Brian's Photo Blog — Article 320
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Troubleshooting My Olympus 75mm Lens
Sunday 4 May 2014   —   Category: Equipment
Have you ever heard the sound of an expensive lens bouncing in the middle of the road? Believe me, you don’t ever want to hear that sickening thud of metal against asphalt!

No, I’m not recounting my latest nightmare. Unfortunately, this scenario was all too real way back in January 2013 when I made a horrible, idiotic mistake. That was when I left the zipper open on my Tamrac Evolution 8 pack, so that my precious Olympus 75mm lens fell out and took a dive. You can read all of the gory details in the article Incompetence at the Coast! I’m sure my heart must have skipped some beats during those awful moments!

Once I had recovered my wits and picked up the lens off the street, I was very relieved to discover that the third-party lens hood which was firmly attached to the lens absorbed the brunt of the impact (as you can see from this photo), saving the lens from a fatal knock-out blow.

The lens itself had one or two small dings on the barrel, but that was just cosmetic damage. What was much more vital was that the delicate glass innards of the lens appeared, miraculously, to be unharmed. Nothing seemed to be loose or cracked. Just to make sure, I took a few test shots, and as far as I could tell the autofocus was working just fine.

Because this accident occurred around the time that I became fed up with photography, I didn’t really use the lens much thereafter — a few shots here and there, and I never noticed anything amiss. It wasn’t until recently that I started to have new doubts. As I was preparing for my recent Micro Four Thirds Lens Kit 2014 Update article, I decided to dust off this 75mm lens and make sure it was really in working order. So I wandered into the front yard with my camera to take some test shots.

Click on the above image to see a version corrected in
Adobe Lightroom which removes the purple fringing.
When I was examining the results in Adobe Lightroom, I was disturbed to see more purple fringing than I would have expected in one of the photos, as you can see for yourself in the one-hundred-percent-magnification cropped image to the right. Numerous professional reviews of this lens have lauded it as the best Micro Four Thirds lens ever, and somehow I had gotten the impression that chromatic aberration (CA) was not really an issue with it. From what I could see in my test photo, CA sure looked like an issue to me. It got me to thinking that perhaps at least one lens element got knocked out of alignment when I had dropped it more than a year ago.

My concern deepened when I tried to photograph a solitary, bloomless tulip stem. The lens absolutely would not autofocus on it, no matter what I tried. I had never experienced my Olympus OM-D E-M5 camera behaving like this before. I was stunned! What in the world was going on?

The next day I tried focusing on that tulip stem with ALL of my lenses, and I experienced the same problem with each one. That made me feel a little better about the 75mm lens. I won’t go into all the details now about that experiment, it’s a story for a future article — see Olympus OM-D E-M5 Autofocus Problem.

Still, I had a strong sense that something was definitely amiss with my 75mm lens. With that kind of negative feeling, it seemed probable that I might never pull it out of my camera case again. I needed to either make sure it was still in working order, or else replace it. So I started considering my options, and how best to solve this problem.

One idea I had was to send the lens in to Olympus for inspection and, if necessary, repair. According to the price quote on the Olympus Service & Repair Web site, it was going to cost me $172.51 to go this route — and perhaps even more if the lens was significantly damaged. Of course, that quote was for repair. I have no idea how much they would charge to just determine if it was broken or not, even if I decided not to have it repaired.

Then there was the whole issue of exactly what the Olympus Service Dept. would be doing with my lens. Would they simply give it an external visual inspection? Would they open it up and check inside? Would they perform optical testing to make sure the lens was still within factory specifications? Without knowing how far Olympus would go to verify the lens condition and performance, I wasn’t sure that this route would bring things to a satisfactory conclusion. Besides, if there really was something wrong with the lens, I would rather put my money towards the $800 cost of buying a new lens rather than spend it on repairing a lens that I would never again have full confidence in.

Then I came up with a brilliant plan! I would order a new 75mm lens from Amazon, and when it arrived it would run the new lens and the old one through a series of test shots together, and then compare the results. If there was not a noticeable difference in lens performance and image quality between the two, I would take advantage of Amazon’s generous return policy and get a refund. If there was a significant difference, I would keep the new lens, send the old one to Olympus for repairs, and then sell it, with full disclosure of its condition and history, at a discounted price.

To complicate things further, for the past ten years I have had State Farm’s Personal Articles Insurance for all of my expensive camera equipment. Not only does this policy cover loss due to theft, but also damage to equipment through sheer clumsiness or stupidity! So now that my incompetence at the coast might have damaged this lens, maybe it was time to take advantage of having such insurance and all the years I have paid for it without ever filing a claim. On the other hand, reporting the damage might cause my rates to go up, and may not end up being the best solution. Well, before I figured all that out I needed to test the two lenses and see what the results were.

With the brand new 75mm lens on my camera, I shot the same test shot as I had done a few days previously with the old lens. Lo and behold! The new lens had the very same problem with purple fringing on the white car. It also had the very same difficulty trying to focus on that troublesome tulip stem. Hmmmmm ... maybe my old lens wasn’t damaged after all. Perhaps my imagination was carrying me away with false symptoms and faulty conclusions!

Before I would finally make up my mind about sending the new lens back to Amazon or keeping it, I decided to put it through one more test. The chromatic aberration around the car windows was definitely noticeable, but still not too severe. It was time to try the scenario which is the ultimate lens CA stress test: photographing dark tree branches against a bright sky. Ambling around the house to the backyard, I pointed my camera west to the huge pine tree in a neighbor’s backyard, with the setting sun right behind it.

Strong purple fringing with my new (temporary) Olympus
75mm at f/1.8. Click on the image to see the same shot
with my old, original 75mm lens which had been dropped.
As you can see from the photo to the right, the new 75mm lens exhibits strong purple fringing when wide open at f/1.8. But amazingly enough it’s just as bad as the shot with my old lens which had been dropped! (Click on the photo to alternate between the two — and note the cool parallax effect!)

These results finally laid the issue to rest: either BOTH lenses were defective, or else my old lens which I had dropped was performing according to specifications. Because the latter conclusion seems much more likely, I decided to pack up the new lens and send it back to Amazon. It had fulfilled its role as a test lens, and had proven that my original lens was just fine. Mission accomplished!

It should be noted that the horrendous purple fringing in the above photo was due to a combination of two factors. First, the aperture was wide open at f/1.8 — many lenses exhibit their worst chromatic aberration (CA) at maximum aperture. Secondly, the photo was overexposed, which also exacerbated the CA problem. Therefore, stopping down the lens to a smaller aperture would have eliminate much of the purple fringing, as other test shots I took demonstrated. While processing the image in Lightroom, I was able to greatly reduce the purple fringing by adjusting the exposure down a stop or two, without even resorting to Lightroom’s Remove Chromatic Aberration feature or its Defringe settings.

In the end, I am VERY happy with the process and results of troubleshooting my Olympus 75mm lens. I was able to verify that it is functioning correctly, so now I can put any doubts about this lens behind me. I can stop shunning it and start using it again on my photo outings. Welcome back to the lens kit, beloved 75mm prime!

And there’s a lot more great news! I didn’t have to send the lens in to Olympus for repair. Hurray! I didn’t have to file an insurance claim with State Farm. Hurray! I didn’t have to spend an additional $800 to buy a new lens as a replacement! Hurray! I didn’t have to repair the lens and try to sell it cheap to some buyer who might not be happy with it. Hip, hip, hurray!
Brian's Photo Blog — Article 320
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