Cheap Chinese extension tubes for macro photography

[Joan]

Not having any real macro lens and wanting to experiment with macro photography without (at least initially) spending too much money, I have bought in Ebay a pack of 3 extension tubes from a Chinese dealer:

http://cgi.ebay.com/ws/eBayISAPI.dll...:X:RTQ:US:1123

The price difference with regard to the original product from Canon is approx 1 to 7:

http://www.ebay.com/itm/Genuine-Cano...item20d587a5de

I am aware that I have probably bought scrap, but since there are no lenses inside the tubes I have decided to take the risk.

I don't care too much for the 60$ that I have spent on these tubes, but I do care (very much) for my lenses. Is there something that I should take into consideration with regard to my beloved and quite expensive Canon lenses when using these extension tubes ? Is there any way that I could damage my lenses by using them ? Has anybody any kind of experience with these Chinese extension tubes ?

Thanks very much for sharing your experiences.

[ST1]

Joan I can't seem to get your link to the product you purchased via eBay to work. However wrt the possibility of you damaging your existing lens, if you are careful you should be ok. Attach the tube (size to fit subject) to the lens first the the combination to the camera body.
Some of these extension tubes are just tubes with no electrical connection between your lens-tube-camera body. The better ones have electrical l connection between all items which; enables camera metering to take place.

[Saorsa]

I had a really cheap set I bought for demo once. The were not the new auto type tubes. They were a very thin plastic and I could feel them flex between the camera and the lens. Not Good!

I also found that the lock and release mechanism was flimsy. The metal flanges were held by very small screws directly into a slightly thicker part of the wall.

From the images, those seem OK. Try pinching them before putting a lens on it. If there is any give you can use them but, don't trust them to hold the weight of the lens.

[DanK]

These look like Chinese imitations of the standard Kenko set. It looks like they have electrical connections. I agree with Peter and Brian--the main issue is just whether they are sturdy. They have to hold the weight of the lens, and you have to make sure that the catch is firm so that they don't accidentally detach. Also, if they flex too much, you could get light leaks, which would damage the photo but not the camera or lens.

[Joan]

Mechanical stiffness is an issue that it is out of question that I will carefully check before hanging any lens from the tubes.

Electrically speaking, there is no possibility of provoking any shortcircuit that may end burning my camera or my lenses ? Are the electrical pins in the camera and the lenses intrinsically safe (that is, is it possible to shortcircuit all of them without any damage to the camera or lens electronics) ?

[Saorsa]

There is always a possibility but those should be straight line connections. You could check them with a continuity checker.

[Glenn NK]

Not only would I be much more inclined to get these:

http://www.bhphotovideo.com/c/produc..._Tube_Set.html

I did.

Bought mine six or seven years ago and have used them extensively. Some bloggers have compared them to the Canon ones, and were hard pressed to see any significant difference.

I bought a Chinese brand tripod that had great features - unfortunately the quality didn't permit the features to be fully realized. Lesson learned.

Glenn

[jcuknz]

Personally I would make a practice of not having the camera switched on when fitting tubes to it as the bayonet action rubs non-matching pins on each other [ or if tube already on camera not attaching lens with camera switched on ]
Perhaps over cautious but thanks for your question which has made me think about the matter as I recently took delivery of a pair of extension tubes with bayonet fitting for my MFT

When fitting any accessory between camera and lens [ telephoto converter in my case ] main problem is the locking pins not functioning and my memory reminds me of the guy whose lens fell off due to stiff focusing of the lens caused the lens mount to rotate [ a few months ago on CiC ]