Camera and lens question

[Marin]

Hi to all,

as you can seen I am a newbie to this forum but have been surfing on this site for some time now.

My current camera is Canon S1 IS but in near future I am going to buy DSLR with some lenses. As I am a keen windsurfer and I like to take a good windsurfing photo my choice is Canon EOS 20D with original 18-55 mm and Sigma 80-400 mm EX OS lenses.

As I stated before my only experience is with Powershot which has a 35-350 mm lens. This equals 10X optical zoom. Does this mean that with 640 mm on EOS 20D (400 mmx1,6 crop factor) I would have around 20X optical zoom?

I also wonder if the photos taken in cloudy weather at maximum zoom (with particular Sigma lens) will be usable due to low light enviroment? Can this be compensated with Canon's high and noise free ISO setting?

How usable is this lens on 300-400 mm setting without using tripod?

What about using 2x converter with this sigma lens? Would it take away too much light (too high f stop)?

I also like to shoot landscapes. Would original Canon 18-55 mm lens suit me fine or should I invest in some other lens?

[EOSThree]

The 10X refers to the range of the zoom itself, not the magnification of the zoom. In other words 10X35=350. The sigma at 80-400 is a 5X zoom 5X80=400. With a lens of f/4.5-5.6 you will have to up the ISO on a cloudy day to be able to select a shutter speed that will stop the action. I find my 300 f/4 to be slow quite often at the edge of light.
The 18-55(about 3x zoom)is merely an adequate lens. It is capable of taking fine photographs, but tends to be a little soft at wider apertures. The 17-40 f/4L or 17-85 IS are better choices optically.
I have read the OS system is quite good on the Sigma, although I have never used one. This would make it reasonably handholdable. I handhold my 300(non IS) all of the time and usually have a few shots that look pretty good at 100% crops. There are some review on this site:http://www.photographyreview.com/PRD...1_3128crx.aspx

[mikishots]

Crop factors are not to be considered when calculating optical zoom specs. The sensor just shows a section of the view, it does not magnify anything.

If at all possible, increase your chances of a sharp, properly exposed photo by using a tripod. Increasing ISO is a technique to increase DOF, increase shutter speed, or for use if a tripod is not feasible.
The 20D makes this differentiation less of an issue, because of its high image quality at high ISO's.

The lens is very usable at these settings without a tripod as long as you can alleviate camera shake with higher ISO's or by having good light.

A 2X converter will play games with your autofocus if the maximum effective aperture is greater than f5.6. As an example, I use a 2X on my 1D - it will work on my 70-200 f/2.8L, but not on my 70-200mm f/4L. The f/2.8L becomes an f/5.6 (still o.k.) but my f/4L becomes an f/8 - autofocus is gone.

I don't shoot landscapes very often, but when I do, I prefer a telephoto. That's just me.

[peted56]

I don't shoot landscapes very often, but when I do, I prefer a telephoto. That's just me.

Thats confusing, does this mean you only like looking at a small part of the landscape?

[Marin]

This is a bit confusing. Is there any way of comparing lens lenght in mm with optical magnification (like in binoculars)?

How would I know what lens lenght is enough? Shoul I buy a telephoto then?

What is the difference in 100 mm in focal lenght in real world?

Ok, I see that 80-400 mm is 5 times zoom, but 80 mm is not like human eye, what can we compare it to?

Thanks for answer anyhow .

[peted56]

This is a bit confusing. Is there any way of comparing lens lenght in mm with optical magnification (like in binoculars)?

How would I know what lens lenght is enough? Shoul I buy a telephoto then?

What is the difference in 100 mm in focal lenght in real world?

Ok, I see that 80-400 mm is 5 times zoom, but 80 mm is not like human eye, what can we compare it to?

Thanks for answer anyhow .

What you need to know is the crop factor of the D-SLR you want, for ease let say it's 1.5.

This means the 80-400mm becomes a 120-600mm effective size, thats sort of 5 times zoom but only across the range of that lens. A "normal lens is aound 50mm "effective" size or about a 34mm, to be the equivalent of the "standard" wide angle of say a 28mm you need to drop the size to around 18mm.

So if you follow all the stuff above to compare with a camera that has one lens that does all your zooming it will give you the equivalent of around 28-600 using a 18-50 and a 80-400 and that is a zoom from wide angle to very zoomy, you do the math. Of course depending how far away your subject is that may still not be big enough and you may need a 300-800mm or the likes.

Cheers.

Pete

[Michael Fanelli]

What you need to know is the crop factor of the D-SLR you want, for ease let say it's 1.5.

This means the 80-400mm becomes a 120-600mm effective size, thats sort of 5 times zoom but only across the range of that lens. A "normal lens is aound 50mm "effective" size or about a 34mm, to be the equivalent of the "standard" wide angle of say a 28mm you need to drop the size to around 18mm.

Not quite true. Only the field of view is changed. Everything else stays the same. For example, perspective and magnification are linked to the real focal length of the lens, not the "35 equivalent.." Look through the camera using a 50mm lens. It looks just like what you'd expect from a 50mm lens other than it being narrower.