How do I choose which 24-70mm lens?

Question

This is not 'which should I choose?' but 'how do I make the decision?'.
My experience is quite limited, I've not had my first DSLR a year yet.

The closest I can find is Michael Clark's answer to Which lens is sharper? The Sigma 18-50mm f2.8 or the Tamron 17-50mm f2.8? which points out things between those 2 lenses I wouldn't have even known to look for.

My criteria are
approx 24-70mm
f2.8
'sharp'
after that I'm at a bit of a loss

I want it to cover my existing, but soon to be sold, kit 18-55mm & Nikon 24-120mm [which I don't like much at all] but am not interested in going wider than ~24mm for now.
I tend towards portrait & macro photography; lots of light, tripod & remote shutter release. I like bokeh, or to be more precise, I like out of focus backgrounds with clear emphasis on the subject.
I'm also, for this lens, hoping to use it as a general-purpose walkabout, just in case. The 24-120 covered that nicely, but it doesn't really satisfy for my studio work.
I have a 70-300mm lens I am satisfied with for longer ranges.

The choices as I see it are

• AF-S Nikkor 24-70mm f/2.8G ED at approx £750-1000 - lots of choice on the used market
• Tokina AT-X 24-70mm F2.8 Pro FX - £675-900 - little choice of used, lower market presence altogether so opinions are thin on the ground..

• Tamron SP 24-70mm f/2.8 Di VC USD - £600-800 - fair choice of used.

  & the rank outsider right now

• Tamron SP AF 28-75mm f/2.8 XR Di LD Aspherical IF Macro - approx £200 used.

I'm assuming that based on price alone, that's about the correct order for quality.

Ken Rockwell seems to like the Tokina, & I like what he has to say about it, even with the negative comment that it's bit slow to focus.
The Nikon would seem, though, to be the best bet... as it's a Nikon, if for no other reason.
The Tamrons, one pricier than the other so let's assume the cheap one will be... cheap.

Of course, no-one can choose for me - but how do I go about making the decision? Trying them all out at home is really not an option, so I'm going to have to choose from 'spec' & 'reviews'.

Maybe I'm looking for the "gotchas", the 'I wouldn't use abc for portraits', or 'watch out for the xyz at longer lengths'; 'the abc is soft at the edges'... 'the QC isn't so good & you can easily get a bad one'...
or maybe I'm looking for a simple, reinforced statement - 'you can't go wrong with abc for the money, don't waste it on xyz'...

Answer 1

I've recently been round this loop, although admittedly on the Canon side rather than Nikon. Fortunately, The Digital Picture did a very nice comparison of most of the available 24-70 lenses:

• Canon (both original and II)
• Sigma (not quite sure why you're not including this one in your possibilities, as it seems to be available in F mount)
• Tamron

The primary conclusion is the expected one: the Canon lens is the best, particularly in the corners on full-frame. But then it should be as it's twice the cost of the rest. I'd imagine the Nikon 24-70 is pretty much up there with the Canon in terms of image quality. The other notable point is that the Sigma is reported in multiple reviews as being very poor at 70mm f/2.8 - if that's important for you, you probably want to avoid it. Unfortunately, The Digital Picture haven't done a review of the Tokina, but it is generally reviewed as being a very sharp lens, but beware about the focus motor.

For what it's worth, I went for the Tamron in the end: a combination of the image stabilization and a good price from a well known Hong Kong retailer was what made the decision in the end. Am I happy with it? Yes - it was bought to let me do some gig photography, and lets me do that. I personally wouldn't use it as a "walkaround" lens though - it's too big and heavy. You may be more prepared to put up with that than me though!

As for how you make the decision, to me it's a question of what you want the lens for. If you need that corner sharpness, then the first party lens is what you need. If you don't, it's a toss-up between the Tokina and the Tamron. The Tokina is probably sharper, but the Tamron has quieter focusing and VC. I'd probably avoid the Sigma (due to the poor performance at 70mm f/2.8 - why are you buying an f/2.8 lens if you're not going to use it at f/2.8?) and the cheap Tamron.

Two final comments:

• Everyone is waiting to see what the Sigma 24-70 Art is like - due out real soon now. If it's anything like the quality of the recent Art lenses, it will be a real competitor with the first party lenses - but will probably also have a price tag to match.
• I wouldn't trust anyone other than Lens Rentals if they say "you can get a bad copy": firstly because what is a "good copy" on one body can be a "bad copy" on a different body, and because you need to see more than one copy of a lens to know if it's bad QC or just you being unlucky.

Answer 2

I've got an acquaintance who does some very high quality work with a Nikon D810 and the Tamron SP 24-70mm f/2.8 Di VC as his main combination. The lens is competitive with the the big boys. It might not be quite as good under laboratory conditions as some of the others (sometimes it is, though) but you can take some very nice pictures with it. If I had not bought an EF 24-70mm f/2.8 (original version) barely a month before Tamron announced this lens back in 2012, I would have plenty of personal experience to add myself. If I were to need another 24-70/2.8 tomorrow it would be the first place I would look.

Since you are looking at the used market, you might need to be aware that a few of the very earliest examples of the Tamron bought by lensrentals.com had an issue with the back element of the first group getting loose inside the lens. Roger Cicala made a blog entry about it back in September 2012. As Roger showed in a subsequent blog entry from January 2013, Tamron had modified the lens' design slightly to correct the problem. Roger has said more recently that he hasn't seen the issue any more after the initial batch from back in 2012. All of the ones that failed did so in the first few months lensrentals had them. The torture test of two trips via FedEx or UPS that his lenses are subjected to for almost every time one is rented is a crucible into which most lenses will never find themselves placed. Even though six months at lensrentals is probably more like several years in most of our camera bags, I can't imagine one of the early defective lenses is still in circulation without having failed and needed to be sent to Tamron for repair unless it has been sitting on a shelf unused for over four years. I've not seen any reports of the issue other than the one from Roger. And Tamron does offer a five year warranty, compared to one year for most everyone else.

Answer 3

Sharpness certainly is the prime requirement when it comes to lenses. Software is certainly unable to compensate for a soft lens. Other aberrations from most problematic to easiest to correct in software:

• Distortion - Any correction in distortion affects framing.
• Flare - Causes plenty of issue uneven zones of contrasts plus artifacts.
• Poor Contrast
• Chromatic aberrations
• Vignetting

So when choosing a lens, I consider its performance in these areas in that order. As much as I hate vignetting, it is much better to have light fall-off than distortion.

The other thing that software cannot compensate for is slow autofocus speed. Once the shot is out of focus, it's out. This matters less if you shoot mostly static subjects.

Given those consideration, I am highly surprised you are not considering the Sigma Art 24-70mm F/2.8 DG OS HSM. It is extremely sharp, has excellent resistence to flare and low distortion.

Second to that the Nikon is very sharp through its entire focal-length even when wide open. Plus, it focuses very quickly. The Nikon shows almost no vignetting and extremely little distortion.

Heard good things about the Tokina but I have never actually seen one.

The Tamron should be avoided given that you intend to shoot portraits with it. While this is one of the better Tamron lenses and it is reasonably sharp towards the wide end, you still need to stop it down to F/5.6 to get as sharp as the Sigma or Nikon and then, it's goodbye bokeh. Near the long end, it is quite soft wide open and still needs to be taken down to F/5.6 to be sharp. For landscapes, this would be OK, but not when your typical portrait is usually taken between 50-70mm at F/2.8 which is when this lens is at its weakest.