Canon 2X III Tele-Converter
When I bought the Canon 70-200mm f/2.8 from Allen's Camera, I also bought a 2x Tele-converter. My thought process was that if I needed extra reach, I would have an instant 140-400mm lens. Except the only thing is that you lose two stops of light when you use the tele-converter. It turns your 70-200mm f/2.8 lens into a 140-400mm f/5.6 lens.
The other night I dialed in the settings at a hockey game. I figured out the settings with the 70-200mm lens in about three frames, so I knew I was spot on. During one of the breaks, I took out the 2x tele-converter to try and reach across the rink and get a picture of the coach. This was the picture:
I downloaded the pictures at home and...aw, shit, I forgot to change my settings. I was fortunate that I was shooting in RAW, so I could rescue the image by adding two stops of light in Lightroom.
Not great, but saved. Since I was already shooting at ISO 3200, the additional noise that was added in Lightroom wasn't ideal. As a B&W image, it was OK if I added a lot of contrast.
Hopefully I will remember next time!