A question about auto extension tubes

Hi all, I'm looking tp purchase a set of auto extension tubes. But also need them to be auto focusing. Can anyone give me information of the better brands to purchase.

Do not think such a thing exist's the best you will get will be the A contact one's to control the metering. I may be wrong tho

I've never heard of such a thing either - the image would be probably too dark for the AF system. Having the electronic contacts is sensible though, so maybe Amazon, or maybe one of the supplier websites such as SRS, Park, Jessops, etc.

In macro work most people switch off AF anyway.

Kenko used to make them for Pentax, I had a set once. Alas I don't think Kenko cater for Pentax any more.
They are not cheap should you find a set.

Thanks for the replies. I have a set of the "A" setting ones. My friends have the Kenko ones (Canon and Nikon users) I was looking for something similar. They retail around the £120 mark. Looks like I'm going to be disappointed.

Keep looking on e-bay and the like. They do come up for sale occasionally. The person who bought mine had been looking for a couple of months.
A pity they have stopped making them for Pentax.

Don't know the quality and it's only a 25mm piece but it looks ok
http://srb-photographic.co.uk/pentax-k-auto-extension-tube-5913-p.asp

Another alternative is to buy a 2x AF Teleconverter and remove the glass. I've just bought one off the Forum and may consider doing this, depending on whether the glass meets my approval for sharpness.

You can get a new 2x AF TC for about £110, a used one will be less but they are quite hard to find. They won't give much extension, less than a full set of tubes, but if AF is critical for you this will be your best bet.

Personally, I find AF of very limited use for macro work as the Depth of field is often so thin that using AF is not practical.

Regards
David

This +1

If autofocus is really that important (and you've got to ask how the camera is supposed to know exactly what part of the object you want to be the focus point anyway) then perhaps a dedicated autofocus macro lens would be worth looking at, given the costs associated with achieving autofocus via the extension tubes approach.

When you consider that most macro photographers seem to prefer manual focus, why do you think you need auto focus extension tubes? Please don't tell me that it's only because your Canon/Nikon buddies have them.

I do a fair amount of macro work. I never use auto focus because when I tried to use it years ago, the camera got it wrong more often than not. When I've tried it more recently with a modern camera, it still gets it wrong.

For macro, use manual focus and put the money I've saved you towards a dedicated macro lens. Much more useful.

I'm not sure what use AF would be for sapping with tubes, but indeed Aperture contacts is highly useful.

Jessops made a set, I have some. Beware that the naive people who designed them didn't realise that the body of the lens/tubes is part of the electrical circuit that is used to determine aperture setting in A mode.

The Jessops tubes are anodised and thus the circuit won't make. You have to get a file and remove a portion of it on each tube in order for them to work.

Thanks for that link. I've been looking for af tubes for pentax for as long as I've been into photographing dragonflies and butterflies. I often use auto extension tubes with my FA*300 F/4.5 to improve close focus. It would be so much easier with af tubes. Trouble is I normally use 65mm of tubes, oh well, can't have everything I guess. Although I see that KooKa also do a set of 20 and 36 tubes as seen here link perhaps srb will get them if I ask nice....

Hi all, Grateful for the comments. In reply to why I want Auto focusing tubes. Is that when I'm shooting, I like to hand hold my camera. I sometimes use my 70-200 f2.8. After a period it becomes a little heavy and is awkward to hold. I sometimes find that when I try and manually focus on my subject. They quite often fly away before I've completely finished my focusing routine. I think Af tubes would help me get a far greater hit rate.

I took this... with extension tubes with a manual focus 50mm 1.7 A lens.


Set your aperture up, but I've found it doesn't give much more or less of a depth of field unfortunately, so I opt for nearly fully open on the lens.
Then set your focus at a distance you're likely to be able to get to your subject in the field. Set the camera for live view (with focus peaking enabled) if suitable for the shot and set it to rapid fire shooting mode. Move the camera in and out to do the focussing.

Seriously the field of view is so damn shallow with the tube the subject will be well gone before you get a chance to get it all right.

I don't think that he OP's cameras support focus peaking.