Are you tired of seeing slow-mo footage yet?

Todd Sheridan · July 16th, 2012, 04:43 PM

Quote:

Originally Posted by Dave Allen

Todd, when you say it doesn't have the low light capability, in your opinion, is that a function of the kit lens it comes with being too slow, or something else? I need to be able to shoot in low light, and have not made any lens purchasing decisions yet. I do see some of the Sony Zeiss lenses in the A mount series down to 1.8.

Hey Dave - I'm not a particularly technical person, but I think it's mostly an issue of sensor size. In fact, I don't even own the kit lens. (I found this article about why larger sensors are better in low light, if you're interested - Why are larger sensors better at low light? - Photography).

The 5D just has a huge full-frame sensor that you don't really get with any other reasonable affordable cameras. The FS700 has a large sensor - larger than most cameras, but that 5D sensor is just huge.
Here is a good chart that compares sensor sizes. You can see that the super 35mm sensor in the FS700 is much larger than most cameras, but still not as large as the 5D.
http://2.bp.blogspot.com/-zkeQmhnxvV...izeChart_2.gif

so, to be clear, I think the FS700 has great low light capacity, but just not quite as nice as the 5D. And of course, there are many things about the FS700 that, in my opinion, make it a much nicer camera to shoot with than the 5D.

Alister Chapman · July 17th, 2012, 11:30 AM

It's not about sensor size, its about pixel size. If you have the same number of pixels a bigger sensor should yield better sensitivity, but the 5D has a lot more pixels than the FS700 and as a result the 5D's pixels are not all that different in size to those on the FS700. Then you have to consider noise, because a noisy sensor is less useful in low light. The sensitivity of any camera is a trade of against noise performance and light gathering ability. Generally the more pixels you have the noisier the image becomes because each pixel contributes a little bit of noise to the overall image. The original 5D MkII does quite well in this respect because all the line skipping etc means that not that many of the pixels on the sensor are actually used in the video modes. That's also why an HD camera is generally noisier and less sensitive than an SD camera with the same size sensor.

In addition clever noise reduction also makes a difference. Sony's EXMOR sensors use both analog and digital CDS noise reduction on the sensor as well noise reduction in the DSP. So while generally speaking bigger pixels (not necessarily bigger sensors) mean lower noise, as sensor and processing technology improves this is not always the case.

When looking at lenses what counts is the f number. The lower the number the faster the lens and the better your low light performance as a result. The kit lens is f3.5 at best so it needs 3 times as much light as an f1.4 lens, but your not going to get a zoom lens with the kind of zoom ratio (10x) of the kit lens that is f1.8 or f2.8 without spending very large sums of money. You can certainly get plenty of prime lenses that are f1.4/f1.8/f2.8 especially if you get the Metabones adapter and start to consider Canon lenses.

Tom Gresham · July 18th, 2012, 09:19 AM

<The lower the number the faster the lens and the better your low light performance as a result. The kit lens is f3.5 at best so it needs 3 times as much light as an f1.4 lens,>

It's worse than that.

If you go from f/1.4 to f/2, that's half the light.

Go from f/2 to f2.8, that's half the light, again. 1/4th as much as at 1.4.

Go from f/2.8 to f/4, that's half the light, again. 1/8th as much light at f/1.4.

So, in reality, the kit lens needs almost 8 times as much light as does a lens at f/1.4. With a lens that has a variable f/stop as it zooms, you could need 16 times as much light when zoomed out as you would need with a lens at f/1.4.

It's about the square root of 2, and some other math stuff. ;)

In addition to the more shallow depth of field, there's a big reason seasoned photojournalists have always liked fast lenses. Fortunately, we can now buy fast lens inexpensively -- think used.

July 17th, 2012, 11:30 AM	#17
Alister Chapman Inner Circle Join Date: Dec 2005 Location: Bracknell, Berkshire, UK Posts: 4,957	Re: Are you tired of seeing slow-mo footage yet? It's not about sensor size, its about pixel size. If you have the same number of pixels a bigger sensor should yield better sensitivity, but the 5D has a lot more pixels than the FS700 and as a result the 5D's pixels are not all that different in size to those on the FS700. Then you have to consider noise, because a noisy sensor is less useful in low light. The sensitivity of any camera is a trade of against noise performance and light gathering ability. Generally the more pixels you have the noisier the image becomes because each pixel contributes a little bit of noise to the overall image. The original 5D MkII does quite well in this respect because all the line skipping etc means that not that many of the pixels on the sensor are actually used in the video modes. That's also why an HD camera is generally noisier and less sensitive than an SD camera with the same size sensor. In addition clever noise reduction also makes a difference. Sony's EXMOR sensors use both analog and digital CDS noise reduction on the sensor as well noise reduction in the DSP. So while generally speaking bigger pixels (not necessarily bigger sensors) mean lower noise, as sensor and processing technology improves this is not always the case. When looking at lenses what counts is the f number. The lower the number the faster the lens and the better your low light performance as a result. The kit lens is f3.5 at best so it needs 3 times as much light as an f1.4 lens, but your not going to get a zoom lens with the kind of zoom ratio (10x) of the kit lens that is f1.8 or f2.8 without spending very large sums of money. You can certainly get plenty of prime lenses that are f1.4/f1.8/f2.8 especially if you get the Metabones adapter and start to consider Canon lenses. __________________ Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com

July 18th, 2012, 09:19 AM	#18
Tom Gresham Regular Crew Join Date: Apr 2007 Location: Covington, Louisiana Posts: 179	Re: Are you tired of seeing slow-mo footage yet? <The lower the number the faster the lens and the better your low light performance as a result. The kit lens is f3.5 at best so it needs 3 times as much light as an f1.4 lens,> It's worse than that. If you go from f/1.4 to f/2, that's half the light. Go from f/2 to f2.8, that's half the light, again. 1/4th as much as at 1.4. Go from f/2.8 to f/4, that's half the light, again. 1/8th as much light at f/1.4. So, in reality, the kit lens needs almost 8 times as much light as does a lens at f/1.4. With a lens that has a variable f/stop as it zooms, you could need 16 times as much light when zoomed out as you would need with a lens at f/1.4. It's about the square root of 2, and some other math stuff. ;) In addition to the more shallow depth of field, there's a big reason seasoned photojournalists have always liked fast lenses. Fortunately, we can now buy fast lens inexpensively -- think used.