What aperture settings should I use for taking macro photos of artwork?

Question

So I'm using the macro to photograph artwork with a T2i. I'm still just testing right now without studio lighting, but when I tried to zoom in (digitally) and focus with the camera display it seems to be such a fine adjustment. Not even the auto focus can get it right. Even if I get it right for one section manually there is no way to fully focus on other parts because if the painting is out of line by a millimeter it won't be in the same focus. It seems way too precise.

Sadly I can't check full results on my computer screen as my main computer died. But all said and done, zooming in fully on the camera's screen, I seem to to be getting slightly better results from the stock zoom lens. I found if i set it at about 35mm the edge distortions are minimal, I'm able to be much closer to the artwork then the 60mm macro, and results seem to be tiny bit sharper.

I thought if I closed up the aperture on a camera (going back 20 years) it would increase the focus-able range, but I'm not sure how to do that?

I'm not sure how the ISO and Aperture work if if they are one in the same. and I'm not sure if the 2.8 is a fixed setting or what. (sorry I've been overwhelmed trying to figure it all out). I've been inclined to go with 100iso because I understand that captures the most color. But even going up to 400+ doesn't seem to make much difference focusing. With the longer exposure and perhaps the extra length of the macro's distance from the subject, I fear even the shutter is causing micro movements on my budget tripod and perhaps the result is less sharp? Maybe I'll have better results when it's properly lit?

Anyway, just so far the results seem better from the stock lens. But maybe I can make some adjustments to the macro? just because it's not focusing perfectly zoomed in on the screen probably is not why I'm seeing less than stellar results.

Answer 1

ISO and Aperture are two totally different things.

For your purposes, you need a greater depth of field (DOF), which means that you need to decrease the aperture diameter (higher f-number).

Your ISO should be able to stay the same, assuming that you can increase the exposure time to compensate (this shouldn't be a problem if you are using a tripod).

Using a Canon T2i, you probably want to use Av Mode (Aperture Priority), and set the aperture somewhere in the f/5.6-f/8 range. This will probably give you a good sharp image and better DOF.

Answer 2

f/2.8 is NOT a fixed setting, it is the widest the aperture can open up. As you have found, closing it down a bit is usually a good thing. The kit lens has a max aperture of f/5.6 at 55mm, i.e. closest to the macro's focal length, which is two full stops down which gives a lot more depth of field automatically.

What mode is the camera in? Av, Green-square mode, P?

Now, assuming that you are using a tripod (which you should be):

• Set the camera to M mode, this gives you full control over ISO, aperture and shutter speed.
• Set the ISO to 100 and the aperture to whatever you want, I suggest f/8 as a starting point for maximum sharpness.
• Now set the shutter speed to something that will give you a good exposure - since you are on a tripod you have a pretty free hand with the shutter speed. Adjust the shutter speed, and the shutter speed only, to give you the desired exposure.

Answer 3

Remember that while you're focusing and composing your lens is wide open to give you the brightest viewfinder image it can. You can try pressing your depth of field preview button (which stops the lens down to the set aperture) but it will darken the viewfinder a lot.

Macro lenses, when focusing at such close range have a tiny depth of field, that is just the way it is. Even f/16 or more is very very small.

A good method of focusing is to switch the lens to MF and then set the focus to the nearest distance (if that is what you're trying to go for) Then move the camera back and forth to get focus where you want.

Tripod mounted is another way to go, you can also buy macro focusing racks that allow you to wind the camera forward or backward on the tripod head in tiny increments to allow more precise focus.

Answer 4

Are you photographing paintings - relatively 2-d artwork - or sculpture? For paintings you will want to ensure the subject is perpendicular (flat-on) to the lens so that when one part of the painting is in focus, all of it should be in focus.

Regarding your problems with getting focus - it sounds like the auto-focus might be failing due to it being too dark. If you can't change the ambient lighting try using a torch to highlight a spot in the center, then get your camera's center point auto-focus target to lock on using this spot. Assuming you have a static camera and tripod you can then switch to manual focus to keep this setting.

Also, you need to read the manual for your camera to figure out how to set the aperture. Change to aperture-priority mode, set the aperture to something like f8 and see what kind of results you get. Digital film is relatively infinite so try playing around with the settings until you get something you're happy with.