A keeper

Martin B K wrote:

Hi,

I am seriously considering to by either 300 mm F4 or the new 100-400 II to be used for mainly birds photography. I am using a 7D but can surely use all the focal length I can get as long as the quality is good. I expect to ad a 1.4 externder to the 300 mm for that.

What lens would you suggest with regard to image quality ? - so 300 mm with 1.4 ext (or without extender but cropped) vs 100-400 using max focal length.

I will mainly operate in f5.6-f8 (and f4 if/when possible).

As far as sharpness, if you stop the 300/4 IS down to the max aperture of the 100-400 II at 300mm, then it looks to be a wash.

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=972&Camera=453&Sample=0&FLI=3&API=1&LensComp=111&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=1

I am too trying to pick between those two.  The 300/4 IS is 2/3 stop faster at 300mm and a lot lighter.  So when I do astro photography the extra speed is nice and the lighter weight will probably help my sky tracker track better.

The other uses would be Zoo/wildlife and outdoor soccer.  I have been looking at a lot of field sports type pictures of lenses in these focal lengths and f5.0 at 300mm seems to leave a lot of the background still too clear for my liking unless its framed really tight.  I would really want a 300/2.8 but the wife would kill me.  300/4 seems to get at least better speration, but gives up the flexibility of the 100-400 II.  The money saved on the 300/4 IS over the 100-400 II would be nice to use on other photography related upgrades too.