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sigma 150mm f/2.8 light loss


New Member
Unboxed my brand new sigma 150mm f/2.8. All in perfect condition as I'd expect.

Mounted it onto my 40D, and went out into the garden to give it a try.

Excellent quality, and a nice working distance as I'd expected, but I seemed to be getting very slow shutter speeds at 1:1.

Shooting in very bright, direct sunlight at f/8.0, I was only getting 1/125sec at ISO 400. I take the photo and it's correctly exposed. But in the same situation, my old fuji S9600 gives me over 1/250 sec at ISO 200 f/8.0, and that is also properly exposed. Also, if I set it up on the tripod, then move the focusing distance to infinity and back, the shutter speed pretty well quadruples at infinity to what it's at at 1:1. I'm aware that this might also be to do with the cameras metering as the subject goes out of focus, but it does it in all metering modes. And this images at both infinity and at 1:1 are properly exposed, even though the ISO and aperture are the same, but the shutter speed is a quarter of what it is at infinity at 1:1.

I was expecting some lightloss at 1:1, but this seems to be losing 1.5-2 stops.

Obviously to get around this I can increase the ISO, but even with the massively better ISO performance than I used to get, I don't really want to be shooting at ISO 800 or 1600 all the time. Even when I use the tripod (which is most of the time), the slow shutter speeds are still a problem unless there is absolutely no breeze at all.

I've always liked taking macros in natural light rather than flash, and If I can help it I don't want to start using flash. I know natural light macro is always going to be a struggle against camera shake (when handholding) and the wind, but losing 2 stops of light really isn't going to help.

All in all, this is rather worrying me. I already really like the feel and performance of this lens, but I'm just not sure how I can work around 2 stops less shutter speed.

Can anybody help with this?
squishy - let me first say I have never shot on a canon system...I shoot macro with Sony/Sigma...and used to own a Nikon System....

I have a few questions...

1 - Are you shooting Manual...if you are not shooting manual what priority mode are you using...??

2 - Are you shooting AF or MF...??

3 - If you are shooting natural light...are you using reflectors...?

4 - Are you using a tripod or mono-pod...?

5 - Are you shooting RAW or JPG...??

I know most of these are simple questions...but later it might help someone if they have the same issues...

Tony C. :z04_cowboy:
Before I answer your questions, I want to say I've found from looking in the user manual that it is a normal thing for this lens. Also, I've decided it isn't much of a problem after going out shooting properly.

1: aperture priority (also tested in manual and shutter P, same thing occurs)

2: MF

3: No reflectors

4: tripod or handheld (I did the tests on a tripod)

5: RAW
Cool..I looked at the manual online...you might want to get some small portable reflectors...if you want to use natural light...it will help define and sharpen the image...I carry two with me...one to light from the opposite side and one to light from the bottom...

Here is a shot I did in HK with the two reflectors...

View attachment 2076

Have a good one..

Tony C. :z04_cowboy:


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just to remind you of optical rules in the macro area

that come to play here:

double the magnification will result in 1 stop loss

e.g. 1:1 is one f-stop less than 1:2...and so on.

Therefore it`s correct that you don`t have f2.8 at 1:1

Your lens is performing absolutely correct but one cannot deny nature`s law !