It’s been a while since I’ve done a GoA thread but I’ve been meaning to get around to a Macro one for some while. With the weather a bit changeable and being in a geeky mood, I thought it was about time to put pen to paper.
For those unaware, there is a bit of a series of these GoA threads, covering many aspects of photography – there’s a link to the index in the footer to make finding them easier. I use Canon terms occasionally as that’s what I’m familiar with, but the principles apply across any make & model.
OK, so, what do we actually mean when we say “Macro”? Technically, a Macro lens is one that is capable of throwing an image onto a sensor at life-size (known as 1:1) or larger. That means a picture of a 10mm bug would occupy 10mm of real estate on the sensor in your camera. The term (as is often the case) has been abused by manufacturers to sell more lenses – whacking the word “Macro” on a kit lens doesn’t make it a true macro, though it may be better than some at taking pictures reasonably close up. In truth, it doesn’t really matter as long as you know exactly what you’re using, regardless of any labels – even with a proper macro lens, you’re not often taking images at the minimum focus distance, so for this thread, I’ll simply define “Macro” as any shot where you’re getting up close and personal with your subject and assume you’re after detailed pics of bugs, flowers and the like. If you are interested in such subjects, a proper macro lens is a worthwhile investment however; they’re generally f/2.8 prime lenses with a flat focus plane (ie more likely to be in focus across the whole image). They’re also sharp – very sharp. I don’t think anyone makes a macro lens that isn’t sharp (it’s the whole point of them).
Whilst you can get a variety of focal lengths, something around 100mm is the most popular length. Shorter lenses are ok for product photography, but of limited use with bugs (you need to get close to the subject who have an irritating tendency to then fly away!). Longer ones (180mm seems to be the longest) are a bit heavy and cumbersome unless you’re used to using them, though they do allow you to hang back a bit and still get those close-up images. The large objective lens does make it difficult to get ancillary lights on the front too, so stick with something simpler until you’re familiar with the potential issues. This picture shows a Canon 80D with 100mm f/2.8L IS macro (bottom) and a 5D4 with Sigma 180mm f/2.8 macro (top) for comparison.
There are also some extremely specialised Macro lenses – Canon’s MP-E 65mm beast is probably best known. That allows images up to 5x lifesize (ie a 5mm bug would take up 25mm of sensor space!). I won’t be talking about anything quite so exotic though (not least because I don’t own one), I’ll stick to hardware that’s a bit more everyday. Most of the stuff I’ll demonstrate will be using the 80D/100mm combination (just because I don’t get to use it very often, it being Mrs WJ’s setup really). If you REALLY want to get up close to your subject matter, you could try some tubes. These simply attach between your camera and lens, moving the lens away from the body, giving you the ability to get closer (more magnification) at the expense of infinity focus. You may also lose AF completely (or it will be slow) and you’ll lose light – nearly 3 stops in this setup, where I have stacked all three sizes (12mm, 20mm, 36mm) together (which is also why there’s a ring light on the front of the lens). Note, if you’ve forgotten what a Stop is, see the earlier GoA thread
These two pictures were both at minimum focus, first with no tubes, then with all of them, to show how much closer you can get. You really are getting to the point where you need a solid tripod now though, my hand-held effort’s pretty poor!
Finally, as a novel way to get close on a budget, try a reversing ring. This nifty gadget is simply a double ended filter ring – it allows you to reverse a second lens on the front of your normal one. It allows for some fun playing around, but isn’t particularly practical for regular use. If we get snowed in at some stage this winter, I’ll think about doing a demo to add to this thread!
Part 2 coming up.....
