I'm still waiting for mine, but just realized that its minimum aperture is only f/22. What is not clear is, which is the "real" minimum aperture from the shortest distance. F/22 should be minimum for infinite... thanks for helping! 

Perhaps it’s just me, but I don’t understand your question. f/22 ist quite normal for common lenses and one would only use this aperture in rare cases. May you clarify your issue?

thank you for your comment, Olaf. My doubt is: what is the minimum aperture possible from the shortest distance? f/22 should be the minimum aperture from the maximum distance. For example, I also have a nikon 105 mm macro. On the paper, its aperture range is from 2.8 to 32, but f/32 is just the minimum aperture available for shooting to infinite. If you are close to your subject, you can reach f/57. So, my question is: should you take a picture from the minimum distance possible to your subject, what is the lowest aperture possible? Thank you.

You need to be clear about your terms.  There are some macro lenses that stop down to f32 or even f45 -- but that is simply the marked f-stop.  With macro work, the EFFECTIVE f-stop is much different and that might be what you are referring to. 

The effective f-stop is the marked f-stop TIMES (the magnification + 1).  That's important to know only when you are using a hand-held meter and/or an electronic flash -- and not using the TTL meter in the camera.  When you are shooting with an EFFECTIVE f-stop of f128, your flash has to be REALLY close to the subject.

The effective f-stop does not change the physical size of the aperture, and marked f-stops smaller than f22 are not a good idea due to image degradation due to diffraction.  They can be used to increase DOF, but it's better to use a bellows with swings and tilts instead.

I'd recommend Leboewitz's (sp?) book The Manual of Close-up Photography.

Edited November 13, 20223 yr by XKAES

Thank you Xkaes. I admit that my coincern came by reading Ken Rockwell's review of this lens, pointing out that macro shooting usually is made at f/32, and indicating as a "con" that this lens stops to f/22, which is also far less than Nikon...

p.s.: I use ring flash for macro

A few additional points.  While many macro shooters will use f32 or f45 in order to get more DOF, the resolution is not as good as at f16 or f22 -- but much depends on how large a print you want to make.

Also, ring flashes are great -- I use one myself -- but they can be a problem with macro work.  The closer the subject gets to the lens, the less light from the ring flash will hit the subject.  Some ring flashes have suggestions for compensating.  Others, like Minolta, have tilting flashes bars to better aim at the subject.  If the subject is REALLY close to the lens, basically no flash light will hit the subject.  Plus, ring light is very flat, and many macro subjects are better suited for directional lighting to increase contrast -- and produce more of a 3-D effect.

Today I received my lens but looks like it is not in great condition (used): the black metal ring at the end of the lens, with the MF/AF sign on it, is detached. Apparently, there was some glue in it, but it is no longer working. Looks like I'll have to fix it. Still, quality doesn't look great...

If you bought it used, I would send it back and get it from another seller.MPB is a good source for quality used equipment.

Actually, I did buy from MPB LOL. Anyway, looks like this is a more than common issue with this lens: I've fixed it with some glue and it is working fine. Disappointingly, I have discovered that, unlikely Nikon, Sony's lenses do not allow you any aperture smaller than 22, not even from lower distances. Now I see why Sony users are unfamiliar with this concept.

4 hours ago, Egon said:

Actually, I did buy from MPB LOL. Anyway, looks like this is a more than common issue with this lens: I've fixed it with some glue and it is working fine. Disappointingly, I have discovered that, unlikely Nikon, Sony's lenses do not allow you any aperture smaller than 22, not even from lower distances. Now I see why Sony users are unfamiliar with this concept.

The Sony 90mm has a lot of focus breathing so at 1:1 is actually 45mm and f/3.68

The Nikon 105 2.8G at 1:1 is 76mm and f/4 

The depth of field of the 90mm should be more than adequate for all uses due to the construction of the lens however this would be a nightmare for focus stacking

Yes, I've tried the Sigma 105 Macro lens, and actually decided to keep the Sony because of OSS and depth of field. On the other hand, the Sigma lens is definitely better built and its quality is incredible, compared to the Sony, which literally falls apart.

16 minutes ago, Egon said:

Yes, I've tried the Sigma 105 Macro lens, and actually decided to keep the Sony because of OSS and depth of field. On the other hand, the Sigma lens is definitely better built and its quality is incredible, compared to the Sony, which literally falls apart.

However the sigma does not have a stabiliser which in certain situations may be useful - if you shoot with a tripod not at all and for stacking neither