My macros have gone soft!!!!

growse · 8 May 2006 at 18:26

Ok, went on a shoot yesterday (in more ways than one...!) and took around 80 images of people shooting clay pigeons. Camera is a 350d and the lens for the day was a Sigma 24-70 EX DG jobbie. It's about 4 months old and I've not usually had any problems with it.

Most of the shots came out fine - here's a 100% crop of a trap at f5 and 70mm:

Not a problem. The problem was with all of my macro shots of the day. I took all of these at 70mm and f2.8, and using autofocus. Here's an example of a macro at 100%:

Bad. Very bad. All the macro ones at 70mm and 2.8 were like this. I don't think it's camera shake, as that one is at (from memory) 1/400. Just to prove that it's possible only macro shots - here's a far-away shot at f2.8 and 70mm. I know it's ISO800, but it's not particularly blurry, and in low light and hand-held, that could just be shake. Crude, but maybe proves that point:

So then I tried a macro. It's ISO 1600, but came out not too bad, which proves the lens isn't that bad when it does macro stuff:

Therefore, there's a number of posibilities:

1) The cold/light drizzle made the lens not focus properly on macros.
2) For every single shot, I focussed, then moved.
3) There's a temperamental fault with the lens
4) I'm insane.

Any thoughts as to which of these it could be?

growse · 9 May 2006 at 11:02

Hmmmm, it's difficult to go back as it's a bit of a trek. I know f5-8 is sharper, but didn't have a tripod that day with me so was keen on keeping the aperture quite wide. I don't want to go through the faff of returning it and being without it for 6 weeks if it's just mistakes by me rather than a faulty lens.

growse · 9 May 2006 at 13:34

Point taken. I never really took much notice of the shutter speed if it was fast enough. Also on macro shots I tend to go after the small depth of field for some good effects. I'll keep doing shots with it to find out where I'm going wrong.

growse · 9 May 2006 at 21:53

SDK^ said:
You realise that the closer you get to your subject the narrower the depth of field.
At F2.8 you will only get a few millimeters in sharp focus.

I actually didn't know that. I suppose I've been trying to get a tiny depth of field to get that authentic "macro" look, but I realise that it's possibly more about what's in focus as opposed to how small the DOF is.....