It was a given in the old days that third party lenses weren't as good as the camera maker's own equivalent lenses.
This was true because most third party lens makers like Tamron, Tokina or Sigma built their lenses to a budget to compete against the big companies like Canon and Nikon, which produced excellent but consequently more expensive lenses.
Back in the days of film, deficiencies in lenses weren't that obvious since most people could only assess the quality of their lenses when they printed their photos and most of us very rarely went beyond 3 x 6in or 8 x10in prints.
With print sizes this small, many photos, even those taken with really crap lenses, tend to look pretty okay.
Then came the era of digital cameras and now suddenly people could view their shots at 100% on a giant 25in or 30in monitor, looking at every photo down to the pixel level.
With that kind of power in everybody's hands, every deficiency on a lens or camera is magnified tenfold, when these so-called pixel peepers view their images at 100% on a super large screen.
Suddenly, every company that produces lenses started to realise that making lenses "just good enough" doesn't cut it anymore since almost anybody with a PC or Mac and a digital camera could see problems like chromatic aberration and softness in the lens.
So camera makers started to step up their lens designs, producing lenses that were really much better, larger and consequently more expensive than their film era counterparts.
However it was only two or three years ago that third party lens makers have started upping their game and producing lenses which are markedly better.
In fact, with the latest "Art" lenses from Sigma and some newer Tamron “SP” lenses, third party lens makers have made a real paradigm shift (this is the first time I've used the term "paradigm shift" in my 15 years as a reporter!) to produce lenses which actually rival the quality of the camera maker's own lenses.
Sigma for one has released some excellent lenses recently such as the 50mm f/1.4 Art (for full frame and APS-C) and the 18-35mm f/1.8 Art (for APS-C) which are actually better than anything made by first party camera makers.
I recently wanted to upgrade my 24-85mm f/3.5-4.5 kit lens and my aging 60mm macro -- both very important lenses in my daily work -- and did some research on the available first party and third party options out there.
My criteria was to put image quality first and price second. I'm not saying that price was not a concern because it was -- it's just that if there there was a big drop in quality compared with the far more expensive first party option, I'd go for the first party lens instead.
Well, after extensive research, checking out DxO Mark (currently the de facto standard when it comes to software used to test lens quality) scores and actually playing with the lenses myself, I settled on the Tamron SP 24-70mm f/2.8 Di VC USD and I couldn't be happier with the results.
This Tamron lens' optics have been reviewed favourably by various independent resources but what pushed me to buy it over the camera maker's 24-70mm f/2.8 was that the Tamron comes with built-in optical image stabilisation, which is fairly uncommon in 24-70mm zoom lenses.
I've been using the lens now for a while and I have to say I'm very satisfied with the results -- the lens is sharp at f/2.8 at the 24mm end and is still pretty sharp at 70mm at the same aperture although at 70mm sharpness is actually improved further if you stop down to f/4.
Tamron's VC (or vibration compensation, the name they give to their optical image stabilisation system) is particularly notable -- it's pretty good and actually allowed me to shoot at shutter speeds way below what I'd normally be able to handhold.
I was so happy with the Tamron 24-70mm lens that my next purchase was the Tamron SP 90mm f/2.8 Macro Di VC USD, a replacement for my 60mm f/2.8 macro.
All I have to say about this one is that the Tamron is a big upgrade from the 60mm -- it uses a modern ultrasonic motor instead of the screwdrive system on my 60mm which means it focuses nearly silent and it also comes with optical image stabilisation.
The optics on this lens are also top notch -- I have no complaints about it shooting at any aperture except the smallest (where any lens will be soft because of diffraction).
Now it may seem like I’ve been paid by Tamron to plug their product, but I assure you I have not -- in fact, these two lenses were paid for with money out of my own pocket and it just happened that these Tamron lenses fit was I was looking for in my lens upgrades.
My point is that buying a third party lens is no longer considered "a poor man's option" -- these lenses are definitely cheaper than the first party counterparts, sure, but as I've found out, image quality is no longer a compromise.
Just a quick note here -- not all lenses in the lineup of lenses from either Tamron or Sigma are excellent -- in fact there are loads of them that are downright awful and made to fit a budget.
You do have to read reviews and empirical test scores to separate the wheat from the chaff (or the padi from the sekam if you want to give it a Malaysian twist).