Koch asked me to look into getting a macro lens for the DDW experiments. So today I started and it dawned on me… how am I going to differentiate a good lens from a bad one, besides cost? I started looking at specs and I realized I know almost nothing about technical specs of camera systems. And (un)surprisingly macro photography is pretty finicky when it comes to how the camera reacts to the environment.

So now I write to blab about what I’ve learned and what I should look for in a good lens:

• Aperture: In my experience because I’m working in such close proximity the focal plane depth is rather shallow. By this I mean that there isn’t very much in focus unless the subject(s) are all at the same distance. In the case of my seeds, as things grow, stuff comes in and out of focus depending on it’s location. This is why I push all the seeds to the front of the sample chamber so they are all the same distance from the camera. I think this means that for macro photography the aperture is relatively large indicated by a smaller F/(-number). So when it comes to buying a lens from what I’ve read I want to get a lens that has a low F/(-number) where the (-number) is a number that is as low as possible. On the lens that we are using now, this number is something like 5.6
• Shutter Speed: From what I can tell, typically the shutter should be set to slow. I’m not fully understanding why but it just is. This means that you need to have an abundance of light to ensure a good quality photo. Flash is not an option (if it’s on your camera) because the light won’t be able to bounce off your subject because of the proximity of the camera to the subject. I don’t think I’ve been using a slow speed for my pictures, but I suppose that will change when I get a macro lens.
• Focal length: Obviously this is important. The more you can zoom the closer and larger you object will appear. I’m limited in this regard now because the lens can only zoom so much and I’m using a magnification lens that actually gives me less focal play. According to the internet, using an extension column (basically moving your lens further from the ccd) gives you more magnification. And I’ve quickly verified this.

Surprisingly I’ve been doing extensive research on this and only now have I just found the wikipedia article on this topic. The article is very informative (as always) and more useful than what I’ve written here.

Anyways, with my advanced knowledge that I now have, I’m looking into this lens: Sigma 50mm f/2.8 EX DG Macro Lens. It seems to have everything I need. Apparently having a zoom-lens-like-macro-lens (confusing) basically just gives you the opportunity to take pictures from a distance.  I’m choosing the one above because I don’t need distance. I’m actually working in pretty close quarters so I would prefer to keep the camera as close as possible.