Macro Photography With Extension Tubes

Macro photography has always been a popular aspect of aquarium photography. Be it just for a few simple close-up shots reefers shoot to share their new acquisitions, or for better shots taken for POTM contests, to better see detail not depicted by looking at a coral or fish, or simply to post a picture of a coral for selling online....

As with most things in photography (just like reefing) quality photography equipment can get very pricey. Unfortunately, most of the time cutting corners on a lens or a camera body will have very evident effects on image quality or ease of use. Luckily for macro photography, the “poor man macro” techniques, can result in even better results than what the expensive macro lenses are capable of alone. Combining those techniques with quality macro lenses can lead to even better results, but at higher prices as expected.

The purpose of this article is to showcase the value of extension tubes, the way to use them, the limitations that come with them and best practices to improve the quality of the shots. We will avoid complex physics in the optics and stick with the visual results that are easier to grasp, while keeping it focused on specific aquarium-related issues and challenges.

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What are Extension tubes

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Extension tubes are simply hollow tubes with no glass inside that go between camera and lens thus increasing the distance in between; this results of this addition is what we’ll discuss in this article:

Decreased minimum focusing distance
Decreased DOF
Increased magnification

Min Focusing distance

Every lens has a minimum focusing distance or a distance to the object closer than which the lens cannot lock focus. The closer we are to an object the more magnification we will achieve but this is limited by the inherent min focus distance of each lens.

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17-50 2.8 Tamron lens can focus very close to the subject leading to nicer closeup images.

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50mm Nikon lens can only focus from farther distance which doesn't help with closeup/macro photography.

Depth of field (DOF)

We had discussed depth of field in a previous article, which also helps with many of the basics of photography.
https://www.reef2reef.com/threads/your-guide-to-aquarium-photography-1-getting-the-basics.310349/

In short DOF if the amount of the object that is in focus in a shot. 3 main factors affect DOF.
most aknowledged one is Aperture where the larger the aperture (smalller aperture number) the less DOF picture has.

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Aperture 1.4 Focus on 20 notice the limited DOF (very small area of the image looking clear)

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Aperture 1.4 Focus on 20

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Aperture 8 Focus on 20

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Aperture 11 Focus on 20 notice the increase in DOF (more of the image looks clear)

Focal length of a lens measured in mm, which is a characteristic of any lens, has a minor effect on DOF where the higher the focal length the less DOF we get in our pictures.

Distance to object also affects DOF, where the closer we are to the object the less DOF we get. we will see this effect to a much greater extent when using extension tubes as we will see below in this article.

Magnification

The main effect or measure for magnification called Magnification ratio which is ratio of object live size to the size of its picture on camera sensor, anything equal or above 1:1 is considered a true macro.
Much higher magnification ratios can be achieved using extension tubes, bellows and/or reversing rings… focus in this article will be extension tubes, we wont dwell into the physics of calculating magnification ratios and for those interested many online calculators are there where you key in your lense focal distance, inherent magnification ratio, length of tubes added, imaging distance to get the magnification ratios. As extension tubes will limit the working distance to around 15 cm and down to 2-3 cm only when they are stacked this has a major effect on magnification ratios when using a 50mm lense for example.

Extension tubes

Many versions of those exist but the main difference is the following:
-Some have electronic contacts that will allow for automatic focusing.

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-different lengths they come in different lengths but 12-20 and 36mm are quite popular
They can also be stacked up for even more reach.

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The longer the tube or total of tubes stacked the more magnification we get but this comes at the following expense:
limited minimum focusing distance so we basically have to be closer to the object to the point of nearly touching it.

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50mm with 12 mm extension tube focusing range 6-8 inches

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50 mm with 20 mm extension tube focusing range 4-5.5 inches

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50 mm with 32 mm extension tube focusing distance 3.5 inches

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50 mm with 36 mm extension tube focusing distance 3 inches

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50 mm with 48 mm extension tube focusing distance 2.5 inches

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50 mm with 56 mm extension tube focusing distance 2.5 inches

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50 mm with 68 mm extension tube focusing distance 1.5 inches

Limited DOF

DOF at the same aperture will be less with extension tubes or more tube stacked. Heres the DOF difference at same aperture taken with 50mm 1.4 at aperture of 8 without and with different tubes.

