Sigma 105 2.8 DG EX macro lens & ext tubes? Will it work

[redeye64]

Will this work for macro shots (Nikon D5600) for really small subjects? Am long away from macro stuff, recently found this lens tucked away & thought l might try some smaller than usual bugs e.g. aphids, scale etc. l'm trying to avoid buying more gear if possible & have a couple of tubes here somewhere.......

[ameerat42]

I've got a 70mm version of this lens and it is tops. I was hoping to get the 100mm version, but :(

They both give 1:1 image-subject reproduction, and what you're aiming for is a higher image ratio.
The extension tubes will get you a good bit closer to your subject.

To answer your question, yes, it will "work" optically, but it may affect the image quality, since you
will be using the lens outside its ideal operating parameters. BUT... I'd sure give it a go to see just
what you can get, and I laud the idea of "using what you've got".

You may lose some auto functionality, like auto focus and auto diaphragm metering, AND, you may
have to experiment a bit with getting a good aperture setting to eliminate aberrations. You should
be able to use "Aperture Priority" mode, though what aperture it will report is :confused013 ), and certainly
Manual mode. From memory, that lens too, like mine, does not have optical stabilisation, so you
won't "lose" that :p

Let us know soon how it goes :nod:

[arthurking83]

on a technical note, ext tubes usually work 'better' on shorter focal lengths, compared to longer focal lengths.
(up to about 50mm).
This is because the longer focal length already has a longer focus distance from the imaging plane(ie. sensor).

So normally the intended use of ext tube is to get greater magnification .. ie., why the statement that ext tubes work 'better' on shorter focal lengths. The shorter, the better.

But that doesn't mean that you won't get some increase in magnification using a 105mm lens, just that it won't be so obvious when you do.

As a small aside to this, not many folks realise that to achieve the macro focus ability, almost all lenses shorten their focal length from the stated focal length of that lens. I can't remember exactly, but many 100mm-ish macro lenses at macro focus distances are really more like 80-85mm ish lenses, and the internal lenses get pushed up closer to the front of the lens tube which is a kind of psuedo extension tube effect, internal in the lens.

Obviously we don't have any idea on what other gear(lenses) you have, but whatever you have, if you get tubes that can also work on any/all other lenses, and you have other lenses of shorter focal length, you may see better results in using those other lenses.

And the types of other lenses you have will determine how well(or effectively) you can operate the contraption(of camera/tubes/lens) .. because it's not simply a matter of just click all gear on and away you go.

I suspect(this means I'm just guessing) that most likely you may need electronically communicable tubes(and they usually cost a bit more than mere dumb tubes) .. so the end result may be a bit frustrating for 'ya.

Tip: if you can list the gear you have it helps to offer some advice. Check my profile that I have a list of some gear(many lenses) so that when I post a similar question, a members reply can be more specific to a certain lens in my profile area.

If my memory of the Siggy 105 Macro is correct, part of the problem is you don't have an aperture ring to control aperture, so if you connect a dumb ext tube, the aperture will remain fully closed. This is how lenses work. aperture is closed in the 'unmounted' situation. To see this, unmount the lens, and look through the rear lens and note that the aperture is closed(and you can see the aperture blades pattern too). So if you mounted the lens to a camera that can't communicate aperture info, the camera can't communicate the lens to set aperture to position X. Note that at all times, lens mounted to camera and camera turned on, the camera tells the lens to hold aperture at maximum opening(smallest F number), and if you set lens to f/11, only at the time of shooting the image does camera stop down for the shot .. then lens is held at max aperture again.
For all intents and purposes, this is true, except in some specific situations .. but for the purpose of this particular reply lets say that this is true.
OK, so what happens is you have dumb ext tube mounted to siggy, so no communication from lens to camera, you look through the viewfinder or use rear LCD screen and you see pretty much a black view! This is because of two things at play.
1/. lens is set to f/29(or whatever min f value is for the lens)
2/. using extension tubes add an extra degree of darkening. The effect is even smaller f stop that you actually see or set too. eg. f stop set to f/4, but may actually be more like f/5.6. every extension tube length varies this aperture anomaly.

This is why you really need smart extension tubes. That is extension tubes not in the el cheapo $20 range with no comms, but more like (approx) $100 tubes with the communication pins from tube to tube and hence from lens to tube to camera.

So, again with no idea now on your budget for ext tubes, there may be cheaper alternative ways to achieve the same result, but the caveat is that it becomes a 100% fully manual operation when trying to get images.
And I know you said you're trying to avoid buying stuff, but when I write buying stuff, I'm referring to maybe a maximum of (say) $50 .. but usually a lot less(more like $20-30).