Probably very well observedAlso the DOF on the TT artisan is far deeper even if the lens is closer which maybe is something to do with it being a 2:1 lens? I shot it at 1:1 or near that on its scale to try to match up with the Nikon.
Did you compare exposure times?
If yes – were the exposure times much longer with the Artisan?
On your depth of field observation it is often not appreciated that in close up photography some macro lenses including Nikon do not shoot at the selected aperture when using an auto exposure mode
The Nikon is not a symmetrical optical design – the Artisan may be - part to help get increased magnification.
Going back well into last century macro lenses were usually symmetrical optical designs.
This meant at that at infinity an exposure time of one second at f8 became 4 seconds at 1:1 magnification.
Many recent macro lenses let in 2 stops more light at 1:1, maintain an infinity exposure (Nikon does) and reduce depth of field by 2 stops to half what it would be with a symmetrical lens design.
If you put the Nikon Z macro lens manual focus at Infinity and the body at manual exposure at f8 and shine light into the front of the lens while you change focus distance on the focus ring between Infinity and 1:1 you can see the aperture widen by the equivalent of about one stop.
This lets in about f5.6 light (see technical note below) even though the read-out shows f8 !
Many recent macro lenses focus breathe significantly by 1;1, typically if 105mm at infinity becoming about 70-75 mm equivalent at 1:1.
The physical size of the aperture of Nikon 105 Z macro at f8 is mathematically 13.125mm at infinity.
The aperture size of 13.125mm does not change at 1:1 focus though the lens changes to an angle of view of approximately 74mm.
A 13.125 mm aperture size at 74mm is mathematically f5.6 - result 1 stop less dof and a 1 stop brighter viewfinder.
Back to a Nikon Z top plate aperture read-out - at infinity manual focus the smallest aperture available is f32 - increasing to f51 at 1:1 focus !
If the Artisan is a symmetrical design then compared to the Nikon at 1:1 f8 it will have 2 stops more depth of field (double) though a 4 second exposure time when the Nikon exposure time is 1 second.
To get the same dof stop down the Nikon 2 stops or open up the Artisan 2 stops - and you should then get the same exposure time.
Technical note - at 1:1 focus I do not have equipment to determine if precisely 1 stop dof change is due to physically opening up the aperture and precisely 1 stop is due to focus breathing - though the combined effect is close to an infinity exposure time
NEW TOPIC - Chinese lenses.
Chinese and some other Far East lens manufactures are introducing lenses at a third or a quarter of the price of Nikon, Sony and Canon while maintaining good though not quite equal optical performance.
Many buy lens primarily on price due to budget limitations.
Getting a lot for relatively little money is as you observe a big Chinese lens attraction.
The recent Nikon introduction of a 35 mm and 50 mm f1.4 Z with a better than F mount performance but not as good as S at a relatively competitive price point may be a reaction to what is now coming out of China.
From a Japanese manufacturers point of view, the "fertiliser will hit the fan" if a Chinese company starts to make ML bodies at a low price point.
