Luminous Landscape Forum

Equipment & Techniques => Beginner's Questions => Topic started by: Bob_B on June 03, 2013, 09:22:52 am

Title: Advice: Extension tubes and focusing rail for macro
Post by: Bob_B on June 03, 2013, 09:22:52 am
I use a Canon 7D and am interested in purchasing extension tubes and a focusing rail for macro photography. Vello makes a set of extension tubes for the EOS cameras that are in my price range. Are they any good?  Also, the Velbon Super Macro slider rail specs seem to fit my needs. Again, any good? I'm not a pro, just enjoy photography, but I am a stickler for resolution, so I don't want to buy something only to find that it degrades the quality of my Canon EF L zoom lenses.

I'd appreciate advice, suggestions, and guidance, and thank you for your input.

Bob
Title: Re: Advice: Extension tubes and focusing rail for macro
Post by: Jason DiMichele on June 03, 2013, 09:50:08 am
Hi Bob,

I'm not sure about the Vella tubes but you want to get automatic extension tubes which have electronic contacts to relay exposure information to your camera. Much more convenient. I use the Kenko tubes.

As for the macro focusing rails, there are the cheap ones on the auction site for about $50 which actually work pretty good with decent accuracy and build quality. Then there are the really expensive products from Really Right Stuff, Novoflex, etc ($$$) which are absolutely beautiful and extremely precise to use but perhaps overkill for most situations.  I've heard that the Velbon rail is good.

With regard to losing image quality on your lenses, the Canon 250D diopter is a close up filter that is an extremely sharp, corrected optic. You will not notice any real loss of sharpness and you can use it with far less hassle than bellows.

Of course there is also the fact that although a lot of lenses will perform decently when used with extension tubes or diopter, there really aren't many lenses that have the edge to edge sharpness the a macro lens is going to have. So if you want the best possible sharpness you can, you should probably make sure you have a macro lens. My Canon 100 macro is razor sharp. And on your 7D will effectively be a 160mm macro which will give you more working distance.

One last thing I would suggest is that if the macro subjects you are photographing are stationary, you might want to consider focus stacking. This will allow you to use optimal apertures instead of stopping down to f16/22 for depth of field. You can successfully use your macro rail or manually change lens focus to create the stacks.

Cheers!
Title: Re: Advice: Extension tubes and focusing rail for macro
Post by: Bob_B on June 03, 2013, 11:31:28 am
Thanks Jason.
Title: Re: Advice: Extension tubes and focusing rail for macro
Post by: NancyP on June 10, 2013, 12:21:36 pm
I have not seen them in person, but Vello automatic rings (~$80.00 USD) ought to be fine. I have other Vello products including metal items (metal hood) and these are fine. I opted for the Kenko automatic extension rings set a while back, because I wanted to use them on my 400mm f/5.6 lens for 0.2x to 0.35x close-ups of entire smaller birds and entire butterflies, and I wanted a super sturdy product to connect this 3# lens to the camera. Kenko makes teleconverters, and its sister company Tokina makes lenses, so I figured that the extension rings should be strong and with tight precision mounts (yes to both).

I have done crude low-mag focus stacks handheld by holding on to a stick and rocking the camera forward slightly. OK for 0.2x to 0.3x, once you get used to it. Monopod with loose tilt head would be the same,