awacsCZE wrote in post #18359846
I had the Tamron and what I really hated with it was, that I had to use aperture 8 and up to get it a bit sharp. Otherwise it looked terrible. I thought, that it could be caused by incompatibility with the body. That was on 600D. Now, I have 70D and I must say, that AF on that is different. Lot of missed AF shots with L lens, so I'm affraid, that 70D wont be much of a win with third party lens.
I looked throught a flickr and what bugs me, that most of the Sigma photos there are in resolution sub 1000px. Dont know why but to me they try to mask its quality.
I'm well aware of the atmospheric problems, that's why I ended with 70-300 L as my choice in the first place. Anything over will probably be heat-haze terrible.
I want it to be versitile as it will probably be one of my most used lenses, replacing the 70-200 f/4. Im a bit affraid of travelling with 150-600s.
Honest dont know. Brain says 70-300L, heart 100-400 II and you Sigma
Be aware that for aviation distances the atmospheric limitations apply to any focal length you care to use. The degree of resolution reduction will always be the same. It is just that with shorter focal lengths everything is just smaller. Often that just means that you are focal length limited sooner. Remember that I am often focal length limited using a 600mm lens. To get the shot to fill the full APS-C sized sensor I would need to be using a 900mm lens, and if I wanted to use one of the 35mm sized sensors, or film, I would need to use a 1440mm focal length. Remember that once you are FL limited you will have to start cropping the image, which is then increasing the magnification, but with lower recorded resolution. Focal length always wins in this scenario.
I would suggest that if you are suffering a lot of missed focus shots with a 70D, and a 70-200 f/4 then either it is a faulty lens, or you have some sort of serious setup or technique issue, or possibly a combination of the two. You are using AI Servo as your AF mode aren't you? I can't really help with the 70D AF optimisation very much, since I only have a 50D. I would recommend that you try shooting with BBAF, with focus removed from the shutter button. Separating AF and shutter can really help at times.
If you are going to be travelling on aircraft a lot then yes you are likely to be better off with one of the 100-400 options. The 150-600mm lenses are quite large. The Sigma C uses a 95mm filter thread, and the S goes to 105mm. The Canon 100-400 V I uses 72mm IIRC, and I think the new Sigma may even be a little smaller than that. They are also slightly shorter. If I'm remembering correctly the 70-300 L is about the same physical length as the original 100-400.
Personally I don't really see any of these lenses a replacement for a 70-200 f/4 L, they are really in quite different classes. The 70-200 is kind of a really good general purpose mid telephoto zoom. I kind of like the range on the 35mm format, I used a Vivitar 80-200 on my Pentax ME-Super for years. It's also a very good range on APS-C too. The longer zooms that we have been discussing are really too big to be used as a general purpose lens though, they are much more specialised. I have kept my shorter smaller lighter telephoto zoom, because none of the larger options are every day lenses.