500 F4 sharpness question...

Sometimes the focus is soft in overcast days. In full sun, it tracks birds slow and misses sometimes. With or without the 1.4X, this lens is slower than My 400 5.6. I'm using a 50D. Is there something wrong with this lens, of do I need a better camera body??

How long have you been using the 500? I only ask because when I rented one (for 2 weeks), it took me the whole 2 weeks of shooting daily to get to a point where I felt I was getting good results on a 7D.

I shoot a 400 5.6 regularly and felt the 500 was a better overall lens.

I have had it for 2mo. There's no doubt it's better than the 400, it just seems slower. When I shoot BIF I hold down the AF button ( in AI Servo ) The 400 would track good and most of the shots were sharp where most of the 500's were soft...

DegasGoneDigital wrote in post #9683460
Sometimes the focus is soft in overcast days. In full sun, it tracks birds slow and misses sometimes. With or without the 1.4X, this lens is slower than My 400 5.6. I'm using a 50D. Is there something wrong with this lens, of do I need a better camera body??

A bare 500 should AF as fast as the 400. Have you used micro adjustment to see if the lens is focusing correctly?

Is it still soft when shooting a stationary object? I assume that you are using a tripod?

DegasGoneDigital wrote in post #9683501
I have had it for 2mo. There's no doubt it's better than the 400, it just seems slower. When I shoot BIF I hold down the AF button ( in AI Servo ) The 400 would track good and most of the shots were sharp where most of the 500's were soft...

strange. I didn't see the same thing with the 500 I rented...it was fast on AF in AI Servo for me.

My 500mm f/4 is as fast (if not faster) than my former 400 f/5.6. I use it on a 1D MarkIII and a 7D.

One suggestion if you are using a tripod is to turn off the IS ... There can be a slow down of focus when tracking BIF's with the 500 when using a tripod and high shutter speeds.

bhowdy wrote in post #9683798
One suggestion if you are using a tripod is to turn off the IS ... There can be a slow down of focus when tracking BIF's with the 500 when using a tripod and high shutter speeds.

Interesting...wonder why IS slows focus?

First, where the focus limiter is set to? Try the farthest setting. 1.4xTC will slow down AF for sure but the bare lens is real fast. Hard to tell them apart when using 300mm f2.8 IS, 400mm f5.6 or the 500mm f4 IS.

Thanks...... I'm using a 50D, I wonder if that might be the problem....

What aperture are you using ? as the 500 will really punish you if you haven't hit the focus bang on with a low aperture.

I would also suggest microadjusting.

What shutter speeds? When I had the 500 on a 40d, hand held tracking, I noticed the same thing. I realized that my shutter speeds were a little low and therefore producing some soft images. On cloudy days, it was anything under about 1/500 second even with the IS on.

It does sound like your AF is not up to par, but I have to disagree with the sentiment that the 500mm focuses as fast as the 400mm f/5.6

The 400m with it's terrible MFD never has to AF as far as the 500mm might have to if the focus limit switch is not set, and is known to be one of Canons fastest focusing lenses. In many situations it will be the faster of the two.

If this were the only concern, then I'd say your 500mm is fine.

However, the 500mm AF accuracy should not be less than the 400mm at all,. so it does sound like yours needs some kind of adjustment.

I'm not sure what is going on with your 500. I have used mine on a 50D and the focus is immediate. The focus limiter switch could be the problem and also the IS. It takes IS about a second to wind up. Aside from my 300 f 2.8 it is my sharpest lens. Try doing a MA on it and see if your sharpnrss improves. Also keep your shutter speeds up.