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Old Mar 20, 2012, 5:28 PM   #11
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Given the post's title- I was referring of course to the light sensitivity of a given camera- as opposed to using/needing a wide aperture.
But yes- top notch optics and fast autofocus are imperative...

Last edited by SIMON40; Mar 20, 2012 at 5:43 PM.
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Old Mar 20, 2012, 9:12 PM   #12
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THAT IS TRULY INCREDIBLE!!

Great points on all replies.
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Old Mar 21, 2012, 8:57 AM   #13
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Quote:
Originally Posted by SIMON40 View Post
Given the post's title- I was referring of course to the light sensitivity of a given camera- as opposed to using/needing a wide aperture.
But yes- top notch optics and fast autofocus are imperative...
My bad-def agree with you
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Old Mar 21, 2012, 10:20 AM   #14
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Quote:
Originally Posted by SIMON40 View Post
Given the post's title- I was referring of course to the light sensitivity of a given camera- as opposed to using/needing a wide aperture.
But yes- top notch optics and fast autofocus are imperative...
They both go hand in hand.

A camera always focuses with the aperture wide open. That way, you have a brighter viewfinder, and so that the Autofocus Sensors can "see" better to focus. Then, the aperture closes down to the setting the camera is using when the photo is taken.

If you look at some of the tests measuring that kind of thing (for example, the AF tests over at popphoto.com where they use a 50mm f/1.4 in various light levels), the less light the AF sensors get, the slower the Autofocus (where a camera that focuses in 1/10 second in brighter light may take closer to 1 second to lock in very dim light with the same lens.

If you use a dimmer lens, that's just like reducing the light levels. So, a camera that still focused fast in EV 5 level lighting (typical interior light levels at night) with an f/1.4 lens, may drop down to the slower speed it was taking to focus in EV 1 light levels with an f/5.6 lens.

So, even if a lens has a very robust AF System (fast, ring type USM or Nikon's AF-S, etc.), it it's dim, it can take longer for it to lock and maintain focus in lower lighting.

For example, the AF sensors using a lens with a 70-300mm f/4-5.5.6 lens are only going to see 1/4 the light when zoomed in much compared to the light the AF Sensors would get if using a 70-200mm f/2.8 lens (since the widest aperture would be f/5.6 when zoomed in much on the dimmer lens, and f/2.8 is 4 times as bright as f/5.6)

Sure, there are other variables involved, and you have to take each lens on a case by case basis. But, if you want the fastest AF possible in dimmer lighting (for example, indoor sports), a brighter lens is usually going to perform much better than a dimmer lens, even if they both have a similar AF system design.
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Old Mar 21, 2012, 12:36 PM   #15
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All good points JimC....
Maybe with improving high iso noise control,perhaps autofocus in lower light/smaller apertures might be an area for lens manufacturers to improve/look into.....
Then again... why dent your sales of fast (and expensive) lenses...!
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Old Mar 21, 2012, 1:01 PM   #16
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All good points JimC....
Maybe with improving high iso noise control,perhaps autofocus in lower light/smaller apertures might be an area for lens manufacturers to improve/look into.....
Then again... why dent your sales of fast (and expensive) lenses...!
I think you're oversimplifying. The 2 aspects the lens provides to AF is:
1) quality optics - better optics provide better data to the AF system
2) AF motor

What you are ignoring is the AF system within the camera itself. That system has to be up to snuff as well. So, a d4 with a given lens may work well where a d5100 might not. A/F is a chain - lots of pieces play a part.
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Old Mar 21, 2012, 1:06 PM   #17
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There's only so much the lens can do if the aperture is not wide enough, as less light gets through to the camera's AF sensors, so the camera takes longer to process what it can see in order to instruct the lens what to do to change focus.

