Tuesday, October 19, 2010

Macro Photography; Supplemental Post - Photography with Imre - Episodes 29 and 30

Macro photography can open up a whole new world that is often either overlooked or simply missed due to its small size. To start with, I'll quickly discuss the topics covered in episode 29 on the many ways one can accomplish close-up and macro work, and then I'll finish off with the techniques portion which relates to episode 30. And there's a dirty little secret I'll like to get off my chest too; keep reading.

Close-Up and Macro Definitions
The definition of macro photography seems somewhat illusive and unless I'm missing something or haven't poked around enough, I haven't yet found a single and universal one. But that said, most sources I have seen say that if the lens (or combination of lenses) is capable of projecting a one to one ratio or life size image on the focal plane (sensor or film) then you have a true macro lens and are able to take such photos. Some sources also include magnifications up to about 10 to 15 times, beyond which you enter the micro realm. Personally, I'm not that hung up on exactly where macro photography begins and ends, but if you asked my perspective on this, then I would say from life size to a magnification you can reasonably attain using regular lenses, without requiring specialized optics such as a microscope.

And as mentioned in part 1, close-up photography means the size of the subject that appears on the focal plane is smaller than it is in real life. Most point and shoot cameras and non-macro lenses are capable of close-up photography and not true macro. This is one of my pet peeves (though not a huge one) about how manufacturers use the label "macro mode" on many point and shoot models. *sigh*

Macro Lenses and Such
As you saw in part 1, there are numerous methods a photographer can employ in order to take macro (or really close-up) photos. Starting with the obvious (and keep in mind I'm sticking to the dSLR realm), you can get a lens labelled "macro". It doesn't get much easier than this as all one has to do is attach the lens and start shooting. Macro lenses usually come in two flavors, prime and zoom. In regard to quality, prime lenses generally have the edge but they also have a closer working distance that may make them less practical for certain types of subjects. Remember, the working distance is the span between the front of the lens and the subject. In general, the shorter the focal length the smaller the working distance. For shooting shifty subjects like bugs, zoom lenses can give you that additional space which helps snagging pics of creepy crawlies easier; not to mention safer if you want to get a shot of a hornets nest in action.

Moving on, close-up lenses, more commonly referred to as close-up filters as most simply screw onto the thread on the front of a lens, can be a quick and fairly inexpensive method to get some impressive magnification. In particular, these work best on lenses with longer focal lengths and the amount they magnify is determined by their diopter value (see Web Resources below for determining magnification); the greater the value, the higher the magnification, and in most cases close-up filters can be stacked. On the downside, image quality is not as good compared to dedicated macro lenses. Usually images suffer from some softness and progressively become blurry towards the edge of the photo.

Yet another method to increase magnification is to extend the focal length of a lens via extension tubes or bellows. As seen in the video, these are basically hollow tubes that move the lens further away from the focal plane and unlike close-up filters, these provide the greatest increase in magnification with shorter focal length lenses (around 50mm or less). Extension tubes are generally not that pricey (although I think they are considering they're nothing more than empty tubes) and if you stick to the brand that your camera is, many have electrical contacts going through them so auto-focusing amongst other features are retained. Bellows, due to their more complex construction, are usually a bit more expensive and somewhat more cumbersome to use; many also lack electrical contacts to the lens. On the other hand, their major advantage comes from the ability to adjust the distance of the lens from the focal plane. Both extension tubes and bellows may not allow most lenses to focus into the distance.

Teleconverters (aka extenders) are similar in construction to extension tubes, but these have lenses inside which increase the focal length of the lens attached to them by some value, most commonly 1.4X and 2X. Because of their construction, teleconverters can cost as much as some lenses (I think my 2X cost around $450), but on the upside the resulting image quality is quite good and you generally don't have issues focusing into the distance as with tubes or bellows. And if math is not your strong point, then figuring out the new focal length and magnification of the image is simple -multiply the value on the teleconverter with the focal length and there ya go! Like the example in my video, if I put my 2X teleconverter on a 300mm lens, then the effective focal length becomes 600mm (with twice the magnification of course). Other than cost, there are a couple of other cons here. For one, the increase in magnification isn't huge if that's what you're aiming for, and the quality of the converter counts. Although nothing to really complain about, I can notice some softening of the image with my 2X attached, along with a tiny increase in chromatic aberration.

