I assume that you have used binoculars, and are familiar with the magnification they provide? When you are trying to photograph a subject that is distant, and you want it to fill more of the viewfinder, then you need a longer focal length lens..
Similarly, if you are trying to fit a subject into the viewfinder, but cannot fit it all in and cannot walk further back, then you need a shorter focal length..
When it comes to photographing subjects very close, so that small detail is visible, you need a lens with "macro" capability. You will find specialized macro lenses at a variety of focal lengths (50mm, 100mm) and also zooms with macro capability. Typically dedicated macro lenses will focus closer than zooms with macro capability..
Kevin..
Http://www.tamroneurope.com/flc.htm.
Click on the 18-250 lens, on the right side..
Focal length is basically field of view,, What gets seen. Put your hands right next to yoru eyes. Like Blinders on a buggy racing horse. Hold hands aprt, wide view, 18mm..
Hold hadns close to gether, only speerated by a few centimeters, Long view, 250mm..
For macro work, you can get a macro lens, All Macros are goign to be pretty darn good, regardless of who built it, Tamron Canon, nikon Sigma. Yes, oen may be slightly preferable to another but there are not goign to be any slouches in teh macro lens line up.bad thing is, they are not cheap..
Easy way to go macro is with extension tubes and a fixed 50mm lens. even a that zoom you already have, though a fixed length is easier to get focus set..
Most photogs get by with actually relatively little equipment. a 17-40mm or some such for those really wide Panoramic vista's of teh Grand Canyon or wide open prairie's..
A 28-70 or 8-mm for most indoor work or when you need to get a group of people..
70-200 or 300mm for getting close to a subjkect which you may not be able to actually get physically close too..
Like a Running back for your local high school or a raging buffalo who wants to stomp your guts out..
Macro lens lengths are basically set up on the same line..
17- 25mm for use qith a bellows system. Accoridan type of baffling which really gets the glass far away from teh camera and gives greater than 1:1 magnification. Ex would be when shooting pics of motherboard circuitry..
50mm for normal macro work, like plants, flowers, inanimate objects.100mm or 180mm for things you cannot really get close too:poisionous snakes, bee's or other fast moving skittish subjects..
Sorry for typho's lights are dimmed and I never learned how to type.Dave PattersonMidwestshutterbug.com'When the light and composition are strong, nobodynotices things like resolution or pincushion distortion'Gary Friedman..
Hi Gary,.
Thanks for the good Tamron site, it's neat the way you can compare like that. Can you tell me what lens I should pick to compare the zoom range of the Canon SD850 (35-140mm) versus the Panasonic TZ3 (28-280mm)? I want to get an idea using sample pics how much longer the zoom of the Panasonic would be..
Thanks!..
On the Tamron site you can use the arrows to change the tele end of the zoom range and it will highlight which lenses come close. Based on the example they provide comparing a 300mm and a 135mm is the closest you can come to the comparison you're looking for..
There is a significant difference between 140mm and 280mm; double..
Kevin..
Midwestshutterbug wrote:.
Focal length is basically field of view..
Doh! That's not true. Focal length has an *impact* on field of view, a.k.a. angle of view but is not the only variable affecting it, and is certainly not synonymous with it. Field of view is defined by the focal length of the lens and the size of the sensor (or film frame). That's why, say, a 35mm Nikkor on a film body (e.g. on an F6) is going to have a relatively wide angle of view but will not be as wide when mounted on a digital body (e.g. the D2x) whose sensor is smaller than a film frame...
Missy123 wrote:.
I read the section on focal length here, but I am still a littleconfused about the lens size that can be purchased for SLR's..
Get your head around the following (sorry if you know this already):.
1. During the days of 35mm film, cameras pretty much all had the same field of view for a particular focal length. (If you stand in one place and zoom)..
2. In digital days, cameras have different crop factors which affect the effective focal length. That is why you will see the actual focal length, and sometimes the effective focal length using that camera..
3. Close ups - you may require a macro lens which can be 60mm to 120mm and no doubt many other lengths, or you may be happy with a regular lens that can focus quite close. (Lens specs normally list the minimum focus distance)..
So for example a canon 400d has a crop factor of 1.6. That means a 28-80mm lens will effectively perform like a 45-128mm in terms of field of view. (you multiply the numbers).
Using the effective focal length (and not the actual one marked on the lens), and bearing in mind this is a rough guide!.
10-24mm - extreme wide angle. ie it takes in a very wide landscape view. Normally with a bit of distortion..
24-40mm wide angle (wider than the human eye would see as a normal view.), Distortion starts to disappear completely...
Approx 50mm - considered 'normal' ie approx what the human eye percieves as normal..
60-90 - short telephoto - effectively getting closer to distant objects.
100-200 mid telephoto.
200 plus long telephoto - you can see a long way away..
So if you have a canon 400d and a 28-90mm lens you are going from normal to mid telephoto. If you want to take sweeping landscapes, big buildings from close up etc then you may need wider..
If you want to take pics of wildlife or outdoor sports, you will be too short..
The BEST way to make sense of it is to play with a camera (in a shop, or a friends) so you can see what the EFFECTIVE focal length looks like through the viewfinder...
Beginners Forum - -I was trying to Keep It Simple..
Dave PattersonMidwestshutterbug.com'When the light and composition are strong, nobodynotices things like resolution or pincushion distortion'Gary Friedman..