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Some 24 mm comparisons [Nikon/Sigma]
#1
I still don't know if that comparison would be better placed next to the threads for Sigma 24/1.4 A. But since I compared Nikon with Sigma lenses, I thought the Nikon forum would be the right one.

 

What I did was very unscientific. I wanted to know, how bad the "weak" corners really are. I didn't use a chart for that but a fence which had a lot backlight and some structure in it. Also a good indicator for nervous bokeh.

 

I compared those lenses:
  • Sigma 24/1.4 Art
  • Sigma 24-105/4 Art @ 24 mm
  • Nikkor 24/1.4 G which I used a lot
  • Nikkor 14-24/2.8 G which I also use a lot
Camera was D810 on a tripod. I turned it, so the top tube of the fence made a diagonal. Camera was not parallel to it to get an idea of the bokeh. I always used LiveView to focus the left corner and the center. So there's no problem with field curvature, I was just interested in the difference of sharpness  between center and left bottom corner.

 

Here's the whole picture

[Image: i-Z34TRSK-M.jpg]

 

First the centers of the fast primes wide open.

Nikon 24/1.4 @ f/1.4

[Image: i-kj6FM6D-L.jpg]

 

Then the Sigma 24/1.4 Art @ f/1.4

[Image: i-DtVjBdg-L.jpg]

 

To me, the Sigma has a little bit more sharpness and contrast. Now let's take a look at those nasty corners.

First Nikon @ f/1.4

[Image: i-JsJ7Svm-L.jpg]

 

Then the Sigma @ f/1.4

[Image: i-hw38JhS-L.jpg]

 

Of course, no auto-correction of CA involved, otherwise it would be a little pointless. If it's doing alright at f/1.4, I was curious how my other 24 mm capable lenses would do.

 

First The Sigma 24/1.4 @ f/4

[Image: i-JQTmZqQ-L.jpg]

 

Now it's zooming colleague 24-105/4 Art (so that's wide open for that lens)

[Image: i-ktsdBK8-L.jpg]

 

And least the 14-24/2.8 @ f/4

[Image: i-2mGgNFg-L.jpg]

 

I don't want to bore you with all center and corner shots. Anybody interested can see for himself: 24 mm comparison gallery I know, it's not very comfortable but the EXIF-data is included and I tried to give the filenames a little bit of sense.

 

Probably I'll add some night-shots before I sell the Nikkor 24/1.4 but I don't expect dramatic surprises.

#2
Try refocusing the nikon to control the "coma" (field curvature + oblique spherical) in the corners.  It should do very well at f/2 when focused for something between the corner and center ideals.

#3
AiryDiscus, I focused each lens for each aperture and each place (center and left bottom). I don't see the point in refocusing and I don't see the point in refocusing only the Nikon to a different spot - why would I want to focus it between center and corner when I want to have the corner as sharp as possible and f/2 is just not enough DoF?

 

According to the distance measured by the camera, the difference is 0.45 m when focused to the center and 1 m when focused at the corner. Take it with three grains of salt, because some pictures do show 0.84, 0.94 and the "app. 1 m" and the centers differ between 0.45 and 0.47 m. I admit the subject is not the easiest to focus at, even not in LIveView with a loupe. But those are my real life conditions  Smile No OLAF, no MTF chart, no brick-wall, no 17" laptop for tethered shooting. And even LiveView with remote control and mirror up is an exception. Normal conditions to me include phase AF and sometimes questionable shutter speeds.

 

I think the lenses all did quite well and I also think the Sigma prime is a little better in center and much better in the corner because it shows less CA. I'm aware Roger findings are a little different, but then you guys at OLAF control do a great job but not much pictures - no offense meant, of course.

#4
Are you going to use 24mm at such close distances? If not, it might be an idea to do the tests at a bit further distance to see how the lenses perform there...

#5
Yes, I am regularly at close distances with my wide-angles. From very close (which is 0.25 m) to 1.5 m I see quite a lot pictures in Aperture, very often wide open, one or two stops down. That is something "normal" or Macro lenses can't do. I can post some samples when at home. So, I do have a use for fast and sharp wide angle.

 

But for this "test" this was not m main concern. I always was a bit annoyed by the ammount of CA all Nikon f/1.4 lenses show - at least, all I had so far. Ok, those are not the newest designs and the f/1.8 versions are usually better. But I don't want to care about (I'd love to take hat picture wide open but I better close down because of CA). Also, to my taste the Sigma has a slightly nicer bokeh.

#6
Quote:AiryDiscus, I focused each lens for each aperture and each place (center and left bottom). I don't see the point in refocusing and I don't see the point in refocusing only the Nikon to a different spot - why would I want to focus it between center and corner when I want to have the corner as sharp as possible and f/2 is just not enough DoF?

 

According to the distance measured by the camera, the difference is 0.45 m when focused to the center and 1 m when focused at the corner. Take it with three grains of salt, because some pictures do show 0.84, 0.94 and the "app. 1 m" and the centers differ between 0.45 and 0.47 m. I admit the subject is not the easiest to focus at, even not in LIveView with a loupe. But those are my real life conditions  Smile No OLAF, no MTF chart, no brick-wall, no 17" laptop for tethered shooting. And even LiveView with remote control and mirror up is an exception. Normal conditions to me include phase AF and sometimes questionable shutter speeds.

 

I think the lenses all did quite well and I also think the Sigma prime is a little better in center and much better in the corner because it shows less CA. I'm aware Roger findings are a little different, but then you guys at OLAF control do a great job but not much pictures - no offense meant, of course.

I meant for star field tests.  The "coma" as lenstip mislabels it is largely the result of field curvature.  Changing the focus fixes one part of the problem, stopping down to f/2 fixes most of the other half.
#7
Thanks for the info, but I'm not doing star field tests, am I? I'm not certain. I just wanted to have a visual impression of sharpness and CA.

#8
Quote:Probably I'll add some night-shots before I sell the Nikkor 24/1.4 but I don't expect dramatic surprises.
#9
I see. Night-Shots are in my terminology not necessarily star fields, more street scenes or landscapes during night. Unfortunately I couldn't do them tonight, was busy with other things.

#10
Now I did the night-shots. Not many of them, it started to rain again and I'm a little bored with changing lenses and seeking for places with light sources at the right place, distance, brightness.

 

Both shots taken from the same spot. Used LiveView and manual focus to focus on what's in the cropped picture. With some difficulty for the Nikon, because if a lens has flaws it has them in LiveView as well.

 

First the Sigma @ f/1.4:

[Image: i-FLHgcV3-L.jpg]

 

Now the Nikkor

[Image: i-d5nQscD-L.jpg]

 

Same scene, other (left) side with the Sigma

[Image: i-sh8scHv-L.jpg]

 

Now the Nikkor has a bit more troubles with that situation

[Image: i-BK5Sx7s-L.jpg]

 

Probably there is a focus setting which looks a bit better than this one. I didn't do a focus bracketing.

 

Also, one can say "during night i use my tripod and stop down" and that helps, in the center at least. But my reality is
  • I like to use each aperture, not only the stopped down ones
  • I like shooting at night and walking without tripod, so also shooting wide open and at high ISO. IQ? I know how to get higher IQ, those conditions are very static ones and there's no camera doing noiseless pictures at around ISO 10.000 - so, I'm fine with this "noise". I know worse from only ISO 800 films.
  • I like shooting in low light situations
So far, the Nikkor served me well for 5 years. Now there's a new kid in town which is not worse although costing just a little [edit: not more, but] less than half the price of the Nikkor. I don't expect Nikon to make a better one at the same price. So, I can exchange the old with the better new one at practically no costs.

  


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