What is the significance of the typical extension tube lengths?

Question

I've been recently looking into getting an extension tube set for some macro photograpy. I've noticed that a lot of these 3 tube sets (for Canon EOS) have the same, very specific lengths: 13mm, 21mm, and 31mm.

I've done some searching on Google as to the significance of these lengths, but have found nothing. Does anyone know why these lengths in particular seem to be so common?

Asked by ltn100

Answer

It might help if you thought of everything in Imperial units rather than metric. A normal lens for 35mm cameras is a 2-inch lens (50mm), and the tubes are (approximately) 1/2-inch (13mm), 3/4-inch (21mm) and 1 1/4-inch (31mm). That makes both magnification calculation and bellows draw (exposure compensation required for the lens extension) relatively easy to calculate, whether the tubes are used alone or in combination, when the lens is focused to its infinity mark. For instance, combining the 21mm and 31mm tubes would give you a 1:1 magnification ratio with a 2-stop exposure compensation.

The calculations are similarly simple for 24mm, 100-105mm and 200mm lenses, at least in a ballpark sense.

Remember that zoom lenses were once far from ubiquitous, and it was anomalous for a photographer to own a 35mm camera without also owning a 50mm lens. It might also help to remember that TTL metering was, once upon a time, and only if your camera actually had it, something you wouldn't really want to rely on most of the time (almost all metering was center-weighted, and rather depended on the condition of your camera's batteries or the age of the selenium cell).

These days we don't need to rely so much on external metering for most photography, and it's as likely as not that you'll be using a zoom lens as a prime, so maybe the tube lengths don't make as much immediate sense as they used to. But that's why millimeter lengths that are around rounded simple fractions (halves and quarters) of an inch are normal.

Answered by Stan Rogers

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What are the biggest differences between Reversal Rings, Extension Tubes and Macro Lenses?

Question

As far as I understand all three options help you do macro photography but are their other reasons for having the three different items? I figured reversal rings and extension tubes were just for the low cost but with additional more expensive features being added to the two options it seems there may be certain situations for each type? What are their biggest differences and advantages over each other?

• Are there situations where you would have one over the other?
• Do all three options have the same "wafer thin" depth of field?
• Do they all suffer from the same light loss?
• Do any of them affect your photos more negatively than the others?
• Can I achieve the same magnification with rings and tubes that I can with proper lenses?
• Would you ever combine these options together or would there be no need for that?

I ask because I recently bought a cheap extension tube and reversal ring and I'm trying to get a better overall understanding of each. I tend to use the extension tube a lot more, because I can put it on my 70-200 and have a workable distance between subject and lens.

This photo was taken with 49mm of extension tube on the 70-200 I believe which may be greater than 1:1. Would it be sharper with a macro lens?

Larger Version on 500px

Asked by Vian Esterhuizen

Answer

Depth of Field

Reversing a lens will produce a very shallow DOF. You may also get distortion and vignetting and have difficulty focusing, as you can only focus at a very narrow range of distances. From memory extension tubes have less DOF than a macro lens, but I am not certain of that.

Light Loss

You will lose 1-2 stops of light using extension tubes. You can argue that macro lenses at 1:1 lose some light (mine reduces from f/2.8 to f/3.5). I don't know about the loss of light with reversed lenses, but it would would seem clear that the light gathering ability of the lens would be reduced when reversed, given that the aperture opening tends to be quite a bit smaller than the front of the lens.

Magnification

You can achieve 1:1 with extension tubes with say roughly 50mm of tubes and a 50mm prime lens. Reversing a lens you can get greater than 1:1.

Quality and Ease of Use

You will lose sharpness in reversing a lens or using extension tubes. You may lose metering and AF capability with a reversed lens (and some tubes), although some reversing rings and extension tubes have metering capability.

