5DS Underexposing with Canon 100mm F2.8 macro (old non-usm version)

[ryanjoseph]

<p>Recently picked up a Canon 100mm (older non-USM) macro on the cheap and was testing it on some bees yesterday. I noticed as I got closer and closer to subjects that the camera would tend to underexpose, not accounting for light loss in macro range. Is this related to the age of the lens? I seem to lose about two stops at 1:1. I don't mind doing exposure compensation, but I just assumed the camera would compensate for macro range photos itself. Thanks for any input. </p>

[ed_avis2]

<p>Does it happen also in Av mode with a fixed aperture of f/2.8?</p>

[colin carron]

<p>I don't remember my Canon 100 2.8 macro doing that but for anyone to be sure of their answer I suggest you should upload an example photo and also the EXIF info with it.</p>

[ryanjoseph]

<p>Yes it happens in AV mode. Here is a link to an example photo being underexposed. </p>

<p>https://d199bk7kirt65b.cloudfront.net/files/p/E~forums/56327767/3d4d8ce7e9164d26ad8e619369f2b90a</p>

[colin carron]

<p>I've been looking back at similar shots I've taken with the Canon 100mm 2.8 macro. I usually used Av mode with no compensation. The light is a bit different to your shot but I would not have expected it to have made that amount of difference.</p>

<p> </p><div></div>

[colin carron]

<p>...and here is the EXIF data obtained in windows by right-clicking on the original image then select 'properties' then 'details'. In this case you can see there was 0 exp compensation and pattern metering etc</p><div></div>

[bobatkins]

<p>It's a TTL metering system and so should automatically compensate for any light loss due to close focusing. It's possible that there is some miscommunication between the firmware in the old Canon lens and the latest Canon body. I seem to remember that there are some known examples of that. </p>

<p>Do you have another (older) body to test it on. </p>

<p>If you look into the lens and use the DOF preview function, does the aperture look like it's opening and closing properly without any sign of sticking? A sticking aperture can result in exposure problems.</p>

[ryanjoseph]

<p>Sadly I sold my 7D so I no longer have a body to test the lens on other than my 5DS. I have a friend with a 60D I could try it on though. Using DOF preview shows the aperture works fine, with no signs of sticking as far as I can tell. I am getting perplexed by this underexposure problem.</p>

[ed_avis2]

<p>Ryan J, I'm not certain the bee photograph you posted demonstrates an underexposure problem. It depends on the metering mode; if evaluative metering or some other method that takes into account the whole image is used, then it's possible it was trying for a correct exposure of the blue flowers or even the white petals in the corner. You may need to photograph a flatter, more uniform subject to demonstrate the problem.</p>