Extension tubes explained

[Frankman]

Given the interest in this topic I thought I'd do a quick and dirty demo of the sort of magnifications that these can achieve. For this demo, I used the KM 18-70 3.5-5.6 lens. This is the budget kit lens. It's NOT a macro lens, so you should achieve similar results without much effort.

Fiirstly, the setup. Pretty self explanatory - see the picture. I tested all the shots at the same aperture f9, ISO 100 using wireless flash:

http://i18.photobucket.com/albums/b108/frankman6148/setup.jpg

I took the next photo at the minimum focal distance for the kit length. THis is the highest "macro" magnification it's capable of (remember - this is NOT a macro lens):

http://i18.photobucket.com/albums/b108/frankman6148/notubes.jpg


I then took the same shot with a 12mm extension tube:
http://i18.photobucket.com/albums/b108/frankman6148/12mmtube.jpg


Next, with the 20mm extension tube:
http://i18.photobucket.com/albums/b108/frankman6148/20mmtube.jpg


Next, the 36mm extension tube:
http://i18.photobucket.com/albums/b108/frankman6148/36mmtube.jpg


Next, all 3 tubes stacked (total length 12+20+36=68mm):
http://i18.photobucket.com/albums/b108/frankman6148/allthreetubes.jpg

I have not sharpened nor altered these shots in any way - straight from the camera, converted from RAW to jpg. If you want to get into macro, these are a good way to go. However, bear in mind that you will lose infinity focus. I've used these on several of my lenses, as well as my Sigma 105mm macro lens with good effect. Very versatile. Mine are Kenko brand, and have all the AF pins, so they're fully automatic.

HTH, Frank

[foonji]

nice demo mate. will help out peeps for sure. :)

[The_Scroop]

Excellent work. Sticky worthy in my opinion :th3:

[Jester]

are these the same as macro filter things? fantastic results their

[natsdad]

Thank you I feel that I have learned something here,thankyou to all

[Ronbo]

are these the same as macro filter things? fantastic results their

No these are mounted behind the lens directly to the camera moving the lens elements further away to achieve magnification.

Macro filters have short comings like distortion at the edges of the shot.

Both have their side effects but the tubes minimizes that more so than the filters at least in my limited knowledge.

[thing]

Thanks Frank. I have wanted to get into some macro stuff for a while. I had been looking on eBay have had no experience with these things, and was a little hesitant to buy them. I think I shall now get me some!

[SirNobicus]

kewls!
I always wondered how these things worked

[sans2012]

Nice demo mate:)

[enduro]

I have heard a lot about the Kenko tubes in the past and considered purchasing them for macro work.

I understand that tubes do not have a lens inside them, however do they cause a loss of appreciable IQ ?

Secondly, what would the effect of using tubes on my 400mm be. Is it that they will only reduce the MWD?

[Tannin]

Tubes will work just fine with your 400/5.6 Wayne. See this thread (http://www.ausphotography.net.au/forum/showthread.php?t=24888) for an example shot using a 400/5.6 and a 25mm tube. There is a heap of other examples over in this thread (http://www.ausphotography.net.au/forum/showthread.php?t=23544), all taken with a 500/4 and either a 25mm tube or stacked 25mm and 12mm tubes for 37mm in total. Many of my other small bird pictures (posted here and/or on my website) use an extension tube, I often can't remember which ones as it doesn't show up in the EXIF.

For small birds, tubes are pretty much an essential unless you are using one of the very few longer lenses that have a decent minimum focus distance (the Canon 100-400 is an example). Most (all?) longer primes have crazy long MFDs, presumably in an effort to keep the overall physical length of the product down and thus not offend the primary buyers of these lenses: sport photographers.

IQ does not suffer in the slightest. In fact, I believe that extension tubes increase your IQ. This is just my own gut feeling, I've never read anything scientific or official saying this, but it stands to reason that a lens will be better optimised further towards the middle of its focal range, and my results seem to confirm it. (I'm talking here about the situation where, for example, your subject is 3.4 or 3.6 metres away. In theory, it's within the 3.5m MFD of the 400/5.6, but in reality the lens is only just barely able to focus on it. With a tube, however, the lens is well inside its focal distance range. Be all that as it may, tubes certainly don't reduce IQ.

Other effects? You already know the main one: loss of infinity focus. You lose some light as well. I've never measured this and can't tell you how much exactly, but you do sacrifice a small amount of shutter speed for any given light level and aperture/ISO setting. You probably won't notice this in practice. Finally, in theory, you get some vignetting, but that won't apply to your 40D - it doesn't seem to apply on the (larger sensor) ID III either, doubtless it's only if you go full frame that you see it.

Short answer: go for it, they are very, very useful!

[Jordan Compte]

ohhh, so thats what they do? haha

I thought they were an extension for other lens mounts haha

[Carly]

Hi, i'm relatively new to DSLR, just upgraded from my canon powershot pro1 to the 50d with a canon 18-55mm IS lens. I'd like to start shooting closer than the 18-55 lets me, so i'm looking at purchasing a set of extension tubes (also got the hoya close up macro filters on their way from somewhere off ebay).

