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Thread: Macro Math

  1. #1
    Andrew76's Avatar
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    Macro Math

    OK, I'm slowly learning, but have a quick question so please bear with me while I work through this! I understand that if I add a 2x Teleconverter to my 100mm macro lens, I now effectively have a 200mm macro lens, and that my minimum focus distance hasn't changed (well, not drastically anyway).

    So, on a Canon EF-100mm 1:1, the minimum focus distance is 0.31 meters to get 1:1. I've just doubled my magnification, so does this mean that I am now getting 2:1 at 0.31 meters?

    And in addition to that, will the fact that the physical height of the Teleconverter itself is about 4cm change my minimum focus distance?

    Thank you!

  2. #2
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    Re: Macro Math

    Hi Andrew,

    Canon extenders are not compatible with prime lenses below 135mm (with the exception of the tilt shift lenses). This is due to a clash between elements of the extender and elements within the lens. So the extender will not work on the 100mm macro. However I do not know about Kenko extenders. They may work but I am not sure.

    As for your question, I'll have a guess (since it cannot be tested with Canon equipment). The minimum focussing distance is measured from the sensor plane. Moving the lens forward on the extender will presumably move the minimum focus distance forward by the length of the extender. So you would get 2:1 magnification at the min focus distance of about 0.36 meters (assuming a 52.7mm extender length as shown here).

    Alex

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    Re: Macro Math

    My apologies, it is a Kenko extender, and it does work, even gets auto focus - which is essentially useless!

    Thanks for the help. I have put the setup together, and am trying a couple of shots right now. I am happy to get the 2:1, but I didn't really have an accurate way of measuring the minimum focus distance, aside from a measuring ruler, which is a little crude.

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    Re: Macro Math

    I'm curious what you come up with. It seems to me that whether you get to 2:1 will depend on MFD, won't it? E.g., if your MFD increases to absorb all of the change in FOV that the extender gives you, it seems to me that magnification would stay the same, but if MFD is largely unchanged, you should get higher magnification. Will you post your results?

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    Re: Macro Math

    Quote Originally Posted by DanK View Post
    Will you post your results?
    I will!! And, I have the conclusion, well at least partly. So, it seems I HAVE doubled magnification, without significantly changing MFD. I will assume that Herbert is correct, since MFD is measured from the sensor plane, moving the lens out 52.7mm (well that's the measurement on the Canon Extender, I don't have an accurate measurement on the Kenko), has only affected MFD by that much. Which makes me very happy!

    Also, I don't think the quality of the Kenko Extender is that bad either?!?! Considering this took me about 2 minutes to throw together, what do you think?

    Macro Math

    **EDIT - EXIF = 1/100 - f9.0 @ 200mm
    Last edited by Andrew76; 21st November 2012 at 04:31 PM. Reason: Added EXIF

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    Re: Macro Math

    Andrew,

    There is an easy method to determine this...

    Take a ruler and photograph it perfectly parallel to the sensor plane at the MFD both with the teleconverter and without. The resulting photo without the teleconverter should match the size of your sensor (ie: 22.3mm wide) and if you're getting 2:1 magnification with the teleconverter, you should end up with 11.15mm wide.

    - Bill

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    Re: Macro Math

    Hi Bill, thanks for the tip - that is an easy way to determine magnification, never thought about that. I'm pretty sure I am getting 2:1 though, that's not the problem. Trying to figure out how the extender affects the MFD is the issue.

    And now, an even BIGGER issue! I need to get something more substantial than my ball head tripod to hold all of this, and make the focus adjustments more incrimental! Never seems to end, does it?

  8. #8
    ktuli's Avatar
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    Re: Macro Math

    What kind of tripod do you have?

    Also - do you have a flash already?

    I honestly find it easier to shoot handheld with a flash than to use a tripod.

    - Bill

    PS: These threads might help:

    Tripod or Flash?
    Flash for Macro - What to buy?

  9. #9
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    Re: Macro Math

    Thanks again Bill, for the links! I don't remember reading those threads when they came up. I do own several flashes already. I'm afraid that when I get into magnifications greater than 1:1 (as the image below is at 2:1), though, that hand held shooting is not a viable option - both flash, and some form of support are needed.

    I own a Benro A-2691 tripod, which is a great all-round tripod/monopod, but I don't think that any tripod, without some form of a rail, or something that I haven't discovered yet is good enough. Maybe I'm mistaken, but there has to be better options, especially when getting into stacking multiple shots.

    Here's a clementine - shot at 1/100, f9.0 @ 200mm - 2:1 mag. The actual diameter of the whitish part of the stem is 3mm across, and all of those tiny black specs that in my opinion ruin the image, aren't even visible to the naked eye.

    I'm really enjoying this new aspect of photography... If you can't tell!!!!

    Macro Math

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    Re: Macro Math

    Firstly a note for anybody using Canon converters. I use my Canon 1.4x on a Sigma 180 macro lens by placing a 12 mm extension tube between the lens and converter to act as a spacer. Infinity focus is lost but that doesn't matter for macro work.

    With regard to tripods. Everybody seems to have their favourite brand and there probably isn't much between the best of them.

    I use the Manfrotto 055 and have recently switched to the carbon fibre version to save on weight when walking a mile or more to a photo site.

    Which type of head depends on what you mostly shoot. For quick insect shots I prefer a ball head but for slower work on static subjects you may find that a slide adjustable head gives greater precision.

