sorry another IS lens question

[jann1033]

I keep reading the IS helps you in low light situations...so what would the difference be between using an IS lens and one with a wider aperture?
the lens i have now is supposed to be f3.5-5.6 but i can rarely get it even f5 rather than 5.6 ( don't know why except maybe cause it's a piece of crop and that's kind of another subject my confused brain is not handling right now) so basically i am always using a littleish aperture which would also equal slower shutter right?( except outside in bright light which is basically hardly everfor me)


so if i got a lens that went to f2.8( think it was 28-135, it's on one of my many other dumb question threads and i don't remember right this second ) would that be basically comparable to an IS lens????? if IS only helps with camera movement, wouldn't a faster shutter speed do the same thing? which would mean a bigger aperture right?

correct my faulty thinking please!!!!

 

[pisco]

The difference between an IS lens and a larger aperture lens is shutter speed. Large aperture lenses allow for faster shuter speeds by taking in more light by opening wider.

The purpose of IS it to minimize camera shake, which is introduced when the shutter speed is less than the zoom value of the lens. So to get a steady hand-held shot at 300mm with a non IS lens you would need a shutter speed of 1/300 or greater. With an IS lens you could get the same shot at ~1/80 without any visible camera shake. The downside of IS is that with slower shutter speeds subject motion blur is more likely. So if you need to take shots of moving subjects in lower light situations the larger aperture will be a better choice.

 

[JR6ooo4]

Well, assume you need a long shutter to expose your subject correctly even if you are using a Canon 50mm f1.4. IS will definately help.

Faster lenses and IS both work towards achieving the same goal.

Mikeeee

 

[ndelaware]

jann, you can only set the aperature to f/3.5 when you are zoomed out all the way out to the wide end of the lens. As you zoom in, the f/stop will climb. So the best you can do with the lens zoomed all the way in is f/5.6. The Canon 28-135IS is f/3.5-f/5.6 not f/2.8 so you will run into the same problem with f/stop as the lens you have except you can slow the shutter speed to get the more light in and IS will help you with camera shack. On a lens like the Canon EF-S 17-55 f/2.8 IS USM the f/stop is constant throughout the zoom range. It is, however, a fairly expensive lens since it costs more money to produce a lens like this.


Have you tried using a higher than normal ISO speed? This would also help you achieve a faster shutter speed with the lens you are already using.

 

[pisco]

I would strongly recommend reading Understanding Exposure by Bryan Peterson. This book will give you an excellent understanding of the relationship between aperture, shutter speed, film speed and focal length. I always struggled to make sense of all of this untiul I read that book. It made a huge difference for me and allowed me to make the step up to a DSLR with confidence.

 

[jann1033]

I would strongly recommend reading Understanding Exposure by Bryan Peterson. This book will give you an excellent understanding of the relationship between aperture, shutter speed, film speed and focal length. I always struggled to make sense of all of this untiul I read that book. It made a huge difference for me and allowed me to make the step up to a DSLR with confidence.

that's on my list of things to buy unfortunately the list is getting enormous

 

[geetey]

that's on my list of things to buy unfortunately the list is getting enormous

Jann, I feel like you and I are in the same boat.

Now if you lived closer to St Louis, I would let you borrow my Understanding Exposure book (which gets some pretty strange looks from people when I am out and about, carrying it) and you could test out my 17-85mm IS lens.

As ndelaware suggested, I find myself pushing my ISO up higher than 'typical' to increase my shutter speed.

Still searching for my perfect lens. I do like the nifty 50!

 

[jann1033]

thanks all it did work to 3.5 with the zoom all the way rolleyes1 )
i think i'm just gettin the 28-135 IS and 50 f1.8( which i'm hoping the aperture will help ) and figuring if it doesn't work it doesn't work...i think i worried less about gettting married than i have about what lens to buy

 

[fitzperry]

Now if you lived closer to St Louis, I would let you borrow my Understanding Exposure book (which gets some pretty strange looks from people when I am out and about, carrying it) and you could test out my 17-85mm IS lens.

I've noticed the same thing--strange looks, I mean! Come to think of it though, a couple of the shots of his wife sort of fit that image.

 

[TheLionKing]

Remember that changing the aperture also effects the Depth of Field (DOF). So while openning up the aperture may allow you to shoot at a faster shutter speed and avoid camera motion artifact, your subject may or may not be all completely in focus. This is more the case with telephoto lenses where the DOF is narrower rather than wide angle lenses.

Don't forget the "poor man's" IS...... A tripod It can be very useful if one has the time to set up the shot.

 

[boBQuincy]

IS helps with camera movement, faster shutter speed helps with subject movement *and* camera movement.

IS adds $$$ to a lens, a wider aperture (to get the faster shutter speed) adds $$$, size, and weight.

Many of Canon's L series zoom lenses have a constant aperture so you don't have to wonder what will happen if you have your exposure set and then want to zoom a bit.
The f 2.8 models are expensive, the f4 models a little less so.

If it's wide aperture you want there is nothing like prime lenses.

If you have the ISO maxed out then it's on the expensive lenses, otherwise crank the ISO up and use noise reduction software.

 

[geetey]

I've noticed the same thing--strange looks, I mean! Come to think of it though, a couple of the shots of his wife sort of fit that image.

VERY true!