Focus problem regarding Sigma 150mm macro lens

[tarun_kumar1]

Hi Everyone,

I am new to photography was have interest in macro photography. Since I was pretty tight with the budget so I purchased a used lens from amazon.com.

However when I tried to test it, I am getting focuses is different area. PFA is one of thee shot in which I have noticed same.

As you can see above ts the image which I did captured. Now it do have multiple focus like on surface, then some of its legs attached to surface are out of focus then focus same back again on top of the legs. So just want to make ensure that is it something I am making mistake or its some sort of problem with lens itself.

Any pointers will be highly appreciated.

 

[paigew]

What were your setting when you shot this? I would close down your aperture.


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[tarun_kumar1]

What were your setting when you shot this? I would close down your aperture.


Sent from my iPhone using Tapatalk

Hi,
Paigew,

Thanks for prompt reply.

My settings for the shot were :

Aperture f5.6
Focal lenght : 150mm

 

[Overread17 5]

Welcome to macro - what you are getting is perfectly normal behaviour of the lens.

Depth of field in macro is tiny - really tiny! Especially so on DSLR where the sensor is much bigger than it is on a point and shoot camera or a phone; thus the depth of field (area of the photo in focus and sharp) is much much thinner.

For a shot like this if you wanted more of the spider in focus you could shoot at f13 or even f16 ( I wouldn't use apertures much smaller as you will already have some softening from diffraction and beyond those two the softening gets quite noticeable).


This is why you often see a lot of macro done with flash, because that way you can use a small aperture, but keep a nice clean low ISO and a usable shutter speed for the shot.


As a not on focusing try manual focusing; set the focus and then move the camera closer till you get the subject in focus - you'll find that you rock back and forth a little so work with that and take hte shot at the right moment. AF is very tricky in macro and its often a lot easier to use manual focusing.

 

[Overread17 5]

Note - the reason you are seeing parts of legs in and out of focus is because the depth of field is so thin that its only passing through a section of them, the leg is not parallel to the front of the lens, thus anything forward or back of the plane of focus is out of focus.

 

[tarun_kumar1]

Welcome to macro - what you are getting is perfectly normal behaviour of the lens.

Depth of field in macro is tiny - really tiny! Especially so on DSLR where the sensor is much bigger than it is on a point and shoot camera or a phone; thus the depth of field (area of the photo in focus and sharp) is much much thinner.

For a shot like this if you wanted more of the spider in focus you could shoot at f13 or even f16 ( I wouldn't use apertures much smaller as you will already have some softening from diffraction and beyond those two the softening gets quite noticeable).


This is why you often see a lot of macro done with flash, because that way you can use a small aperture, but keep a nice clean low ISO and a usable shutter speed for the shot.


As a not on focusing try manual focusing; set the focus and then move the camera closer till you get the subject in focus - you'll find that you rock back and forth a little so work with that and take hte shot at the right moment. AF is very tricky in macro and its often a lot easier to use manual focusing.

Hi Overread Sir,

Thanks a lot for descriptive and useful pointers. I will keep all the things you did mentioned in mind and will try it all those tips in my next macro for sure.

Happy holidays.