While this lens isn't "rare", it isn't exactly in ready supply either. While exploring Tamron's Adaptall-2 line-up in effort to find an inexpensive alternative relative to the premium name-brand glass, I continually saw mention of the Tamron SP 200-500mm f/5.6 31A but infrequently found any actual results. Mostly people just commented on how large of a lens it is. Having originally retailed for over $1000, I think it is time we had a little more info than this.
Aesthetics/Ergonomics
I have to say this lens was somewhat of an impulse buy. I have no idea what they typically cost since I haven't been on the lookout for one. I just saw one ending on eBay one day, in great condition with what looks to be nearly all of the original accouterments. After having sold another lens and having the money sitting in paypal I reasoned I would just pick it up and give it a try since I wasn't finding much online. Then resell it after I am finished, should it not turn out to be Tamron's best kept secret. Spoiler alert:
it isn't.
That may sound harsher than I intend since this lens isn't a poor performer, just not amazing. But I am getting ahead of myself! We will get to performance.
First impressions of this lens are in agreement with what I have found online: this lens is a
beast.
Being a non-IF (internal focus) zoom lens with such a broad range, this kind of size is inevitable. The built-in hood is great, though this adds another 4" to the length. The physical length of this lens goes from 14" fully compact, to 20" completely extended and hooded.
The overall look and feel of this lens is nothing short of Tamron's best Adaptall design. A solid 6 lbs. of metal and glass. I love the all-black semi-gloss finish. All lettering and info is engraved into the lens barrel. Hints of Tamron's signature turquoise color appear in the distance scale lettering. The barrel sports Infrared scales for 200, 300, and 500mm focal lengths. The 200-500mm f/5.6's front filter is a massive 95mms but the lens is also equipped with a rear 43mm filter tray. Due to the size, the lens was designed with a tripod foot which does rotate 360º. I have read, and do agree, the tripod mount is further back than it should be. Even with a camera mounted, the lens is pretty front-heavy.
Using this lens, I also quickly realized another drawback to the non-IF design of this particular lens. When focusing the lens, (Anywhere from 200-500mm, focal length doesn't matter because that action does occur internally) the front portion of the lens rotates. For one thing, if you were to use a polarizing filter, it would need to be adjusted accordingly as you focus. But secondly this means anytime you are focusing upward, holding the lens at a high angle (and I mean nearly verticle), the sheer weight of the front of the lens creeps back down (toward the infinity focus position). I will say however, this lens manages to stay in place to a pretty severe angle. I assume this will all be dependent on the condition of the lubricants in your particular lens.
Accessories
Accessory-wise, this lens originally sold with a large faux-leather case (L-40) with a red fabric lined interior and foam inserts fitted to the lens. There is also an accessory compartment in the case to accommodate a teleconverter, strap, additional filters/trays, etc.. I do not have the original Tamron 95mm protective filter for the front of the lens and boy are they hard to come by! The lens also came with a cheap fake leather lens cover for the front which is black felt-lined on the inside (which I did get).
Specifications
Focal length: 200-500mm
Filter thread: Front 95mm, Rear tray 43mm
Min. Aperture: f/5.6
Max. Aperture: f/32
Angular field of view (diagonal): 12º-5º
Elements/groups: 14/10
Maximum magnification ratio: 1:3.52 (500mm @ 8.2' [2.5m])
Multi-Coated: Yes, BBAR MC
Min. focusing distance: 8.2' (2.5 m)
Length at ∞: 14.4" (365 mm)
Maximum barrel diameter: 4.1 " (105mm)
Weight: 6.1 lbs. (2780 g)
Lens hood: Built-in
Mount: Adaptall-2
Manufacturer designation: 31A
While this lens is an SP (Super Performance) lens, it does not have any LD (low-dispersion) glass in it. This was to keep costs low since the lens was intended to compete with premium brand lenses but cost the consumer less. Also, regarding the "BBAR MC" designation. From what I am finding online, it seems BBAR may stand for "Broad-Band Anti-Reflection" and then MC obviously "Multi-Coating". Either way, all Tamron's Adaptall-2 line listed in the 200-500mm's brochure were BBAR.
