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Archive 2013 · Sigma 18-35 f/1.8 hands-on and samples online
  
 
jj_glos
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p.3 #1 · p.3 #1 · Sigma 18-35 f/1.8 hands-on and samples online


Well I'm looking forward to seeing how it performs, and it's made me want to see what the 7D replacement brings to the table even more...


Apr 24, 2013 at 10:28 AM
Yohan Pamudji
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p.3 #2 · p.3 #2 · Sigma 18-35 f/1.8 hands-on and samples online


bemyzeke wrote:
Actually DOF works the other way when enlarging. Since crop sensor images have to be enlarged more, the circle of confusion gets bigger and therefore the depth of field is reduced. However the angle of view comes to rescue (like you said) because instead of 75mm I have to shoot with 50mm to get the same frame, and 50mm has better DoF, so the end result is that we get more DOF.


You're right, I misspoke about enlargement. It was late and I was jumping back and forth to make sure I wasn't messing up but still did



Why shoot at the same shutter speed. Why not faster?


Because we're trying to achieve the same photo with DX and FF in this exercise. I understand that higher shutter speeds are desirable in low light conditions, but the same higher shutter speed can be achieved with both DX and FF. It's just a matter of whether you're increasing aperture or ISO to compensate.


This is why I am personally interested in this lens. In poorly lit family rooms, dance halls, sport gyms, where action is happening, I can use all the light that is available to keep my shutter speed high and eliminate subject blur. As long as the focal length works for me, I have no qualms in shooting DX to get the faster shutter speeds. True, if printed at 40x60 the images will be noisier, but noisier images are a hell of a lot better then blurry images. Noise can be removed, details can be recovered, but so far there is no
...Show more

Note here that you agree that the DX will be noisier. Then you said:



Says who?

First of all, in my given scenario, of D800 DX/FX, noise is the same.


So is DX noisier or not in your view? Not sure where you actually stand since you said it would be noisier when printed but here you're saying the opposite.

I'm going to assume that the only thing you disagree with is the 1 stop difference in noise between DX and FF assuming one is trying to create the same exact image with both. This is very easy to verify for yourself if you really want to. Use the settings to achieve the same image as we discussed then compare both images fullscreen on the same monitor or 2 same sized monitors. Use a sufficiently high ISO because otherwise modern cameras are so clean at even medium ISO that you'll be almost noiseless in both images.

You have the ideal camera to test with since it's FF with a DX mode--the D800--and can shoot with the same camera and just attach the right lens for each shot or use the same zoom lens and change the zoom between shots. The same test could be run with any FF camera by just using a shorter lens and cropping to simulate DX mode, although there'd be more math involved to figure out how much to crop instead of the camera doing it for you


Secondly

D800 - D300 = way more than one stop difference
D7100 - Canon 5D = Same level of noise
D7100 - Canon 1Ds Mark I = D7100 beats the pants of this first generation full frame
Fuji X-Trans (what is noise?)
Olympus OM-D - Canon 5D = about same


Why are you comparing different cameras let alone different generations? As I said before it's all other things being equal so you compare the latest tech, and even then comparing different cameras is dicey because of a number of factors. In any case it's not necessary since you can do it all in your D800.

Bottom line for me: the new Sigma brings APS-C in line with FF in terms of getting usable shots in low light. Actually there's one potential benefit it brings over FF: with the larger aperture the AF sensors see more light at f/1.8 than they do with an f/2.8 lens on FF, so AF could be better! In any case it's a very exciting lens, and Canon should take note instead of just doing Mark II lenses.



