Tamron SP 300mm f2.8 LD IF
Description
This is a popular super-telephoto lens in Tamron's "Super Performance" (SP) line. The current model is the 360E (auto focus) and 360B (manual focus) and at the time of this writing they cost about US$2800 at B&H. Its "LD" designation means that it includes "low dispersion" glass elements. The "IF" designation means that it is an "internal focus" lens so the lens body is a fixed length and the front element does not rotate. The lens body is all metal and seems very rugged.
Unfortunately, this lens is not available with a 4/3rds mount. To use it with a 4/3rds camera you must purchase the manual focus version with Tamron's universal Adaptall-2 mount. The Adaptall-2 mount does not connect directly to a camera. Rather, you add one of Tamron's Adaptall-to-camera adapters. In this case you must use their Adaptall-OM adapter and mount it to your 4/3rds camera via one of the OM-to-4/3rds adapters (like the Olympus MF-1).
This lens has attracted recent attention as a possible "low-cost" alternative to the Zuiko Digital (ZD) 300mm f2.8 ED lens. The ZD lens is considered one of the finest available and it is priced accordingly (about US$6000 at B&H). Of course, you must give up any idea of automatic control with the Tamron 300mm. Since it is not a 4/3rds lens, you must operate your camera in either Manual or Aperture Priority mode, set the aperture manually on the lens, and focus manually. As such, it may be a poor choice for action shots that require rapid changes in focus (although an E-1 equipped with a third-party split-prism focusing screen can help quite a bit). Even still, I wouldn't recommend this lens if you plan to snap quick shots of birds in flight owing to its manual focus.
This is a large and heavy lens. It includes a "palm holder" (visible in the first photo above) that connects to the built-in tripod mount to make it a little easier to shoot by hand. However, don't expect to shoot by hand for very much time unless you're a body builder.Besides, you will need to shoot at 1/600th second or faster in order to avoid motion blur unless you have very steady hands.
Since this lens has been in production for quite a while, many used ones are available. Previous models can be purchased at a fraction of their new cost. For this test I purchased a used model 60B in excellent condition for US$489 on eBay.
The big question is, how does it compare to a comparable ZD 4/3rds lens? Remember that all versions of this Tamron 300mm lens are designed for film cameras so its image circle is sized for a 35mm film frame. With a 4/3rds camera, only half that diameter is used and, as a result, you can expect the image to be slightly less bright compared to a lens that focuses all of its light onto a 4/3rds image sensor at the same f-stop.
Specifications (model 60B )
- Focal length (FL): 300mm
- Angle of view (AOV): 8 degrees (4 degrees on a 4/3rds camera)
- Aperture range: f2.8 to f32
- Lens construction: 7 groups, 10 elements
- Coating: BBAR multiple-layer coating
- Minimum focus: 8.2 ft (2.5 m) from the focus plane
- Filter size: 112mm (front), 43mm (rear)
- Length without hood: 9 inches (225mm) with front filter
- Length with hood: 12.75 inches (324mm)
- Weight: 4.7 lbs (2.1 kg).
The following photo shows the hood off the lens so you can see the lens by itself. I also removed the front 112mm Tamron "Normal" filter. Also shown are two teleconverters. The smaller is the 140F 1.4x teleconverter that normally ships with the lens. The larger is an SP 2x teleconverter that is also available. An SP 2x high-performance teleconverter (200F) also exists but I was unable to acquire one for these tests.
All three of these teleconverters were designed by Tamron exclusively for this and their 500mm f8.0 mirror lens. They mount between the Adaptall-2 mount and the Adaptall-to-camera mount. That means you have to remove the Adaptall-OM adapter each time you want to add a teleconverter. It doesn't take very long to do so but it is annoying because it requires that you carefully align the aperture scale pins (the teleconverters each include a second aperture scale which displays the true aperture value with the teleconverter).
The next photo shows the 43mm rear filter that mounts onto a sliding filter frame. A "normal" filter is provided with the lens and should always be installed unless it is replaced with one of several optional filters.