    Previously, I used the Manfrotto 322RC2 ball head but purchased a 468MGRC4 hydrostatic version which is totally solid without any creep. But a bit more expensive.

  11. #11
    ktuli's Avatar
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    Re: Macro Math

    I shoot at 5:1 magnification without a tripod all the time...

    Macro Math

    Note the lines at the top of the frame? That's a ruler with the mm scale showing. The shot was taken handheld with the MP-E65 + the MT24-EX dual macro flash.

    When I do use a tripod, I have a Manfrotto 055XProB legs with the 327RC2 Joystick head. It works pretty well for the macro stuff, and as Geoff teaches... if you put the grip on the left side, you can adjust the tripod with the left hand and be ready to trip the shutter with the right hand.

    For a cheap macro rail, I have one of these - http://www.adorama.com/MCFRS1.html - that I put a quick release plate and a quick release receiver adapter on so I can easily mount it to my tripod and then mount the camera to it.

    - Bill

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    Re: Macro Math

    Thanks for the tips Geoff. I'm going to do a little research today to see which route I'm going to take. The Benro ball head that I own is great for taking landscapes, and portraits etc,- and I take it with me everywhere. But when I discovered the fabulous world of ultra macro just the other day, I find that even the slightest, tiniest, wee little bit of a creep is too much when you're talking about subjects that are <10mm across.

    So, I need to do something. I have seen many people 'make their own' slide rails - but I don't think I'm quite that crafty - nor do I know exactly what I'm looking for, so I would have no idea where to start.

    Yours looks nice, are you happy with it?

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    Re: Macro Math

    Quote Originally Posted by ktuli View Post
    Andrew,

    There is an easy method to determine this...

    Take a ruler and photograph it perfectly parallel to the sensor plane at the MFD both with the teleconverter and without. The resulting photo without the teleconverter should match the size of your sensor (ie: 22.3mm wide) and if you're getting 2:1 magnification with the teleconverter, you should end up with 11.15mm wide.

    - Bill
    Confirmation of 2x magnification:

    Macro Math

  14. #14
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    Re: Macro Math

    Quote Originally Posted by ktuli View Post
    I shoot at 5:1 magnification without a tripod all the time...
    - Bill
    That's amazing! Nice shot Bill! You have steadier hands than mine!

  15. #15
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    Re: Macro Math

    Quote Originally Posted by Andrew76 View Post
    That's amazing! Nice shot Bill! You have steadier hands than mine!
    And a lot of deleted frames of course...

  16. #16

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    Re: Macro Math

    I think a lot of what equipment to use decisions come down to what you intend to photograph.

    For me, shooting nervous insects (10 mm and smaller) amongst the brambles and nettles often balancing the tripod on just two legs requires speed and the ability to change camera angles when following moving subjects and shooting through 'holes in the foliage'.

    Because I'm mostly photographing them for identification purposes I need a couple of shots from different angles of every insect which I encounter; and of sufficient identification quality.

    Sometimes however, when taking 'studio shots' a slide rail would be useful. But many of these shots are of slowed down (chilled) live subjects so quick flexibility is still required as they are liable to move, particularly when they start to warm up. This period of inactivity can be as little as 10 seconds.

    Completely static subjects are a different matter. And the ability to slide smoothly is very useful when a number of shots will be stacked to increase focus depth.

  17. #17
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    Re: Macro Math

    Andrew,

    I found a ball head extremely frustrating for macro. It is very tough to make small adjustments without overshooting, and without having a tiny bit of sag when you tighten it up. those tiny errors really matter with macro.

    For shots in a controlled environment, another macro shooter suggested that I splurge on a geared head, the Manfrotto 410 "junior" geared head. Despite the "junior" name, it is big and heavy. (I think there is a larger one too, hence the name.) It is wonderful for flower macros, because it gives you very fine adjustments in any plane. I eventually added an arca-swiss adapter so that I could leave my standard plate on my camera rather than unscrewing it and screwing on the manfrotto plate, but the adapter is also quite large, so the whole thing is really big. However, I don't carry it around; when I am going to carry my tripod outdoors, I just remove the Manfrotto and screw on my small Induro ball head.

    I thought about adding a rail to this, but it would make the whole thing the size of a small truck. Given the choice, I would rather have the geared head than a rail. I only shoot up to about 2:1 (60mm macro with 68mm of extension is my max), and for that, i find that small adjustments to focus, leaving the camera in place, works fine. With higher magnifications, it might not. Using this method, I routinely stack anywhere from 5 to 15 images, without problems.


    For shots of bugs, I use a monopod, but I rarely go above about 1.3:1 for them.
    Dan

  18. #18
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    Re: Macro Math

    Thanks Dan, it's a learning curve for sure. I've looked at that 410 geared head today, and for the price, I think it's a pretty good option.

    Gear talk aside - I realize that the images I am posting in this thread are not 'artistic', but I'm having way too much fun with this new found toy, so here's one more - the first person who can guess what it is a photo of, wins the cash prize!!

    It's too bad that it is now winter here, no more flowers, and no more bugs. I got a passion for macro 5 months too late!

    Macro Math

  19. #19
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    Re: Macro Math

    I am saying broccoli...........and yes macro is addictive!!

  20. #20
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    Re: Macro Math

    Hi Randy - you're right! Broccoli it is! That was too easy I guess! Yep, I'm addicted, and I have another whole day off tomorrow to play around with it! Can't wait - but I'm running out of ideas, seems everything I'm trying is food of some sort.

    Thanks for commenting!

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