Lastly in this section, we come to reversing a lens on the camera and putting a lens on backwards onto a regularly attached lens. Starting with the former, macro reversing rings allow you to attach a lens in reverse onto your camera. These rings have a bayonet style mount that fits on the camera and the other side is threaded so you can screw the front of the lens onto it; remember to be mindful of the thread size on your lens when selecting these. If you're curious, I purchased mine online from a company called Fotodiox; to be clear, although I'm happy with my purchases, I'm not affiliated with this company and it's up to you to choose the place you want to buy from. This technique works best with short focal length lenses and of course helps increase magnification beyond what the lens is normally capable of.

But as I mentioned in the video (part 1), if you want some impressive magnification you can attach a long focal length lens normally to your camera, and then use a filter to filter coupler to attach a short focal length lens in reverse onto the font of that lens (via the filter threads). This certainly makes for an odd looking configuration, but the results are quite something. As you saw in the video, I attached my 70-300mm lens to the camera as one normally would, then using the coupler I attached in reverse my 35mm macro lens. This yields around 8.5 times magnification (with the 70-300mm zoomed in); in other words I can image an area about 2mm across.

The bad part is there are a few cons to this setup. To begin with, the loss of light will be substantial. I had to place my fluorescent light (it just burned out recently so I'm not quite sure what the wattage was, but I believe it was equivalent to a 60 watt incandescent bulb) right next to the figurine I was shooting to just barely be able to see it through the viewfinder/LCD. It goes without saying, but positioning the subject at such a large magnification, along with focusing, was challenging. In addition, I had to support the lenses to ensure I wouldn't damage the mounts. You could not see this on the video, but I had the camera on a tripod and the end of the lens setup was supported by a book on my bed. Thus, the camera and lenses remained stationary and I moved the subject around for placement and focus. Depth of field (DOF) was also very, very small, likely around 0.5 to 1mm. As with the lack of light issue, this not only made focusing tricky, but I also had difficultly simply identifying the part of the subject I was looking at. Lastly, I advise you to be very careful about using autofocus with such a setup; really, you should not use it. Lenses are not meant to have such a substantial weight at the end, beyond what a couple of thin filters would be. This is why I physically positioned the subject by moving it around.

Techniques
After considering this section for a little while, I have to admit that I must generalize it. Because there are multiple types of subjects that can be shot, along with the numerous macro photography methods that can be used as discussed in the section above, some techniques will obviously work better than others. Nonetheless, I don't believe that even for novice photographers it will be difficult to figure out what works and what doesn't.

In part 2, I started off with hand holding the camera versus using a tripod or monopod. More often than not, I would say that I most commonly hand hold my camera when shooting close-ups and switch to either my tripod or monopod when shooting very small subjects. Since I'm farther away from the subject when shooting close-ups, thus the DOF is a little larger (remember, DOF widens as the distance from your lens to the subject increases), I can keep the aperture open a little wider achieving faster shutter speeds; plus I usually have the image stabilizer turned on which I'm sure helps a little when the shutter speed drops closers to the shaky hand threshold.

But when I start getting really close to subjects and enter that macro realm, I find that a monopod offers that extra bit of stability. In addition, a monopod can be quickly relocated as they're not as gangly as tripods; great for when you need to change position often, like chasing after insects. However, the tripod is difficult to beat in terms of both stability and fine tuning. Simply said, three legs are better than one to hold firm and although you can attach various heads to most monopods, they're easier to use on tripods. For example, I often favor my Manfrotto Junior Geared Head as I can quite precisely and slowly aim the lens with it. Although I also have a standard three way head, I find they're too jerky when moving them, and as I tighten the grip to lock the position the aim tends to shift ever so slightly. So as you can probably figure, tripods are better for finicky work where magnification is quite high.

Oh! And before I forget, I wanted to suggest the use of a ball head on a monopod. When you want to change your shooting angle and the camera is directly attached to the monopod, then you pretty much have to tilt the whole stick around to aim. But with a ball head, the pod can remain more or less in one place and the camera can be quite easily swiveled and even rotated with far less overall movement.

