Venus Optics officially launches the Laowa 25mm F2.8 2.5-5X Ultra Macro

At the best case? At the best case it is 1:1 or more like 1.25:1. In worst case it is 1:2 or 1:4 or even less!

This should just have had "Macro" without anything else. It would have been correct.

Thanks for the (effort of) information! ;-)

I'm not sure, but I suppose (because of the indicated working distances) that Canon's MP-E65 (which I don't own) does not keep constant the 65mm focal length over the whole magnification range.

Thank you, but my question was from a technical point of view.

That is the technical reason why this type of lens exists. It is the reason Canon made the Canon MP-E 65mm f2.8 1-5x lens, and before that Olympus made their telescopic auto extension tube. I appreciate it might not be a limitation to yourself if you don't use macro lenses out in the field.

25mm is 25mm, regardless even if you would use a ruler with imperial scale...

You do NOT change the magnification value what so ever.
Forget the equivalence, it is BS.

1:1 is 1:1 is 1:1. There is nothing else.
It is optical magnification value, what is in front of the lens will get projected back of the lens in same size. That is Macro.

Macro is from 1:1 up to 10:1 so you can magnify the subject 10 times of its real life size!

My advice is to buy lenses to use them, not to resell them. This lens is cheap enough anyway. Why compromise every time you use a lens just because you might get 50 bucks more if you decide to sell it?

Disagree - use of stacking depends on the use of the photo you are taking

Yes it's useful and I will often use it, but it's not essential in the commercial photography I do with such lenses (I don't do insects/plants so YMMV)

I don't think this would work with the auto-focus-stacking on the D850, would it?

Agree, as most of their other lenses has A-mount as well, very strange...

This isn't the first all-manual SLR lens not available in A-mount. I keep looking at those $100 85mm F1.8s that are only available in Nikon F and Canon EF.

The reason for omitting the filter thread (to attach a macro flash) might be that the working distances from lens end (or top) to focused object are not sufficient:

I read:
2.5x magnificatiuon: 45 mm
5.0x magnification: 40 mm

Concerning the iris which must be closed manually before shooting and therefore results in a dark (or - mirrorless - bright but noisy) preview image:

It a pitty that noone of the developpers remembers the analog photo times, when people used a bellows an a macro or almost micro lesn for such purposes.
And the clue was a cable release socket at the front side of the bellows and a (mechanical) double cable release:
By pressing it, first the preselected iris of the lens closed and after that the second cable relesead the camera shutter.
Simple but effective!

Why not revitalize such a good idea, maybe with an additional mechanical (thread) to electrical (usually mini jack) adapter for the camera relase

Above text edited:

The reason for omitting the filter thread (to attach a macro flash) might be that the working distances from lens end (or top) to focused object are not sufficient:

I read:
2.5x magnificatiuon: 45 mm
5.0x magnification: 40 mm

Concerning the iris which must be closed manually before shooting and therefore results in a dark (or - mirrorless - maybe bright but noisy) preview image:

It's a pitty that noone of the developers seems to remember the analog photo times, when macro photographers used bellows and a macro or even micro lens with iris for such purposes.
And for the case that the bellows were not an auto bellows or the lens had not auto iris, the clue was a cable release socket at the lens side of the manual bellows and a (mechanical) double cable release:
By pressing it, first the preselected iris of the lens was closed and immediately after that the second cable attached to the camera relesead the shutter.
Simple but effective!

continued from above:

Why not revitalize such a good idea, maybe additional to the standard double cable release with a mechanical (thread) to electrical (usually mini jack) adapter for the electronic camera relase.

text correction:

".. .. And for the case that the bellows were not an auto bellows or the lens had not auto iris, .. .."

should read:

.. .. And for the case that the bellows were no auto bellows (with iris transmission) but the lens did have an auto iris, .. ..

text correction:

".. .. And for the case that the bellows were not an auto bellows or the lens had not auto iris, .. .."

should read

".. .. And for the case that the bellows were no auto bellows (with iris transmission) but the lens did have an auto iris, .. .."

And then I realize auto exposure won't work with this lens because it doesn't have electronic contacts. Stupid Nikon keeps you from using the AE system if the camera does not recognize the lens on their lower end cameras. It's not even a physical limitation it is just an attempt by Nikon to discourage you from using lenses from other manufacturers (exposure works fine of course with Sigma, and Tamron lenses).

I get the need to reduce the light occlusion from the front of the lens (which this appears to do much less effectively than the - optically simpler - Mitakon), but the article specifically says "Ultimately, this lens was designed to be as portable as possible" - which seems odd.

Gavin: I could still have this wrong, but...

Nikon don't support metering on low-end bodies because there's no way to tell a mechanical Nikkor (whose aperture changes when the stop-down meter moves) from a completely uncoupled lens. With no aperture follower ring (expensive mechanics by D3x00 standards) the meter can't tell how much the lens will stop down. Live view is a separate problem, although you can eyeball exposure and some models have histograms. I do wish Nikon still had stop-down metering (especially on the Df).

So there *is* a physical limitation; if you could tell the camera the difference between lenses you could get around it, but that complicates a consumer body's UI.

I'm less sure why Canon won't use their digital rangefinder on manual lenses. Maybe something to do with wanting to select between AF points based on max aperture?

I'm sure both want you to buy their latest electronic lenses, but that obviously doesn't help when there's no equivalent available.

On higher end bodies there is a way to tell the camera what is mounted via menu system. They stripped that out on the beginner models which I find extremely irritating.

The working distance is not bad, and not that different to the Canon MP-E 65mm f2.8 1-5x macro lens at comparable magnifications. The working distance of the Canon MP-E 65mm is 41mm at 5x, 51mm at 3x and 63mm at 2x (the Laowa lens starts at 2.5x, and the working distances are marked on the Canon lens, but only for full increments, and not half distances).

Thanks.

That is not how Olympus reports it for their macro lenses.

tEdolph

@tedolf

I think that is because Olympus haven’t any real macro lenses in their current arsenal. Instead they have multi purpose lenses that may or may not go down to 1:1. A true macro lens is something else.

@tedolf

I meant a macro lens as a lens that only does macro. The Oly is a multi-purpose lens that goes to infinity, and may, because of that, have different designations to the sensor rather than working distance as from the front of the lens.

@shigzeo

They are both dedicated macro lenses.

Tedolph

The Olympus lens focuses to infinity, though, and isn't as such a dedicated macro lens. That is, unless I'm reading it correctly. Please correct me if I'm wrong.