Measurements
My measurements are based on the Imatest system (version 1.6.3). The lens was mounted on a tripod and located an appropriate distance away from each of several precision test targets. All tests were performed with my Olympus E-1 with an MF-1 OM adapter and an RM-CB1 remote shutter release cable. My E-1 is outfitted with a Katz Eye Optics (KEO) split-prism focusing screen and an HLD-2 battery grip. The mirror was locked up (anti-shock mode) for each shot.
During the sharpness tests the lens had to be located a sizeable distance from the test target. Since I tested several lenses on the same day (some with focal lengths as high as 1000mm with teleconverters) it was necessary to perform these tests outdoors. Fortunately, the sky was overcast, transforming the sun into a diffuse light source.
Sharpness - The easiest way to measure the sharpness or resolution of a lens is with a camera. However, this makes the camera a part of the measurement. That means we are measuring the lens and camera together---the camera cannot be removed from the measurement. For this reason it would be best to use a camera whose image sensor has the highest available resolution. That's why PhotoZone uses an E-300 for its 4/3rds lens measurements. I don't have an E-300 or E-500 (both 8 megapixel cameras) so I used my trusty E-1 (a 5 megapixel camera). Therefore the values I measured will not be the highest possible.
Fortunately, this should not present a problem because we are not making absolute measurements of the lens' optical resolution. What we are doing is making relative measurements where we compare one lens to another on the same camera. I chose to use my award-winning ZD 150mm f2.0 ED lens for these comparisons because: (1) it is recognized as a very high quality, high resolution lens, (2) it should be comparable in quality to the ZD 300mm f2.8 ED lens and (3) it is the best telephoto lens that I own.
There are several measures of image sharpness and before we can compare results, we have to make sure that we use the same measure. I chose to measure MTF50 in lw/ph. The MTF50 is the "modulation transfer function" or spatial frequency where the contrast drops to half (50%) of its low-frequency value. I know that sounds technical and you don't need to understand it because as long as you read my tests, I'll always measure the same thing so we can compare "apples to apples". But readers of my review should not compare my results to those of another reviewer unless they first make certain that they measured MTF50 also. As for "lw/ph", it is the units and it means line widths per picture height. Lw/ph is calculated as follows: lw/ph = 2 x lp/mm x picture height. Where lp/mm is the number of line pairs per millimeter and the picture height is also in millimeters. I won't bore you with any more technobabble. Suffice it to say that if you want to compare someone else's sharpness measurements to mine, they need to measure MTF50 in lw/ph using an E-1 camera. For more information about measurements, see Imatest.
I measured the sharpness of the Tamron 300mm at each full f-stop. Here are the results:
Notice that I made two measurements at each f-stop. First, I measured the sharpness in the center of the field of view (FOV). Second, I measured the sharpness in one of the corners of the FOV (I used the lower left corner). That way you can see whether a lens is sharper in the center or at a corner.
Let's begin at the left end of the graph. Notice the severe drop-off at f2.8. This lens obviously gets pretty soft when its aperture is wide open. But what do the numbers mean in practical terms? An MTF50 less than 1000 lw/ph should be considered "bad" or "poor" because it will produce a very soft picture with low contrast. You need at least 1150 lw/ph before the picture begins to look "good" and I'd rather see 1450 lw/ph or more. But remember that many lenses, even good "pro" lenses, suffer from a loss in sharpness when the aperture is fully open.
Now, let's move to the right end of the graph. All lenses, no matter how wonderful their glass is, will begin to lose sharpness at small apertures (high f-stops) because of diffraction as the light passes through the small iris in the lens. So the roll-off that begins at about f11 and gets worse as the aperture closes to f32 is fairly normal. This will be obvious when we compare it to a ZD lens shortly.
Next, I wanted to see what effect Tamron's large 112mm front "normal" filter would have on the sharpness. I repeated three of the measurements with the filter on. This is shown below:
I didn't expect there to be a significant difference but I was surprised to see that the presence of the filter increased the sharpness quite a bit when the aperture was wide open (f2.8). Personally, I wouldn't want to use this lens below f4.0. But if I did, I certainly would use the filter. Besides, it also protects the front lens element.
Now, the moment we've all been waiting for... How does the Tamron 300mm f2.8 compare to the ZD 150mm f2.0? The next graph shows:
Here's the same comparison again only I used a line graph instead of a bar graph. I also added a line to include the sharpness of the Tamron lens at f2.8 with the front filter.