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50 mm

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50mm with 12mm extension tube

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50mm with 20mm extension tube

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50mm with 36mm extension tube

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50mm with 32mm extension tube

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50mm with 48mm extension tube

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50mm with 56mm extension tube

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50mm with 68mm extension tube


So to relate those effects to the use of extension tubes for aquarium photography here are the pros and cons:

Increased magnification is the main advantage as that’s the purpose we’re after but this entails consequences we will discuss later on in the article.

Decreased focusing distance, can be good for top down shots where we have limited distance between lens and frag in shallow frag tanks, for example, but is no good for corals farther away from around 8 inches from the glass as beyond that it’s a total blur.

Decreased DOF can be good to a certain extent to isolate the background but here we are talking about hairline thin DOF which is on the edge of what we want.

Good focusing technique is a must and perfectly nailing the focus is key.

We can also use a smaller aperture (bigger aperture number) to gain DOF but there are limitations against that in aquarium use as that will require more light = which we usually don’t have in tanks and use of flash can result in color getting washed out. Very small apertures can also cause diffraction to appear in the pictures which can also be a limiting factor.

Keys for success:

With the increase in magnification other factors are also magnified and more evident in our pictures, so, here’s a quick list of those with suggestions on how to get better results.

Motion:

With the increase in image size, any camera motion or object motion will be much more visible on the images especially when viewed at 100 percent magnification which is where we want to look at a macro image and especially if pictures are for the purpose of printing.

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Macro image viewed at small size, focus point is on marked polyp. Image doesn't show any motion blur.

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Same picture as above blown to 100%. It shows decreased sharpness due to motion.

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Same picture taken using a tripod for better stability.

A few ways around this in aquarium photography would be to turn off flow in the tank, make sure your camera is on a sturdy tripod, or supported against glass at least, turning on all lights at max to be able to use the fastest shutter speed possible. Taking it to the extreme level would be using either a cable shutter release or a wireless one which prevents camera shake while pressing the shutter. You can also use the delay timer if you don’t have a remote switch. Some cameras offer a mirror-up option where the mirror is locked up, and then when you release your shutter by shutter-button press or remote release the mirror only shuts down instead of opening and closing which is said to minimize shake due to mirror motion by 50% as minute as that may sound. Extreme macro does call for extreme measures for best possible quality.

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Noise:

As with motion, noise size is also magnified and noise is more visible on extreme macro shots. A few ways around this is to ensure your shot is properly exposed, shots over exposed by 1-2 stops and adjusted in post processing are better than underexposed shots which are enhanced while processing as increasing exposure leads to noise appearing in the shadows. Other ways around this is using Full Frame cameras vs cropped-sensor cameras as the larger sensors allows for less noise appearing in the images. Newer cameras also offer better noise at high ISO performance, and this is crucial as most of the time we need to bump the ISO to get fast enough shutter speeds as aquarium lighting is limited and use of flash with extreme macro isn’t easy due to proximity of lens to the object especially as we’re shooting from behind the glass so we have limited space to maneuver a flash and properly diffuse it.


Focusing:

Some extension tubes allow for auto focusing as they have electronic pins (make sure to buy ones made for your camera brand even if third party) Kenko is a very popular brand, and I’ve been using my set extensively for the last 10 years. Still auto focusing is of limited value in extreme macro as most cameras won’t be able to lock focus with the magnification levels and the proximity to the object. Manual focusing becomes the alternative and knowing how to manually focus is key. Another way is to invest in a macro focusing rail which attaches to your tripod and holds your camera, then the rail can move front or back (some offer side movement as well) in minute increments in rotating a focusing wheel. This will allow you good control over your focus and will allow you to point your focus point to a specific polyp or branch. For advanced users, doing auto focus stack where multiple shots are taken with shifting your focus, macro rail is a much needed tool.

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Camera/lens choice for Macro.

