UKC

I am interested in trying out some macro photography. Couple of questions:

1. How do extension tubes compare to dedicated macro lenses? Seems to me that given how cheap these tubes are, macro lenses are either completely overpriced or must offer something better.

2. I have a Sony A7iii and a trinity of lenses (16-35 f/4, 20-70 f/2.8, 70-200 f/4). Which of these at which focal length would work best with what size extension tube?

Any other tips would also be appreciated! Thanks!

I got some £20 ones for my canon ef-s setup.

They are inconvenient to use - you need to stop the aperture down before removing the lens. And depth of field and lighting are always tricky.

In terms of image quality it works out fine however. And I would recommend anyone considers them. Its a bargain even if you only use them a few times. 

Nice! I take it these are fully manual ones? 

I have seen there are some auto-focus tubes available. I suppose at this distance it's best to focus manually anyway, but I hadn't thought about dialing in aperture, which would probably need the electronics to pass through as well. 

I went for fully manual with no electronic connections, hence having to pre set the aperture. 

The wired ones aren't a lot more. This should allow the aperture to be set, although manual focusing would usually be best in this sort of situation - in practice you might just set the focus for the magnification and working distance you want and move the camera until focus is achieved. 

I use Kenko extension tubes on my macro lens, they are pretty cheap, but still have all the auto functions on my lens. Macro I usually take with the lens on manual focus anyway.

A great option would be to try a Raynox DCR-250 Macro Attachment, it's compatible with lenses between 52mm and 67mm diameter, only issue I've heard is people who have tried to use it with bridge or compact cameras where the lens will retract back into the body after a set time.

A few of my naturalist friend use it and have always found their photos clear and sharp, envious sometimes as they can be comparable with what I take with a dedicated macro lens. 

Cost wise around £65 from Amazon and the benefit is you could try it out on all 3 lenses as long as their diameter is less than 67mm or greater than 52mm. I do keep on thinking of getting one myself as it would mean 1 less lens to carry around if I was just wanted to go for a wander and still have the option of macro photography.

I have some auto-focus ones for my A7R2 (I think they have to be AF for Sony lenses as most are focus-by-wire?) - have used them with my 85mm and 50mm and they do they what they're meant to.

As there's no glass in them, they don't impact on image quality other than reducing light. 

Cheap and do the job - if was more into macro, i'd get a dedicated lens, but for dabbling they're fine.

That's not strictly speaking true otherwise you wouldn't get lenses with 10+ elements in them. camera lenses a set of compromises and are designed to work at a very specific lens-to-focal-plane distance and a variable subject-to-lens distance. Adding extension tubes extends to lens-to-focal-plane distance away from their design specification. Whether that makes a trivial or big difference to the image quality will depend on the specific lens design. In general a 'middle of the road' lens like a 50mm f1.8 will be pretty forgiving. Very wide angle or telephoto lenses less so. 

Personally I've found that using something like a reversed 50mm in front of a telephoto zoom works far better - more control, better image quality - and all for the cost of a reversing ring (assuming you do own a 50mm lens)

I have the PK (non focusing - completely manual) ones which have no glass. At the moment, with a 105mm 1:1 macro and a massive sensor they are hardly ever used. They do work, but I used to bracket film for work as exposure with flash was a bit tricky to judge with the ring flash. 

Thanks all! Ordered a pack of 10 and 16mm autofocus tubes on Amazon to try them out.