Question for all 15-85 (and other Canon Zoom) owners

Started Jun 27, 2010 | Discussions thread
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Doug_PS Contributing Member • Posts: 812
Question for all 15-85 (and other Canon Zoom) owners

I'm noticing a phenomenon with my 15-85 zoom lens. I wanted to post a few pictures to illustrate what is going on and ask other owners of this lens (or other Canon zoom lenses) if they are experiencing the same thing.

This is my 1st mid-range zoom and I'm noticing the 15-85 seems to be severely underexposing (I've referred to this as a "dark cast" in other similar posts). My body is a 50D and I've tested the lens on a 7D and noticed the same "dark cast" doesn't appear to be a problem with the body.

When I compare the exposure of the 15-85 to either my 60 macro or 85 1.8 primes, I notice the same phenomenon (ie the 15-85 underexposes with all variables being equal). I'll post 8 pictures below to illustrate the point. The 1st 4 were taken with the 60 macro in AV mode at f 5.6 (at zero exposure compensation, -1/3, -2/3 and -1.0). The next 4 were taken with the 15-85 at 60mm in AV mode at f 5.6 (at zero exposure compensation, +1/3, +2/3 and +1.0). The conditions are: bright sunny sky (ie same conditions for all 8 shots). Focus point is: middle of the 3 flowers on the left side of the pot.

My questions are:

1. Is this a characteristic of this lens (or all Canon zooms) in general? Or, does my particular lens have a problem that can be corrected by a trip to Canon service center?

2. If this is a characteristic of this lens in general (or of zooms in general), is it best to leave the Exposure compensation at zero and adjust exposure in post processing (ie Lightroom in my case), or to preset the exposure compensation for this lens.

To my eye, around +2/3 to +1 exposure compensation is needed for the 15-85 to equate to the same level of exposure as I'm seeing on the 60 macro. is a link to another thread where I posted similar test pictures comparing the 15-85 to my 85 1.8 (same phenomenon).

1. 60 Macro Pic #1: zero Exposure Comp:

2. 60 Macro Pic #2: -1/3:

3. 60 Macro Pic #3: -2/3:

2. 60 Macro Pic #4: -1.0:

15-85 Pictures:
1. 15-85 Pic #2: Zero Exposure Compensation:

2. 15-85 Pic #2: +1/3:

3. 15-85 Pic #3: +2/3:

4. 15-85 Pic #4: +1.0:

 Doug_PS's gear list:Doug_PS's gear list
Canon EOS 7D Mark II Canon EOS 5D Mark IV Canon EOS M6 Canon EF 400mm f/5.6L USM Canon EF 100mm F2.8L Macro IS USM +9 more
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