Apr 24, 2013 at 04:03 PM
Yohan Pamudji
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p.3 #3 · p.3 #3 · Sigma 18-35 f/1.8 hands-on and samples online


Snopchenko wrote:
I was hoping for some discussion of the new and exciting lens (and probably its usability on APS-H bodies, courtesy of Ian), but instead it's all more of the same "equivalence" stuff...
http://www.skyscrapercity.com/images/smilies/deadthread.gif


The lens was just recently announced. I'm sure we'll have more concrete performance info soon, although the early samples from that Korean site were very encouraging. Meanwhile we only have theory to occupy our time



Apr 24, 2013 at 04:06 PM
outlawyer
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p.3 #4 · p.3 #4 · Sigma 18-35 f/1.8 hands-on and samples online


super35 wrote:
bemyzeke, you are right there in the forest but you have missed the trees. I have a question for you.

The premise:
I make a photo in FX mode and then another DX mode with a D800 of the same subject. I use the same aperture, shutter speed, angle of view, and ISO. Now, I print both images at the same size of 24x36 inches.

The million dollar question:
Which print has more noise?

Bonus question:
Which image has more resolution?


Are not the number of photons which form the image circle at 1.8 the same regardless of the size of the sensor on which the circle is formed?
If so, this would seem to render the phrase, "light gathering ability" a misnomer.
That said, an endearment for the 85L is "light vacuum"



Apr 24, 2013 at 04:15 PM
HopeIsEternal
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p.3 #5 · p.3 #5 · Sigma 18-35 f/1.8 hands-on and samples online


I myself never really bought into the Full Frame (35mm) automatic 1 stop high ISO gain. I don't really believe that twice the area of FF sensor compared to APS-C automatically means that I can shoot the same scene and use 1 stop higher ISO on the FF and still have equivalent noise levels.

Here is why:

1. Smaller sensors generally have better design processes and efficiency since most of the R&D goes there for mass market sales compared to the smaller FF market. Frequently, the process technology takes a while to move up the chain to larger sensors like FF.

2. Older FF cameras like the Contax N Digital definitely don't have 1-stop noise advantage than the latest SONY 16mpx APS-C based cameras.

So it is not guaranteed that you get 1 stop ISO improvement by shooting FF. That is the maximum theoretical advantage. In some cases you get the same performance as can be seen with Sony's A99 compared to the current high ISO APS-C champs.

So I don't think that when comparing lens equivalency between FF and APS-C that FF should automatically get one additional stop improvement in "light gathering" or ISO equivalency.

Finally, although this new Sigma f/1.8 zoom lens is a DC (crop) lens, none of us know what the image circle is. For all we know, this zoom could have close to FF coverage as the Nikon DX 35mm f/1.8 does on FF.




Apr 24, 2013 at 07:54 PM
super35
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p.3 #6 · p.3 #6 · Sigma 18-35 f/1.8 hands-on and samples online


outlawyer wrote:
Are not the number of photons which form the image circle at 1.8 the same regardless of the size of the sensor on which the circle is formed?
If so, this would seem to render the phrase, "light gathering ability" a misnomer.
That said, an endearment for the 85L is "light vacuum"


The f-number or f-stop is the ratio of the lens's focal length to the diameter of the entrance pupil. Read that again because that is the key to equivalence. I think everyone will agree that the a 50mm lens on Canon 1.6 crop is a close equivalent to an 85mm lens on FF.

Have you ever looked into a 50mm and an 85mm lens stopped down to f/5.6? If you do you will be able to easily see that the aperture opening of the 85mm at f/5.6 is larger than the 50mm at f/5.6.

That difference in the aperture diameter is what gives FF a little more than a 1 stop advantage over 1.6 crop APS-C and 2 stops over m4/3rds.

Yes, you need to compare same generation sensors of approximately equal efficiency. Then as an informed photographer you will understand why smaller sensors are always at a disadvantage compared to larger sensors given that they are using the same technology.

One last point not related to equivalence. Larger sensors can also resolve more detail than smaller sensors with equal quality lenses. This is another HUGE advantage gained as sensor size increases and the reason why m4/3 will need world class optics just to compete with common optics on FF.



Apr 24, 2013 at 08:42 PM
Yohan Pamudji
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p.3 #7 · p.3 #7 · Sigma 18-35 f/1.8 hands-on and samples online


HopeIsEternal wrote:
So it is not guaranteed that you get 1 stop ISO improvement by shooting FF. That is the maximum theoretical advantage.


