full sun light to use it!)  Of course, fast lenses are more expensive than slow lenses (sometimes as much as 3X more expensive, compare the Canon 50mm/f1.4 to the Canon 50mm/f1.8! ($294 vs $80 as of 1/22/05)).

Why isn't there a 10-300mm lens?  I don't know, I'm not an optical engineer, but I would guess that it's just not a good idea.  It could probably be done, but the picture quality would be horrible.  Once again, a tool made for a specific purpose is always better than a general purpose tool (also relates to the prime vs zoom lens argument).   In general terms, the focal length steps seem to be (plus or minus 10%) 10-30mm, 30-70mm,  70-300mm, and 300mm  or greater.

Note: For those people with a P&S camera or video camera with 300X zoom, it's a electronic zoom (really cropping) and the quality at 300X zoom is almost ZERO!  I know, I have a Sony TVR-340 camcorder with 300X zoom, it sucks at 300X zoom (I've locked out electronic zoom on my TVR-340).  Never go past the OPTICAL zoom on any camera!  (You can always "zoom" in on your pictures or video using a computer later using software, the quality will be the same (or maybe better)).

To be continued...

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