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Thread: Kenko Tube Effect!

  1. #1

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    Kenko Tube Effect!

    It all started when I began looking for a light weight macro option for backpacking that would not require two lenses. Unable to find much information about what extension tubes could do for a Nikon 18-105mm I wasn't sure what to expect. It seemed like it could be the best option. Just in case I am not the only one with questions I thought I would post my first picture, using the 36mm tube, along with the same without any extension for comparison. These are both at 105mm, no cropping. Kenko Tube Effect!Kenko Tube Effect!I like it. You do run out of focus fast as you move away from 105mm focal length and as you move away from the subject. Didn't check to see exactly where, but before the 18mm focal length the lens cannot be focused. Also no way to maintain a safe distance from the subject, but thats okay as I have found most flowers to be fairly tame.
    Last edited by Colin Southern; 29th April 2012 at 01:02 PM.

  2. #2

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    Re: Kenko Tube Affect!

    The only slight drawback with extension tubes is that you can lose a bit of light. But this usually only requires a slight adjustment, like one step up in ISO for example. There is no quality loss.

    The only other requirement is being physically able to move a little closer.

  3. #3

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    Re: Kenko Tube Affect!

    But do you lose more light than with a macro lens of the same focal length and extension (to get the same magnification)?

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    Re: Kenko Tube Affect!

    Quote Originally Posted by revi View Post
    But do you lose more light than with a macro lens of the same focal length and extension (to get the same magnification)?
    No, same focal length and extension will render the same "light loss", which is actually nothing but the virtual f-number increasing with increasing distance of the lens from the sensor. Modern macro lenses however often do not change the virtual f-number when focusing, but the focal length, which is shorter when getting closer. Thus they lose no light, and moreover, they focus to a greater "magnification" than the combo of 36 mm extension with a 105 mm lens.

    However, an extension tube is not an optimal companion to a zoom lens for various reasons. One of them is that focus shifts when zooming, getting closer to the front element at shorter focal length, until reaching the very surface of the front element. At shorter focal lengths, focus will be inside the lens.

    Zoom lenses also are not corrected for very close distances, although a 105 mm lens with a 36 mm extension will not really be anywhere close to where a macro lens will render the subject. It works, but it is not the best combination, and due to what's mentioned above, usefulness is very limited. Zooming out to get closer will invariably mean getting so close that the lens itself disturbs the light falling upon the subject. Flowers may remain where they are when getting close, but flies will not.

    The most reasonable closeup accessory for a zoom lens, particularly one with a rather long focal length, is a closeup lens, a positive lens of about +3 diopters if it's a single element or +5 to +7 diopters for a composed lens. They are generally cheaper than extension tubes, and there are obvious advantages. VR works as usual, AF may be used for fine tuning of sharpness, and there is no focus shift by zooming, so the zoom can also be used normally, to compose the shot and decide the angle of view. You will get reasonably large reproduction scale at a comfortable working distance, which will remain the same when you zoom. And there is no "light loss", whether you regard it as significant or not. The extension tube OTOH is a good companion to shoot very close with a prime lens, where focusing is done by moving back and forth. The closeup lens approach with the zoom is simpler, as AF will work within certain limits.

    The caveat that most people run into when they haven't tried this before is that focusing range is very limited, and it is necessary to find the point within the range in order to work comfortably. This is easiest accomplished by using some kind of measure, as a string with one or two knots that mark out the distance where you will get sharp images, or making a similar mark on the neckstrap if it suits you better. It is rather easy to calculate that distance:
    The diopters of the closeup lens gives the far distance, beyond which you cannot focus. +3 diopters is roughly 1'1".
    If the camera lens without closeup lens focuses down to 1―' it is roughly equivalent to +3 diopters,
    so adding +3 diopters gives a span for focusing of about +3 to +6 diopters or from 1' in front of the lens to about 5" closer.

    Mind that such a combo works best with small angles of view, so zooming out much will introduce more optical errors. From about 50 mm up to the largest end 105 mm, it works fine and optical deficiencies are minimal. It works great for most normal subjects, but is unsuitable for reproducing straight lines or flat objects as stamps and similar. Neither will an extension tube with the zoom be any good. For that kind of work, a macro lens is needed.

  5. #5

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    Re: Kenko Tube Affect!

    Hi All

    Firstly, I havenīt had the time to visit here in a while, but now, that I have been busy photographing a lo,t I require to go back to studying stuff. I have forgotten how to start a thread. So I will add my question here. I have a Canon 7D, with a 100mm L Macro lens. I would like to double this with extension tubes, but havenīt a clue on how to go about it. All I have read is that the Kenko brand is the way to go, but how do I choose the tubes? Do I buy a set? Do I buy one? What do I need to look out for when purchasing these? Please help. Thanks in advance.
    Quixxxie

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    Re: Kenko Tube Affect!

    With modern lenses designed to be controlled by the camera there is a problem that if you do not get the extension tubes with electrical connections to maintain contact the lens will default to wide open [ I found this out the hard way when using cheaper [ A$30 ] 'plain tubes' between my Canon and its lens ]. If you baulk at the price of the tubes with connections then you need to get an older lens with manual aperture setting ability. My preference for most big close-ups I take is to use a close-up lens on a long focal length lens. here you use the CU lens to enable the lens to focus a bit closer than it normally does and the long focal length to get a tight framing.