Any DSLR with a good lens and using extension tubes is capable of decent quality extreme macros if above discussed aspects are respected, yet better cameras and lenses will have many advantages which will affect your results.

If you shoot macros frequently you need to consider the following before choosing a camera, DSLR mostly came with cropped sensors, recently vendors went back to producing full-frame sensors (still producing cropped as well). I won’t dwell much into sensor sizes and physics behind it but to quickly describe it, cropped sensor cameras will squeeze the same number of pixels (if comparing similar Megapixel cameras) over a smaller space which has the benefit of increasing magnification where a lens of for example 50mm on a Nikon cropped sensor (DX for Nikon) will act like a 75mm lens. Unfortunately this also leads to a bit more noise in the image which can be a deterring factor for aquarium macro photography especially as light is limited.

Another factor is auto focusing where full-frame cameras are mostly considered a higher level and come with better auto focusing than their cropped sensor equivalents.

Low-noise, High-Iso performance again is a plus for full frame cameras which is also key in macro.
Another aspect to consider is that full-frame cameras tend to be provide higher-end images so any imperfection in the lens will be more visible on the final image. Therefore, using full-frame camera bodies will necessitate you invest in higher quality full-frame lenses which can be very costly. Full-frame cameras, will accept cropped lenses but you will get a vignette (black circle around the lens where sensor is larger) this can be digitally cut by the camera or in post processing but then the added megapixel advantage is lost and being that most full-frame lenses are sharper than their counterparts made for cropped sensors, basically we are at a dual loss here.

Another aspect for lenses is the quality of the lens, and here we look at 2 areas, fixed lenses or zoom lenses with a fixed 1.4-2-2.8 minimum apertures which are considered pro lenses versus ones where minimal aperture changes as you zoom and goes from 3.5 to 5.6. considering that a lens is mostly sharp around 2-3 stops above minimum aperture a 1.4 lens for example is very sharp at 2.8 and allowing much more light than lenses with a minimum aperture of 5.6 where you have to use f8 to get to the sharpest point (also called sweet point) and which means much darker images where you have to compensate by bumping the ISO which also causes much more noise.

One other aspect to consider about lens choice is whether to choose a zoom lens vs prime lens. Zoom lenses as the name says can zoom from a wide to a more focused focal distance for example 24-70 or 70-300. They might still be considered pro glass especially when they have a fixed 2.8 aperture at all zoom levels but they typically tend to be softer that prime lenses or lenses that are fixed for specific focal distance. Prime lenses are typically made from less glass elements compared to zooms and are typically made from better glass which makes them much sharper at same focal length and even wide-open apertures. Utilizing prime lenses when you can will give much better image quality. Utilizing a macro lens with tubes would even be better as the lens is designed for magnification and smooth backgrounds. Some quality lenses like the 50mm 1.8 or maybe going for Tamron or Sigma lenses which are made for Nikon or Canon mounts might save you a lot of money and guarantee very good image quality.

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24-120 f4 AT f7.1 50mm

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50 mm 1.4 at f7.1 Notice the sharper overall look of prime-lens shots VS zoom lens


Hope this article was helpful in better understanding macro photography and a booster to try different techniques to achieve even greater magnifications and image quality.
About author
maroun.c
Maroun is a hard core reefer from lebanon since 2000. In a country with (until recently) limited quality livestock and hardware, he was lucky to be a frequent traveller which allowed him to gather an impressive coral collection over the years and to connect with many reefers and reefkeeping masters. He has kept different tanks throughout the years 23g, 80g, 150g and currently runs a 400g tank linked to an 800g total system with multiple frag tanks and sump in basement. Maroun has contributed to the hobby by starting forums in the middle east and as part of the moderating team on R2R. He connected with many reefers and helped them start up and run their tanks. His strongest areas of knowledge are in system design and setup as well as in his other passion: photography and aquarium photography. His build threads speak about his dedication even when facing multiple ups and downs and running an elaborate setup while being located in a different country...a new challenge and a true test of the robustness of his setup and his remote coaching skills to his wife who has been caring successfully for the tank over the last 9 months.

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Beautiful Thread
looks awesome! Very healthy. Nice work !

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