SLR basics needed..

[Michael_Lambert]

Alright everyone.

As we know im very new to the SLR world with my currently purchased Rebel.. and now im looking around at some lens's and confused..

This is what i have..

18 -55 mm and a 28 -105 mm

What i want to know is this..

1) What do these Numbers mean?
2) What kind of lens would i be looking at for shooting Wildlife, Aquariums and People ..

I assume the 18-55 and the 28-105 are good for people shooting.. But what am i looking interms of a Macro for my aquarium i seen somthing called a 28-90mm Macro.. So when looking for a macro lens am i looking for a smaller first # or or higher 2nd# ?

and for shooting wildlife, We are talking Birds and such at a distance.. so what would be be looking for.. I mean teh 105 mm Lens i have really does not do much interms of Zooming in..

Thanks
Michael.

[angnak]

hmmm... tagging along

[sanblas]

check these forums out, wealth of knowledge
http://www.dpreview.com/forums/

also, you should pick up a basic photography book, would probably help a lot

another great book is 'understanding exposure' helps with the ideas of shutter speed and aperture, and great photo ideas in it too

[Warnberg]

Macro lens means that it will macro focus.. i.e it will focus on things up really close to the end of the lens. As for the numbers 28mm - 55mm, that is how close or far away the image will look to you when taking the picture. In other words if you take a picture of someone with the lens set at 28mm and are standing 10 feet away, they may actually look like they are 20 feet away, then change the lens to 55mm (zoom in) and take a picture from the same spot, now the person may look like they are only 5 feet away but you nor the person moved.

Also remember F stop controlls "Depth of field" that is range that is in focus, the larger the f-stop the more in front and behind of your target will be in focus.

Yes I took a few photography courses in my day.

To answer your question, if you want to take pictures of birds you my want to go to a 70mm - 210mm or larger. The higher the mm the more it will zoom in, however you give up F-Stop's with larger lenses and it will usually need a lot of light to take a good picture or longer exposures... "the ability to STOP something in motion like hummingbirds wings"

Dave

[jcoopergd]

Generaly, yes - the longer the focal length (105mm +) the smaller aperature you have - which is ok, if you shoot outdoors, with plenty of light, but if you want longer focal length, and need lower light situations, you can get a bigger lens - i.e. - sports photographers often shoot in night situations, and are often a-ways from the action - they get great pictures because thier lenses have "more glass" - (look at a sports photographers lenses - they are gigantic..)

I have a 55mm lens, that i use, and it has an aperature of 1.2 - which is quite a large aperature considering the one that came with the rebel only goes to 2.8 i believe.

Something i do for macro shooting is use a dipolar (sp?) - Its an add on lens that screws into the end of your shooting lens, and increases the focal length to a shorter distance (1-3 inches).

I dont know the price of these compared to other lenses, but it might be a cheaper route (although, you still need a good lens to work with, as the dipolar reduces light through the lens)

some more camera info - f-stop (aperature) is directly porportional to shutter speed. i.e. a shot taken at 1/60th shutter speed and 5.6 aperature, will be the same exposure as a picture taken at 1/125 shutter, and 4 aperature. Why then the different locations? Depth of field is related to the acutal aperature. The larger the aperature, the more items in your pic will be in focus - both near and far - Ansel Adams (nature phographer) took most of his pictures at a apertaure of f/64. For more aquarium shooting - you may want everything to be out of focus, except your subject - then, the lower f/stop would be good to shoot -

Now shutter speed affects your motion in your pic - a fast shutter speed will stop motion, wheras a slow shutter speed will blur moving objects. Take a waterfall - a shutter speed of 1000, will stop the droplets of water in a waterfall - whereas a shutter speed of 1/60th will blur the waterfall, and keep everything thats not moving sharp.

So, essentially, you have to pick and choose how you want your pic, and then make the appropriate decisions based off of what you want, and what your light meter lets you have.

hopefully i didnt confuse you - thankfully with the digital age, the learning curve is faster, as you see your outcome immeaditaly - when i learned, it was all about writing down the settings and then developing the film, and then developing the picture, and finally seeing what each setting did to the picture.

hope that helps!
and try this link too -
F-Stop Lesson

j

[Travis]

Sorry I haven't posted here sooner... I actually did the other day and my internet connection went down while I was typing... Then I forgot. Sorry.


Anyway... about a lens and the numbers.

We'll take 2 examples:

Canon EF 28-135 f/3.5-5.6 IS
Canon EF 100mm f/2.8 macro USM

1. It's a Canon
2. lens family (EF fits all modern Canon SLR's, FD are old non-autofocus lenses)
3. focal length minimum- maximum
4. maximum aperture at minimum focal length-max. aperture at max. focal length
5. Image Stabilization

So the 28-135 has a focal length of 28mm when zoomed all the way "out" and 135mm when zoomed all the way "in."
Additionally, at 28mm the lowest f-stop number you can get with this lens is f/3.5. At 135mm, the lowest f-stop you can get is f/5.6.
IS means it has image stabilization technology.

Now, the 100mm macro is not a zoom lens- it has one focal length, that's it- 100mm. It also has one maximum aperture- the lowest f-stop number you can get with it is f/2.8. "Macro" means just that, and "USM" means the autofocus has an ultrasonic motor- those are generally faster and quieter than non-USM lenses.

As far as jcooper's comments:

-It's called a diopter, a good one can be very effective at turning a normal lens into a macro lens.
-They do NOT reduce the amount of light, therefore do not effect shutter speeds.
-The CAN effect image quality. A chain is only as strong as its weakest link, and likewise, a lens is only as good as the piece of glass in front of it.
-I often use, and highly recommend, Canon's 500D diopter for longer lenses. I'm sure the 250D is just as good for shorter focal lengths but have no experience with it.

There is another option to diopters- extension tubes. While these don't effect image quality, they do reduce the amount of light available- so you're trading a slower shutter for closer focusing at the same image quality as the lens.

Hope this helps some...

T