Canon Community

Some explanation, I've been looking to upgrade to a newer camera from my older Canon 60D. For some context I do sport/motorsport photography and I cant decide between the 90D or the R7. I can find both on Ebay for around the same price used/refurbish...

I recently acquired a Ver1 300mm f/2.8 IS, it's a complete lens except the tripod collar is missing. Does anyone know an aftermarket one that'll fit? Or perhaps where I can obtained a OEM one?