Comments made by derek897 - Page 152

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Emleyman, Ok i understand the point that you are making.
You may be correct, as it seem odd that the lens could be more open than its max aperture, unless its max aperture is set by manufacturers, not for its physical limitations but for quality control, aberrations / sharpness.
I can test this tomorrow as i have a spare set of tubes that are completely manual, no contacts.
I will set the lens on these to f2.8 and take the same scene with the new tubes at f1.2. All settings will be the same.
Will be interesting to see if the exposure, shot will change.
Thanks for taking the time to explain your point again

Derek

Comment by derek897 posted on Sigma 105mm macro f1.2 at 09/04/2017 - 22:32

3 and 14 stand out for me.
As above, the low angle sun has worked really well.

Comment by derek897 posted on Mud at 09/04/2017 - 11:08

sebas77 wrote:
haha I actually just realised you were asking about your lens

Ah yes. It's not just a random question.

Emelyman, what you're saying makes no sense to me at all.
It sounds like regardless of the f1.2 question, anyone shooting with tubes can't shoot wide open because at f2.8 it's really f11, at least thats what im getting from what you're saying.
The lens will stop at the following extra stops.

F1.2 f1.3 f1.4 f1.5 f1.6 f1.7 f1.8 f1.9 f2 f2.1 f2.2 f2.3 f2.4 f2.5 f2.6 f2.7

I do shoot macro wide open at times
(Previous thread )
So I know what my dof should look like.
And it's nothing as shallow as the f1.2 shots at the least magnification, furthest focusing distance.

Comment by derek897 posted on Sigma 105mm macro f1.2 at 08/04/2017 - 20:17

emleyman wrote:
The way Iunderstand it is that the lens transmits the info on largest aperture and number of stops to smallest. In this case, incorrectly f1.2. When you set aperture to f2.8 on the camera you are actually telling the lens to decrease aperture by 4 stops, so although the exif says f2.8 (f1.2 + 4 stops) you are actually shooting at f11 (f2.8 + 4 stops).

Dont understand that at all

Comment by derek897 posted on Sigma 105mm macro f1.2 at 08/04/2017 - 17:10

redbusa99 wrote:
surely the mechanical action of the lens cannot open beyond 2.8 , that is as far as it can go, so i would think that is what you are actually getting and the 1.2 is the electronics misreading it.

If you look at the latest 2 shots of the blossom.
Top one is f1.2 as recorded in exif and 2nd one is at f2.8.
Even without the exif data the dof difference is huge.
So I dont think it's just a case of it recording it as 1.2 and shooting 2.8. There is a huge difference in exposure shooting manually too.

Comment by derek897 posted on Sigma 105mm macro f1.2 at 08/04/2017 - 12:19

Nice indeed.

Comment by derek897 posted on Boris the spider at 08/04/2017 - 10:22

Cheers. The lens works normally without the tubes.
Cant see much use for it other than the odd dreamy shot. But it might come in handy sometime.

Comment by derek897 posted on Sigma 105mm macro f1.2 at 08/04/2017 - 08:45

A couple of shots at f1.2 taken with a sigma 105mm macro f2.8 and one at f2.8