Notice tha amazingly strong sharpness of the ZD 150mm all the way down to f2.0. That is phenomenal. See my second ZD 150mm review for all of my test results. There's no way that the Tamron lens can approach the sharpness of the ZD lens below f11. I'm sure the same would be true if I had a ZD 300mm lens to measure also. But is the Tamron lens bad? I don't think so. Using a scale of poor-mediocre-okay-good-very good-excellent, I rate the sharpness of this lens between "poor" and "mediocre" below f4.0, between "okay" and "good" from f4.0 to f11, and gradually sinking toward "poor" at f32.
Next, let's see what the Tamron 140F 1.4x teleconverter does to the sharpness. The next graph repeats all of the previous measurements with the 140F installed. Note, the front filter was left off for all of the following measurements so you can assume that the sharpness with a wide-open aperture will be a bit better if the filter is used.
Notice that you loose one f-stop whenever you add a 1.4x teleconverter. That means that the aperture range of the lens will shift up to f4.0 to f45 when the 140F is installed.
Next, I swapped the 140F for the SP 2x teleconverter. A 2x teleconverter eats two f-stops so the lens now has a range of f5.6 to f64.
The last teleconverter I tried was the Olympus Digital EC-14, also a 1.4x tele. It produced results similar to the 140F as shown below:
Finally, the next graph compares all three teleconverters. The bottom line: The 140F looks pretty good. As long as you use it in the middle of its range, you shouldn't need to be concerned about losing significant sharpness. The EC-14 was a pleasant surprise---it was almost as good as the 140F even though it is not optimized for the lens like the 140F is. Sadly, the SP 2x does not look so great. I think I would avoid it. Although, if you use it in the middle of its range, say around f16, it won't reduce the lens sharpness significantly. However, by f16 you're beginning to suffer from diffraction through the aperture so the sharpness is not that great to begin with.
Chromatic Aberration (CA) - This test measures color fringing. I measured CA every time that I measured sharpness. It stayed below 0.5 pixels which is considered "insignificant". Overall, this Tamron 300mm lens appears to have no CA problems on my E-1. This is probably due in part to the fact that the small image sensor of a 4/3rds camera is only using the center half of the lens where CA is naturally the lowest. Remember also that this lens contains some LD elements which help reduce CA.
Distortion - This test measures whether or not parts of the image are bent, stretched or squished. An extreme example would be the barrel distortion that is common to some wide-angle lenses like a "fisheye" lens. To measure it, a grid pattern of equally spaced horizontal and vertical lines are photographed and measured. This Tamron 300mm lens is basically free of distortion by itself or when it is used with a Tamron teleconverter. The highest deviation I measured was 0.112% which is very small. The distortion was noticeably higher when the lens was used with the Olympus EC-14 teleconverter. However, the highest deviation was -0.947% which is still modest.
Vignetting - This test measures the light drop-off near the corners of the picture. I used worse-case conditions with the lens focused to infinity. The lens exhibited very little vignetting---no more than -0.371 f-stops (or EV). Most of the time it was less than -0.1 f-stops which is quite good. As with the low CA, the low vignetting is probably due to the fact that only the center half of the lens is being used on a 4/3rds camera and most vignetting, if it exists, probably occurs outside this area closer to the edge of the lens image circle.
Conclusions
Pros - This is a well-made super-telephoto lens with a strong metal body, low CA, low distortion and low vignetting. It accepts both front and rear filters. The small size of the rear filters can save money. It often includes a nice 1.4x teleconverter. It has several nice features, like a focus detente that the user can set, a built-in rotating tripod mount, large hood, palm rest, case and the body is an olive green color so the lens easily blends into outdoor surroundings.
Cons - Since it is not a 4/3rds lens, it must be manually focused, the aperture must be manually set, and you cannot use the Program or Shutter Priority modes of your camera. The sharpness is okay but it is not that great---a super high-grade 4/3rds ZD lens is much sharper. You have to carry the weight of a large-aperture f2.8 lens yet you can't use f2.8 if you want sharp pictures. The lens is not weatherproof.
On balance, I think this lens manages to barely earn a "good" rating.
Copyright © 2006 by Harris Technologies, Inc. All rights reserved.
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Originally Posted by refiningman