The idea is to compare systems, i.e. FF vs. APS-C, not compare individual cameras. I'm talking about theory, hence maximum theoretical advantage as you said, but in practice this can be easily tested by say using the D800 in FF and DX modes and comparing. They would have the exact same sensor tech because they're from the same sensor so the 1 stop difference would hold. I think we agree on that.

Now if you're doing a specific comparison say for gear shopping purposes such as, "I have a 5D Classic and 24-70 f/2.8. I wonder if I could get better results with a 7D and 18-35mm f/1.8?" then sure that makes sense to compare the actual cameras as well. But it pays to know how the theoretical aspects apply when comparing actual cameras as well. Without that it would be easy to be fooled into thinking the 18-35mm f/1.8 on APS-C automatically gives it an advantage over an f/2.8 lens on FF when in fact it doesn't.



Apr 24, 2013 at 09:28 PM
Snopchenko
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p.3 #8 · p.3 #8 · Sigma 18-35 f/1.8 hands-on and samples online


HopeIsEternal wrote:
Finally, although this new Sigma f/1.8 zoom lens is a DC (crop) lens, none of us know what the image circle is. For all we know, this zoom could have close to FF coverage as the Nikon DX 35mm f/1.8 does on FF.

There were some samples (by now deleted) shot with a 5D Mark II (the URL is still available from the other 18-35/1.8 thread but it's empty now). The coverage is never complete but better at 35mm than at 18mm. On APS-H cameras it's almost certainly usable at 35mm, less likely at 18mm but probably salvageable.

When it's out, I'll most likely try it on my 1D Mark II N, if only for fun.



Apr 24, 2013 at 09:37 PM
jj_glos
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p.3 #9 · p.3 #9 · Sigma 18-35 f/1.8 hands-on and samples online


Yohan Pamudji wrote:
The idea is to compare systems, i.e. FF vs. APS-C, not compare individual cameras. I'm talking about theory, hence maximum theoretical advantage as you said, but in practice this can be easily tested by say using the D800 in FF and DX modes and comparing. They would have the exact same sensor tech because they're from the same sensor so the 1 stop difference would hold. I think we agree on that.

Now if you're doing a specific comparison say for gear shopping purposes such as, "I have a 5D Classic and 24-70 f/2.8. I wonder if I could get
...Show more

You have to compare individual cameras as it is all down to the performance of the sensor. athough in reality even if an amazing APS-C sensor is released that beats current FF tech, it is likely that the same tech will find its way into FF so the larger area advantage of capturing the exact same scene will still hold true. The difference between a D800 and 7D is likely more than the 5D3 and D7100. Then it all comes down to your presentation size anyway.



Apr 24, 2013 at 09:55 PM
 

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andyjaggy82
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p.3 #10 · p.3 #10 · Sigma 18-35 f/1.8 hands-on and samples online


So let's assume that at best makes the APS-C equal to the full frame sensor in the area of noise, since you'll be able to use a lower ISO at the APS-C sensor because of the 1.8.

We also know that it provides pretty equivalent depth of field the 1.8 on APS-C vs 2.8 on full frame.

What about actual shutter speed for freezing motion though? Say you don't care about noise, are there going to be advantages of being able to get a fast shutter speed on the APS-C system with the 1.8? Are you going to be able to freeze motion better than you could on the full frame with a 2.8 zoom?




Apr 24, 2013 at 10:02 PM
Yohan Pamudji
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p.3 #11 · p.3 #11 · Sigma 18-35 f/1.8 hands-on and samples online


andyjaggy82 wrote:
So let's assume that at best makes the APS-C equal to the full frame sensor in the area of noise, since you'll be able to use a lower ISO at the APS-C sensor because of the 1.8.

We also know that it provides pretty equivalent depth of field the 1.8 on APS-C vs 2.8 on full frame.

