f/4 lens and f/2.8 lens equal ?
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jOhO
Senior Member
ever try focusing on the black button on a black suit under low tungsten light? not that it's a very intresting subject, but maybe u would be able to tell a difference there.
ever try focusing on the black button on a black suit under low tungsten light? not that it's a very intresting subject, but maybe u would be able to tell a difference there.
I always focus on something darker such as the eye's iris or some other darker stuffs. Still feels the same though.
nikolaiski
New Member
wa lao eh...for those who have said that f/4 and f/2.8 is negligible, I beg to differ as well. I'm a newbie no doubt, just got my 30D a few weeks ago, but I'm very much into event photography, especially car photography at night.
An f/2.8 lens is totally desirable under such conditions, even in overcast days at the track. I never found out how useable, or rather, valuable the 70-200 F/2.8L was to me until i borrowed it one day...even the added zoom of the 300mm f4 couldn't satisfy the "oomph" of the additional stop. With the L, the camera focuses faster, and the picture is taken sooner. Less chance of that car getting away from me.
Then again, unless we use these lenses in situations like these, i guess we will never appreciate the significance of them all
This is just one of those revelations for a newbie like me...:bsmilie:
An f/2.8 lens is totally desirable under such conditions, even in overcast days at the track. I never found out how useable, or rather, valuable the 70-200 F/2.8L was to me until i borrowed it one day...even the added zoom of the 300mm f4 couldn't satisfy the "oomph" of the additional stop. With the L, the camera focuses faster, and the picture is taken sooner. Less chance of that car getting away from me.
Then again, unless we use these lenses in situations like these, i guess we will never appreciate the significance of them all
This is just one of those revelations for a newbie like me...:bsmilie:
i definitely agree. not only on the shutter speed but it also helps to better focus in low light.
U mean the 300mm f/4L IS? Haven't use that lens though. I don't really take a lot of events but usually my Tamron 28-300 does all the job well. A few time also used 70-200 f/4 and f/2.8, of cos results were better.
When it's bright, the speed of the AF on both the lenses are comparable.
But when it comes to low light focusing, which u think can lock-on faster?
.
do you mean you use it to do macro lens on eye's iris? if focusing on eyes is pretty easily due to the contrast between the skin and eyes.
OMG, when we descibe a lens as a fast lens, we meant the fast f stop..... not the af focusing speed. :bsmilie:
comparing focusing speed is really quite far off my mind.
faster as in faster by 1 stop. you get it?
oh well, sometime a question like this people will change the answering to tell you the cherry qq consume less petrol and is cheaper yet still get you to the finish line. LOL :bsmilie:
Are they then identical in proformance ?
Yes.. most lenses are at their sharpest at f8. The f2.8 would have a brighter view though..
Or should I say that the F/2.8 lens does not have an advantage over the f/4 lens in this case.
Yes it does. It would focus faster and have brighter view.
So gentlemen.. would it make the f/4 lens less worthy than the f/2.8 lens in such a situation ??
Nope.. optical qualities are neglible at f8 but.. if you are trying to focus, you're more likely to lock on faster with the 2.8 than the f4. The F4 would also have an advantage being IS hence you'd probably get a sharper still image than the f2.8.
what the hell has IS got to do with a f2.8 and f4 lens? :nono:
if you wanna compare IS, theres also a 70-200 f2.8L IS
Wahaha!! That the prob with forums. ;p
Low light focusing is comparable when only in more extreme low light conditions. But faster is also not like faster by a few seconds.
In terms of AF speed, we Canon users are so priveleged. We're spoilt for choice with all the USM lenses. Even between f/2.8 and f/4 lenses, the AF speed difference is rather negligible. I've used a friend's 17-35L and a 17-40L and the AF is, in both cases, almost instantaneous under most circumstances.
So ignorant and yet so rude. :nono:
The 24-105 is an IS lens. How can the 70-200 be in the equation? Read the OP.
Nowhere was it stated which two lenses we were comparing. More likely to be 70-200 since there are 70-200 f/2.8 and f/4, and their IS counterparts.
Yeah...hail the USM technology! :bsmilie:
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