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It started out as one of these, but got converted into more than fifty pieces by the time I was done with it. Here's a teaser image:



If you want the whole teardown with descriptions, I posted a Picassa web album of it, here:

http://picasaweb.google.com/10467904944 ... directlink

Explains why these things cost so much money.

Cost me $105 but every now and then a good deal on eBay turns out to be a bum deal, and in this case, the lens had gone sloppy and soft from excessive wear and dust accumulation in the elements. I started to tear it down to see if I could clean some of the elements, but once I saw how badly some of the plastic bits were worn, I decided to go for broke (more or less literally). Enjoy

Nice job and thank you for a good show. Since I've been a writer for a photography magazine a few years back I've seen some seriously cool stuff during events and so, but I have to say that this is right up there.

Aphasia wrote:

Nice job and thank you for a good show. Since I've been a writer for a photography magazine a few years back I've seen some seriously cool stuff during events and so, but I have to say that this is right up there.

Thanks

I figured I was out the hundred bucks either way so I might as well learn something useful.

With all of the other good lenses in your collection, why did you want to acquire the 28-105?

The 28-135mm is a large, heavy lens and is prone to telescoping on account of the weighty 72mm front element group. Since I only use it for casual walk-around and always switch over to a prime in low light, meaning the IS doesn't help me that much, I was curious whether the smaller 28-105mm would be more suitable.

The 28-105mm was a more practical lens apart from the specific problems with my sample, but after comparing them back-to-back, I think I'll just keep the 28-135mm until I can afford either the EF-S 17-55mm f/2.8 IS USM or the EF 24-70mm f/2.8L USM.

I have the EF-S 17-55mm f/2.8 IS USM. It stays on my camera most of the time. For less than half the price, the ($460 -45 MIR) Tamron Di-II 17-50mm f/2.8 is frequently mentioned as a worthy alternative. FWIW, besides the 17-55, my other lenses are the EF 85mm f/1.8 USM, EF 100mm f/2.8 Macro USM and the EF 100-400mm f/4.5-5.6L IS USM.


Your disassembly of the lens is impressive. Did you gain any insight into how your other lenses work?

JustAnEngineer wrote:

For less than half the price, the ($460 -45 MIR) Tamron Di-II 17-50mm f/2.8 is frequently mentioned as a worthy alternative.[/url].

We may have a winner here. That's more in line with my budget range and the 67mm filter adapter matches my 70-200mm f/4L, which would simplify my collection after ditching the 20mm prime and the 28-135mm zoom. And the sale of those would basically pay for this lens.

Your disassembly of the lens is impressive. Did you gain any insight into how your other lenses work?

Somewhat, this lens didn't have an image stabilizer so I don't exactly know what that mechanism looks like. I also imagine that the older push/pull zooms have some unique quirks compared to this lens, as well.

Well, looks like that hundred and five bucks wasn't a total loss. I partially disassembled my EF 85 f/1.8 this evening to fish a large dust fleck out of the innermost element group and clean some dust-corrupted lubricant out of the USM focus wheel. I was able to unscrew, pop, and snap apart, and then put back together again, in less than thirty minutes. And it still worked fine afterwards.

Meanwhile, I stopped by a local camera shop and asked about the Tamron 17-50 f/2.8. Turns out they did have one of these in stock, same basic thing but with vibration compensation, and handed it to me on a 7D body. Conclusion? My Canon EF 28-135 feels like a badly-made toy next to this thing, and I will beg, borrow, or steal to get one of the two Tamrons. Other than seeing the zoom barrel travel outside the body, I could have been holding an 'L' lens. Canon can go eat rocks for charging over a grand for the EF-S 17-55 f/2.8 IS USM.

So you're into the clean room lens repair business now. Very impressive!


The VC version of the Tamron 17-50 doesn't get as high marks optically as the older non-VC version (which scores well except for strong field curvature). A brand-new contender would be the $669 Sigma 17-50mm f/2.8 OS. I haven't read many technical reviews of this new lens yet, but the forum users who bought them seem to be pretty happy (especially the Nikon users).
http://www.photozone.de/canon-eos/482-t ... 28vc_canon
http://www.photozone.de/canon-eos/531-sigma1750f28os

I probably won't buy the VC version anyway. Although the construction is clearly superior to the EF 28-135, it's just as big and heavy and uses the 72mm filter adapter. Getting the non-VC version gets me a 67mm adapter and lets me share filters with the 70-200 f/4L. It also lets me ditch the 28-135 and the 20mm f/2.8 for even money, eliminating the 72mm filter size from my collection. That's simplification I can use.

Well, payroll came around again, so I got the 17-50 (non-VC) ordered, and started the cross-sale by putting the 28-135mm up on Craigslist and the Bargain Basement. I'll lose the 20mm prime once I'm certain that I can find a suitable lens correction profile for the Tamron seeing as how Canon's editor won't recognize the lens.

I chose Amazon's Super-Snail free shipping so I probably won't see it until the end of next week, but I can wait. Will still have plenty of time to apply for the rebate.

The Tamron arrived. I felt a slight tinge of Hardware Snob's Regret when I realized that the lens used a conventional DC motor and doesn't do FTMF like the 28-135mm, but that went away real quick after shooting some test images. Optics are very impressive, and it's rather a treat to get an AF lock with the lens targeting a subject in low light at a distance of about seven inches.

Interestingly, the Canon Digital Photo Professional software will execute curvature correction on images from this lens. Wouldn't have expected that.

The only thing I don't like is that the zoom-lock switch only engages at 17mm, which seems kind of pointless. The lens isn't really prone to telescoping, and it would be nice if it could be locked at any zoom position to avoid jostling the zoom wheel while running in manual focus mode. Oh well.

That was fast The Tamron rebate arrived early this week, slightly less than three weeks after I mailed it in.