Thursday, March 17, 2016

How to get a stuck filter off of your camera lens

Allow me to diverge from my usual sewing chatter to talk about something rather techy. We all take photos, don't we? Well, doesn't this photo make your heart skip a beat?

You can see the impact on the lower right side, and the lines of the shattered glass radiate from here.
This is my Canon 24-70, and it was on my camera, in my camera bag, perched on top of the luggage for a family trip to grandma's house. The phrase "baggage may shift during your flight" comes to mind. Guess what happened when the hatch was opened? Crash!

My camera bag is one of those trendy cool bags where the padding all comes separately. Hence, it has no padding. The camera fell right onto the lens and the filter cracked.

I set my dad and husband to the task of removing the filter, but alas, no one was able to budge the broken filter. I tried myself, but that is a measly attempt since I have very little brute strength in my hands, I can't even open jars of marinara in the kitchen. I probably couldn't strangle a mouse if I tried.

Another view. Ugh, it makes me shudder!

It looked like the filter took a hit on one side, and was probably just a touch out of true. But there was no visible dent, so it must have been just enough to prevent the threads from turning.

Meanwhile, the camera and lens seemed to function perfectly fine. Autofocus worked like aways, and the lens felt solid, no unusual play in the motion. Shooting through the broken glass, pictures looked perfect except when the light hit the crack in funny ways and left artifacts on the pictures.

Of course I scoured the internet for solutions, and very little came up. This was 2 years ago! I tried rubber bands, pliers, plumbing tools, and pieces of rubber drawer liner. I even tried heating the filter up with a hair dryer (not bold enough to try a heat gun!)

This is a freakin' expensive lens, so I thought I would do the right thing and send it to a professional. I was willing to pay a couple hundred for some professional assistance. The estimate blew my mind, upwards of $500. They quoted me the flat rate for the lens, assuming that there was other damage. I just wasn't willing to fork over that amount. I researched other options and had it packed up to send to KEH, whose flat rate fee for lenses is half that of Canon's. I would have sent it except when I took it in to UPS, they refused to insure it for the amount I requested unless I used a box that gave 4 inches of padding in all directions. I took it back home and it sat around while I waited for the right box to come my way.

Then I went to a conference, and the trade fair both for Canon featured a real, live tech. I should have brought the darn lens! Instead, I chatted with the tech. So, beyond rubber bands and rubber drawer liner, apparently the tactic is to break the glass on the filter and then cut it off with nippers, all the while trying not to damage the glass on the front element or to further damage the threads on the end of the lens.

I guess I thought the pros would have some magical tool.

In any case, I was emboldened, and when I got home I pulled out the hammer! As carefully as I could I tapped a hole in the lens, and picked the pieces of glass out, like an archeologist excavating an artifact.

I DO NOT suggest you do this at home. Take your lens to a pro!

But, if you are going this crazy route, keep in mind that the filter on may be VERY close to the lens element. Also, lens elements are rounded, so there will be more room to play on the edges. My filter was nearly touching the lens element at the center, but on the sides there were 3-4 mm of space between the filter and the lens. Once I got wise to this, I used a screw driver like a chisel, tapping the end of it near the edge of the circle, then prying bits of crumbled glass away from the lens element.

TA-DA! No more glass!

Lens with the broken filter still attached, but no glass!

It seemed to me at this point, there might be some hope of removing the filter without cutting. Without the pressure of the glass against the circle of metal, perhaps there would be some additional play. I couldn't budge it... but my husband, with a bit of effort, was able to twist it off!

Ugly broken filter. Most of the visible damage is from trying to remove it with various unsuitable tools.
Finally, my lens is free!

Lens with no filter! The rim and threads are undamaged. The front element looks pretty clean... 
So, I ran the lens through its paces with a downloaded resolution chart. I checked all of the focal lengths, and just for fun, all of the f-stops. I will decline from showing you all 20 or so test shots because they are wonderfully dull. It is universally sharp within expected tolerances.

Just one test. I think this is at 35mm, f-16. Don't quote me on that though, they almost all look the same: darn sharp!
Methodically testing the focal lengths and f-stops with a chart was actually a good exercise. I've never bothered before! I had known lenses fall off towards the far ends of their focal lengths, and it was interesting that I noticed almost no distortion at the wide end, only a bit at the edges at 50mm, and just a bit more at the edges, along with some chromatic fringing (cyan) at 70mm. Another interesting result was that at f-2.8, it seems that autofocus is unreliable. It is totally sharp if I manually focus, but it will produce results from totally sharp to unacceptable blurry with autofocus. When I did a quick search of this problem, it seems that other people have observed the same issue, and sending it to be serviced did not help.

I'm pretty sure I was having this problem before the impact that caused this 2 year saga-- I frequently shoot at 2.8 because I love shallow depth of field and am frequently shooting in low light, and I recall being disappointed with the sharpness of some of my images. According to my tests, I'll probably be happier with my results if I stick to f-4 and above, using f-2.8 only when I really need it, and perhaps using manual focus.

The other thing that this experience has taught me was that I really love shooting with a fixed 35mm focal length lens. It is light and versatile... works great for nearly all of my blog shots, family photos, and the vast majority of the other art photos and video that I shoot. Before my EF24-70 was out of commission I was lugging it everywhere (it is HEAVY), but now I'm much more comfortable going out with just the 35mm, which is much better for the tendons in my overused right hand and my back.

So, I hope that this helps someone else out there. I'm totally thrilled that this lens is back in action- it is a great lens and for some situations, having access to this range of focal lengths is fantastic.

Okay, done photo geeking. I promise.


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