A question was asked elsewhere (on the R5 thread) about using an extender on the macro lens to get the subject larger in the frame, so I've had a little experiment. The Canon 1.4x extender won't fit directly on to the Canon 100mm f/2.8 lens as the extender has a pokey out bit (technical term) preventing it. However, you can add a small tube to the extender to allow it to be used, so I gave it a try. I also have a Sigma 1.4x extender (I normally use it with the Sigma 180mm f/2.8 macro) which doesn't have such a large pokey out bit, so I tried that too. This pic shows the two extenders so you can see the difference
I used my little wooden mouse subject for all these pics, all at minimum focus. The lens was wide open (f/2.8), but it was interesting to note that the pictures' exifs did not report the aperture OR the focal length correctly. All these images show 100mm f/2.8, when they should have been 140mm f/4 (you lose a stop of light when you gain the focal length by adding an extender). AF worked each time, so communication was established between camera and lens, I can only assume that bolting bits together that are not normal interrupts the regular reporting between camera and lens. One other thing to note on AF. Well, two actually. AF through the viewfinder (I was using the Canon 5D4) didn't work very well - it kept hunting - so I used Liveview instead (which was fine). Infinity focus was lost however, when using the Canon extender + tube. This is not surprising as you always lose infinity when using tubes, but worth considering should you want to use this method. The Sigma 1.4x extender focussed to infinity OK (as expected). So, some pics. These are in pairs - an image showing each setup, together with a ruler to give an idea of the working distance, and the actual image taken. The images were all taken with AF (which locked each time) but the depth of field is very thin, so don't expect brilliant pictures!. What we're really interested in is the size difference of our subject
First, this is the basic camera + lens
The unit on the front of the lens is an LED ring light (in case you'd forgotten!). Working distance around 13.5cm
This is with the lens and the Sigma 1.4x extender
Working distance around 12cm
Now the Canon 1.4x + 12mm tube
Working distance around 11cm
Now, finally, the lens on its own but with a stack of tubes attached
Working distance about 8.5cm
So, what have we learned from all this? It does make sense if you think about it. Adding the Sigma extender gives you a bigger image, but your working distance shrinks by about the same amount as the extender thickness (which is 20mm). That's because the extender isn't reducing the minimum focus distance (which is measured to the camera sensor). So, a useful gain in subject size (or, put another way, you could hang back a bit to get the same size image). The Canon gives you a bigger image again, but that's because we have a tube as well as the extender. Putting a whole bunch of tubes in place gets you closer still - but none of this helps with trying to hold back in order to avoid scaring your subject.
So, for this pair of pictures, I used the lens + Sigma 1.4x and moved my subject away until the framing approximated that of the bare lens, to see how much further away I could get for the same image
Working distance around 15.5mm. So I gained about 3.5cm - nearly an inch & a half for all the messing around. Not sure if it's worth it!
Finally, I thought I'd put my other suggestion to the test - the 100-400 Mk2. This is a great bug lens, with a 3ft minimum focus, but it definitely gives you a smaller image
You do get a 63cm working distance though - far more useful for twitchy insects. If you add some tubes - this is the full set - your working distance falls to 31cm, but the subject size is actually not that far off that of the standard macro lens. OK, you're going to need extra light (I should probably have added flash on these two pics) and, as with any tubes, Liveview focus seems more reliable than through the viewfinder, but.....
Final word - these are all taken with the Canon 5D4, which is a full frame body. Remember that using a cropped sensor camera will help pull the image closer as well. The little mouse is about 22mm from the tip of his nose to his bottom (in case you were wondering!
Interesting. I must admit, I was surprised the difference of a converter was that low - a 20% improvement. It should have been closer to 40%, shouldn't it? I suppose there might be a bit of difference due to the length of converter/tubes reducing working distance, so perhaps at longer distances, it will approach the 40% as the length of the converter will have less of an impact at longer distances. My interest is piqued and I'll try a few experiments myself.
I think you're losing the EXIF info because you need the extender between the lens and the converter. If I attach a 1.4 converter to the 105mm macro and put the extension tube between the camera and converter it does recognise it as a 150mm focal length in EXIF data.
Anyway, I generally find it easier to use a converter than an extension tube as you don't lose infinity focusing and it doesn't hunt as much. Extension tubes are fine in the studio but can be a pain in the wild. Just my preference!