Hi, I'd like to try a 400mm just for fun for shooting bird and other animals, spending nothing, something like a Soligor, Panagor, etc. with the first good offer on ebay. I've looked at the image threads on this site and I'm ok with the IQ of the cheap ones: https://www.google.it/?q=site:https://www.mu-43.com+adapted+400mm I already have a Tamron 70-210/3.5 19AH and I'm wondering if it could be better to just buy a 2x TC for the same price. This means f8 but I expect to have to stop down a little the prime lenses too. But with the TC I'm not stopping down the lens and at f4 the zoom is not bad but not great either, it starts to shine from 5.6 on. Pro TC: - zoom lens - TC is smaller, more versatile - no extra adapter Pro 400mm lens: - faster lens But I have no idea how the image quality could be. It is a good zoom lens with TC against a cheap prime lens. What do you think?