Performance
So who cares about all that stuff. Is the lens any good optically? Well I'll tell you what, I care about all that other stuff. But agreed, I think it is important that we understand if this lens is worth its weight optically too.
Since the time I initially got this lens, I haven't had a whole lot of time to get out and use it for birding or various other long-range activities for which it was designed. But I did a fair amount of image comparison which should suffice to at least show what this lens is capable of.
Here I had the rig mounted on a sturdy tripod. I used a D700 @ ISO 800 to ensure high enough shutter speeds so I was not affected by camera shake. The sun was at my back to the left. I cropped these images and enlarged them by about 50% so that you can see the pixels. Only a hair of sharpening to combat the web softening images slightly when posted here. All images were made in RAW.
200mm
Below is the key image made of the Clark Bridge in Alton, IL @ 200mm.
f/5.6
f/8
f/11
500mm
Here is a key for that same Clark Bridge @ 500mm.
f/5.6
f/8
f/11
f/16
Beyond f/16 the wind began affecting the shots. Being out by the river, the winds can get pretty intense.
Analysis
As always the lens shows slight softness wide open but is still pretty sharp! I am impressed with the sharpness of this lens at both 200 and 500mms. Center sharpness as well as corner sharpness with this lens is quite acceptable.
As far as contrast, I would say the lens again performs well. These shots aren't the best examples to show contrast but I assure you from other use with this lens, you will not be disappointed with the rendering of a scene!
Flare doesn't appear to be much of an issue, nor does any concern for stray light affecting the image. The built-in hood provides copious coverage.
Now to address the issue that plagues the Tamron SP line, Chromatic Aberration. CA seems to be the biggest downfall of even Tamron's best LD lenses. While this lens has no LD glass, it is designed to compensate for CA in other ways. Nevertheless, CA is quite visible even at f/8. The best way to handle this issue is either to avoid shooting in situations that produce CA (extreme high contrast) or deal with it in post.
Recommendations
Since the introduction of this lens in 1984, the industry has made leaps and bounds toward better zoom technology. The 31A is pleasantly sharp wide open and performs quite well beyond that. However the CA can be a bit much at early apertures and the effort to keep your zoom/focus in check can prove a bit of a challenge, especially in fast paced environments. While I love the build and look of this lens, the reality is that it isn't very practical by today's standards. The Tamron SP 200-500mm f/5.6 31A is a great choice if you need sharpness and zoom for a low price. Also the adaptall feature allows you some portability in between systems if needed. I haven't tested the newer Tamron 200-500mm f/5-6.3 Di AF but I imagine it is a much more manageable lens (also nearly 3 times as expensive). There is a Tamron 200-400mm f/5.6 D AF that costs a little less than this adaptall actually (as of 10/2010) but I have heard nothing about it. The Tokina 400mm f/5.6 AT-X and the 80-400mm f/4-5.6 may be other options and can be had for around the same price as this adaptall ($300-400). Both of which have AF and are considerably lighter. But I know little about their performance at the long end which tends to be where these zooms struggle.
Plain and simple, the ability to get similar zoom, same f# or faster, and AF for the same price as the 31A makes buying this lens more about nostalgia for well-made Adaptall lenses than anything else. If you can afford to take your time and are just looking for a sharp 500mm that can double as a weapon, all for one low price, here it is! Optically, it's no slouch, but technology has moved quite a bit beyond this.
Links/Resources
NEW!! - I received the owner's manual with this lens and have scanned it into a PDF document.
Click HERE to download the User's Manual for the Tamron SP 200-500mm f/5.6 31A
Adaptall-2.org (mirror site of the previous adaptall-2 site) - Tamron SP 200-500mm f/5.6 31A
Here's link to Pentax Forum's profile on this lens.
