100-300mm f/4 Tokina AT-X SD
TheTokina AT-X 100-300mm zoom exhibits build quality that is easily as good as the best lenses made by Minolta.

If you have read my 'Background' page with its brief review of the sharpness of zooms versus primes, you might wonder why I own any zooms at all! You might also think that if I was going to own a zoom, then surely it would be a Minolta zoom. After all, aren't brand name lenses always better than third-party lenses?

Well, the reason that I own this lens is that I was reading the local camera trader magazine, and I came across the advertisment for the lens at a very reasonable price. I was intriged by it's fast speed (at f/4 it is a full third of a stop faster than the Minolta 300mm prime), and I wanted to see how it compared. After all, the Tokina AT-X line had been marketed as a professional line of lenses, the top of three seperate lens lines including consumer and enthusiast models. Upon purchasing the lens I was told by the seller that I would be amazed by the sharpness it delivered, but I wasn't sure what to think - after all, he was selling the lens, surely he would say it was sharp. I wanted to see for myself the results that the lens could produce.

The first thing that I noticed about the zoom is that it is big and heavy, with what looks to be outstanding build quality. At around 24cm in length it is 4cm longer than the 300mm f/4.5 MD, and as far as the weight is concerned, it is significantly heavier at 1.35kg compared to the prime's weight of 754gm. The front element is also larger, at 77mm compared to the Minolta standard of 72mm. It is easy to see why a tripod mount is necessary for the lens!

The Tokina AT-X 100-300mm f/4 SD was released in 1986 with a list price of US$719, or approximately $1,180 in current value (after allowing for inflation), so it was certainly not an inexpensive lens.

I had some spare time on a Saturday, so I took out the zoom, together with the Minolta 200mm f/2.8 MD Rokkor-X and the 300mm f/4.5 MD Rokkor-X. I wanted to get some concrete answers - how would this lens compare with the primes?

Tests at 300mm
Here's the results when compared to the 300mm f/4.5 MD Rokkor-X, a lens with a great reputation for corner to corner sharpness.
The original image shot with the 100-300mm at 300mm, f/8 Apologies for the boring image!
Performance at f/4

100-300mm f/4 at f/4 - centre

300mm f/4.5 at f/4.5 - centre

100-300mm f/4 at f/4 - side
300mm f/4.5 at f/4.5 - side
100-300mm f/4 at f/4 - corner
300mm f/4.5 at f/4.5 - corner

Based upon the above, I would reach the conclusion that at f/4, the zoom is actually sharper in the centre than the prime, softening slightly towards the edges. This is an outstanding result for the zoom, particularly when it is considered that the zoom is at f/4, compared to the prime's f/4.5.

When designing a lens, one can either endeavour for higher centre sharpness at the cost of some edge resolution, or better overall sharpness with a slight reduction in centre resolution. With the 300mm f/4.5 MD I believe that the lens designers actually decided to forego some centre sharpness in order to optimise sharpness to the edges. Accordingly, its overall performance is excellent. With the zoom, I believe that the objective was to obtain maximum centre sharpness, at the cost of some edge detail.

However, for the lens to even come close to the prime's resolution, let alone surpass it in one aspect, is an incredible result and a tribute to this design. I am starting to think that my investment in this lens was money well spent!

Performance at f/8

100-300mm f/4 at f/8 - centre

300mm f/4.5 at f/8 - centre

100-300mm f/4 at f/8 - side
300mm f/4.5 at f/8 - side
100-300mm f/4 at f/8 - corner
300mm f/4.5 at f/8 - corner

At f/8 the results are more of the same - the prime beats the zoom at the edges, and the zoom outperforms the prime in the middle. By the way, I should apologise for the film quality in these tests. The shots were all taken on Kodak Gold 400, instead of the Fuji Reala that I would normally use for lens tests.

I actually plan to test this lens again using a finer grain print film as soon as I have my 5400 dpi film scanner. At that stage we will really see what it is capable of producing.

Tests at 200mm
Here's the results when compared to the 200mm f/2.8 MD Rokkor-X, a lens which would naturally be expected to have significantly better results than the zoom.
The original image shot with the 100-300mm at 200mm
Performance at f/4

100-300mm f/4 at f/4 - centre

200mm f/2.8 at f/4 - centre

100-300mm f/4 at f/4 - side
200mm f/2.8 at f/4 - side
100-300mm f/4 at f/4 - corner
200mm f/2.8 at f/4 - corner

At f/4 the magnificent 200mm f/2.8 MD Rokkor-X records a sharper result than the zoom across the entire frame, but the performance of the zoom is still very good. The main difference between the two is that the prime does record better contrast.

Based upon the crops shown above we can conclude that the zoom is a very good performer at 200mm, providing sharp results right to the corners. Given that this is achieved wide open when the prime is stopped down one stop is even more impressive.

Performance at f/5.6

100-300mm f/4 at f/5.6 - centre

200mm f/2.8 at f/5.6 - centre

100-300mm f/4 at f/5.6 - side
200mm f/2.8 at f/5.6 - side
100-300mm f/4 at f/5.6 - corner
200mm f/2.8 at f/5.6 - corner

The results at f/5.6 tell the same story - excellent sharpness which is nearly on a par with the legendary 200mm f/2.8 lens. Contrast is marginally below the level of the prime, but overall the lens is an outstanding optic, and I am totally comfortable selecting it for use in circumstances where an ability to change focal lengths quickly would be advantageous. When a photographer is as 'zoom-phobic' as me, a statement like this means a great deal.

With the internal focus construction of the lens, the fast speed and the tripod mount the 100-300mm is an obvious choice for sports photography. This is because the focus can be adjusted quickly (internal focus construction), the tripod mount is great for use with a monopod, and the bright viewfinder makes fast, accurate focusing a breeze.

100-300mm Tokina AT-X zoom Werribee Open Plains Zoo, Melbourne Australia

This lens is an absolute pleasure to use, and I can see that its speed and sharpness are going to be very advantageous when shooting sports events. While the tests I have conducted are preliminary, they amply demonstrate the capabilities of the lens, and are enough to make me reassess my preconceived notions about the quality of zooms.

The build quality is truly excellent and the equivalent of Minolta's best lenses, and overall I I can't help but give this lens the praise it is due. If you get a chance to purchase one of these lenses don't think twice, just get it - you will not regret it.

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