An important difference to me is that macro lenses can focus from their min distance to infinity (other two options have a narrow range of focus ability, so the camera and subject must be a certain distance apart). So once you reverse your lens or put on some extension tubes, you will be locking in a certain magnification and subject-camera distance, where a macro lens you can move closer or further away from your subject to compose the shot.

Reversing a lens, or sticking it at the end of some extension tubes, you are not using the lens for what it was originally designed and optimised for, so you wont get the same performance as a dedicated macro lens.

But both options do a good job considering the relatively low cost.

Re: your new question about using them together. Yes, you can use an extension tube or teleconverter with a macro lens to increase magnification, or to give you more working distance for the same magnification. With more working distance and the same magnification, because you are focusing at a greater distance, you should end up with more DOF as well.

Answered by MikeW

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Nikon D7000 and extension tube with 35G 1.8

Question

Recently i purchased an extension tube. (chepest one, with no af..etc..). Just for fun.

I attached it to my camera, and than the 35G. Unfortunatelly picture, and finder is dark too. I read somewhere this is why G type lens has no apperature ring, and normally the smallest apperature set when attach a lens.

On my body i get error F0. I read this is when optics did not attached well. I checked, its ok.

Is it possible to use this tube with my G type lens on this D7K body? Any way to set apparature on body?

Thank you

Asked by Holian

Answer

If you use a cheap extension tube without CPU connections between the lens and the camera, then as far as the camera is concerned there is no lens connected, which is why it says F0.

The lens automatically closes to its smallest aperture when it's detached, and if your extension tube doesn't hold it open, it will stay that way, because without a CPU connection, there's no way for the camera to control any part of the lens.

You can still take photographs, by setting the camera to Manual mode (M on the dial), but you will need long exposure times to get enough light in to expose properly.

The best solution would be to buy an old lens with a manual aperture ring; they are quite cheap. This will allow you to get decent shutter speeds using Manual mode. Otherwise you will need to invest in a set of extension tubes with a CPU connection.

Answered by ElendilTheTall

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How *Auto* Are Pentax Auto Extension Tubes?

Question

While asking for extension tubes for a Pentax DSLR, Pentax replied:

As requested, please find the following extension tubes available. Product 30535, auto extension tube set B Product 30551, life-size auto extension tube B 50mm w/case Product 30556, life-size auto extension tube B 100mm w/case

After searching for these products online I found different information regarding them. One forum post somewhere said the only auto part is that the meter at the widest aperture and stop down to the smallest. Is this true?

My intuition is that extension tubes stop down to whatever aperture is set in the camera. Perhaps they would be able to autofocus too but I do not care about that :) Only that there is still control over aperture without a lens with an aperture ring.

Does anyone know how the automatic aperture and metering work with these tubes?

Asked by Itai

Answer

As far as I know, the Pentax-brand tubes rely on an aperture set on the lens, so while they'll work with manual-focus K-mount lenses and most of the FA-series, they won't let you work properly with the D-series lenses that don't have an aperture ring. They are "auto" in the sense that they allow you to focus and meter wide-open, then stop the lens down to the set aperture mechanically, but they don't appear to have the contacts necessary for electronic aperture control. (The newer digital-intent lenses are essentially stopped-down to minimum aperture mechanically all of the time, as you would have to do with a lens having an aperture ring if you wanted to use the aperture setting on the camera body.)

Kenko used to make a proper set of automatic tubes for the Pentax that gave full electronic aperture control and screw-drive autofocus, but while they still show up on the used market from time to time, they appear to have been discontinued. There are, of course, any number of off-brand (Chinese) tubes out there claiming to be auto, but they tend not to give away too many secrets in their ads and placements, and I'd suspect they're just K-mount mechanical linkages since I can't see anything that looks like electrical contacts in any of the pictures.

Answered by Stan Rogers

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Why does my camera show “f00” when using extension tubes for shooting close ups?

Question

As a beginner in close up photography, I am using extension tubes with my Canon 550D and standard 18-55mm lens. I noticed that when I use this, the f-stop meter in the camera does not work and always shows f00. I am using the Fotodiox extension tubes that I bought from Amazon. Is this normal or am I connecting these extension tubes wrong?

