IS substitute for faster glass in low light? Not convinced.

[00Q]

Many people say that having IS gives you 3 stops of compensation. Which means that you can have a faster shutter speed of 3 stops.

Im not totally convinced by this. take a 24-70 f/2.8 and the 24-105 f/4 IS. This means, (if we skip out the details regarding DOF, bokeh etc and just focus on getting a shot,) that in low light, say shooting at 70mm:

1)if your 24-70 is giving you a shutter speed of 1/4 second which assume you can't hand hold..

2)then according to 24-105 without the IS at f/4, your shutter speed will be 1/2 second due to smaller aperature

3)but IS means that you gain 3 stops when means your effective shutter speed is 1/16 second, much better than the 24-70mm f/2.8 and so you could get a crisp shot.

Im not totally convinced that it really translates to 3 stops in low light. I have shot with both lenses before. Could someone confirm this?

i.e. what Im trying to say is that if we have the option to purely getting a crisp shot in low light and have the option to either get a faster lens or a slower lens with IS, it is not equivalent. Because this means it is much cheaper getting IS than faster glass (given IS claims to be 3-4 stops)

thanks,

 

[marekjoz]

The image is not as sharp or simply blurry? Comparing this way different lenses could lead to misinterpration. Maybe it's better to check the same on 24-105 with IS on and off. This would be better probably. Comapring images from different lenses and interpreting them this way may be confusing, ie because 24-70 is a better lens than 24-105. What comes from the comparison between 24-70 and 24-105 (wth IS off) set on same apperture and focal?

 

[ghosh9691]

IS does not change the shutter speed. It just allows you to hand hold at lower shutter speeds easily. In your example, your 24-105 would still use 1/2 second shutter speed, but because of IS your chances of getting a sharper image would be higher. But if your subject has any kind of motion, even IS will not help and it will be blurred.

 

[00Q]

IS does not change the shutter speed. It just allows you to hand hold at lower shutter speeds easily. In your example, your 24-105 would still use 1/2 second shutter speed, but because of IS your chances of getting a sharper image would be higher. But if your subject has any kind of motion, even IS will not help and it will be blurred.

yes exactly. now the questions is if the 24-105 requires 1/4 of a second (compared to 1/2 on the f/2.8), the IS allows you to hand hold it more steady, so what is the "effective" shutter speed? People claim that IS compensates 3-4 stops. does this translates to directly an effective shutter speed?

 

[Hillsilly]

If taking a photo of a stationary object, then you'd have a greater chance of a sharp photo with the f/4 IS. But you're still stuck with a 1/2 second shutter speed. If you're taking photos of people or anything involving action, the faster shutter speed of a f/2.8 lens might work better.

 

[Jim K]

yes exactly. now the questions is if the 24-105 requires 1/4 of a second (compared to 1/2 on the f/2.8), the IS allows you to hand hold it more steady, so what is the "effective" shutter speed? People claim that IS compensates 3-4 stops. does this translates to directly an effective shutter speed?

Are you thinking that IS changes the shutter speed or ISO setting? It doesn't.

If the f/2.8 requires 1/2 sec at 2.8 then the 24-105 f/4 will require 1 sec at f/4. If the IS compensates 3 stops it would be like trying to hold the camera at 1/8 sec. both lenses require the same amount of light to make the shot.

At a higher shutter speed you may move out of the "shake" zone and into an area where you can handhold better. If the scene requires 1/15 at f/2.8 at the ISO you picked it will require 1/8 at f/4 with either lens but holding a lens with 3 stop IS at 1/8 sec is like holding a no IS lens at 1/60 sec because the lens reduces the vibration/movement AS IF the camera was shooting with a shutter speed 3 stops faster. 3 stops.

 

[Loswr]

IMO, IS is a substitute for faster glass, if you're shooting static subjects (or want motion blur, but not shake blur, in your shot). IS is not a substitute for fast glass with moving subjects - in those cases, you need more light to allow a faster shutter speed to freeze motion, and the fact that IS allows shooting at even slower shutter speeds than normally possible is not helpful.

