Hi Guys
Some time ago, as some of you may know I had a fantastic Canon 70-200mm F/2.8L Lens, it never let me down and performed beautifully, I still have it, but I broke it.
The front barrel became a bit loose so I figured I would dismantle and fix it, but I actually broke it instead, not on purpose mind you, but the electronics were damaged beyond repair.
Canon were going to charge nearly $1700.00 for the repair, ouch !!
Well that was just crazy so here I was with a optically great lens that was basically useless, so what do I do with this expensive optical brick, that wouldn’t do anything,.
When connected to the Camera it showed error after error, electronically it was useless, plus the diaphragm was stuck on F/32, nothing worked.
I did try again to repair it but it was to no avail, so it was put in it’s bag and there it stayed for some time, however occasionally it would spring to mind as what to do with this broken lens.
Maybe I could sell it for bits, which I tried but then withdrew it as it was hard to let go of something that was worth a lot of money in its day.
It then came to me, why not make it a totally manual 70-200mm F/2.8 Lens, the optics were pristine and it would still focus manually, I mean what was there to lose, it was stuffed anyway.
However it had to be done so the Camera would not recognise that it had a lens attached through the electrical contacts.
So after some more thought, and with screw driver and cutters in hand I dismantled the thing, unscrewed and cut of all the electronic bits, but there was still that stuck diaphragm.
So whilst in there I removed the diaphragm mechanism and to my delight found that it had a little switch of sorts on the reverse side that could move forward and reverse altering the aperture from F/32 to F/2.8 and anywhere in between.
Well that was all good, but it still would not work once reassembled because the electronics had been cut.
It was my intention to use this lens which I have always done for lightning shots meaning I had to set the aperture to what I had always used when shooting lightning, being F/11 or F/8.00, and then leave it set at that and re assemble the thing.
So by dividing the focal length, being 70mm by the required F stop being F/11 and also doing the same for F/8.0 I came up with 6.363mm and 8.750mm respectively, I then added them together and divided by two which gave me an average aperture hole diameter of 7.5mm, this would be pretty good for what I needed to do for lightning at about ISO 100-200 depending on flash brightness.
So after re assembling the lens fitting it to the Camera which thinks that there is no lens because it has no electronic readings it works perfectly a totally manual Canon 70-200mm f/2.8L Lens, so at least I will get some use out of it.
Now all I need now is a storm and plenty of strikes so I can give it a test run
Leon
