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Thread: Sigma 105mm Macro + EX-25 Advice Reqd.

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    Default Sigma 105mm Macro + EX-25 Advice Reqd.

    Hello, I love shooting macro and those of you that do aswell know how addictive it is. I want to get closer, I have the 105mm sigma macro and have taken some fantastic shots with it, BUT i want to go closer for more detail, so i put to you...

    Can i use the EX-25 with the sigma 105mm? is this worth doing? will it benefit me? and what extra will i get in terms of Ratio?

    sorry for the many questions i hope you peeps can help

    Ta Ed

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    Default Re: Sigma 105mm Macro + EX-25 Advice Reqd.

    You certainly can use the EX-25 to gain more magnification. How much more, I'm not sure. I believe the Sigma 105 is one of those lenses that lowers its focal length as it focuses closer. If we estimate that it's 70mm fully racked out to 1:1, then perhaps you can go to 1.3:1 or so? Just a guess. If it doesn't drop focal length then the boost will be much less.

    You can also consider adding an EC-14 instead.

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    Default Re: Sigma 105mm Macro + EX-25 Advice Reqd.

    I'd go with Acme here and recommend a TC instead of a tube for your 105/2.8. In addition to the reason he stated, you also lose working distance with tubes, whereas you gain working distance with a TC.

    More working distance is almost always a good thing... the only time I've ever wanted less working distance was once shooting a 400mm telephoto with a flash... my flash bracket wasn't long enough to throw side lighting on my subject!

    If you want to get REALLY close, you can stack a TC and extension tube... mount it like camera->TC->tube->lens. TCs magnify whatever is in front of them, so putting the tube in front of it gives you more magnification (25mm*1.4=35mm) than putting it behind. I've done this with similar hardware and gotten some great results in the 2x range.
    Chris


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    Default Re: Sigma 105mm Macro + EX-25 Advice Reqd.

    hmmm...interesting replies guys thank you very much. Im interested in getting nearer 2:1, so you reckon a tc-14 would be better than a tube?

    interesting i hadnt thought of that

    thats exactly the kind of help i needed, cheers guys you bunch of legends

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    Default Re: Sigma 105mm Macro + EX-25 Advice Reqd.

    A 1.4x TC will take your 1:1 macro lens to 1.4:1, so it won't get you quite there. A 2x TC would get you 2:1, but then you lose more image quality and yet another stop aperture... I don't know about you, but a dim viewfinder image is a pain for me when focusing closeups!

    I don't have a Sigma 105/2.8, so I don't know the exact magnification you'll get with tubes. Like acme said, many macro lenses shorten in focal length as you focus closer, which greatly complicates calculating magnification with tubes.

    If a lens were to keep its focal length when focused closer, you could calculate magnification when focused to infinity by using the formula [mag] = 1: ([focal length]/[extension]). So a 50mm lens with a 25mm tube could focus to 1:2 at its furthest.

    I ran the numbers for my Canon 100/2.8 a while back (which shortens to about 60mm at 1:1). These won't be exact for your Sigma, but they should be close... these are minimum and maximum magnification ratios with the given mounted hardware. I have three tubes for my Canon kit (12mm, 20mm, and 36mm) so the "XXmm" numbers are all the tubes added together:

    100/2.8 bare 00mm 0.00-1.00
    100/2.8 bare 12mm 0.11-1.29
    100/2.8 bare 20mm 0.18-1.42
    100/2.8 bare 36mm 0.36-1.69
    100/2.8 bare 32mm 0.32-1.57
    100/2.8 bare 48mm 0.52-1.83
    100/2.8 bare 56mm 0.59-2.0
    100/2.8 bare 68mm 0.71-2.2
    100/2.8 bare 00mm 0.00-1.4
    100/2.8 1.4x 12mm 0.15-1.76
    100/2.8 1.4x 20mm 0.31-1.83
    100/2.8 1.4x 36mm 0.5-2.2


    I stopped calculating at 2x, cause I told myself that if I ever need to go past that I'll buy Canon's 5:1 macro lens. And I haven't yet.

    Also, keep in mind that on Four Thirds, 1:1 means you can fill the frame with an object that's 17.3mm wide. 2:1 gets you down to nearly an 8mm object. That's extremely small! If you don't need to get that small, life is a lot easier below 2x.
    Chris


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    Default Re: Sigma 105mm Macro + EX-25 Advice Reqd.

    that puts it quite nicely thanks a lot

    i think i will start with a cheap set of tubes (as the cheapest option) lock the aperture off with DoF preview and try that. See what results i get. Then i will try TC's, tc's with tubes etc and i may try a 50mm om backwards on the front.

    Thanks chaps

    and yeh agreed i dont need to go above 2:1 lol, i just want to do some really detailed close shots as well as the 1:1 and 1:2 stuff, may have to focus stack tho as focusing is gonna be a nightmare lol especially with a dim viewfinder.....

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    Default Re: Sigma 105mm Macro + EX-25 Advice Reqd.

    Quote Originally Posted by MrEd View Post
    that puts it quite nicely thanks a lot

    i think i will start with a cheap set of tubes (as the cheapest option) lock the aperture off with DoF preview and try that. See what results i get. Then i will try TC's, tc's with tubes etc and i may try a 50mm om backwards on the front.

    Thanks chaps

    and yeh agreed i dont need to go above 2:1 lol, i just want to do some really detailed close shots as well as the 1:1 and 1:2 stuff, may have to focus stack tho as focusing is gonna be a nightmare lol especially with a dim viewfinder.....
    No problem! Have fun with the tube. Shooting extreme closeups is a lot of fun! Don't be surprised if you burn a ton of money on closeup gear and flash equipment in the next few months...
    Chris


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    Default Re: Sigma 105mm Macro + EX-25 Advice Reqd.

    Quote Originally Posted by ckrueger View Post
    No problem! Have fun with the tube. Shooting extreme closeups is a lot of fun! Don't be surprised if you burn a ton of money on closeup gear and flash equipment in the next few months...
    lol! i already done that, been shooting amcro for about a year, got external flas, tripod mount etc etc i just want to get closer but dont wanna just go dumo a ton of money at it yet till i have given extremem close up a try! in case i dont like it....

    i love shooting 1:1 tho

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    Default Re: Sigma 105mm Macro + EX-25 Advice Reqd.

    Other options are close up lenses, or an OM auto bellows ($50-$125) and 80mm f/4 ($125-$300) bellows macro. The 80mm is designed for magnification from 1:2 to 2:1 and produces good results on fourthirds.

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