Say I have a shot at ~100mm on FF, that means I'd nominally need 1/100 s to effectively handhold the shot. Say I have a lens with a 4-stop IS system, that means I can, in theory, handhold that shot at 1/6 s and still get a reasonably crisp shot.

So...below an example using a 4-stop IS lens at 95mm, completely handheld (no bracing, no leaning against a wall, just free standing on a narrow bridge)...exposure time is 0.5 s - a full stop more than the rated IS benefit. I used f/5.6 to get an even longer exposure for more blur of the falling water. Now, at 100% you can see some shake-induced blur in the shot, but even at 1600 pixels (click the image, then view all sizes > original), it not really evident.


EOS 5D Mark II, EF 70-200mm f/2.8L IS II USM @ 95mm, 1/2 s, f/5.6, ISO 100

 

[triggermike]

I have shot many photos handheld with the 24-105 at 1/8 of a second with perfect results. As previously mentioned before, IS does nothing for moving objects. In situations where the subjects are moving (does not have to be fast-moving), low f-stops are king to obtain fastest "real" speed.

BTW, who says the 24-70 is a much better lens than the 24-105?

 

[marekjoz]

BTW, who says the 24-70 is a much better lens than the 24-105?

No, not me (I don't have 24-70), though I think you refered to my post. I meant that comparing images from 24-70 to 24-105 (with IS on) should not lead to statement, that IS doesn't work as it should (allowing longer exposures with same lighting conditions) but rather that some other cicrumstances could occur (like in example, that someting which interpreted as blurred was just not sharp or even that lens has better IQ than the other with current apperture and focal). I pointed that better comparison would be to compare images on same lens with IS on and off with different exposure times. On the other hand excluding other factors than IS could be made by comparing images from 24-70 to 24-105 (with IS off) and shoot with the same apperture.
English is not my native language so sorry for misunderstaning if that's the case.

 

[00Q]

If taking a photo of a stationary object, then you'd have a greater chance of a sharp photo with the f/4 IS. But you're still stuck with a 1/2 second shutter speed. If you're taking photos of people or anything involving action, the faster shutter speed of a f/2.8 lens might work better.

+1 thanks so much. This clears up everything.

 

[skitron]

(or want motion blur, but not shake blur, in your shot

To me, this is one of the coolest things about IS, you can get a clean background and good subject motion blur without much fuss. Plus 'IS pan mode' where you can get essentially the opposite, a clean subject and plenty of background 'motion' blur. Of course it's also nice for stationary subjects too. All in all a very nice feature to have (especially since it has an off switch) as long as it's fully understood and expectations are set accordingly.

 

[awinphoto]

it will be adequate for reducing/eliminating camera shake in some situations, but wont reduce motion blur. If given a chance between F4 and IS and F2.8 and no IS, the IS may give you an additional stop or two compensation that the 2.8 wont, but try to always shoot at the fastest shutter or tripod when in doubt

 

[keithfullermusic]

IS allows me to use my 100-400mm at 400mm with no shake blur - and thats the old IS. Clearly it won't help if my subject is moving, but it is still incredibly useful at times.

 

[Mt Spokane Photography]

Many people say that having IS gives you 3 stops of compensation. Which means that you can have a faster shutter speed of 3 stops.

It does not mean you can use a faster shutter speed. IS lets you use a slower shutter speed and reviewers often test it, and it works. BUT- only for static subjects.

You are always free to use faster shutter speeds as long as there is enough light.

Here is a image on my 100-400mmL handheld thru my back window at 1/25 sec 400mm. I grabbed my camera and snapped the image with whatever settings were on it. I was amazed that a 1/25 sec image came out at all. Seconds later, he slowly started to roll the baby goat off, and motion blur took over. He loves the goats, but it hurts when they play on his back. A few months ago, we watched a new set of babies, and one was on the roof of his goat house and jumped on the horses back as he walked by. As soon as the horse took one step, the goat left. It can be a real circus.