What about actual shutter speed for freezing motion though? Say you don't care about noise, are there going to be advantages of being able to get a fast shutter speed on the APS-C system with the 1.8? Are you going to be able to
...Show more

No, because you could achieve the same on FF. Say you're at this setting:

f/2.8
1/100
ISO 1600

Then you figure you could open up more on APS-C with this lens and get a higher shutter speed:

APS-C:
f/1.8
1/250
ISO 1600

You would get roughly the same results on FF by doing this:

FF:
f/2.8
1/250
ISO 4000

Just 2 different ways of achieving the same result.



Apr 24, 2013 at 10:21 PM
jj_glos
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p.3 #12 · p.3 #12 · Sigma 18-35 f/1.8 hands-on and samples online


Yohan Pamudji wrote:
No, because you could achieve the same on FF. Say you're at this setting:

f/2.8
1/100
ISO 1600

Then you figure you could open up more on APS-C with this lens and get a higher shutter speed:

APS-C:
f/1.8
1/250
ISO 1600

You would get roughly the same results on FF by doing this:

FF:
f/2.8
1/250
ISO 4000

Just 2 different ways of achieving the same result.


If you've got a modern FF body that's great, my poor old 1Ds2 won't even do ISO 4000



Apr 24, 2013 at 10:41 PM
Mescalamba
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p.3 #13 · p.3 #13 · Sigma 18-35 f/1.8 hands-on and samples online


You can get ISO 4000, just push 3200 in PP. Until very recent cams, most sensors ended natively around ISO 1600 and rest was like in 1Ds MK2, just software.

And in Canon case I doubt they have sensors with native ISO over 1600 (tho it might be possible, just unlikely).



Apr 25, 2013 at 01:27 AM
jj_glos
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p.3 #14 · p.3 #14 · Sigma 18-35 f/1.8 hands-on and samples online


Mescalamba wrote:
You can get ISO 4000, just push 3200 in PP. Until very recent cams, most sensors ended natively around ISO 1600 and rest was like in 1Ds MK2, just software.

And in Canon case I doubt they have sensors with native ISO over 1600 (tho it might be possible, just unlikely).


No thanks, it's awful. I've had to do it in emergencies but would never do it by choice. That's why this lens on a 7D could be quite handy...



Apr 25, 2013 at 06:40 AM
Mescalamba
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p.3 #15 · p.3 #15 · Sigma 18-35 f/1.8 hands-on and samples online


jj_glos wrote:
No thanks, it's awful. I've had to do it in emergencies but would never do it by choice. That's why this lens on a 7D could be quite handy...


Sure that lens could be handy pretty much on any APS-C. But ISO 4000 on 7D really wont be better than your push process on 1Ds MK2. In reality it will be worse..



Apr 25, 2013 at 02:11 PM
Yohan Pamudji
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p.3 #16 · p.3 #16 · Sigma 18-35 f/1.8 hands-on and samples online


Mescalamba wrote:
Sure that lens could be handy pretty much on any APS-C. But ISO 4000 on 7D really wont be better than your push process on 1Ds MK2. In reality it will be worse..


With this lens on the 7D he'd be at f/1.8 ISO 1600, not f/2.8 ISO 4000 like he would on the 1DsII.



Apr 25, 2013 at 02:28 PM
jj_glos
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p.3 #17 · p.3 #17 · Sigma 18-35 f/1.8 hands-on and samples online


Mescalamba wrote:
Sure that lens could be handy pretty much on any APS-C. But ISO 4000 on 7D really wont be better than your push process on 1Ds MK2. In reality it will be worse..


Nope, as already said I wouldn't need to be at ISO 4000 on the 7D. I use a 7D and 1Ds2 side by side so know quite well how they compare thanks.



Apr 25, 2013 at 03:11 PM
super35
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p.3 #18 · p.3 #18 · Sigma 18-35 f/1.8 hands-on and samples online


nt


Apr 25, 2013 at 03:13 PM
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