Just got a sigma 105 lens

bikeit

Senior Member
So i just picked up my first macro lens, a Sigma 105mm F2.8 EX DG so any one offer any help regarding lens and camera settings,
 

Marcel

Happily retired
Staff member
Super Mod
Use manual focus to get in the wanted range. After that, leave the focus ring alone and S L O W L Y move back and forth to get the focus exactly where you want it to be.
 

hark

Administrator
Staff member
Super Mod
Contributor
Use manual focus to get in the wanted range. After that, leave the focus ring alone and S L O W L Y move back and forth to get the focus exactly where you want it to be.

^^^This or get a focus rail to mount on a tripod. Keep in mind that when your lens is so close to the subject, your DOF is extremely shallow. That means your aperture might be f/16 or around there. If you use f/5.6, not much will be sharp because the depth of field is too shallow.
 

bikeit

Senior Member
Thanks folks, i notice the F stop showing on the camera will not be more that F3 when the lens is F2.8 is this normal for a macro lens?
 

nickt

Senior Member
Thanks folks, i notice the F stop showing on the camera will not be more that F3 when the lens is F2.8 is this normal for a macro lens?
When you say 'more', I assume you mean bigger opening, a lower number? It's stuck at 3 and you expect to see 2.8? If thats what you mean, yes that is normal. Focus on something far away and you will get down to 2.8 if you need it. You will never need it for a closeup. I forget what this lens property is called, but its normal behavior for this lens.
 

hark

Administrator
Staff member
Super Mod
Contributor
When you say 'more', I assume you mean bigger opening, a lower number? It's stuck at 3 and you expect to see 2.8? If thats what you mean, yes that is normal. Focus on something far away and you will get down to 2.8 if you need it. You will never need it for a closeup. I forget what this lens property is called, but its normal behavior for this lens.

Yes, my Nikon 105 macro works the same way.
 

Marcel

Happily retired
Staff member
Super Mod
Thanks folks, i notice the F stop showing on the camera will not be more that F3 when the lens is F2.8 is this normal for a macro lens?
This is quite normal as when you get into a magnification close to 1:1 you loose light and the 2.8 aperture that you've selected becomes around f 3.5. The actual larger F number is effective when you focus at infinity. So, even if you set the aperture to 2.8, if you focus at the closest focusing distance, the exif will show a smaller aperture.
 
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