    If you want to get very tight framing CU lens is not the answer and tubes and/or bellows is the way to go. But I have not heard of bellows with electrical connections.

    A dioptre is 1000mm and dividing that by two gives you a two dioptre lens of 500mm focal length, a 7 dioptre CU lens would have a focal length of 143mm. When placed in front of the camera lens it means the working range will be between 143mm and whatever the lens's focusing can add. Using a 2dioptre on my 432mm lens I can work between 20" and about 13". The lens normally cannot focus closer than about two metres. [at 13" a subject about 35mm across filling sensor, FZ50 Panasonic]

    This is using my Pentax 135mm lens with bellows for a close-up of a clothespeg with plenty of space between lens and subject.
    Kenko Tube Effect!

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    Re: Kenko Tube Affect!

    Quote Originally Posted by jcuknz View Post
    With modern lenses designed to be controlled by the camera there is a problem that if you do not get the extension tubes with electrical connections to maintain contact the lens will default to wide open
    A quick and dirty work-around is to mount the lens on the camera without the extension tube - dial in the aperture you want - hit the DoF preview button - and then remove the lens (with the power still on).

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    Re: Kenko Tube Affect!

    I do not know if the above 2 replies were for me- because I am now totally lost. If they were for me- may I add some more info on my equipment.
    Canon 7D body
    Lenses: Canon=100mm Macro, 70-300mm telephoto, 24-105mm prime,
    Sigma= 50mm macro (no IS), 18-250mm IS
    Tokina = 11-16mm

    Now, As stated previously, I have done macro photos a lot with te 100mm macro lens- but I am somehow not so satisfied with my results- more because they dont jump out to the eye- while I view otherīs photos on flickr- doing great stuff with extension tubes- dont get me wrong- my pics are clear & some are nice (not all) but what I am looking for (now that I am on a budget) is to get some eye popping pics - any advice with the equipment I have? I do use a tripod for macro too. Thanks in advance- this study - should take me to the next level of photography. Sincerely thanks

  9. #9

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    Re: Kenko Tube Affect!

    Quote Originally Posted by Quixxxie2000 View Post
    I do not know if the above 2 replies were for me
    Apologies ... my reply was for jcuknz (but some others might find it useful)

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    Re: Kenko Tube Affect!

    Quote Originally Posted by Quixxxie2000 View Post
    I have done macro photos a lot with te 100mm macro lens- but I am somehow not so satisfied with my results- more because they don't jump out to the eye- while I view others photos on flickr- doing great stuff with extension tubes- don't get me wrong- my pics are clear & some are nice (not all).

    What I am looking for (I am on a budget) is to get some eye popping pics - any advice with the equipment I have?

    I do use a tripod for macro too.
    Hi "quixxee",

    I think I know what you mean about being a little disatisfied with results (I have been/am there myself), without having seen any of your efforts, I hope I won't offend with the following.

    I wonder if, in concentrating on the subject and the macro aspects, you are overlooking the photography basics of a good simple composition, rule of thirds, leading lines, et al?

    Also, I don't know your level of competency with sharpening or PP in general, so may be that side is letting you down(?). This is all guesswork on my part of course, you may be great at these things

    Another area I have yet to embrace is that of focus stacking, this really does help get stunning results, you only have to look at some of Frank Miller's work here to name but one member and there are others.

    Finally, you may have noticed that at CiC we prefer to use real first names when addressing each other, to that end, could I ask you to Edit your Profile here at CiC and add a first name in the Real Name field and a location (e.g. city/county/state and country) in the Location field - many thanks.

    Oh, one last thing, starting a new thread, it's easy; just open the required forum (e.g.) and you will find a button at the top on left which says "+ Post New Thread", it is in roughly the same place as the "+ Reply to Thread" button is above here.

    Cheers,

  11. #11

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    Re: Kenko Tube Affect!

    Quote Originally Posted by Dave Humphries View Post
    Hi "quixxee",

    I think I know what you mean about being a little disatisfied with results (I have been/am there myself), without having seen any of your efforts, I hope I won't offend with the following.

    I wonder if, in concentrating on the subject and the macro aspects, you are overlooking the photography basics of a good simple composition, rule of thirds, leading lines, et al?

    Also, I don't know your level of competency with sharpening or PP in general, so may be that side is letting you down(?). This is all guesswork on my part of course, you may be great at these things

    Another area I have yet to embrace is that of focus stacking, this really does help get stunning results, you only have to look at some of Frank Miller's work here to name but one member and there are others.

    Finally, you may have noticed that at CiC we prefer to use real first names when addressing each other, to that end, could I ask you to Edit your Profile here at CiC and add a first name in the Real Name field and a location (e.g. city/county/state and country) in the Location field - many thanks.

    Oh, one last thing, starting a new thread, it's easy; just open the required forum (e.g.) and you will find a button at the top on left which says "+ Post New Thread", it is in roughly the same place as the "+ Reply to Thread" button is above here.

