Commlite Macro Extension Tubes

[sanger]

Hi,
Iv'e bought a set of these off ebay for my nikon d3100. They are a third of the price of Kenko so I thought why not. They supposedly have all of the electronics to work with auto focus etc and their description is identical to Kenko.
Anyway they seem to work on manual ok but I can't make them work on AF or control aperture.
Anyone used these cheapies with success using AF ?

[macmich]

you are better of with manually focusing with macro photography, i have kenko but always use on manual

[sanger]

Yeh they do work ok on manual. Out of curiosty do the kenko's work on auto focus ?

[Mary Anne]

Yes they do, I just did a quick shot for you it was a little dark in this room so I had to use a very high ISO and removed the noise.

Taken with the Canon 5D MK11, Canon 100mm Macro lens, Kenko Extension tubes 36mm 20mm and 12mm

Shot on Manual and AF 1/100 f/7.1 ISO 12,800 This is a full size jpeg image out of camera just resized.




PS. Forgot to mention the camera did hunt a little that is why its best to use Manual Focus with Extension tubes.

[sanger]

Great, thanks.
I'll provide the ebay seller with some feedback on their claim that they will work on AF on all nikon cameras and lens.

[arthurking83]

What lens are you using?
AF is not simply AF!
I'm assuming that the lens you're using auto focuses on the camera without the extension tube(s)?
If so, then the lens is AF-S .. so technically the lens should AF with these tubes.

But something that needs to be taken into account: AF will not be guaranteed with the extension tubes!!

This is because (of the electronics) the lens and camera take distance information into account when focusing. That is, the lens passes distance info to the camera, which then uses it to calculate how and where to focus.

Because the extension tubes forces the lens work in a distance range much shorter than the lens normally does, and the distances preprogrammed into the lenses chip are already set .. the actual distance is not the same as the distance relayed back to the camera.

So the seller should have said: it can AF, it may AF .. but it's not guaranteed to AF!

Also: AF at shorter(or macro) distances is much harder to do. The best way to get focus is to manually focus to a good approximation of where focus should be(through the viewfinder or Liveview), then try AF from there.
Even that is a bit hit and miss sometimes. And the subject you are focusing on can also be the issue too.

I have the Nikon 105VR(macro lens) and at up to about 1:3 magnification range AF is OK(not fantastic, just OK) .... eg. chasing bees and shots of flowers and so on.
From 1:3 to 1:1 AF is pretty much useless, unless you have the patience of a Pitch Drop experimenter.
Focus racks back and forth endlessly if this is something you like to watch .. and may never actually lock. Then sometimes it does lock on .. it's all random and can't be predicted.

The 105VR lens is a proper macro lens and has all the proper distance info from the electronics to help it too .. and it still struggles with AF(at close range).

Another thing that could affect AF is the actual lens you are using.
All lenses focus differently .. some faster than others, others more accurately.
If it's a zoom lens(like an 18-55 or 18-105) it may focus differently at different focal lengths.
eg. it may struggle to focus at 18mm .. but focus OK-ish at 50mm ... or whatever.

Finally, you D3100 will have a pretty basic focusing system. ie. it's a the lower end of the ability scale(to be expected tho).
While it work within the parameters set out by Nikon when they designed it .. using AF capable extension tubes is not one of those parameters.

You may find that these tubes focus ok, with your lens when fitted to (eg.) a D7100!

[sanger]

http://www.ebay.com.au/itm/P4PM-AF-A...item5d51518f6d

Thanks for that info, these are the ones.

[MissionMan]

Agree with Arthur's comments. I have the kenko and even then, they will still hunt so manual focus normally works a little better. The electronics are normally a lot more helpful for lenses without manual aperture settings.

[arthurking83]

I've seen those tubes before, and have a few on watch(my eventual plan is to also get some of these 'connected' tubes too).

I have a small set of Nikon tubes, and while they have aperture linkage, they have no information control at all.

That is, like MM said about the aperture control .. I can't use the 105VR with these Nikon tubes, even tho the aperture control linkage is there. There is no information from the lens back to the camera.(105VR is a G lens and hence no aperture ring to control on the lens).

I don't see the electronic communication through the tubes as a means to AF(for AF-S lenses), but more so to help with exposure/metering.

Although in saying that, there seems to be an errant belief that extension tubes don't affect aperture size, which is completely incorrect.

Because I don't have a set of these 'connected' tubes, I have no idea if the physical aperture change is reported properly to the camera via these tubes.( I don't expect that it is).

The more extension you use, the smaller the actual aperture size will be.

[sanger]

A follow up on these things.

It's clear now they are faulty and do not do what they claim.
Maybe we were unlucky and just got a bad set, who knows.

We tried them on a D3100 and D3300.
12mm...works on both, AF, aperture control, etc
20mm dead on both.
36mm dead on 3100 and works sometimes on 3300 if it locks in.