The camera's AF system versus the lens is the bottleneck trying to use a dim lens in lower light, all else being equal (e.g., trying to use a lens that only has f/5.6 available if you zoom in much in less than optimum lighting), since the AF sensors and processing algorithms can't cope with light that low, and it take's the camera longer to figure out how to instruct the lens to focus (as f/5.6 is very dim for indoor use if you need faster Autofocus, just as if you were shooting in a much lower light level), sometimes moving it a little at a time to figure out if there is any improvement, resulting in "hunting" with failure to lock at all if light gets really low.

You get the same thing that you'd get dimming the lighting if you use a lens that only lets in a fraction of the light that you get with a brighter lens (for example, only 1/4 the light gets through with a lens that only has f/5.6 available versus one that has f/2.8 available) in dimmer light, since using a dimmer lens is just like turning down the light levels the camera's AF system sees, and if you look at AF performance tests using the same lens in different light levels, lower light results in slower AF with dSLR models.

Look at the pophoto.com dSLR reviews for an example of that, where they graph a camera's AF performance in a variety of light levels using a 50mm f/1.4 lens when possible, where you see a downward turn in the AF speed as light levels start to get lower, even when using a lens that bright, because the AF sensors don't get enough light. If you went to a lens that only let in a fraction of the light, AF speed would drop off just like it would using a brighter lens in very low light.

Now, the OP's D4 has a super AF system design, with superior AF processing speed compared to most cameras. But, it's still going to slow down using a dim lens on it in low light compared to using a brighter lens on it (just as a camera's AF system is going to take longer to lock if you dimmed the lights).

I used a D3 for a while, and although it's AF system was vastly superior to most cameras (and the new D4's is probably even better), the camera could still struggle some in very dim lighting using a relatively bright lens. For example, trying to use a Nikkor 24-70mm f/2.8 AF-S lens in a *very* dim bar (needing ISO 12,800 and f/2.8 to get shutter speeds up to around 1/20 second), with me trying to find something with enough contrast to lock on). With a dimmer f/5.6 lens, it wouldn't have been able to lock at all in light that low. You have to have enough light getting through for the AF sensors to "see" for best AF performance, and a dimmer lens less less light through.

Now, you've got much better lighting than that in a gym. But, a brighter lens is still going to give you faster AF performance with most camera designs.
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Old Mar 27, 2012, 8:42 AM   #18
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Well, the indoor shooting season is over. I shot the boy's state championship game last weekend with the D3 and D4 and these are my impressions, the second time out.

The D4 feels more comfortable and lighter in my hands than the D3, although the D3 feels more familiar, if that makes sense. My first go around, i inadvertently changed the shutter speed on a couple occasions but this time that didnt happen. Perhaps i was aware of it subconsciously? I still need to determine which button i will use to lock it.
I miss a second CF slot. ive never run out of space shooting a 16 and an 8 gig card with the D3. Just put them in and forget it. I dont have a usb 3 port on my computer yet so i havent used the xqd, dxq, qdx or whatever the heck it is. Frankly, I hate the thought of having to deal with a second type of card. Big negative for me.

The AF is amazing compared to my D3.

My usual work flow is NX2 for post with only in camera sharpening, and I save and store the full processed jpeg along with the raw file. Then I size the jpeg to 1100 and sharpen if necessary. In the past, inevitably, i would have to selective sharpen about 10-15% of 150-200 shots because the D3 didnt maintain focus while tracking or the player was too close to me with the 70-200. In my second processing session Ive only had to selective sharpen three images out of 450. Amazing!

This is the type of shot the D3 would rarely capture with that lens.



The D4, hasnt missed this yet.

100% crop. D4, 70-200 at f/2.8, 1/1000sec and ISO 5000. No NR

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Old Mar 28, 2012, 2:44 PM   #19
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Not bad at all....!!!
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Old Mar 28, 2012, 2:47 PM   #20
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These look great DRG!.
I don't know when I'll get my hands on one here in the UK, (not pre ordered), as most stock will be going out to the big hitters in the Agencies etc ready for the Olympics . Kind regards Graham.
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