Extension Tube Discussion

ziggy53ziggy53 Still learnin'still lovinPosts: 19,158Super Moderators moderator
edited October 9, 2017 in Technique

This discussion is an extension of another discussion relating to Teleconverters/Telextenders.

ziggy53
Moderator of the Cameras and Accessories forums

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  • ziggy53ziggy53 Still learnin'still lovin Posts: 19,158Super Moderators moderator

    @petrochemist said:

    It seems was wrong with teleconverters then (most cameras these days would be either Nikon or Canon). The web discussion I was remembering may have been about extension tubes - do Canon correct EXIF aperture for extension?
    AFAIK none of my TCs or extension tubes alter electronic details at all (unless they don't pass them through at all!).

    I don't know of any camera manufacturer which has extension tube exposure correction.

    ziggy53
    Moderator of the Cameras and Accessories forums
  • ziggy53ziggy53 Still learnin'still lovin Posts: 19,158Super Moderators moderator

    While discussing extension tubes, I have some views on their use:

    I do not use, nor do I recommend using, extension tubes on any zoom lenses, and only rarely on prime lenses, with the exception of true "macro lenses". (I define a true macro lens as one which has 1:1 [or better] magnification capability.)

    The reason is that most general purpose lenses have a specific flange-focus distance by design. An extension tube works beyond those design limits.

    Extension tubes do work extremely well on true macro prime lenses. I have also seen good results with some telephoto prime lenses and extension tubes, but only with a relatively short extension length, and it seems better with telephoto primes with a fixed rear element or where the rear-most element is not too close to the flange/mount.

    ziggy53
    Moderator of the Cameras and Accessories forums
  • pathfinderpathfinder Drive By Digital Shooter western IndianaPosts: 14,095Super Moderators moderator
    edited October 9, 2017

    Ziggy, I defer to your discussion of flange to sensor distances.

    I do confess to using a 12mm or even a 25mm extension tube with a Tamron 200-500mm lens or a Canon 100-400 V2 lens sometimes. These are fairly small, lightweight zooms, used at their longest focal length, to let me get closer to butterflies while remaining at least 2-3 feet away from said butterflies and not disturbing them.

    I originally started with the Tamron 180 macro needing a bit of extension tube for shooting butterflies, and from there it was easy to go to longer teles with short extension tubes. The desire is just to be able to get a bit closer than the native close focal point of the zoomed telephoto lens, not to try to achieve a 1:1 image size.

    From what you said a 300mm prime would be a better choice, but my 300mm primes are f2.8 and are too heavy to do this handily for me, while the Tamron ( 200-500 originally and now the 150-600 ) are smaller and lighter and easier to handle hand held which is what I need for trying to capture fluttering butterflies. The Canon 100-400 V2 seems to work well with short extension tubes as well in my limited experience.

    When using telephotos with extension tubes, all the demands of telephoto shooting remain or are accentuated - the lens must not move relative to the subject or the background, and a high shutter speed is required. I usually try to keep my shutter speed at least twice the focal length e.g. 1/800 or 1/1000th or higher. unless I am using flash. Tripod mounting would be better but is just not practical chasing butterflies for me.

    My Kenko extension tubes are aluminum tubes that extend the lens a stated distance ( 12mm or 25mm ) from the sensor and exclude any light from entering the camera. They do connect electrically with the body and the lens, as the lens aperture does stop down automatically with exposure and reopens after the shutter closes on my Canon body, and the camera retains the ability to work in Av and Tv mode. I am not aware of exposure compensation due to lens extensions and the relative diminishment of the iris aperture as the lens is extended. This is a bigger issue with bellows extension than extension tubes due to the distance the lens is extended with a bellows.

    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
  • puzzledpaulpuzzledpaul low down bum Posts: 1,558Registered Users Major grins
    edited October 11, 2017

    I've added tubes - of similar type to Pathfinder's - into the mix whenever I think it'll help to get the pic I'm after.
    Most memorable (for me, anyway) was when trying to get pics of rats messing around in a stream under a pedestrian bridge near a school (which attracted a fair range of comments, btw)
    Most shots were taken with a 12mm tube on my 500 f4 ... and maybe I also tried the 25 too - but can't remember - iirc I had AF difficulties with the 25.

    One result is on my OLD flickr page, btw,

    pp

  • petrochemistpetrochemist Essex UKPosts: 10Registered Users Big grins

    Many older lenses focus purely by moving the entire lens further from the sensor.
    Extension tubes are doing exactly the same thing, for these lenses I can't see any optical issues from using extension tubes, all they are doing is extending the focusing range.
    Internally focusing lenses may well behave differently, but I've never seen examples showing any clear issues from using them with tubes either.

    There are quite a few macro primes that only reach 1:2 without a 'dedicated' extension tube. I think some of the 1:2 macros use a dedicated diopter instead of tubes but I'm not sure on this.
    My Cosina 100mm macro had been separated from the dedicated 1:1 adapter (included with the lens when new). My Tamron SP90 macro is also without the 1:1 adapter but I gather in this case it was an optional extra (& is an extension tube).

    I don't class my macro shots as particularly impressive, but I've not noticed any issues using short extensions with zooms. I do this quite often to give moderately closer focusing to my 50-200mm MFT lens (not getting to actual macro magnifications)

    I've seen numerous examples on the web or in print from those more skilled at macro than myself, where VERY impressive results have been achieved using extension tubes (even home made ones) with a wide variety of non macro lenses. Quite a number also use lenses that can't be natively mounted on the camera, such as enlarger lenses, microscope objectives & microfiche lenses.

  • puzzledpaulpuzzledpaul low down bum Posts: 1,558Registered Users Major grins

    If you're not already aware of this site, I'd strongly suggest you visit it - for both excellent examples of macro (and micro) photography and in-depth discussions of setups and techniques used to take said pics.
    Whilst technically still a member there, I've not visited for several years (since switching to waterfowl) - but I found the depth of knowledge - based on actual trials / usage etc extensive - and some of the techniques / setups - were probably? at the time - ground breaking within the amateur field.

    I have also played around with some of different types of lenses you mention - including old Canon FD series lenses via a home made EF/FD converter - which, without optics essentially served as an extension tube ... Fun days :)

    Btw, this illustrates one of my hacks using the home-made converter mentioned above ...

    pp

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