Canon 135mm f/2 vs. Sigma 85mm f/1.4

Yesterday I received the 135mm f/2 and really didn't have a whole lot of time to spend using it but I did come across one scenerio that puzzled me.

I was just taking a few random shots as I was sitting at my computer desk. One of the shots being at one of my dogs orange rubber ball that was on the carpet approx. 12 ft. away or so. The room is not the greatest for lighting. Abovewhere I was sitting, there is a ceiling fan that has three lightbulbs and then farther down the room approx. 10 ft. behind the ball there was a small lamp that was turned on.

To make a long story short, the Canon 135mm could not focus on this ball. The only setting I remember (I'm at work now) was that I had it at f/2. I tried repeatedly to get at least one shot at various shutter speeds and the lens would not focus and I could not get the camera to fire one shot.

I then I put the Sigma 85mm on at set it at f/2 and it focused quickly and I was able to get numerous shots with no problem whatsoever.

Just a quick observation that I found puzzling. I mean isn't that 135mm f/2 suppose to be a fast focusing low light lens? All in all, the light was not even THAT low for it to not be able to even fire a somewhat dark shot at least.

Denise

I am not sure the comparison between any 85mm lens and the 135mm lens and a picture taken in the same room at the same distance of any object would be a fair comparison of how the AF works with one and not the other.


Since the ball would appear over 50% larger to the 135mm the AF system may just have had a problem picking a good contrast point to focus on. It would be a more fair comparison if you moved closer to the ball with the 85mm and see how it acted.

What were your camera settings if available? I was able to catch a couple of indoor shots of my pets when i owned the 135l without much of a bother in my opinion. I used both manual and auto focus as well. did you have the camera set to auto or manual mode? i have used it on the 40D at the time, and i still feel it was doing ok. i cant provide a sample, and even if i did they are not superior quality :) !

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Originally Posted by HDNitehawk

I am not sure the comparison between any 85mm lens and the 135mm lens and a picture taken in the same room at the same distance of any object would be a fair comparison of how the AF works with one and not the other.


Since the ball would appear over 50% larger to the 135mm the AF system may just have had a problem picking a good contrast point to focus on. It would be a more fair comparison if you moved closer to the ball with the 85mm and see how it acted.
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You are correct, it was not a fair (nor planned) comparison. I guess even without bringing the 85mm into the scenerio at all, I was just puzzled that the 135mm lens could not pick up this very bright orange ball and focus on it.

It had no problem focusing on anything else throughout the night so for whatever reason, it just didn't like that setup I guess.

Canon L lenses have developed an aversion to the color orange....that

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Originally Posted by Sean Setters

Canon L lenses have developed an aversion to the color orange....that's why you don't see them at the University of Tennessee football games anymore.
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LOL! Maybe I should try it out on red &amp; white or better yet pro colors like green &amp; gold!!

That kinda makes sense Sean. I managed to keep up with the whole technical component of your reply.


So just don't shoot orange Denise. You could be in trouble if your sqirrels start eating oranges instead of green apples. [;)]


Enough levity, I would have thought along the same lines as you concerning the 135's low light capability. Hope the tech experts herecan shed some light.


i'm sure you'll have it sorted soon, can't wait to see some pics.


Steve

Only thing that occurs to me is to wonder how large the ball was relative to the AF point...if it was big enough at 135mm to cover the entire AF point on the sensor, there would probably not be sufficient contrast to lock in; the wider view of 85mm (meaning the ball would effectively be 'smaller') would let the 'edges' of the ball (in a 2D projection) cross the lines of the sensor. The light level should be a non-issue between the two lenses, since the AF system is either f/5.6-sensitive or f/2.8-sensitive, but once across the f/2.8 threshold for the higher-precision center AF point, there's no extra benefit to an even faster lens (Daniel explained this in another thread some time back).

You got that thing dialed in yet, denise?

I still have not really had much of a chance to use the 135mm. I have it set right now at +3 and hopefully tomorrow I will have more a chance to see how this works out for me.


I only have these two shots that I took tonight just to see how they would look ...


@ f/2.5


http://farm6.static.flickr.com/5286/...f5a8f4a9_z.jpg

@ 2.8


http://farm6.static.flickr.com/5290/...80e64eb5_z.jpg

More than anything, with these settings I was trying to get an improved appearance of my very wrinkled black backdrop as possible but still keep as much of the statue in focus as I could. I didn't have much room to move the backdrop back any.


Hopefully, I'll have some better photos tomorrow.


Denise