[The Kurly One]

I built a light box and am trying to get the sharpest Pics possible with some Macro shots.

Hers what I have available

Pentax K-x

18-55 kit lens
DA 55-200 ( slightly above a kit lens I think)
50mm f2.0 Pentax A

Which lens should I use with what camera settings to get the best results? I have a remote and a good Tripod set up with it so camera movement wont be a problem

LMK what you think thae best settings are to help me expiremnt and learn how to get the most in focus and sharpest results. Thank you in advance!

[Just1MoreDave]

I think the DA 18-55 kit lens gives you the best combination of magnification and closest focus distance, of the lenses you have. The settings depend a little on your subject size. I take a lot of photos of lenses with a similar setup, and for something that big, I use f9.5 to f11 for reasonable depth of field. For smaller subjects, you'll need f16 and up. Since you don't care about shutter speed and will be adjusting aperture a lot, use Av mode.

With my lens photos, the meter is always wrong. The lens is black and the light box is white, and the meter can't quite get that right. I usually start with +0.5 exposure compensation, less if the subject fills the viewfinder and more if I have a lot of white space. Take some test shots to get the exposure right. The histogram should be as far to the right as possible without blinking highlight clipping warnings. That will help in processing the image.

In theory, something called diffraction will start to make your photos look softer at apertures like f11. There's a tradeoff between diffraction and depth of field, so after you get the exposure right, take a series of shots at different apertures. Each full stop should be fine: f11, f16, f22, etc. Then look at the images to see the effect of increasing depth of field and diffraction.

That should be enough to give you some more questions to ask.

[Marc Sabatella]

None of those are macro lenses, though, so while sharpness per se won't necessarily be problem, just getting closeup enough might be. To solve that problem a Raynox 150 closeup lens for youe 50-200 is the easiest / cheapest solution.

When using the tripod, use the two-scnd timer mode, whihc invokes mirror lockup and also disables SR.

[RioRico]

That depends on how 'macro' you plan to go. As Marc said, none of those is a macro lens -- none, as is, will give you anywhere near 1:1 magnification. A Raynox on the longer zoom is one solution. For not much more $$$, you could get (used) some M42 macro tubes, a flanged M42-PK adapter, and a VERY SHARP Takumar 55mm or 50mm or 35mm lens. The lenses needn't be fast, and slower lenses cost less. On any specific tube extension, a shorter lens gives you greater magnification. An advantage of such a setup is that you place no extra glass between the lens and the subject, so you get the highest possible image quality.

[The Kurly One]

Wow thanks for the great tips!

I found a fairly cheap Lens at a local shop, Ricoh 28mm f2.8

Would that lens help me at all?

I'll try adjusting the f stops after I drop off my son at school. My daughter wants to sit in the box today and get her picture taken with her Barbies. The box is a white sheet around my Pool Table light, I've also built a diffuser that I am going to try today as well that has a 150w Compact flourescent bulb ib it (Biggest bulb I've ever seen dunno how its a compact!)

[GoremanX]

The kit lens may not be labeled "macro", but as Dave mentioned, it allows some pretty awesome close-focusing. As long as you avoid the extreme focal lengths like 18mm and 55mm, and stick to the mid-level apertures like F8 to F11, then you can get some surprisingly sharp results. Technically, anything that isn't "wide open" (ie. F5.6 @ 50mm) will give good results.

[The Kurly One]

What should be my closest distance to an object? Any suggestions?

[Clicker]

About 2 feet

[Marc Sabatella]

I found a fairly cheap Lens at a local shop, Ricoh 28mm f2.8

Would that lens help me at all?

Highly unlikely. You might want to Google around or get a book on photography to learn about the basic fundamental concepts of macro photography. A lens is either a macro lens or it isn't. No zoom lens is a macro lens (although it might try to bill itself that way), and of the prime (non-zoom) lenses, only ones specifically labeled macro will be. What makes a lens macro is basically one thing: how large of an image it allows you to make of small objects. The sensor is an inch wide, give or take. If you can get close enough to an inch-long object to fill the frame with it and still focus, that's "1:1" macro (object is exactly as large on the sensor as it is in real life). The shorter the focal length of the lens, the closer you'd have to get to achieve 1:1. The 18-55 does only 1:3 - meaning you can fill the frame with objects three inches across (when at maximum zoom and minimum focus distance). That's not bad for what it is, but assuming when you use the term "macro" you have in mind smaller objects, then you'll need a real macro lens, or else extension tubes for your 50, or a Raynox for your 50-200. Again, Google is your friend for explaining all this, and there are tons of existing threads in these forums on both extension tubes and the Raynox adapters.

a 150w Compact flourescent bulb ib it (Biggest bulb I've ever seen dunno how its a compact!)

Compared to traditional 4-foot long tubes that used to be about the only way to get fluorescent lighting.

[RioRico]

My daughter wants to sit in the box today and get her picture taken with her Barbies. The box is a white sheet around my Pool Table light

This doesn't sound like what we would call 'macro', which implies EXTREME close-ups. (Not unless your daughter is a Thumbellina the size of a Barbie doll!!) This sounds more like you're trying for shadowless shots, sort of like product shooting of stuff about a yard or two across. You can do this with your kit lens a couple ways, depending on what you want.

You could set the lens to very wide (18-20mm) and the aperture wide open, with your daughter and her dolls (THE GALS) lined up about the same distance from the lens. So you'll be in Av mode, aperture at f/3.5 or f/4, and focus carefully so the gals are all pretty sharp. Try shots varying the exposure plus and minus a couple EV's. Try tweaking the focus just a little to highlight details in faces. The picture should be a bit soft around the edges.

Or you could try for more sharpness. Now you must make sure that the gals are well away from the backdrop sheet (or the detail of its weave and draping will be distracting). Still in Av mode, set the aperture to f/5.6 or f/8. Focus a bit in front of the gals, say at a point almost halfway between them and your camera. Now shoot, again varying EV's and focus a little. Your goal here is to have them very sharp, but the background again fuzzy, not distracting.

These are ways of playing with DOF (depth of field), the zone of sharpness. In the first, just the faces are sharp, everything else is soft. In the second, all the subjects are sharp, but you've front-focused to pull them away from the backdrop. Give'em a try.

A little more: Here's something you can do with the28mm lens. Get the gals in the tent. Mount the 28mm. Set up the camera so the gals are all visible in the lens. Measure how far away from the camera they are, and the background is. Play with the lens, turning the aperture ring, seeing which f-stops line up with a distance that is just in front of the gals, and that same f-stop (on the other side) with a distance just behind the gals, but not as far as the backdrop. Here, you're trying to set a DOF that includes the gals but nothing else. Set that aperture and shoot; and again, try shots with varying EV's and tweaked focus.