I'm looking at buying a used Pentax K5 II as my main camera rig. The most important use of this camera will be for documenting fieldwork, including photographing specimens in the field. I'd like to have a small selection of quality lenses that will cover me for most situations. I've been doing research, but there are so many options that it's hard for me to decide. Can you help me?
OK, so following this recent AskMe
I've decided to pick up a lightly-used Pentax K5 II. I'll be using this camera a lot for day-to-day purposes, but the main reason I'm buying it is because I want to upgrade to a decent dSLR for use when I'm out doing fieldwork. I sometimes act as my field team's unofficial documentarian, and I also use my camera for taking standardized photos of all of the specimens (small frogs) that I collect; also, there's a lot to see and photograph in Central Africa and photography has long been a hobby of mine.
Having settled on a camera body, the next step obviously is to find out what lenses I am going to want to bring with me. I will definitely need a macro lens or extension tube (I'm not really clear on the pros and cons of each option but would love to hear an explanation), something for taking "standard" photos (i.e. 50mm equivalent), and something for moderate telephoto. The K5 II has an APS-C class sensor with a crop factor of 1.54 compared to full frame.
Size and weight are obviously important, since I'm going to be humping this stuff all over Cameroon. I want to be able to minimize the number of lenses I have to carry (no more than three) and I'd like for the ones I do have to be on the smaller/lighter side of their class. I have always taken a lot of low-light photos and love wide apertures, so that's something I'm interested in having in a lens as well. I'm not concerned about what brand the lenses are or about buying new vs. used. (The K5 ii is compatible with all K-mount lenses, and the image stabilizer is in the camera rather than in the lens.) I do however want good value for money – I'm looking for quality lenses that can be had for reasonable prices.
What do you think my best overall strategy is, and what specific lenses can you recommend? Currently my thought is that the best way to get what I want while saving weight and space is to go with a prime standard lens (30-40mm), a prime telephoto lens (around 100mm), and a macro extension tube. I'd especially like it if the standard lens had a maximum aperture f/2 or less, and if the telephoto lens had a maximum aperture of f/4 or less. Another option of course would be to get a good zoom lens that covered a range from at least 30mm to 100mm, and then either an extension tube or a macro lens to go with it, but so far I'm more interested in prime lenses unless someone here can talk me out of it.
Thanks very much as always for your input. I look forward to hearing everyone's recommendations.