    Cheers,
    Thanks Dave

    I have done as requested, & also have posted a thread. It is here...
    Extension Tubes
    I love this site, it is so informative.
    Dona

  12. #12

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    Re: Kenko Tube Affect!

    Quote Originally Posted by Dave Humphries View Post
    Hi "quixxee",

    I think I know what you mean about being a little disatisfied with results (I have been/am there myself), without having seen any of your efforts, I hope I won't offend with the following.

    I wonder if, in concentrating on the subject and the macro aspects, you are overlooking the photography basics of a good simple composition, rule of thirds, leading lines, et al?

    Also, I don't know your level of competency with sharpening or PP in general, so may be that side is letting you down(?). This is all guesswork on my part of course, you may be great at these things

    Another area I have yet to embrace is that of focus stacking, this really does help get stunning results, you only have to look at some of Frank Miller's work here to name but one member and there are others.


    Cheers,
    Iīm not sure how to apply rule of 3rds to macro fotos. While I use very little PP- maybe just sharpening image in Canonīs Digital Photo Professional. I also havenīt got a clue about focus stacking, any links to such a topic would be helpful. Thanks in advance

  13. #13
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    Re: Kenko Tube Affect!

    Quote Originally Posted by Quixxxie2000 View Post
    Iīm not sure how to apply rule of 3rds to macro fotos. While I use very little PP- maybe just sharpening image in Canonīs Digital Photo Professional. I also havenīt got a clue about focus stacking, any links to such a topic would be helpful. Thanks in advance
    Hi Dona,

    Glad you're sorted now.

    OK I had a look at your examples from the link posted in the new thread.

    First let me say you do have some good shots there and you're clearly getting as much right in camera as you can - although the occasional one is slightly mis-focused (when you view the full size 'original' link), that is almost unavoidable shooting live subjects.

    Here's what I'd do differently;
    I would use something simple and inexpensive like Photoshop Elements for PP, this would allow you to;
    Selectively sharpen images at an optimum radius, amount and threshold.
    Clone out, tone down exposure and/or blur, parts of the image that are not the main subject.
    Downsize your images (and sharpen again) before uploading - the default sizes Flickr produce will not be properly sharpened and may be a lower jpg quality than we would wish - hence the lack of pop.

    Applying the rule of thirds to macro is no different to normal photography, just a case of getting a sympathetic arrangement of image elements - it may not always be possible. That said, I didn't think any of your compositions or crops were bad, so this is less an issue.

    Focus stacking; tutorial here and the Macro tag cloud here. This may also be helpful, although with other specific replies, you may be past this stage by now.

    Cheers,

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    Re: Kenko Tube Affect!

    hi everyone, i have my nikor105mm macro lens but not so satisfied with the magnification..then i heard that some said they use the kenko extension tube to magnify and some said they use the raynox 250.. please help me to decide which one should i get, since i don't have any idea of what this two things can give me.. thanks

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    Re: Kenko Tube Affect!

    You should do better with regard to magnification with extension tubes*, you can use as many as you like depending on other considerations, than with Close-up lens. The Raynox 250 I understand is just a 4 dioptre and there are more powerful available like 10 dioptre. The problem is that DSLR lenses tend to be of rather large diameter so the CU lens has to be big and expensive. CU lenses are really for bridge cameras [ super-zooms]. Unless of good quality the IQ suffers with magnification power where the lens in a long tube doesn't and it is normal to reverse the lens when working with a long tube. Not sure that will work with a zoom. Once I used the 25mm lens of my 16mm Movie camera, reversed, on the bellows and achieved x9 magnification, ie four one millimetre marks on a ruler filling a 35mm film gate [ 36mm across ]. I think by reversing the lens you get better result by projecting an image of the subject onto the sensor, at least that's how I think of it, I could be wrong.

    *back when I wanted to copy a 16mm film frame I attached the 50mm lens to one tube set, another to the camera and connected the two loosely with a plastic tube. The film was held in a projector gate** and back lit, I was working in the basement with no lights on so there was no fogging from holes between tube and the gear. **part of an optical printer I built for work :-)

    To elaborate how things work .... if the camera lens will focus to 5cm you effectively have a 1000/50= 20 dioptre lens.
    If you add a 4 dioptre CU lens you now have 20+4=24. 1000/24= 41.6mm

    The difference between 50mm and 41mm is not worth bothering about. but if you add more extension you are well away :-)

    I would suggest the idea is to use your 'big' lens even though you will need more extension with it and use its narrow angle of view to get the tight framing you are after. This is how bridge cameras get what owners call double extension, its not of course, but it is pretty tight by the time they print it or display on monitor.

    To get "double extension" with a 300mm lens you will need 300mm of tubes between camera and lens [ six sets! :-) ] and you will get a subject around 24mm filling the sensor and you will still be some way back from the subject to permit you to light it etc as my photo above shows of the clothespeg ... 120mm extension is not quite DE with a 135mm lens but I got slightly better with the focusing power of the lens. 19mm filling the 24mm sensor ?

    I hope this ramble helps you decide which way to go :-)
    Last edited by jcuknz; 30th April 2012 at 11:04 AM.

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