TeamSpeed wrote in post #18720638
Shh, my gear didn't get that message, and I don't want them to hear that.
At only f/5.6, I think that the potential can be there. One would have to give the AF a test drive in limited light to see what the AF potential is with the OP's camera. In my outlook, AF ability is the main factor in deciding whether or not a TC is useful.
Some points to bring up as I shoot HS football once in a while using zooms, crops and TCs.
1) One tends to shoot at high ISO for games. A 2x will raise that ISO 2 more stops, a 1.4x will raise your ISO 1 stop. Unless you like the noise or know how to deal with it well, this can be an issue.
It's not an issue at all, IMO, provided that you are using the TC to avoid cropping. A higher ISO due to higher magnification is not an increase in subject-level noise, and likely an improvement in noise character. IMO, the higher ISO argument against TCs is myth, provided you are using the TC in lieu of cropping. If you back the 70-200 out to 200mm ("100mm" on the lens barrel) with the 2x TC on instead of using 200mm without the TC, then you are actually losing subject-level SNR, as you would also do if you stepped further back to fit something in the frame instead of removing the TC. In any given light and distance from the subject, it's really about the size of your entrance pupil (the max is unchanged by a TC, but drastically reduced when zooming out), and the shutter speed.
The answer really depends on what your ISO levels are now on the 7D. If you are able to tell what you are normally shooting at now, it will help determine whether you can go aggressive with the 2x or stay with a 1.4x. If you decide on the 2x, then I think a new lens might better personally.
Again, I would disagree here. Higher ISO due to higher magnification is actually neutral to beneficial, at the subject level. It is certainly damaging to 100% pixel views of bokeh, but that is not practically relevant.
Now regarding the 1.4x decision... Newer cameras are substantially better at high ISO and resolution. If there is any way you can get a newer camera, it would be like getting a built-in 1.4x due to resolution without any penalty. For example, an 80D yields almost 40% more total resolution,
That's only 1.158x the linear resolution; a bit short of a 1.4x TC.
but comes with a better AF system and better ISO management. If you go with a 1.4x, I wonder if a newer camera wouldn't be a better choice for a number of reasons. The 7D is pretty good in its time, I could shoot ISO 6400 all the time with it, 12800 when needed, but it required some good post processing techniques.
As long as the 7D is what is used, it is still AF ability alone, IMO, which should determine TC usability. I never worried about ISO going up on my 7D because of a TC, or any camera. As much as it is hard to believe looking at 100% pixel views, the higher ISO and magnification gives a better subject-normalized capture.
People need to stop thinking about increased ISO due to TCs in terms similar to raising the ISO while lowering the light levels, or unnecessarily doubling shutter speed. The light is *NOT* lost with a TC; it is just spread wider on the sensor plane. Higher ISOs generally add *less* noise than lower ones to a given amount of subject light, and higher magnification makes the AA filter and CFA patterns *finer* and less intrusive on subject-normalized detail.
Again, loss of AF is the *only* reason I would choose cropping over a TC. A quality TC, of course, with minimal haloing and added veiling glare.