300 mm lens test
A focal length of 300 mm lies at the borderline between medium and long telephoto lenses. 300 mm f/2.8 lenses are generally regarded as professional (not the least, because of their weight and cost). All major DSLR camera brands offer at least one model with these specifications. However, lenses of the same focal length and speed are also marketed by at least three third-party lens manufacturers (although the Tamron and Tokina are so similar in design that they could be essentially the same lens), and Sigma sells also a 120-300 f/2.8 zoom. Although still expensive, these lenses are within the reach of many serious amateurs. There are even a few "monster" 300 mm f/2 lenses. You probably can't afford to buy one of them unless you take out a second mortgage on your house.
Roughly mid-way in the price range, Nikon manufactures a 300 mm f/4 which is relatively affordable, Sigma has a pro/semi-pro 100-300 f/4. At the low end of the price range, numerous consumer zooms reach this focal length with a speed of f/5.6. In short, there is a lot to choose from at this focal length. 300 mm lenses are also at the borderline between lenses that can be used handheld without serious difficulty, and lenses that almost always require a heavy tripod for stabilization. 300 mm is a popular choice of focal length for many uses. It lies at the high end for "normal" photography, is frequently used for sports, events and celebrities, and lies at the low end for bird and wildlife photography. But how much money do you need to pay, and how much weight must you carry on your shoulders in order to get a quality that is sufficient/satisfactory for your needs?
In this page, I compare the performance of a 300 mm prime and a few 300 mm zooms that I own and/or use. As usual for this site, I only cover the range of lenses I have directly available.
At the high end of the range of lenses I use is the Tamron SP AF LD 300 mm f/2.8 (above, rightmost). This is a lens of supposedly high quality and rather high price (albeit substantially less than its Nikkor equivalents). The matte camouflage finish is not standard, but adhesive-backed cloth I attached onto the lens barrel and shade to make it less conspicuous. At the opposite extreme is the Nikkor AF 70-300 mm f/4-5.6 G (above, leftmost), which is a cheap consumer-grade lens designed to do away with all complications and sophistication that Nikon regards unnecessary for the budget-conscious amateur. On the second-hand market, the Tamron 300 still commands a rather high price. In my case, I bought second-hand a rather old version of this lens in quite good condition, and it did not cost me much less than my new-bought Sigma 100-300 f/4. The Nikkor 70-300, on the other hand, can be bought used for peanuts (literally - in Japan it costs like a couple of large peanut bags).
To go even cheaper, one can rummage among the broken lenses found in the junk bins of Japanese second-hand shops. I did, and came up with a Tamron Aspherical LD "Macro" 28-300 mm f/3.5-6.3, and a Sigma Apo "Macro" 70-300 f/4-5.6 D (above). I could not see anything obviously wrong with these lenses in the shop, and in fact it turned out there isn't. Perhaps they were junked because their second-hand value was regarded as so low that they did not deserve a place in the locked-up cabinets. Interestingly, I see every day worse junk advertised on eBay for much higher prices. These two lenses constitute the absolute bottom-line for this test. In addition, I also considered the Sigma Apo 100-300 mm f/4 EX DG. This lens is reviewed in detail here.
The difference in size of the two lenses tested here is even more evident when the lens shades are mounted. Both lens shades can be mounted in reversed position on the lens. The lens shade of the Tamron 300 is partly made of plastic, with a rubber-lined front edge and, in some models, a rubber ring near its mount.
Nikkor AF 70-300 mm f/4-5.6 G
This lens is in the G series, and therefore lacks an aperture ring. The aperture is set automatically by the camera, or manually by turning a dial on the camera body. The lens is very lightweight (500 g) for a zoom that reaches 300 mm.
The zoom ring is large and rubber-clad, and you hold the lens by this ring. Autofocus is of the mechanical type. The focus ring is very small (albeit not as minuscule as the one of other cheap Nikkors, like the AF 35-70 f/3.3-4.5) and permanently engaged to the autofocus gears. It turns when autofocusing, so you better remember not to block it, or something may break. Autofocus can be disengaged on the camera body only. The front element turns when focusing, so you are left to your own devices if you want to use a polarizer. Just do not hold the polarizer to prevent it from rotating while the lens focuses, because the barrel wobbles noticeably when touched, especially at full zoom, and feels very fragile. Both the focus and the zoom rings feel imprecise when turned manually.
There is no tripod collar, and no part of the barrel that you can lay onto a stable surface for steadying the lens (unless you are willing to give up zooming).
