Tamron AF 2x Teleconverter

Product reviewed: TAMRON-F AF TELE-CONVERTER 2X Px-AF BBAR MC7.

I have used this TC for a couple of months now, and I must say that I am quite impressed with it's performance. My first impression was "quality". Here are the lenses and DSLR camera body currently being used (all previously owned):

• PENTAX *ist D digital SLR camera.
• PENTAX SMC PENTAX-F F2.8 100mm MACRO lens.
• TAKUMAR-A ZOOM F3.5-4.5 28-80mm lens. (MF-only).
• SMC PENTAX-A* F4 300mm lens. (MF-only).

Of these, I almost exclusively use the TC with the 300mm for wildlife/bird shots. Plus, taking into account the PENTAX 1.5X sensor crop factor, it gives an effective 35mm equivalent focal length of a whooping 900mm! That is more than enough to nearly fill up the viewfinder frame with a little black-capped chickadee from a few meters away. And, with MF-only lenses you need as much "reach" as possible in order to focus more accurately.

DOF is quite shallow at maximum aperture, a little tweaking of the MF ring causes a huge focus shift in the image. I would recommend using a tripod or alternative support whenever possible.

Visible chromatic aberrations are always present, especially in high-contrast situations, such as tree branches against an overcast sky... ugly greenish, magenta, and blue fringing in such scenarios. With more normal situations, like a sparrow on an out-of-focus plants background, the results can be pretty good. Stopping down the aperture helps a bit, though not a huge amount.

Sharpness does not deteriorate much at all, in my opinion. The trick is to get the focus right, and if lighting conditions allow, stop the aperture down for better sharpness and more importantly, better DOF.

Another point worthy of note is the auto-focus. On the 100mm F2.8 MACRO lens/*ist D, AF is very noticeably degraded. It becomes sluggish, racking the lens barrel out all the way out and then back in again, never locking on. Plus, when it does manage to lock on, the image is often still out-of-focus. I don't own any PENTAX SDM lenses, so I can't comment on whether SDM works or not with this TC. There are two SDM golden contacts, though.

One of my major complaints about this TC has nothing to do with image quality: The -2 stop aperture and 2X focal length conversion are not displayed in image EXIF data! For example, a picture with the 100mm F2.8 lens at F2.8 will record in EXIF as 100mm F2.8. In reality, it should have been 200mm F5.6.

Also, the maximum aperture I am allowed to chose with the 300mm F4 lens/2X TC/*ist D is F1.7! Clearly there is something "fishy" going on in the connections, since F4 is F4 and cannot be "increased" to anything faster than F4.

Overall, this is a neat accessory to have at hand. I would recommend it for people who want to minimize weight, bulk, and cost. Remember that TC's convert the focal length, as well as any lens defects and TC defects too. Use a quality base lens for better photos, prime fixed-focal-length is usually best.

Feel free to visit my gallery here at PhotographyREVIEW.com to view product images, and samples.

• Doubles lens focal length, ideal for long-distance bird and wildlife shots.
• Good when you aren't planning to make huge printouts, and if you can tolerate CA problems.
• Small, lightweight. A lot lighter than a "true" telephoto lens.
• Easy and smooth operation when attaching/detaching. Clicks smoothly.
• Good surface finish, and with a rubber grip around the barrel.
• Works with a macro lens for very extreme close-ups (e.g. frame-filling kiwi fruit seeds).
• Cheaper alternative to expensive telephoto lenses.
• Much lighter alternative to heavier telephoto lenses.

• 2 f-stop light loss is quite noticeable.
• Increases image softness, at all apertures.
• Focal length doubling not displayed in image EXIF data. (Better have a good memory and/or write down what equipment you used for each photograph).
• -2 F-stop loss not displayed in image EXIF data. (Better have a good memory and/or write down what equipment you used for each photograph).
• Maximum available aperture is messed up (see my review summary).
• Chromatic aberration problems can be severe, especially on the edges/corners. CA fringing is never 100% invisible when image is viewed full-size.
• Screw-drive AF performance suffers noticeably.
• Slightly harder to focus manually, due to softness even at peak focus point.
• Gives a dim viewfinder image with a lens that has a maximum aperture F4 or smaller. (Make sure there is good lighting when you shoot).

• Vivitar 1.5X tele-converter lens. (Screw-onto-filter-thread type).
• Vivitar 0.55X wide-converter lens. (Screw-onto-filter-thread type).
• Far too many screw-on lens filters.

• Haven't contacted TAMRON.

Normally i hook up this tele on my 80-200 F2.8 lens to snip on street or basic bird photography. It provide a low cost alternative to go up to 400mm (equiv to 600mm on a 1.5 crop factor Dynax 7D) without the need to purchase expensive 400mm. Image appear slightly softer but acceptable for print up to 6R. The quality is so far as good although some chromatic abbreration on the edge of the photo.

Low cost Good alternative to double the zoom length provided you have a fast base lens.

Chromatic Abbreration at edge.

Never did

This 2x teleconverter and the Quantaray sold by Ritz camera look suspiciously similar. Although Quantary is usually made by Sigma, I suspect they did something different here. The Quantaray is much cheaper (only $80), and as far as I can tell, optically identical when comparing pictures side by side. I used this TC with a Sigma 28-300 macro lens (which is a surprisingly good lens - sharp even at 300mm). With the TC, I had an effective 52-600 lens. To my surprise, sharpness was fairly good at 600mm in the center of the photos, especially if I stopped down the main lens slightly. But toward the edges there was chromatic aberration that degraded the photo quality. There was an overall loss of contrast with this TC compared to without it. This TC works OK, but you should get the Quantaray version, which seems to have identical lens elements, but is 1/2 the price.

Not awful.

More expensive than identical Quantaray. Minor chromatic aberration at edges.

Quantaray 2x TC