I'm a bit confused though as to which extension tubes I should go for. All being equal i'd love to go for the kenko set (~$150), from all reviews they seem equal to the Canon (which is ridiculously priced for some pieces of tube!) and much lower price. But! price is an issue here (looking at the 55-200mm for more zoom - it's on special for $299 at teds atm), so instead i'm looking at the cheap ones from Asia (on ebay), there seem to be a couple of different types though, namely the ones with "AF Confirm" )(~$50) (the ones with the electrical chips on them) and those without (~$10-15). From my understanding the "AF confirm" ones talk with the camera and a "beep" will come from the camera when the image is in focus (still using a manual focus, auto is not possible with extension tubes right?)

Are there any other differences between the two types? any recommendations of tubes from ebay? I need to ensure they work for EF-S right? I'm also a bit wary of the ones with the "AF Confirm" electrical contacts as i've read a couple of stories where if they're incorrectly (sloppily) manufactured it can cause electrical shortage and bye bye camera.. :(

Mostly looking at shooting flowers/bugs etc ..

Thanks very much :)

- Carly

[old dog]

good explanation Frank. I just got a set off ebay and playing around with them ATM. Have the tamron 90 macro as well so I am trying to get close as I can. Having fun also. Kenko DG tubes.

[enduro]

Tubes will work just fine with your 400/5.6 Wayne. See this thread (http://www.ausphotography.net.au/forum/showthread.php?t=24888) for an example shot using a 400/5.6 and a 25mm tube. There is a heap of other examples over in this thread (http://www.ausphotography.net.au/forum/showthread.php?t=23544), all taken with a 500/4 and either a 25mm tube or stacked 25mm and 12mm tubes for 37mm in total. Many of my other small bird pictures (posted here and/or on my website) use an extension tube, I often can't remember which ones as it doesn't show up in the EXIF.

For small birds, tubes are pretty much an essential unless you are using one of the very few longer lenses that have a decent minimum focus distance (the Canon 100-400 is an example). Most (all?) longer primes have crazy long MFDs, presumably in an effort to keep the overall physical length of the product down and thus not offend the primary buyers of these lenses: sport photographers.

IQ does not suffer in the slightest. In fact, I believe that extension tubes increase your IQ. This is just my own gut feeling, I've never read anything scientific or official saying this, but it stands to reason that a lens will be better optimised further towards the middle of its focal range, and my results seem to confirm it. (I'm talking here about the situation where, for example, your subject is 3.4 or 3.6 metres away. In theory, it's within the 3.5m MFD of the 400/5.6, but in reality the lens is only just barely able to focus on it. With a tube, however, the lens is well inside its focal distance range. Be all that as it may, tubes certainly don't reduce IQ.

Other effects? You already know the main one: loss of infinity focus. You lose some light as well. I've never measured this and can't tell you how much exactly, but you do sacrifice a small amount of shutter speed for any given light level and aperture/ISO setting. You probably won't notice this in practice. Finally, in theory, you get some vignetting, but that won't apply to your 40D - it doesn't seem to apply on the (larger sensor) ID III either, doubtless it's only if you go full frame that you see it.

Short answer: go for it, they are very, very useful!

Interesting this thread came up again just as I am purchasing a set which will hopefully arrive next week.

[MarkChap]

Carly,
You will have to be careful to ensure that you get a set of tubes that accept EF-S lenses, my kenco set will not mount with an EF-S lens.

I have seen some on flea-bay that state they fit EF and EF-S lenses but am unable to tell if they have the electrical contacts, which I imagine would be pretty important on a Canon lens to allow you to close down your aperture for DoF control.

I really think it is a case of buyer beware and you will get what you pay for

[davesmith]

Tubes will work just fine with your 400/5.6 Wayne. See this thread (http://www.ausphotography.net.au/forum/showthread.php?t=24888) for an example shot using a 400/5.6 and a 25mm tube. There is a heap of other examples over in this thread (http://www.ausphotography.net.au/forum/showthread.php?t=23544), all taken with a 500/4 and either a 25mm tube or stacked 25mm and 12mm tubes for 37mm in total. Many of my other small bird pictures (posted here and/or on my website) use an extension tube, I often can't remember which ones as it doesn't show up in the EXIF.

For small birds, tubes are pretty much an essential unless you are using one of the very few longer lenses that have a decent minimum focus distance (the Canon 100-400 is an example). Most (all?) longer primes have crazy long MFDs, presumably in an effort to keep the overall physical length of the product down and thus not offend the primary buyers of these lenses: sport photographers.

IQ does not suffer in the slightest. In fact, I believe that extension tubes increase your IQ. This is just my own gut feeling, I've never read anything scientific or official saying this, but it stands to reason that a lens will be better optimised further towards the middle of its focal range, and my results seem to confirm it. (I'm talking here about the situation where, for example, your subject is 3.4 or 3.6 metres away. In theory, it's within the 3.5m MFD of the 400/5.6, but in reality the lens is only just barely able to focus on it. With a tube, however, the lens is well inside its focal distance range. Be all that as it may, tubes certainly don't reduce IQ.

