D800 Portrait Lens Battle!

Started Sep 30, 2013 | Discussions thread
Mariner77
New MemberPosts: 6
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Re: D800 Portrait Lens Battle!
In reply to Shotcents, Oct 1, 2013

Shotcents wrote:

Mariner77 wrote:

As I understand, macro lenses because of their structure can not get enough light at same aperture when compard to normal lenses. But DOF doesn't chage, so when we settled f/2.8 (but shoot f/4), DOF is still f/2.8 but ligt ability is f/4?(So, bokeh still acts as f2.8) I wonder if I got correctly.

In many reviews they always say this situation happens only at macro distances. But as I understand even at portrait distances macro lenses still acts the same. I got confused because there are lots of photos at flicker which were taken at f/2.8. How did they succeed it so?Even lots of 105 vr photos at f/2.8.

At closer portrait distances macro lenses drop to slower F-stops, but I've never bothered to really note when.

Robert

Dear Robert,

I have found a formula to find effective aperture formula here:

Effective Aperture = Lens Aperture x (1 + Magnification)

There is also magnification calculator here:

http://www.mystd.de/album/calculator/

When I calculate for (Tamron) 90mm focal length, 2.8 f number and 1 meter (about 40 inches) focusuing distance , magnification result is 0.11.

In this case effective aperture=2.8x(1+0.11)=3,10

I am confused how your apperture got f4, because it seems you were not closer than 40 inches acording to your models position.

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