97 replies to this topic

[bmyates]

How does one get greater magnification than 1:1 from a lens that only focuses down to 1:1? Teleconverters? Diopters? Some combination?

The lenses I'm specifically interested in doing this with are:
Canon 100mm macro
Sigma 50mm and 150mm macro

Will the same technique work equally well with all three (and others)?

[james]

Hi Bruce,

Both teleconverters and diopters will help increase magnification. Teleconverters maintain working distance, but steal light. So an f2.8 50mm lens with a 1.4x TC becomes a 70mm f4 lens.

Diopters decrease working distance but don't steal any light. They are effective with lenses which start with a long working distance. Shorter working distance lenses like the 50mm do not benefit from the diopter as you don't have enough working distance to make a photo (the close focus is literally inside the port...lol). There are wet diopters that mount on the outside of the port and dry diopters that mount on the lens. There are achromat (multiple element) diopters which are better than the single element type because they reduce chromatic aberration (spelling???).

HTH
James

[Viz'art]

The extension tubes will allows closer focusing resulting in higher magnification, this without loss of opticall quality but the drawback is proximity, you end up being much closer so use only with longer focal lenght.

James: go back to bed, you are a newly wed and should still be trying to reproduce (or at least pretend to)

[Kasey]

THis subject is of interest to me - I've been shooting various combinations of TCs and diopters, but I've never tried an extension uw. My understanding of extension is that the degree of magnification depends on the ratio of the extension to the native focal length. In other words, a short lens like a 60mm would get double magnification (100%)when used with a 60mm extension, but that same extension would only give 60% improvement when placed behind a 100mm. Hence, I thought that extension worked best with shorter focal lengths. Am I incorrect here? What specific combinations of lenses and extensions have you guys used? What degree of magnification have you achieved?

[randapex]

I've been working a little with the 2xTC on my 105mm. Never really had it on where the conditions were perfect as the magnification doesn't allow much in the way of water movement. And, I've ended up with lots of junk as well, but it's great when it works. Shot this in Florida a couple weeks ago:



Rand

[CeeDave]

Rand,

Cool!

Which 2X are you using? I haven't found many choices for Nikon AF (vis a vis AF-S) lenses.

Thanks,
Chris

[bmyates]

(Nice shot, Rand!)

A TC question. My recollection is that Canon's 1.4x and 2x TC's only work with their L series lenses. What TC's are usable with Canon's non-L and/or more generic (e.g., Sigma) lenses?

[randapex]

This is the one I use:
Kenko

[Viz'art]

Kasey, the 60mm has a built in "extension" to attain 1:1 so if I remember well, somewhere around 30mm should give you the 2:1, but hey, I could be wrong on that one, any engineer want to coraborate or demolish this theory.

The way I figure the lens and a 60mm tube would give you 1:1 if the focus was left at infinity...

[bmyates]

I assume that using an extension tube costs you some light (you're adding a small dark tunnel) - any rule of thumb as to how MUCH light you forfeit?

And if you can double the magnification with an extension tube, why would anyone use a 2X TC, which has a (significantly) higher price, and which introduces extra glass and thereby reduces photo quality to boot?!

[Kasey]

Extensions are long and unweildy - a TC provides a more compact package

[kriptap]

I use the Canon 100MM, if I know I am going for some really small stuff then I use my EF25II extention tube, it will let you focus to about 6-8 inches but only has a focus range of about 12, so anything past 12 inches you can't focus on.

[randapex]

And if you can double the magnification with an extension tube, why would anyone use a 2X TC, which has a (significantly) higher price, and which introduces extra glass and thereby reduces photo quality to boot?!  

<{POST_SNAPBACK}>

I'm not convinced that using the 2x results in un-acceptable photo quality. Frankly, my goal is to spend enough time with this set-up to show that the photos are up to snuff. It's just the right dive trip conditions need to present themsleves. One more with the 2xTC:



Rand

[Viz'art]

Indeed there is light loss, you loose 1 stop when youre at 1:1, I remember that Canon use a cheater when displaying their F stop, it's described somewhere in the lens or camera manual, but with Nikon when your at 1:1 your display shows F:4 not F:2,8 at maximum aperture and minimum focusing. once you are at f:4 or smaller, the system maintain the f stop choosen, on the opposite side your smallest is f:45 at minimum but convert to f:32 at infinity focus. hope It make senses

[Viz'art]

On the topic of teleconverter, they do induce a quality loss, but I suspect that since we use the center part of the lens and converter, the quality loss is not as dramatic as it used to be with full frame. I for one find these converter perform better now in digital than before in 35mm. In the end whatever work for you is best for you.

[CeeDave]

This is the one I use:
Kenko

<{POST_SNAPBACK}>

Okay, that's what I have, too.

[herbko]

The extension tubes will allows closer focusing resulting in higher magnification, this without loss of opticall quality but the drawback is proximity, you end up being much closer so use only with longer focal lenght.

<{POST_SNAPBACK}>

I don't think you can make this assumption for evey lens. Even though an extension has no glass to distort the image, it places the lens further away from the image plane than it is designed for. The optical quality is not guaranteed.

I've used both TC and diopters with good results. Sometimes both at the same time. The shot below was taken with the Canon 100mm with a 1.4x TC and a +2 diopter. F/6.3 which is effictively F/9 for shallow DOF.

[james]

That's a killer shot Herb. With that setup on a 1.6x crop camera, you are talking about a very small field of view!

Cheers
James

[Kasey]

Good TCs should induce little degradation when used on macro lenses in artificial light and relatively small apertures. This is according to John Shaw's texts. Remember that TCs are designed for much more demanding situations - shooting distant subjects at wide apertures. Birders would envy the results we get shooting 2X or 3X TCs under water!

[MikeVeitch]

Rand, killer shot on that Christmas tree worm, absolutely love it!

I am using a lot of close up filters myself these days, was going to use the 1.4TC but they sent me the wrong one....

I like the limited DOF it gives and i think is an easy way to go, without having to worry about extra length on your lenses and ports.
Too bad Chris Bangs doesn't seem to post on here these days, he has some great examples of using all sorts of combinations as that is one of his specialties (guess he is too busy taking photos of children!!!! )

However, i do find that the filters do work with a 60mm, this is an example of 60mm with a +4. True, i had to get right on them to get this full frame but..it worked...luckily they were turned this way

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