Maybe others have done this before, but I want to relate a little story of how I solved an issue with my Fujinon 18-55mm and a persistent blob of dust on the inside of the front element.
I had this big piece of dust on the inside front element of the lenses. This didn’t adversely affect the image in any way but was annoying me. I believe it was a dust mite, it even seemed to move around a little and would come towards the edge of the lens when I shone a torch there. But I could not shift it completely, it kept returning to the front element.
I read some advice about killing mites in lenses by freezing. So I sealed the lens in a ziplock bag and put it in the freezer for a few hours. I didn’t release the lens from the bag until it had returned to room temperature. Whatever the dust blob was it didn’t move again after this. But it was still sat there in the middle of the front element. I had killed the beast but not shifted it.
Now I’ve seen all the pictures of smashed front elements still taking pictures. This wasn’t really about image quality, but about something of mine not being how I wanted it. I get that. This was a slightly obsessional thing. And while I have no plans to ever part with this excellent lens I could hardly sell it with a corpse of an invading entity sat their bang in the middle of the front element.
So just now I was looking at this blob of dust and my thoughts went in the direction of the ultrasonic vibration some cameras use to remove dust from the sensor. Many modern cameras shake the sensor at start up and shut down to remove particles of dust. What if made the front element of the lens vibrate? Would that help? What should I use to vibrate the lens?1
I tried my Phillips rotary shaver first. But the damn thing was too smooth. It didn’t vibrate much. I held the body of the shaver against the edge of the lens’ filter ring. No luck. Then I remembered that my beard trimmer vibrated much more as it used reciprocal motion rather than a rotary movement. I fetched that, held the side against the filter ring and fired it up.
Within seconds that pesky blob of dust fell away harmlessly into the corrugations of the inside of the lens barrel. It had been smote by my silly idea. I’m not sure If I’m trying to pass on advice here. Warn you not to be so silly with your gear. Or just sharing something that made me laugh. But there you go, an ad hoc method of removing persistent front element lens dust.2
1No sniggering at the back there.
2I accept no blame for you damaging equipment, or for your significant other asking what exactly are you doing with their vibrating device.