Advanced' Photography Tutorials

Due to the length of this tutorial I've divided it into two parts. This part will cover how I'm going to compare the different options, and cover off a couple of basic ones: Close up lenses, and the macro function on a budget point and shoot camera. The second part will cover Extension tubes and Lens Reversal, and it'll conclude with a mini glossary.

I have a bit of a gear problem. If I find out about a "home-brew" solution for something photography related I feel I have to give it a go. Often I don't get around to it, sometimes I do. Couple this gear problem that I have with a bit of passion for macro photography, and I've ended up owning most of the cheap solutions to macro photography. So this puts me in a good position to compare all these cheap solutions, and share my findings with my Worth friends. As the title suggests, this tutorial is going to focus on macro options for SLR users - for those who have cameras with interchangeable lenses. You know who you are.

Some of these options can be used with cameras with fixed lenses, which I call "point and shoots", but I'm not going to go into that.

My "macro" gear:

I took a range of images using all of this gear.
1) A cheap set of extension tubes (Canon mount)
2) A couple of cheap manual lenses purchased with the main purpose of using with the extension tubes:
- a Suntar 135mm f/2.8 (closest focusing distance 1.5m, M42 mount)
- a Ricoh 50mm f/2 (closest focusing distance 0.6m)
I have an M42-Canon adapter for the Suntar lens
The Ricoh lens had an incompatible mount for my camera, so I used the smallest ring from the extension tube set to make a home brew mount for it. More on this later.
3) A spare body cap modified to make a lens reversal mount by combining with a 52mm UV filter (glass removed). See this tutorial at diyphotography.net
4) A set of three close up lenses. (1,2 and 4 diopter, fit a 55mm filter thread)
5) A cheap, mediocre point and shoot digital camera - Olympus mju 760. This has a "super macro" mode which acts as a good comparison.

At the top is my 400D with the Canon 50mm f/1.8 fitted, and to the right are my two standard zoom lenses, the 17-85mm IS f/4-5.6, and the 75-300mm f/4-5.6. When combined with the extension tubes, these can be used for macro too!

Back in October of last year I set about taking loads of photos with all of these different macro options, taking care with my set-up so that my subject could nicely demonstrate the range, choosing lighting that was consistent throughout and would work with the really close shots as well as wider shots. (See my post below if you're interested in how I went about doing all this. I didn't want to waffle on too long!)

150 photos later, I had all my shots. That's right, 150 - I kid you not. I thought that was the hard bit done. Ha ha ha, silly me. I then quickly realized that the real challenge lay in how to present all of the information I'd collected in such a way that would:
- provide a nice comparison of these methods
- not involve posting 150 photos of the same subject (yawn)
- not confuse all but the most tech literate geeks - a boring spreadsheet anyone?

I created a few images like this:

17-85mm zoom lens @ 85mm f/5.6, minimum focusing distance.

Ah, yes lovely. But viewing a lot of those would get old very quickly, not to mention take ages to load the page and take a long time to look at, and aren't actually that easy to compare. Need I go on? No? I didn't think so.
So I've done my best to devise a visual way of demonstrating a particular set-up. Most photographers are visual people right? I've also tried to make it so my little diagrams give a good comparison to the "ideal", without actually having to compare images directly.

But don't fret if you prefer numbers, because I've included some of those too, but hopefully not too much to confuse people.

If you get confused by any of the terms I've used, I've included a mini glossary at the end. I'll add to this if necessary, based on feedback.

So first up, I'll point out what I consider to be important factors for an "ideal" macro system, hopefully you'll agree:
- good "magnification". I've expressed this as a ratio of the size of the image on the camera's sensor to the size of the subject. Typically magnification of 1:1 is considered good. This would mean a 15mm wide subject would produce a 15mm wide image on the sensor. As this is the width of an APS-c sensor it'll fill the frame on the short side.
- a flexible working distance or field of view so you can have your subject fill the frame, or only fill part of the frame, depending on what you want. This gives you the flexibility to frame your subject how you choose and get the composition that you want.
- having flexibility with depth of field, so you can have shallow DoF or lots of DoF. With very close macro work getting enough depth of field becomes difficult.

You can skip over this bit if you like. Scroll down to the first diagram, and if it all makes perfect sense to you, you may not need to read my explanation. You should probably read the first paragraph though.

At the top right is a little diagram that shows how much a 15mm diameter subject will fill the frame. If you're limited to only one focusing distance and field of view, this will be represented as an empty circle. In the example below, the lens will focus at any distance beyond the minimum focusing distance. So you can make a 15mm diameter object appear as large in the frame as shown, or smaller, but no larger. You can focus on the subject from several meters away and make it appear as a tiny dot in the frame - if you want. Just below that diagram I've stated the magnification, which I explained earlier. This is expressed as a ratio of image size to object size.

The ruler in the middle shows the "focusing distance". This is measured as the distance between the subject and the sensor plane on my camera. Not to the front of the lens. The sensor plane on my camera is represent by this little symbol on the top:

And all along you thought that was a guerrilla marketing tactic for the London Underground ;-) - sorry to burst your bubble. It just shows you where the sensor sits.

Back to my diagram.
Any point on the red line is a distance from which you can take a photo with this set up. In a couple of cases there is only one focusing distance, I've used this symbol here:

I've also used this when the line is so short that it might be hard to spot. Ignore the thickness (height) of the line, it's the length that matters. In some cases I've made it thicker to make it easier to see (when it's really short).

