Testing the Sigma 50mm Art lens in my style of photography

[infared]

However, from what I've read and saw in person, the extra special coatings on the Sigma, actually seem to make it a bit slower than 1.4. It almost seemed that it was about 3/4 of a full stop slower than the Canon.
I'm still wavering, but at this point, I'm leaning towards the 50L 1.2. I was able to shoot some MIGHTY dark bars with this and no additional lights with the 1.2 wide open.
So for when you need very low light...at this point, I'm leaning towards getting the canon 50L 1.2.

There are some topics relating experiences with F1.4 lens in Canon digital cameras, I did not find now, but the conclusion is surprising:

A member of CR did a test with an F1.4 lens (at F1.4) mounted on a Canon DSLR camera with all manual settings, and photographed a target with controlled lighting. Then he repeated the shot with everything the same, except that he put duct tape on the electrical contacts of the lens, so the camera could not identify which lens was being used.

He found that the picture looked darker when the camera could not identify which lens was being used. Neuro then gave a simple explanation and terrifying:

Digital cameras (unlike film) do not capture well the light that hits the sensor at a very tilted angle. How F1.4 lenses (and more luminous) many light rays arrive at quite tilted sensor, and do not penetrate well into the photodiodes. To circumvent this problem, Canon pushes the ISO (in secret) to simulate the use of light rays that exists in the film. Ie. When you select ISO100, the camera secretly push the ISO up to 153 (for example) and compensates for the lower utilization of light rays.

If you select ISO 1600, the camera pushes secretly up to ISO 2129 (for example), and compensates for the lower utilization of light rays. In this case, the noise will be larger than an ISO 1600 "true".

If the lens is not manufactured by Canon itself, ISO not be pushed secret, and the lens will appear darker than a Canon lens that had the ISO pushed.

Terrifying?... I save that adjective for things like Ebola and perhaps automatic weapons pointed at me. LOL! 8)

 

[tcmatthews]

I am increasingly coming to the conclusion that all of the focus inconsistencies are coming from the combination of the advanced Canon focus systems (like in the 5d III) and the sigma lenses. If you look into the the Canon manuals you will notice that on some lens certain focus positions are disabled. Lens and auto focus points are grouped. I do not have a 5D III so I do not know how this affects third party lens.

It is very likely that this auto focus point information is not correctly being sent by the Sigma Art lenses to the Camera. Then when the standard AF Micro-adjustments are done in camera it just makes the situation worst.

It is very possible that the USB Dock is the only way to adjust the Art lenses consistently.

Given the state of Canon 50mm I am really considering getting a Sigma Art 50mm. So if anyone has experience regarding calibration using the USB Dock it would be appreciated.

 

[NancyP]

A good f/2 lens will be very sharp at f/2.8. A great f/2.8 lens will be tack sharp at f/2.8 eg Zeiss 21mm f/2.8.

 

[docsmith]

Not discounting others experiences with the 50A, just saying that my 50A AFs just fine with a 5DIII using the center point or the side points. After reading this thread, I went and tested it again, and still no more variation than any other lens.

 

[ajfotofilmagem]

However, from what I've read and saw in person, the extra special coatings on the Sigma, actually seem to make it a bit slower than 1.4. It almost seemed that it was about 3/4 of a full stop slower than the Canon.
I'm still wavering, but at this point, I'm leaning towards the 50L 1.2. I was able to shoot some MIGHTY dark bars with this and no additional lights with the 1.2 wide open.
So for when you need very low light...at this point, I'm leaning towards getting the canon 50L 1.2.

There are some topics relating experiences with F1.4 lens in Canon digital cameras, I did not find now, but the conclusion is surprising:

A member of CR did a test with an F1.4 lens (at F1.4) mounted on a Canon DSLR camera with all manual settings, and photographed a target with controlled lighting. Then he repeated the shot with everything the same, except that he put duct tape on the electrical contacts of the lens, so the camera could not identify which lens was being used.

He found that the picture looked darker when the camera could not identify which lens was being used. Neuro then gave a simple explanation and terrifying:

Digital cameras (unlike film) do not capture well the light that hits the sensor at a very tilted angle. How F1.4 lenses (and more luminous) many light rays arrive at quite tilted sensor, and do not penetrate well into the photodiodes. To circumvent this problem, Canon pushes the ISO (in secret) to simulate the use of light rays that exists in the film. Ie. When you select ISO100, the camera secretly push the ISO up to 153 (for example) and compensates for the lower utilization of light rays.

Terrifying?... I save that adjective for things like Ebola and perhaps automatic weapons pointed at me. LOL! 8)

In fact, I was terrified when I discovered that my Canon 50 F1.4 only becomes sharp and contrast when used in F2.8. I was also terrified of the price of Canon 50L with a sharpness well below that Sigma Art.

 

[Eldar]

The Sigma 50A is an optically fantastic lens, with a very poor and unstable AF system. As I have stated in other threads, I do not understand how Sigma can push something as inconsistent as this to the market.

 

[zlatko]

The Sigma 50A is an optically fantastic lens, with a very poor and unstable AF system. As I have stated in other threads, I do not understand how Sigma can push something as inconsistent as this to the market.

