Trying to Macro with a sigma 70-300 APO, not much joy though

[wildman]

Its driving me nuts. It looks like I have a crisp sharp image in the viewfinder, then when I get the pictures back to the PC there is always something slightly out of focus.

e.g I was macro shooting some daffodils, the centre was razor sharp but where the petals were slightly back they were some what out of focus.

I was at a focal length of 300 with macro switch on lens flicked to on. Was using F5.6. I guess I need to increase the DOF and maybe raise F to around 11 ?

Also I have to stand crazy far away from the subject to get it focused in the begining ? SHould I thnk about maybe investing in some extension tubes and using the kit 18-70 lens instead

 

[wildman]

Yeah a 300mm lens even at the Sigma's MFD will give very shallow DoF. You'll need to look at a tripod/flashgun to really have a feasible chance of getting good shots with it except in really bright daylight.

Was already using a tripod. Flash gun is something I need to invest in, the built in one on the A200 is weak sauce.

Do you think I would yield better results by investing in a set of the kenko extension tubes and possibly using either my 50 f1.8 or maybe even the original kit lens ? Not sure if I am ready to part with 400 notes for a dedicated macro lens just yet

 

[wildman]

Your problem is solely down to lack of DoF.

For sure you will need a good tripod and head, plus macro flash to really get very far, but you need to shoot at f/16 or so.

Really you need to do focus stacking if you want a sufficiently large DoF to get soemthing small to be completely in focus.

The Dof is purely a function of magnification ratio and aperture. It doesn't matter what lens/focal length/extension tube/focal distance you are using, if you magnify the subject to the same image proportion then you will get the same DoF a the same aperture.

Sorry for the dumb question, but what exactly is focus stacking ? Is it taking multiple shots at different DoF and then adding them together say in PS ? WOuld this be as simple as simply taking multiple shots at differetn F settings and then putting them altogether ?

Sorry I am new to macro photography