The optical design seems similar to the one employed by the AF Nikkor 70-300 f/4-5.6 ED. However, the latter has a special-glass element that is not present in the G model. The ED model also has a metal bayonet, a larger, rubber-clad focusing ring, an aperture ring, and an overall more solid feel. It is also significantly more expensive.
The G model looks better than it feels. It has the same black plastic finish of more expensive Nikkor lenses. There is also a silver version that matches the silver D50 body. I have not seen many of these, and I should expect the silver paint to wear or scratch more easily than the standard black plastic.
This is a cheap consumer-grade lens, and it does feel like one when handled. It is made entirely of plastic (except the lenses and small internal parts). Even the bayonet to attach the lens to the camera body is made of plastic. I have seen several cheap Nikkor lenses with broken plastic bayonets in Japanese second-hand camera stores. Apparently, it is sufficient to drop the camera from a moderate height, hit an object with the lens barrel, or grab the camera by the lens barrel and have the neck strap snag something to break off the plastic bayonet. The Nikon F bayonet used by all lenses for Nikon DSLRs simply is not designed to be made of plastic. As a whole, the Nikkor 70-300 G is as close to a disposable DSLR lens as I have seen so far.
If you get past the obvious weaknesses of this lens, you have a cheap and lightweight consumer zoom that does not perform too badly (see below). In practical use, it shows a propensity for chromatic aberration, diffused flare and haloes around high-contrast edges. It perform better with scenes of moderate contrast. It may be attractive if you have extreme budget constraints, or need the lightest possible lens that reaches 300 mm, or know that you will use it only occasionally. Should you decide later that you need a better lens, because of the low price you will hardly regret spending the money on this lens in the first place. In spite of owning much better lenses, I still carry it now and then, especially when I am forced to use a small camera bag.
Tamron SP AF LD 300 mm f/2.8
This is a heavy lens (2.8 kg) that has been manufactured in several models in the course of many years. My specimen is a rather old one with a telescoping metal sleeve that slides backwards to cover the focusing ring when using autofocus (because you are not supposed to turn or block the focusing ring manually in autofocus mode). Autofocus is mechanical in all models, but more recent ones have a clutch to disengage the focusing ring, instead of a sleeve to cover it (you push the focus ring forward and back to engage and disengage autofocus). Focusing is internal, so turning the focus ring requires very little force, and can be done literally with a fingertip. A model with interchangeable (Adaptall 2 series) camera mounts had conventional and manual-only focus. The whole lens barrel is made of metal, except for small parts like the aperture ring and most of the lens shade. The focus scale is covered by a transparent window.
My model is painted in a grey enamel, but there are also black and even white ones. I covered most of the lens with adhesive-backed camouflage cloth, which makes the lens less noticeable, cuts reflexes, makes it easier to hand-hold, and also provides some protection against scratches and bumps.
The lens rotates within the tripod collar very smoothly when the knob on its left side is loosened. The collar apparently is lubricated internally with viscous fat, and cannot be removed.
The tripod shoe is very small, and very close to the lens. This has both good and bad consequences. A shoe located close to the centre of mass of the lens makes it easier to balance on a tripod when inclined up or down. On the other hand, the surface of the shoe is so small that it is difficult to tighten properly on a tripod head or plate. In particular, platforms or heads covered with a rubber pad must be tightened very hard, or the lens will wobble and vibrate. The shoe has both a 1/4 in. and a 5/8 in. socket. I keep a 1/4 in. adapter permanently screwed into the larger socket, because all my tripod heads have 1/4 in. studs. If you use a plate or head with an elongated screw hole, you may want to use both sockets to make the joint more rigid. The two sockets are quite close to each other, so you must use two screws with small heads.
My model has a lug at the back of the tripod shoe that can be used to fasten a strap. Other models have a lug on the collar itself. A neck or shoulder strap is obviously a must to carry this lens when not in a bag. In fact, I initially tried to carry the lens, with camera, teleconverter and monopod attached, by cradling it in my arms. It is not easy to do so, because the lens is heavy and quite smooth. After a short time, I accidentally pressed the lens-release button of the teleconverter, and the camera and teleconverter fell onto a dusty road. No damage done, but I learned the lesson. Afterwards, I always placed both the lens strap and the camera strap around my neck. The camera body came loose a couple more times, but with no consequences.
