Canon 70-300 IS, questions

[rgrebby]

As I understand with this lens you can shoot at 1/60 when you would normally shoot at 1/500 at 300mm

Is there some mathematical solution for this?
ie, at 70mm normally I would need around 1/100ish on my 400D so what could I get away with using the IS?

Thanks in advance.

 

[rgrebby]

am I right in thinking 1stop = shutterspeed / 2

So 3 stops down from 1/500 is 1/62.5
and 3 stops down from 1/70 is 1/8.75

If so thats amazing, not sure I can believe I could shoot at 1/9 at 70mm and still have a sharp image.

 

[susie]

If my understanding is right the IS just stops the shake, so you don't need to use as fast a shutter speed to stop the action at long distances from whatever the subject is.
I don't think you can drop the speed as much as you are saying though, I go from perhaps 250 down to 200 but for what I shoot the would be a hell of a lot of movement blur if I dropped to around 60

I will let someone else explain the stops though!!

 

[Jelster]

I don't think it's "that" good - I know I can't shoot that slow at 70mm with mine !

It does mean that you can cope with a bit less light than you may have done without IS.

Steve

 

[mmcp42]

IS generally gives you 2 stops
so instead of 1/300 at 300mm
you could use 1/75 or to be realistic 1/100
still not bad!

if you decided 3 stops was acheivable then
1/37.5 or 1/40 to be sensible

but you'd need a steady hand for that

1 stop = 2/300 = 1/50
2 stop = 4/300 = 2/150 = 1/75
3 stop = 8/300 = 4/150 = 2/75 = 1/37.5

all based on you being able to hand hold 300mm at 1/300 in the first place!

 

[stevewestern]

1 stop equals one shutter speed reduction - ie from 1/500th of a second to 1/250th is one stop, so two stops is down to 125th, and 3 is 1/60th.
In theory all is fine.
In practice, for most normal people, you can get away with using a 125th without a problem, some can do better. However, you are only stopping the camera moving - if the subjecy moves, then you are stuffed.
I had the 70-300 lens, and it was too slow to focus in low light, and my subject moved when I tried to use slow shutter speeds - I nw understand why people pay shed-loads for faster lenses...

 

[Gofer]

I don't think it's "that" good - I know I can't shoot that slow at 70mm with mine !

It does mean that you can cope with a bit less light than you may have done without IS.

Steve

IS does have its limitations but I didn't think this shot was too bad considering it was shot handheld at 1/15, f5.6, 210mm. Subject was approx 35ft away :

 

[ditchdigger]

as ken rockwell says your percentage of good pics will drop so take more so that one will be usable

 

[RichardC27]

That's a brilliant photo, really funny. IS basically means you can, with good technique, use a much lower shutter speed than you normally could get away with. I find all these claims of "3 stops slower" etc to be a tad misleading. It depends what you're shooting, whether it is mobile or static, and if it's moving, how fast it's moving. It does let you get away with a lot more, but it is not a cure for poor technique.

 

[StewartR]

It does let you get away with a lot more, but it is not a cure for poor technique.

Good point, Richard. I'd be willing to bet that the variation in the shutter speeds which different people can manage hand-held is wider than 3 stops. Yes, IS might give you 2 or 3 stops, but learning good technique if you don't have it already can probably achieve the same or better improvement.

(And don't get me started about those people who us the Live View LCD as a viewfinder....)

 

[Gofer]

That's a brilliant photo, really funny. IS basically means you can, with good technique, use a much lower shutter speed than you normally could get away with. I find all these claims of "3 stops slower" etc to be a tad misleading. It depends what you're shooting, whether it is mobile or static, and if it's moving, how fast it's moving. It does let you get away with a lot more, but it is not a cure for poor technique.

Thanks Richard. He was a cheeky little begger, By his stance I wouldn't have been surprised to have seen the two finger salute. I agree with you and Stewart that IS is not really a substitute for good technique but it certainly has it's uses.

 

[pearce_jj]

just to throw in another perspective, I suffer from quite badly shaky hands and find the IS on the 24..105mm F4L IS is simply that good that I never really get camera shake with that lens. The bigger problem is motion blur, as it can come up with some rediculously slow shutter speeds at times.