Finally at the bottom of the diagram is a couple of images, full frame shots that have been resized to fit. In between these I've noted what the Depth of Field is. I've calculated these numbers, they're probably not 100% accurate, but they shouldn't be too far off. The numbers are there for the "numbers people" (like me), and the pictures are there for everyone. Because we all like pictures. :-)

So here's my diagram to display, in this example, what my 17-85mm "standard" zoom is capable of. This is the same setup as used for the above example picture.

Example "real world" shot

So this is fairly representative of a standard kit lens. The 18-55mm kit lens has similar macro capability. I'm guessing kit lenses for other cameras will be in the same ballpark.

The magnification is 1:4.5, so the image on the sensor is 4.5 times smaller than the actual subject (at least the part of the subject that is at the point of focus).

You might have noticed that the red line in this example starts just after the 30cm mark. This lens actually states "Macro 0.35m" on the side. And all those clued up on metric measurements will know that that's the same as 35cm, but when I took my sample shot my camera beeped it's "focus confirm" beep at 30.5cm. Maybe that's why the sample shot is a bit soft?

So now here's a diagram of what an "ideal" would look like using my system for comparison. For this I've use the Canon 100mm macro lens described here at www.kenrockwell.com as my "ideal". You may not agree that this is the ideal macro lens, but that's not really important. What's important is to show just how well these cheap options stack up against gear that's designed for the purpose.

Sorry, no sample pictures. I don't own this lens.
Yet. ;-)

As you can see the circle fills the frame from top to bottom. This is a true 1:1 macro lens. Again you can focus on any object beyond that minimum focusing distance, so the circle is completely blacked in. Therefore you can fill your frame with a 15mm diameter subject, or half fill the frame, or make it a tiny dot, all without changing the lens. But you may have to move, of course.

Now on to the nitty gritty.

As I mentioned earlier these are often called Close Up Filters. They screw into the filter thread of your camera lens, but they are actually lenses, much like a magnifying glass. But I?ll call them filters from now on, because otherwise it might get confusing. They come with different "diopter" ratings and different filter diameters. I have a set of three that fit a 55mm filter diameter. They are 1,2 and 4 diopter. Close up filters are available in higher diopter values than this. They allow you to focus much closer to your subject than normal, so you get better magnification. The larger the diopter number the closer you can focus.

I use a 52-55 step-up ring and use my set of CU filters on my 50mm Canon lens, as it has a 52mm filter thread. They can be fitted to both of my manual lenses too. I'll talk about that later.

Any bit of glass that you put in front of your lens will degrade the optical quality, and these are no exception. Expect more quality degradation with higher diopter lenses, and quality varies between manufacturers. You can stack these on top of each other, but quality gets markedly worse the more of them you stack together.

So lets see how they stack up (groan):

1 Diopter Close Up Lens:

You may also notice that I've split the sample image on the left in half - I've displayed both the wide aperture/low depth of field shot and the narrow aperture/high depth of field shot together to give you a visual of what the depth of field range is. I hope this isn't too confusing, as I've done it for most of the remaining diagrams.

So with a max magnification of 1:5 this set up doesn't get you as much magnification as the kit lens. Also there's a little white hole in the middle of that circle, and the red "focusing distance" line is of limited length. That's because putting any close up filter onto your lens will prevent you from focusing to infinity. And as you'll soon see, pretty much all of these cheap macro options do the same thing, each to a different extent.

So does this make the 1 diopter close up filter completely useless to me? No it doesn't, and for a couple of reasons. First up it's actually sharper. Cheap as the 50mm lens it's fitted to may be, it's still a prime lens, and at this range it's sharper than my zoom, even with that extra bit of glass in front of it. Even wide open. The other benefit is the 50mm lens has an aperture of f/1.8 so I can have a nice low DoF if I want it, and isolate my subject from the background.

The number 4 close up filter is of more use, giving significantly superior magnification to the kit lens, of about 1:3

Now I haven't bothered to show you the diagram for my close up filter #2 to save a bit of space. It gives an intermediate between the 1&4 diopter options, but as these two practically overlap, I didn't think it was necessary. Here's a little diagram of how the focusing distances compare on this set of close up filters.

This is a pretty cheap macro option, as most of us SLR owners also have a cheap point and shoot these days, just because of their convenience. It's also nice to have a comparison of their capabilities compared to going to the significant trouble of getting good macro results on your SLR.

So, based on the magnification I've stated here it looks the same as my "kit lens". This is not the real magnification though, just an equivalent with regards to how much of the frame it fills. Because the sensor on the camera is only 6.16mm wide compared to 22.2mm for an APS-c sensor, the actual magnification in only 1:6.7

Do you notice something odd about this image compared to the others? I know I do. The image is fairly distorted, and that's because this camera's macro setting works best at the wide angle end of the zoom range. The minimum focusing distance is only 81mm, which is really close. I measured this from the middle of the tripod mount, figuring this was close to the sensor plane. The front of the lens extends 30mm beyond this, meaning the face of the lens is 50mm from the subject. Anyway, the subject's really close, and the field of view is quite wide, so you get that weird perspective distortion. You might find this desirable in some shots, but most of the time it'll just look odd.

Continue to part two