The tripod shoe is so small because a longer one would not allow the lens shade to be mounted on the lens in reversed position. A plate attached to the shoe likewise prevents this, so if you want to keep a plate permanently attached to this lens, you are in for some modification work. My suggestion is to manufacture a block of aluminium 39 by 39 mm wide (the area of the shoe) by 17 mm thick (to clear the lens shade when reversed). This block should attach to the shoe via its screw sockets, and a plate (or shoe with tripod sockets) attached at the bottom of the block. The plate or shoe should also be several cm longer than the block in the forward direction, because the centre of mass of the lens (at least with a medium-weight camera) lies forward of the lens shoe. The above measurements apply to my model only.
There is at least one model with a long and high tripod shoe that should not need modification. This tripod shoe can be removed from the collar by unscrewing two large knobs.
The lens shade is mostly thick plastic with a rubber-lined edge and a rubber ring on its outside, and has a metal ring at its base that attaches to a metal ring around the filter mount of the lens by two military-style friction wing nuts. The nuts have a small handle that can be turned up for tightening, and pushed flat into a recessed socket on the sides of the lens shade when the lens is stored or in use. It takes some time to tighten and untighten the wing nuts, but when set they hold the lens shade rock-steady.
The lens cap is a large, rigid, red velvet-lined black leather disk with high sides. It fits onto the outer edge of the lens shade when the latter is mounted in either position. The lens cap has two elastic strings than can be unclipped to remove or put on the cap. When the lens shade is in its position of use, at least one string must be unclipped to remove or mount the cap (the rubber edge of the lens shade prevents its removal otherwise). On the other hand, the cap slides easily on and off the lens shade when the latter is mounted in reversed position (in fact, so easily that lifting the lens out of a bag leaves the cap at its bottom). You cannot use the cap if the lens shade is not mounted in either position.
The filter mount on the front of the lens has a diameter of 112 mm. It is possible to find a skylight or protector of this size, but a polarizer would be prohibitively expensive. When the lens shade is reversed, its mouth is deep enough to completely shelter a mounted filter. This is a nice design that avoids putting all the weight on the filter ring when the lens is stored with its front lowermost.
There is an internal filter holder that inserts near the diaphragm ring. It holds filters with a diameter of 43 mm. The lens comes with 2-3 filter holders. You can put a polarizer here, but there is no way to turn it when mounted in the lens (newer models have solved this problem). There is a further, important catch with this filter holder. The lens optical design has all elements in front of the diaphragm, which you could touch by inserting a finger deep into the back opening of the lens mount. The filter inserts at the back of the diaphragm. This implies that light reflected by the sensor of a DSLR (which acts as a fairly good mirror) during exposure hits the filter, and then is reflected back once more onto the sensor. Thus, when using an internal filter, light sources in the subject produce a double-image of themselves, enlarged and slightly out-of-focus. In practice, this rules out the use of internal filters in most instances.
The above problem is a legacy of lenses designed for use with film, which does not reflect the light in the same way as a digital sensor. I do not know whether current models of the Tamron 300 employ a different optical design, or a different placement of the internal filter. In view of the relatively low price I paid for this second-hand lens, and of the fact that I rarely use filters in digital photography (especially with long telephoto lenses), I do not find this to be a major problem. Nonetheless, it is something you should be aware of when considering a lens with these characteristics.
A practical problem I found with this lens is that it seems to suffer from a frequent back-focus problem when autofocusing. In this situation, autofocus locks and tracks normally. However, pictures taken with autofocus centred on a small subject that stands out on a slightly farther background show that the plane of focus lies slightly beyond the subject. Naturally, this is more evident at wide apertures. If the subject is very small, or if a mode of autofocus is used that automatically locks onto another area of the picture, this is to be expected with any telephoto lens. However, this happens more often, and also with larger subjects, with the Tamron 300 when used on my D70s. I do not believe that the autofocus of my camera is improperly trimmed (this can happen to individual Nikon DSLRs, and can be solved by regulating the rest position of the camera mirror by adjusting the lateral pegs it stops on), because the problem is not constant. On the other hand, using a fast super-telephoto lens is likely to make any problem with autofocus worse. There is a slight possibility that the Tamron 300 would autofocus better with a transparent filter mounted in the internal filter carrier, because lenses with internal filter carriers often are designed to perform optimally with a transparent filter always mounted in this position. On the other hand, this is not an option for me, because of the above problem with internal reflections.
The figure below shows 1:1 crops of the centre portion of the frame (300 by 300 pixels) taken with the Tamron 300 and the Nikkor 70-300 at 300 mm. The subject of the tests is a detail from a tea brush () on a shelf about 8 m from the camera. All tests were carried out by illuminating the subject with a Nikon SB-800 electronic flash under wireless control by the camera. This eliminates spurious results due to vibration of the camera and tripod.
