Comments on: A Tilted Element Demonstration

By: User in Canada

User in Canada — Wed, 08 Aug 2012 08:56:09 +0000

Thanks Roger, very interesting read on optically adjusting a lens. I guess my conclusion (an optically compromised lens is a lost lens) is true most of the time, and accordingly, I’ll donate any future underperforming lens to the first unsuspecting squiggy at a red light and save the repair money for a new lens.

By: Walter Freeman

Walter Freeman — Mon, 06 Aug 2012 20:05:04 +0000

I have a Zuiko 50-200 f/2.8-3.5 that I bought used, and had a rubber gasket break loose and damage the zoom mechanism inside a few months after I got it. I sent it back to Olympus and they fixed it (for $300), but it came back with significant wobble in the barrel and — most worryingly — unsharp images at 200 f/3.5, especially when used with a teleconverter … which is how I use it most of the time. So it went back to Olympus, and they fixed the wobble but it’s still not sharp. It’s “good enough” at most apertures and focal lengths, but not with the TC, which is how I’d like to use it.

I can’t in good conscience sell it (although I’m thinking about switching systems to an EM-5 with a legacy 300/2.8), so I guess all there is to do is to open it up and see if I can figure out what’s the matter.

By: Roger Cicala

Roger Cicala — Sun, 05 Aug 2012 21:00:20 +0000

User in Canada, you might want to read: http://www.lensrentals.com/blog/2012/07/optically-adjusting-a-lens

The process of optical adjustment is really time consuming and I think most of the manufacturers aren’t willing or able to spend hours getting it right. Not to mention sometimes there’s a major part out of true that can’t be detected by inspection. Replacement is the only option.

The problem we’d have with opening a repair facility is we have to reverse engineer everything we know. That ends up meaning we know Nikon and Canon 24-70s, 70-200s and other common lenses, but we’d be clueless about some of the less common ones. Plus there are a lot of adjustments and repairs that require specific Canon or Nikon testing equipment that they won’d sell.

Roger

By: User in Canada

User in Canada — Sun, 05 Aug 2012 16:18:22 +0000

I second the idea of a repair shop. I had a 2K$ L lens develop some kind of misalignement and the official Canon Repair never managed to repair it satisfactorily. I returned it 3 times. First they said it was “within tolerance” and returned it to me, probably untouched, although it produced images almost as bad as your first test chart. Then they held on to it for two months, saying they had to send it to Toronto, then, some other lame excuse, and after much protest and me showing them the crappy images it produced, to their credit, they eventually (6 months later) kept it and send me another one that worked as expected. That’s the kind of Service you get for buying 2000$ lenses. 6 months without the lens… I also had a 100/2.0 sent to them for repair after a fall and although they charged dearly for their service, they never could get the image quality back to normal. I though that a lens had to be unrepairable, but apparently you guys can repair one

By: Roger Cicala

Roger Cicala — Sat, 04 Aug 2012 21:48:50 +0000

Kim,
Absolutely not. I would be totally paranoid the fumes would settle on the elements and do something awful. We just use the same type of for-glass Loctite the manufacturers used originally. The element fits into a ‘clip grove’ that seems to hold it by itself, but Nikon had a dab of red Loctite at the edge of the element and we replaced that.

Roger

By: KimH

KimH — Sat, 04 Aug 2012 06:36:44 +0000

Hi Roger,

yet another great article, thanks for making them.

When you say “we glued the lens back” i stopped and thought, glue…? What type of glue?

This is another piece of science. Superglue surely not (for about 100 reasons of which i can think of only a handful), but, what type and how did you find out?

Kim

By: Roger Cicala

Roger Cicala — Fri, 03 Aug 2012 16:20:09 +0000

Maybe 1 in 200 lenses come back damaged, slightly higher for cameras. But that makes for several a day.

ME TOO!! and thank you.

By: Traveler 2012

Traveler 2012 — Fri, 03 Aug 2012 16:15:44 +0000

Just out of curiosity what percentage of lenses come back after being dropped? Or thrown, stepped on, eaten by dog etc.

A side note: Glad you retired, the blogs are great.

By: Adam

Adam — Thu, 02 Aug 2012 23:45:16 +0000

CarVac,
I started with a couple of cheap throwaway lens first. A film kit lens, old 50 with fungus, or a hanimex/soligor/etc 135mm or something similar can usually be plucked from a bargain bin/ebay lot etc for under $10 bucks.

That said, most manual focus lenses aren’t really complex. One good piece of advice is take a photo of each step so you’ll have some idea of what it should look like going back together.

The hardest parts are generally be if you should somehow take the lens apart at the focus helicoid (you’ll have to put it back together correctly to retain infinity/close focus). If you leave that alone, the other important thing is making sure you put the lenses back in in the same direction (it sounds dumb but it’s easy to flip biconvex or biconcave lenses with similar radii).

Have a small pill box, egg carton, or similar compartmentalized box to put the screws/parts from each step in, and don’t force anything, there’s sometimes hidden screws that are preventing something that would normally be easy to remove.

You’ll probably want a lens spanner, and definitely want a good set of jeweler’s screwdrivers. I keep a garlic peeler handy for removing front elements.

By: aleksander

aleksander — Thu, 02 Aug 2012 23:02:36 +0000

I have a mental picture of Robin (that would be Aaron) sitting next to Adam West (that would be you) whamming the lens back into proper alignment.