It is hard to reconcile the diverse opinions about this lens. Some people like yourself report poor & unstable AF. But reading the reviews on B&H, some seem to find the lens outstanding in every way, including AF. So many reviews absolutely glow with praise! I will have to try the 50A for myself at some point. Is it possible that some copies are truly excellent while others are defective?

 

[ajfotofilmagem]

The Sigma 50A is an optically fantastic lens, with a very poor and unstable AF system. As I have stated in other threads, I do not understand how Sigma can push something as inconsistent as this to the market.

It is hard to reconcile the diverse opinions about this lens. Some people like yourself report poor & unstable AF. But reading the reviews on B&H, some seem to find the lens outstanding in every way, including AF. So many reviews absolutely glow with praise! I will have to try the 50A for myself at some point. Is it possible that some copies are truly excellent while others are defective?

Yes, it is possible some Sigma Art work very well and others being inconsistent. But why? I suspect that different bodies behave differently in relation to AF Sigma lenses.

But, and tests that use 5D Mark iii successfully, and others with focus problems? I think the firmware version of the body can cause unpredictable behaviors of AF.

 

[VeloDramatic]

Infrared and VeloDramatic... Glad you are having good luck with the 50 Art lens.

What body are you using your 50 Art on?

Do you use the outer focus points or mainly the center point?

I use the 50 Art on 1Dx, 1D4 and 5D3 bodies. When shooting everything but landscape I'm focused on dynamic composition and don't favor any focus point. As a sports shooter I'm using rear-button focus, cross-type only, often in Servo mode provided the light is decent.

 

[VeloDramatic]

I just purchased the Sigma 50mm Art and without question it's a fantastic lens. It doesn't have the AF response of the 200 f2 but AF is great and the lens is exceptionally sharp. I'm just back from the Hebrides, and a landscape change of pace, where the Sigma 50 performed terrifically... including in portrait orientation with a RRS pano tripod setup for some really nice stitches.

It sounds like a great lens for landscape where you likely stopped down. But did you also try using it at or near its widest aperture? If so, was the autofocus good and accurate most of the time? I'm also curious which camera body you used with the 50 Art and whether the outer AF points performed OK. Thanks in advance.

Sure, I'll shoot below f2 if the light conditions warrant/necessitate or I'm after a particularly shallow look for a particular shot but I'm just not fixated on f1.4. I don't buy quality glass or solely judge it's performance by how it performs at the limit. I know that's not why you are asking but it's always in my thoughts when thinking about lens performance. You get people who say why would you bother spending more to buy a f1.4 lens and shoot it at f2 or f4? Answer, because it's better glass and a stop or two of performance can sometimes save your ass on a job.

I haven't seen any AF problems yet at any aperture. I have the USB dock but haven't done any additional calibration. Bodies are 1Dx, 1D4, 5D3 and 5D2. I've shot the 50 art on all four.

 

[infared]

The Sigma 50A is an optically fantastic lens, with a very poor and unstable AF system. As I have stated in other threads, I do not understand how Sigma can push something as inconsistent as this to the market.

It is hard to reconcile the diverse opinions about this lens. Some people like yourself report poor & unstable AF. But reading the reviews on B&H, some seem to find the lens outstanding in every way, including AF. So many reviews absolutely glow with praise! I will have to try the 50A for myself at some point. Is it possible that some copies are truly excellent while others are defective?

Yes...I got a defective one from B&H...spent a day screwing around with the Sigma Dock..etc...was making me CRAZY and I though..."why am I doing someone else's work for them??? on a $950 lens no less..."
I called B&H and told them the situation..and they were well aware of the issue..at least in a one-on-one situation and they sent me out another lens right away. It was great...just some minor little tweeks on the Sigma Dock... Works great for my needs. BTW I am running the latest version of firmware on my 5DIII....but my experience would tell me that it is a lens issue..not a firmware issue...
For how the lens WOW's me....I thought that it was certainly worth the hassel. ...and let's face it..the experience that I had is total bull shit! LOL!

 

[StudentOfLight]

Are the AF issues across the board (i.e. with all bodies) or does it only happen with the 61pt AF system bodies?

For example, my Tamron 24-70 VC does not work well with the 5D-III but works fine with my 6D and 1Ds-III. So does the Sigma lens have a compatibility issue with the 61pt AF system or is it just completely unreliable due to some design issue (e.g. excessive slop in AF gearing or field curvature etc...) ???

 

[Ripley]

Are the AF issues across the board (i.e. with all bodies) or does it only happen with the 61pt AF system bodies?

For example, my Tamron 24-70 VC does not work well with the 5D-III but works fine with my 6D and 1Ds-III. So does the Sigma lens have a compatibility issue with the 61pt AF system or is it just completely unreliable due to some design issue (e.g. excessive slop in AF gearing or field curvature etc...) ???

I can't comment on your question directly because I only have one camera body. However, looking back at the shoots I did while I had this lens I'm noticing something... it only front focused in the low light situations but all of the daytime shots look spot on.

The focus ring on the copy I rented was tightly assembled... stiffer than either of my f2.8 zooms. I know that doesn't necessarily correlate to AF performance, but thought someone might care to know.