Asked by kabir

Answer

These extension tubes do NOT have any electrical contacts to send lens information to your camera, therefore, the camera assumes there is no lens attached and shows f00. These extension tubes just increase the distance between your camera sensor and the lens which enables you to focus closer and achieve greater magnification. Needless to say, you lose any control over your lens while using these extension tubes the same way you do in reverse-lens macro technique.

However, there are some extension tubes available which has electrical contacts and allow you to communicate with your lens while being used i.e change aperture, auto-focus but they are way more expensive.

Ideally, you should set the aperture prior to detaching the lens off the body (by pressing and holding the DOF preview button while taking the lens off) and mount the extension tubes in between. Lack of AF shouldn't bother you much as the DOF is too shallow, you'd have to focus manually in most of the case.

Answered by ShutterBug

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How important is auto focus and aperture control in a macro setup?

Question

I'm thinking of starting some amateur macro photography, and I'm not sure I want to go with macro lenses, due to their price.

I currently have the following lenses:

• Canon EF 50mm f/1.8 II
• Canon EF 24-85mm f/3.5-4.5 USM

And I was thinking of buying either:

• Macro Extension Tube
• Reverse Adapter

My questions are:

1. What is the difference between the tube and the reverse-ring if I want to use one of my lenses for macro?
2. How important is auto-focus in macro-photography?
3. How important is the ability to change the aperture macro-photography?

Answer

The answer to your first question is answered here. Both are good low-cost ways to get started in macro photography.

Autofocus is not very effective as you near 1:1 magnification. Most AF systems will struggle to find focus, you have such a narrow DOF anyway that holding focus is very hard. With anything that is not moving, you are far better to set up a tripod and use live view to focus, if you have it. Or manually focus, then move the camera to and fro to get the subject in focus.

If you have a macro lens, you may not use it at 1:1 as often as you think, in which case AF can be very handy. I use it when shooting bees - it's very hit and miss, but for me slightly more successful than manual focus.

If you use extension tubes or reversal ring, you will be forced to be a certain range of distance from your subject (you can no longer focus over a wide range of distances), so AF is not really useful at all.

Aperture is important. You have a very narrow DOF, so you will often want to stop down in order to get as much DOF as possible. Or if you are shooting hand-held you may need a wide open aperture to avoid blur. If you reverse a lens, or have manual extension tubes and aren't able to control aperture, it's not a killer blow, but it isn't ideal.

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How can I calculate what the effect of an extension tube will be?

Question

There must be a mathematical description of the difference that an extension tube makes to a lens -- is it something that can be easily described?

(For example, with teleconverters you can say things like "a 2x teleconverter will turn a Y-mm lens into a 2Y-mm lens, and will lose you 2 stops." Is there something similar for extension tubes?)

If there's nothing much you can say about magnification, in general, what about the change in closest focal distance? Is that also lens-dependent?

What about if we factor out the lens: is there any general way to compare the effects of (say) a 12mm and a 24mm extension tube on the same lens?

Answer

I do believe there are some formulas you can use. To Matt Grum's point, I have not tested these with zoom lenses, and to my current knowledge, they apply only to prime (fixed focal length) lenses. You did not specifically specify zoom lenses, so...

The simplest way to calculate the magnification of a lens is via the following formula:

  Magnification = TotalExtension / FocalLength
  M = TE / F

To calculate the magnification with an extension tube, you need to know the total extension...that is, the extension provided by the lens itself, as well as that provided by the extension tube. Most lens statistics these days include the intrinsic magnification. If we take Canon's 50mm f/1.8 lens, the intrinsic magnification is 0.15x. We can solve for the lenses built in extension like so:

   0.15 = TE / 50
   TE = 50 * 0.15
   TE = 7.5mm

The magnification with additional extension can now be computed as follows:

  Magnification = (IntrinsicExtension + TubeExtension) / FocalLength
  M = IE + TE / F

If we assume 25mm of additional extension via an extension tube:

  M = 7.5mm + 25mm / 50mm
  M = 32.5mm / 50mm
  M = 0.65x

A fairly simple formula that allows us to calculate magnification fairly easily, assuming you know the intrinsic magnification of the lens (or its intrinsic extension.) If we assume the wonderful 50mm lens is the lens you are extending, to create a 1:1 macro magnification, you would need 50mm worth of extension. The problem here is that if you add too much extension, the plane of the world that is in focus (the virtual image) might just end up inside the lens itself. Additionally, this assumes a "simple" lens, one with very well-defined and well-known characteristics (i.e. a simple single-element lens.)

In a real-world scenario, having a clear understanding of any particular lenses characteristics is unlikely. With lenses that focus internally, or zoom lenses, the simple formula above is insufficient to allow you to calculate exactly what your minimum focusing distance and magnification can be for any given lens, focal length, and extension. There are too many variables, most of which are likely to be unknown, to calculate a meaningful value.

Here are some resources that I have found that provide some useful information that might help in your endeavor:

• Lens Tutorial
  • Some great mathematics for lenses, including MFD and Mag
• Lens Calculator
  • A javascript based lens calculator that can calculate a wide variety of values for you
  • Not really sure how accurate it is in the case of internally focusing
• Wikipedia: Magnification
• Forum Post about Extension, Magnification, MFD
  • Limited applicability, assumes too much
• Forum post about Extension and MDF
  • Limited applicability, assumes too much

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Which suits better for hobby usage: extension tubes vs. close-up filter?

Question

I am looking to do a little macro work, but am not ready to invest in a macro lens. For hobby work like photographing flowers and such would it be better to invest in a set of extension tubes or in a good close up filter? I would like to utilize my Canon 40D with either the 24-70mm f/2.8L or the 50mm f/1.2L lens I already own.

Answer

I've used extension tubes in the past, with success, but what I did find was that you'll have to manual focus because the AF sensor gets really crazy with tubes. For most macro work you'll want to focus manually anyway, so use your camera's live view.

I would stay away from close up filters. They're bulky and the quality is very poor.

In general, if you don't already own a portrait lens, a macro lens with a short focal length (say, the EF-s 60 or EF 100 macro lenses) can double portrait lenses.

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Are there any downsides to buying a third party extension tubes for Canon?

Question

I would like to get a little higher magnification out of my Canon 100mm Macro, so I am looking at extension tubes.

I know Canon makes the EF25, but it seems pretty expensive considering there isn't even glass involved. I saw a "Kenko" extension tube set that is only a little more expensive for a 12, 20, and 36mm. Are there any downsides to buying a third party extension tube?

Answer

As far as I know there should be no real difference. The extension tube have no lens elements but is merely (as the name suggests) a tube. The Kenko extension tubes feature the same electrical connections as the Canon one (judging from reviews and images on the net). According to this review, there are two versions of the Kenko tubes; an older one that is not compatible with EF-S lenses, and a newer one that is. Worth keeping in mind if you have such lenses.

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Can I use macro extension tubes with telephoto lenses?

Question

What I really want is an extension tube for my telephoto lens. (70-200mm Canon) I have an opportunity to purchase a number of macro tubes. Will those also work with the telephoto lens?

Answer

Yup, they'll work - tubes should work* with any lens, even a reversed one for extreme macro.

But the magnification is relative to the focal length - so adding 50mm of extension tubes to 200mm doesn't get you super close, show stopping macro shots. Using it at the 70mm end will produce higher magnification shots (although probably not 1:1), but less working distance.

Also, check out How can I estimate the reproduction ratio of an unknown macro setup? and How can I calculate the change an extension tube makes to the maximum magnfication of a lens?