Starting to roll

Over he goes, and the goats leave quickly. IS does not let you freeze moving subjects!

 

[AprilForever]

Many people say that having IS gives you 3 stops of compensation. Which means that you can have a faster shutter speed of 3 stops.

It does not mean you can use a faster shutter speed. IS lets you use a slower shutter speed and reviewers often test it, and it works. BUT- only for static subjects.

You are always free to use faster shutter speeds as long as there is enough light.

Here is a image on my 100-400mmL handheld thru my back window at 1/25 sec 400mm. I grabbed my camera and snapped the image with whatever settings were on it. I was amazed that a 1/25 sec image came out at all. Seconds later, he slowly started to roll the baby goat off, and motion blur took over. He loves the goats, but it hurts when they play on his back. A few months ago, we watched a new set of babies, and one was on the roof of his goat house and jumped on the horses back as he walked by. As soon as the horse took one step, the goat left. It can be a real circus.

Starting to roll

Over he goes, and the goats leave quickly. IS does not let you freeze moving subjects!

Indeed. Although, a supertele lens without IS is extremely hard to use hand-held...

 

[7enderbender]

IMO, IS is a substitute for faster glass, if you're shooting static subjects (or want motion blur, but not shake blur, in your shot). IS is not a substitute for fast glass with moving subjects - in those cases, you need more light to allow a faster shutter speed to freeze motion, and the fact that IS allows shooting at even slower shutter speeds than normally possible is not helpful.

Say I have a shot at ~100mm on FF, that means I'd nominally need 1/100 s to effectively handhold the shot. Say I have a lens with a 4-stop IS system, that means I can, in theory, handhold that shot at 1/6 s and still get a reasonably crisp shot.

So...below an example using a 4-stop IS lens at 95mm, completely handheld (no bracing, no leaning against a wall, just free standing on a narrow bridge)...exposure time is 0.5 s - a full stop more than the rated IS benefit. I used f/5.6 to get an even longer exposure for more blur of the falling water. Now, at 100% you can see some shake-induced blur in the shot, but even at 1600 pixels (click the image, then view all sizes > original), it not really evident.


EOS 5D Mark II, EF 70-200mm f/2.8L IS II USM @ 95mm, 1/2 s, f/5.6, ISO 100

What he said. Only I would argue that it does NOT make IS a substitute for fast glass. It's really for different applications which is one of the reasons why any comparison between the 24-70 and the 24-105 to me always results in, yeah, there are reasons to own both...

It is my experience that IS on the 24-105 works surprisingly well given the limitations outlined by Neuro above. I recently used it for a live music shoot and the results were better than I had expected. No, it obviously doesn't help with motion blur but if things are relatively static you can increase DOF by stopping down a little as opposed to the look of a fast prime for example. All depends. Not sure how this would compare to having a monopod in such a scenario. That may actually be better overall. Plus I personally fully expect the IS to go bust within a few years or at least go out of whack. It's a loosely moving lens element. That can't be good in the long run. So I usually have it turned off and really just bought the 24-105 because it was scuh a good deal with the 5DII. It's good for what it is but I don't rally love it. Still hoping to trade it for a 24-70 (original) at some point.

 

[JFeldhaus]

I have a question that somehow belongs to this topic:

Is there any benefit of turning IS off if you don't need it? esp. if it's a cheap lense ..?

 

[keithfullermusic]

You can turn it off if you're on a tripod. You can also turn it off if you don't need it (shorter focal length and really bright) because it uses more battery.

 

[briansquibb]

Sometimes you just need a greater DOF than using fast glass wide open can buy you

higher ISO might be a substitute for faster glass

 

[JFeldhaus]

You can turn it off if you're on a tripod. You can also turn it off if you don't need it (shorter focal length and really bright) because it uses more battery.

So the only benefit from switching off IS is less battery usage? Does it it affect the image in any way?