Thomas902 Loc: Washington DC

"What do you think. ... Be honest..." Jules it looks like your copy of that AF-S 50mm f/1.4G is a tad better than the one I recently sold...

That said I've got a better idea... Why don't you be the judge... While I know my copy of the Sigma 17-50mm f/2.8 was far better than my AF-S 50mm f/2.8 Nikkor sample variations can indeed play into the mix...

So below is a shot I just set up to test the Sigma for you on a D7200...
It is a worst case scenario at near minimum focus distance for 50mm at f/2.8
Hand holding at 1/320 and pushed the ISO up to 3200 (yes I know you're at 5000 on your series) but my D7200 doesn't like to go above 3200. Illumination was from a small desk lamp...

Ok, I turned off AutoFine tune so this is the native focus acuity right out of the box (which is spot on)
Yes I had Sigma's OS turned on...

If you pixel peep you'll see that the Sigma has only a very faint trace of color fringing (chromatic aberration) wide open (unlike the Nikkor which looks like 4th of July fireworks wide open). This occurs at the edges of the frame primarily... in the center they are totally absent.

In this image I focused on the word "Nikon" thus there are certainly out of focus high contrast edges as you move away from "Nikon" however no glaring baby blue and pink color fringing... only near the edge at the very top can traces of magenta be seen around the fonts...

Also you can judge the distortion which is likely at it's max at this short distance... same with vignette... yes the Sigma vignettes a tad but is easily handled in post...

btw this image was downsized to 10x15 from 13.33x20... so resolution isn't near max... trust me it's razor sharp for any portion within critical focus...

Now the 800 lbs gorilla in the room... it's a Zoom! You aren't forced to compromise... you can easily fill the frame... again how cool is that!

Now the down side: The focus ring moves when you press your AF button so fingers have to stay clear... While this hasn't been a problem for me, however I've become one with this lens by now... just needed to give you a heads up about the way you hold this massive heavy Pro-Glass... makes the 50mm Nikkor feel like a toy... (it actually weight over twice as much as the 50mm f/1.4 Nikkor)

However please don't take my word for this last time I looked B&H had over 700 reviews on this epic piece of kit...
I totally love this Sigma because it works for me... Others may have a completely different take on this...
Best Advice? Take your time... test and test again... keep an open mind and remember you can save way over $100 on a Nikon USA Refurb of that 50mm Nikkor.

As far as how quick to lock focus? Using the center cross-type AF point my copy of the Sigma is faster...
Using the outer edge AF points I'm guessing they are about the same... I don't have the 50mm any more to double check... Read the reviews on B&H they should give you an better idea. folks like to bitch and moan if their lens doesn't meet and or exceed expectations... lol

Hope this helps...

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Thomas902 Loc: Washington DC

Jules after sleeping on this here are my honest thoughts albeit given that I've sold my AF-S 50mm f/1.4G Nikkor they aren't as relevant since a current real-time test isn't an option.

First and aforemost.... Totally loved your series on the High School girls Basketball... You have an excellent eye for aesthetics... epic compositions... You truly captured the spirit of this team event. Fabulous Cheerleaders, if a little taller they could walk the fashion runways....

Ok, my best guess is to try the Nikkor at f/2.5 rather than f/2.2... Sometimes even a third of a stop can produce dramatic improvements when shooting close to wide open... This comes from countless hours of testing my glass...

You got lucky since DxOmark tested both lenses... however only the Sigma was tested on a D500... and obviously the Nikkor is going to looks epic on a D800e... FX does hold an advantage there...

However after careful deliberation I'm thinking the Nikkor will have better edge to edge acuity at f/2.5 then the Sigma at f/2.8. The kicker is with the Sigma being able to crop to fill frame may result in a "wash' when averaging many captures a.k.a. prime against a zoom. Don't know but I will say this... I've come to love being able to shoot at 17mm (25mm equivalent) without having to change lenses. Sometimes wide angle can (and does) yield some breathtaking perspectives...

From my experience the Nikkor is pretty much equal to the Sigma at f/2.8 and above... and it's Full Frame so you actually get a 75mm on DX and 50mm on FF... That's nice. And since it's a Nikkor it will focus spot on... no missing focus silliness that many Sigma's are famous for... though my copy of the 17-50mm always nail focus (but I always use the single center cross type AF point). Uncertain how it would handle on the D500's vast array of focus points or it's "Group" focus point scenario... I gave up on using "Group" on my D810 since it kept locking on the nearest player and not the one with the ball.

As you can image there are a myriad of factors to contend with in this mix... Bottom Line? I sold my AF-S 50mm f/1.4G because for my needs my AF 60mm f/2.8D was head and shoulders sharper across the frame and better than the 50mm Nikkor at the aperture I'm using in my work... besides that AF 60mm f/2.8D is Pro Quality Glass... however being a "micro" it doesn't focus fast enough for shooting sports. Thus the Sigma is my choice for action... Your situation(s) and scenarios may be entirely different so you have to decide what will work best for your specific needs.

One thing for certain you have an amazing ability to get the "shot" in sports so I'm looking forward to more of your epic sports series...

All the best on your journey Jules...

Jules Karney Loc: Las Vegas, Nevada

Thank you Sir Thomas for your continuing efforts to lead me and others in the right direction regarding photography in general and on the lens choice. Your time is special and what you say is indescribable.

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pnittoly Loc: Mountainside, New Jersey

This addressed to Tom.
I echo my friend Jules’ comments. Thanks for sharing your valuable experiences with us, especially neophytes like me ! Paul

Thomas902 Loc: Washington DC

I appreciate your taking the time to view and reflect pnittoly... Glad you found it of merit...
btw, We're all in this together, i.e. we stand on the shoulders of those who have gone before us...

Oft said it's not the gear it's the photographer that matters... While I totally agree with this inference however for a commercial sports photographer sadly their kit does matter a lot more so than many other genres. There is a barrier to entry in commercial sports, that being the glass needed to freeze dynamic motion, also to isolate players at distance... neither of these attributes come cheap thus like many others I constantly search for cost effective solutions to this dilemma. Especially for Nikon shooters since Nikon's offerings are becoming less and less competitive for the features and attributes they bring to the table.

Nikon sadly refuses to produce Pro Grade DX glass... their marketing strategies ring loud and clear... Force users to pony up full price for FX glass... likely in hopes that they will "see the light" and migrate to Full Frame. In the current marketplace third party glass has become a more realistic option. In this case, Nikon hasn't updated their AF-S 50mm f/1.4 since 2008! That's over a decade...

There are no easy solutions and the fabulous Sigma 50mm AF f/1.4 DG HSM ART lens is pricey at just under 1K and weighs in at just over 800 grams which removes it from the cost effective solution mix.

btw, I still have and use my AF 85mm f/1.4D which is optically well suited to my tastes in editorial fashion... and the AF-S 85mm f/1.8G which is likely the very best solution (on a Full Frame body) for basket ball, and volley ball (in door) in my humble estimation. DxOMark gives the AF-S 85mm f/1.8G it's highest ratings... I concur completely from my experience with my copy for this "made in china" plastic fantastic... lol

Thanks again pnittoly

pnittoly Loc: Mountainside, New Jersey

Thanks again Tom for your thoughts and observations. Paul

Jules Karney Loc: Las Vegas, Nevada

Sir Thomas is the best.

DelRae Loc: Oregon

You really do great Pictures Thanks for sharing them DelRae