For direct comparison, below are examples from the Sigma 100-300, Sigma 70-300 and Tamron 28-300, all at 300 mm and their maximum apertures.
The tests show that all lenses are fuzzy to varying extents at maximum aperture, but the Tamron 300 and Sigma 100-300 less than the others. This is as expected, since these lenses are by several times more expensive than the rest. These two lenses are also 1 to 3 stops faster, which makes their design more difficult. However, the Tamron 300 also shows a considerable amount of chromatic fringing at maximum aperture, which is surprising to find near the centre of the frame. It is possible that my sample just has a poorly aligned element.
Closing the diaphragm to f/4 makes the images of the Tamron 300 the sharpest of the whole lot. There is a further, albeit less visible improvement at f/5.6. Beyond this point, if there any differences, up to f/16 they are too small to detect in my test images. The 100-300 is also a very sharp lens, as tested here, but the Tamron 300 is in a higher category. This is especially true when pictures at the same stops are compared. In this case, the Tamron 300 wins hands down at all apertures.
The Sigma 70-300 and Tamron 28-300 improve when stopped down, but never become quite sharp. In addition, the Tamron 28-300 does not reach its nominal maximum focal length, and instead is rather a 250 to 270 mm. The Nikkor 70-300 is rather sharp at f/11, and clearly sharper than the two other consumer zooms. Overall, it performance is not at all bad for a lens of this class. In fact, I would rate its performance as surprisingly good for its price. Weak mechanical construction notwithstanding, it is a lens worth having if you are forced to carry a small pack or bag, but still want a 300 mm. As a whole, none of the lenses tested herein are decidedly bad, including the "junked" ones. In fact, compared with film pictures I took many years ago with a consumer-grade Tamron 300 mm f/5.6 (which I no longer have), all lenses tested on this page are decidedly sharper. On the other hand, if you are after pictures that look sharp even when enlarged to A2 size or larger, only an expensive lens like the Sigma 100-300 and Tamron 300 will provide this.
Since the Tamron 300 is so good, and the Sigma 100-300 proved good in my earlier tests, it is interesting to check how well they perform with different teleconverters. Unfortunately, the Nikon TC-20E, for which I had high expectations, even when modified as described here, cannot mount on the Tamron 300 - the baffle inside the rear end of the latter is too narrow, by a fraction of a mm, to admit the front element of the TC-20E.
In the following table, the focal lengths and apertures of the lenses are specified as unadjusted for the teleconverters (of all the combinations of lenses and teleconverters tested here, only the Sigma EX 1.4x on the Sigma 100-300 transmits adjusted values to the camera). The Sigma 100-300 is in the left column, and the Tamron 300 in the right one. Only values for f/5.6 and f/11 are shown, because this is the most useful range in practice, and the performance at f/8 is not too different from the two extremes. Empty cells indicate combinations that were not tested. Comparable tests with the Sigma 100-300, 50-500, Sigma 1.4x and Nikon TC-20E are available here.
The Tamron 300 gives good to excellent results with all teleconverters tested, including the Kenko/Tamron 1.4x and 2x, which do not give good results with the Sigma 100-300. In fact, even with a 2x teleconverter the Tamron 300 is at least as sharp as the Nikkor 70-300 without teleconverters, and definitely sharper than the Sigma 70-300 and Tamron 28-300 without teleconverters. These are the best results I have ever obtained with teleconverters. It is particularly significant that the Tamron 300 is sharper than the Sigma 100-300 even when both are used with the Sigma 1.4x EX teleconverter, which is designed specifically to work optimally with Sigma telephoto lenses.
In conclusion, the Tamron 300 is a lens that can be used with teleconverters without fear of loosing sharpness. Naturally, it is necessary to close the diaphragm to at least f/4 or f/5.6 (i.e., f/8 to f/11 effective), and it is of paramount importance to use good lens technique and a very steady tripod. An effective focal length of 450 or 600 mm (i.e., equivalent to 600 or 900 mm on 35 mm film) is unforgiving of any camera vibration. This test was particularly useful to me to prove that any un-sharp results I obtain with this lens and these teleconverters is not due to optical limitation of this particular combination, and must be due to other causes. While optical limitations are essentially unsolvable (except by using different optics), any other problem of technique or tripod/head combination can be solved in a variety of ways, especially now that I have narrowed them down a bit.