Lisa,
Sorry, I tried to explain before, but I'll give it another go...
First off... yes, you are correct. I use a few extra things to get the magnification in my macro shots. The
Canon Powershot series of cameras is considered "point and shoot". They are not designed to work with external lenses or flash. The internal lens on my camera is small, but has a 35 mm to 105 mm range in 35 mm film equivalent terms. This is actually pretty workable for most point and shoot type use. You can find oodles of detail about my camera at the
BeBit site.
First off, I knew I needed a way to stick other lenses on the camera, but there are no threads on the front lens plane like you get with SLR lenses (for filters and such). I purchased a
lens adapter from CKC Power Digital for about $50 US that would give me 37mm threads just in front of the internal lens at it's furthest extension. Now, you can't put standard SLR lenses on the camera with 37mm threads, but you can add some specialty lenses and magnifiers called diopters. Diopters look like a magnifying glass... convex glass. Initially, I purchased a couple of diopters (+7 and +10... they came in a set) from
Tiffen. A neat thing about these tiny diopters is that you can stack them to get a somewhat additive effect on magnification. There are definite limitations and you kinda have to play with some combinations to get good results... or "optical marriages".
Important note: when stacking diopters, always put the largest magnification closest the camera lens.
One immediately evident byproduct of magnification is that depth of field (DOF) is related in inverse proportion. The higher the magnification, the smaller the DOF. Actually, at extreme magnification, the DOF becomes paper thin... seriously. This is troublesome when trying to get a moving subject in focus... or more specifically part of a subject. The widely accepted technique is to lock your focus and then rock the camera back and forth to shift your focal plane over the subject. It takes practice. I've been practicing a lot and I still suck.
Extension tubes are another way of getting some magnification, but I haven't tried any because of the limitations of my camera construction.
Another "trick" of the trade in the traditional film SLR world to get increased macro performance on a budget is to take an SLR lens and flip it over and mount it in reverse... using the filter threads on the end of the lens to screw it on. In order to do this you need accepting female threads of the correct size (ie. 37mm won't cut it) and a
macro coupling ring. I purchased a 37mm to 52mm (standard for Canon and Nikon lenses) step-up ring and a male to male 52mm macro coupling ring.
Michael had a splendid Nikkor f1.4 50mm lens that he let me borrow to experiment with... the larger the aperture the better because you need as fast a lens as you can get to flood the light in when reversing lenses. The reversed 50mm gave me much better results than the stacked diopters. It was harder to work with due to the even further reduced working distance, but the quality and magnification were better.
Working distance is another immediately noticeable artifact of macro photography. When using these techniques (macro on a budget), you will find that you need to get literally within inches (less than 1 inch in the case of lens reversal) to bring a subject into focus. You can readily see how this is problematic when an insect is shy. Flowers don't get embarrassed so easily. Heh. It requires some strategy and attention to technique. It's very challenging and something you will continually get better at... practice is where it's at.
Sometimes, you want to get a close look at a subject, but not too close... macro flora photography is an example. It's easy to get so zoomed that you miss part of the flower's beauty. Magnification and working distance... always a give and take relationship. Which brings me back to "optical marriages". My macro photography hero,
Mark Plonsky, offered a technique where you use stacked diopters to up the magnification and then place a optical teleconverter at the end of the stack to increase working distance. I tried this with a 37mm Tiffen MegaPlus 2x TC and it was a great "optical marriage". The key is experimentation.
Michael had tried taking a 105mm micro lens with a PN-11 extension tube and placing a reversed 24mm Nikkor on the end only to find that the magnification was phenomenally spectacular, but the DOF and working distance was damn near unworkable. It was a bad "
optical marriage". You have to try out what works best for you and your camera for the shot you are trying to get.
Please understand that I'm just a beginner at this hoo-ha, so take what I say with a grain of salt. I just am sharing some tidbits I've learned over the last few months. I'm sure that over time my technique will improve and I'll probably figure out I've been doing some stuff wrong this whole time, but for now it's just great fun and a wonderful hobby. I like sharing my photos and I love hearing what you guys think of them.
Happy shooting!