*_{Obviously if they don't have electrical contacts you'll lose a lot of auto stuff, but that's not relevant to the focal length issue.}

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What macro extensions tubes are compatible with Nikon AF-S?

Question

I am looking for a set of macro extension tubes for a Nikon D40 that will work with the AF-S system (i.e. will send all the relevant stuff between lens and body for full auto operation).

I have found lots of extension tubes online, but they tend not to have much detail associated with them and I can't find any that are compatible with the AF-S set up.

Answer

Any tubes that say that they have the electrical contacts should work with the AF-S system. I have the Zeikos Extension tubes. They work great, fit well, work with AF-S lenses, and transmit all the various information. I have no particular issues with them at all.

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Macro photography with an ultra-wide lens and extension tubes?

Question

While reading some reviews of Canon EF-S 10-22mm f/3.5-4.5 USM, I was a bit surprised to notice that the lens is supposed to be compatible with 12mm and 25mm extension tubes, and with those one should be able to get maximum magnifications better than 1:1.

An ultra-wide lens for macro work sounds like a fun alternative, but does it really work in practice at all?

Have people had any success with taking macro shots using ultra-wides and extension tubes? Do you have any working distance at all between the lens and your subject? What about lighting the subject, does it become near-impossible with the lens shadowing everything?

Answer

Here's Estonian reverse of 1 euro-cent shot with my widest lens, Zenitar 16, at f/11 on 19mm extension tubes, giving 1.18x magnification:

Not much room for lighting indeed, sidelight or glow-through with a translucent subject seem to be the only options:

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What am I losing when using extension tubes instead of a macro lens?

Question

After playing around with macro photography on-the-cheap (read: reversed lens, rev. lens mounted on a straight lens, passive extension tubes), I would like to get further with this. The problems with the techniques I used is that focus is manual and aperture control is problematic at best. This limited my setup to still subjects (read: dead insects) Now, as spring is approaching, I want to be able to shoot live insects. I believe that for this, autofocus and settable aperture will be of great help.

So, one obvious but expensive option is a macro lens (say, EF 100mm Macro) However, I am not really interested in yet another prime lens. An alternative is the electrical extension tubes.

Except for maximum focusing distance, what am I losing when using tubes (coupled with a fine lens, say EF70-200/2.8) instead of a macro lens?

Answer

as others have noted you lose light but with extension tubes you gain versatility that is sometimes not available with a EF 100.

I have a EF70-200/2.8 that I use with extension tubes (kenko 12mm, 20mm, 36mm) especially for taking photos of insects. the Minimum Working Distance from the front of the lens to the subject with the lens zoomed to 200mm:

58cm with 12mm extension tube
72cm with 20mm extension tube
86cm with 36mm extension tube

setting the lens to the 70mm position brings your MWD numbers down to the 30cm range

I have the EF 100 macro that I prefer using whenever its expedient but very often the bugs get nervous and skitter away when I get close enough to fill the frame with them. So I use the 70-200 with extension tubes so I can position the lens a couple feet from them and still get very sharp pictures of the bug.

I prefer to not use a flash to take pictures of bugs for a number of reasons consequently another problem with the EF 100 is that when I come in close I often end up blocking the light source or casting a shadow over the subject that changes the dynamic of the picture. By using the extension tubes and the EF 70-200 I can take advantage of a natural light source.

When I do use a flash I use a Canon MR-14EX Macro Ring Lite (I tried a lot of other options and finally bit the bullet) mounted on the EF 100.

as a side note, while purists will sniff disdain, I do stage shots with live bugs - usually what I do is capture several of them the day before and store then in Tupperware in the refrigerator overnight then bring them to the scene I want for a backdrop in a cooler. The cold doesn't kill them but it does slow them down quite a bit so you can stage the shot. Also butterflys are suckers for hummingbird feeder juice made with vodka - they drink some of it then they perch somewhere nearby and move their wings very slowly and don't seem to mind if you get real close to them. Of course if they drink too much and fall over on their side its not a pretty picture.

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