Other effects? You already know the main one: loss of infinity focus. You lose some light as well. I've never measured this and can't tell you how much exactly, but you do sacrifice a small amount of shutter speed for any given light level and aperture/ISO setting. You probably won't notice this in practice. Finally, in theory, you get some vignetting, but that won't apply to your 40D - it doesn't seem to apply on the (larger sensor) ID III either, doubtless it's only if you go full frame that you see it.

Short answer: go for it, they are very, very useful!

Having never used either, what's the difference or advantage of using extension tubes compared to teleconverters, particularly away from macro?

From what I see, usually if someone is after a bit of extra reach it's more common to go for a tc on a fast long lens, but that always goes with the potential loss of image quality. On your anecdotal evidence, is it more of an advantage to use tubes instead of a tc? What are the limitations in comparison to each other?

[enduro]

Having never used either, what's the difference or advantage of using extension tubes compared to teleconverters, particularly away from macro?

From what I see, usually if someone is after a bit of extra reach it's more common to go for a tc on a fast long lens, but that always goes with the potential loss of image quality. On your anecdotal evidence, is it more of an advantage to use tubes instead of a tc? What are the limitations in comparison to each other?

Here is a good link that will save me a lot of typing and getting things wrong:

http://everything2.com/title/Extension%2520tubes%2520and%2520teleconverters

[Carly]

Thanks Mark, you're right I had a look and most of the ones on ebay only mention "EF". Some of the kenko ones say EF/EFS (maybe a newer model?) Still it's $150, probably more than i can squeeze out of my other half atm ;) Anyone know of any other cheaper options? (next step up is the macro lens right at ~$400 right?)

[enduro]

... it's $150, probably more than i can squeeze out of my other half atm ;) Anyone know of any other cheaper options? (next step up is the macro lens right at ~$400 right?)

The Tamron 90mm is going for about $500 on the bay, I don't know the local price. The Canon 100mm f/2.8 is going for about $600 on the bay and about $950 locally.

Cheaper options other than macro lenses above may not provide the quality results you may be pursuing.

A good option might be look at reverse mounting (with the appropriate ring) a 50mm onto one of your lenses. I have seen some excellent results with that sort of combo. Several ppl I have observed posts from use older model 2nd hand lenses with excellent results.

From experience, I'd steer clear of screw on macro filters.

[pollen]

Having purchased Extension Tubes, I wish someone had told me not to. They are extremely impractical, and if you have the time and patience to fiddle with them all day, they are ok, but if you're always in a rush or are in a time and composition sensitive application, they are very impractical.

The issue is although they shorten your MFD (which is good to get more magnification) they also significantly shorten your MaxFD. This gets worse the shorter the lens. For instance, a 70mm lens with a 25mm Extension tube has a focusing range of 3cm. Imagine using a Prime Lens where you can't foot zoom. That's what an ET feels like on a normal lens. You can't change your composition to any great extent because you are virtually locked at a certain FOV.


Having never used either, what's the difference or advantage of using extension tubes compared to teleconverters, particularly away from macro?

They both have their uses for Macro. Though TCs degrade IQ more, they make the background more blurry though which is very useful for flower photography or when you need a lot of DOF but a blurry background. Some Flower Photographers stack a 1.4X and 2X on a Macro lens for flowers to get nice blurry backgrounds at small apertures like f/16



IQ does not suffer in the slightest. In fact, I believe that extension tubes increase your IQ. This is just my own gut feeling, I've never read anything scientific or official saying this, but it stands to reason that a lens will be better optimised further towards the middle of its focal range, and my results seem to confirm it. (I'm talking here about the situation where, for example, your subject is 3.4 or 3.6 metres away. In theory, it's within the 3.5m MFD of the 400/5.6, but in reality the lens is only just barely able to focus on it. With a tube, however, the lens is well inside its focal distance range. Be all that as it may, tubes certainly don't reduce IQ.

Other effects? You already know the main one: loss of infinity focus. You lose some light as well. I've never measured this and can't tell you how much exactly, but you do sacrifice a small amount of shutter speed for any given light level and aperture/ISO setting. You probably won't notice this in practice. Finally, in theory, you get some vignetting, but that won't apply to your 40D - it doesn't seem to apply on the (larger sensor) ID III either, doubtless it's only if you go full frame that you see it.

Short answer: go for it, they are very, very useful!
I used to think so as well, in theory it's stated that infinity focus is lost and IQ is not affected, but I find in practice the reality is much different

With IQ, ETs magnify optical defects, especially CA and even worse, spherical aberrations. Many lenses perform very poorly at MFD, especially the 35L, some 17-55 IS and 70-200 f/4L IS. They have some residual spherical aberrations which really rear their ugly heads at MFD, and these only look worse with an ET.

With infinity focus, the literature suggests losing focus at infinity, but imo it is a spectacular understatement. For my 70-200 for example, with a 25mm ET, it can't focus beyond about 2 metres at the long end, and beyond about 1 metre at the short end. If >1 metre is considered "infinity" I need to relearn my english :)