Up next is manual focusing when shooting macro. In this case the video spoke for itself, as in some situations and due mostly in part to very narrow DOF ranges, auto focusing may not only be a little sluggish (depending on the lens you're using), but as good as cameras are getting, they still don't have much of a clue what you're shooting. This leads to the camera picking a spot that you may not want in focus, hence a missed photo opp. By manually focusing, whether simply selecting one spot and sticking to it or manually adjusting as you go, you're likely to have better results; I prefer this method and for me, this has proven more successful than trusting the camera's brains. If you haven't manually focused much, then be prepared for a little learning curve, but hopefully with a little practice you'll find it satisfactory (even for other types of photography for that matter).

Now to get a larger DOF you can simply stop down your lens, and if that's what you're after (i.e. to get an image with more of the subject in focus) then I say go for it! Even though the diffraction effect may worsen a little, the drop in quality isn't detrimental and to some point can be recovered with a little sharpening and image massaging. If you want to find out more about diffraction, there's a nice link below to Cambridge in Color's tutorial on the subject. The more substantial problem when stopping down the lens in my humble opinion is that with reduced light hitting the sensor, the camera has little choice but to slow the shutter speed way down. As you can guess, welcome blurry shots... not good.

If you happen to shooting subjects that don't move then slow shutter speeds are generally not a problem, as on most digital SLRs the mirror can be locked up for a couple of seconds before taking a shot (to prevent blurring caused by the mirror suddenly slapping up) and waiting patiently until the exposure completes. But unless you can control wind to make it stop blowing your flowers or command bugs to stop moving around (unless you smack'em dead, which I hope you won't do!), then another method must be found to increase the shutter speed.

One method to increase shutter speed is to increase the sensitivity of the sensor. This does pose the problem of more noise in the photo, but if your camera is newer and doesn't suffer as much from this or you don't mind the extra grain, then you may be able to return to shutter speeds that can freeze the action more adequately. The second way is to add more light to your scene, and as you saw in the video, the good old electronic flash works wonders for this. Depending on what you're shooting, certain types of flashes will be more useful than others. For some close-ups, the camera's pop-up flash may provide enough power to illuminate the subject well; keep in mind that some lenses may cast a shadow if they're physically long or have a large lens hood; at least a lens hood can be removed. In other cases, external flashes can be employed.

I would consider the ring flash to be one of the most commonly used for macro photography. These units usually attach onto the front of the lens (although big expensive models have specialized rigs) and provide very even illumination; they're also quite common for portraitures. Twin flashes are very similar, but they usually illuminate from two sides opposite from one another, and the power of each flash can be adjusted so a photographer can be more creative with their lighting needs. In my video, I simply used my FL-50 attached to the hotshoe via a flash extension core (and my dirty little secret... it's made by Canon! The store didn't have an Olympus one in stock, but the Canon one ended up being less expensive and with the right number of electrical contacts... works for me!). This one flash method works quite well, but keep in mind that one of your hands will be used up holding the unit, and there will likely be a shadow cast on the subject. Like I mentioned in the video, some people like me may not mind as it offers a little definition to the subject, but others may not like that as much. To conclude this bit, I'm sure there are many other ways to get light onto your subject, but I quickly wanted to mention the reflector. Whether you choose to purchase a fancy one with changeable covers or you prefer a simple white piece of paper, they may be beneficial as the light they bounce back onto the subject will be somewhat gently than what a flash can do. Thought I'd mention this in case some of you out there like to experiment with such things.

And there you have it! I think this post took me the longest to write out of all the ones I've written so far, mostly thanks to my life becoming a little busier these days. Next episode will likely be a Q&A one, so if you have a question about photography, then by all means feel free to contact me (e.g. leave a comment or email me; address in my profile). My soup is waiting and I'm hungry, so off I run! Happy shooting!

Web Resources
http://www.cambridgeincolour.com/tutorials/macro-lenses.htm
Diopter and magnification: http://www.bertech.com/product8/magnifi_notes.htm
Fotodiox: http://www.fotodiox.com/