close-up focusing?

[Theninjaseal]

I'm new to the ILC/dSLR world and I really miss the close-up focusing of my oldd point-and-shoot. What's the best (cheapest) way for me to allow my camera to focus really up close for macro shots? Like less than two inches maybe. Is that even possible for a dSLR frame? Any suggestions on lenses or accessories that would let me focus really close and still use autofocus? Thanks.

 

[480sparky]

Click here.

Cheapest and best are mutually exclusive.

Cheap...... screw-on close-up filters.

Best....... that depends on how deep your pockets are.

 

[tirediron]

The best compromise is a set of extension tubes.

 

[Theninjaseal]

Are extension tubes with contacts for aperture / focus control super-expensive?
would I need to buy several in order to get the focus really close?
Do tubes reduce image quality/brightness by more than a stop or two?
And can you use autofocus with lens diopters / conversion lenses?
Sorry for all the questions, I'm a bit of a newb

 

[480sparky]

Are extension tubes with contacts for aperture / focus control super-expensive?

They do cost more than simple extension tubes.

would I need to buy several in order to get the focus really close?

They usually come in a set of 3.... 12, 20 and 36mm are common in a set. But some sell individual tubes. The more extension you put in, the closer you can focus.

Do tubes reduce image quality/brightness by more than a stop or two?

They don't affect IQ in the way add-on optical methods do (like filters) because there's no glass in them. But you can find some IQ loss because the lens you're using isn't designed for this type of use.

And can you use autofocus with lens diopters / conversion lenses?

Yes.

Sorry for all the questions, I'm a bit of a newb

That's why we're all here!

 

[Theninjaseal]

Thanks! I'm looking at the Kenko m4/3 tube set.

I'm thinking about the following setup: GH2 Body > non-af tubes (fotodiox, $10) > Nikon F-series adapter > Vivitar 75-205 manual lens (quality glass from 1974) > 58mm-52mm step down filter adapter > any further CPL or closeup lens filters I need at that point (no vignetting, I checked)

The step-down adapter only because I all my filters are 52mm, for my kit lens. I don't want my rig to end up four feet long, but I think the above would be manageable in a studio-type shoot until I can get the kenko tube and a better m4/3 lens

Does that sound reasonable? I mean, it makes sense in my head but I'm not totally sure. Thanks for your help

 

[Overread]

For reference the OP has a Lumix GH2


As for your idea it might help to know the rough formula for extension tubes:

(Length of the extension tubes in mm - divided by - the focal length of the lens) + base magnification of the lens = magnification : 1

For example a 100mm lens on a 50mm length of extension tube would be:

50/100 = 0.5:1

Or a 50mm lens on 50mm of tubes:

50/50 = 1:1

Note I left out the base magnification of the lens itself because that will vary lens to lens, but is generally quite a small value for lenses which are not macro dedicated.

Also as a reference point, 1:1 is the magnification of a true macro lens, where:
size of the subject as reflected on the sensor by the lens : size of the subject in real life.

Thus you can see that adding extension tubes to shorter focal length lenses results in more magnification over longer ones. There is a limit though, as with very short lenses you can end up adding enough extension tube length so that the focus point moves inside the lens itself (thus the lens is incapable of focusing).

I would also strongly advise getting extension tubes with the metal contacts to retain AF and aperture control over your lens. Losing AF isn't as much a problem as most focusing is done manually for macro; but losing aperture control makes it a lot harder to take photos; you're either reliant on a manual aperture lever on the lens (many modern lenses do not have this) or on tricks to close the aperture blades constantly (which makes focusing difficult and is not possible on all brand lenses).

 

[TCampbell]

There are a few ways to do this.

1 - Get a true macro lens

The highest-quality (but most expensive) way is to buy a "true" macro lens. Purists regard a "true" macro as a lens which can focus a subject at 1:1 scale. The scale is based on how large the image is on the camera sensor. Here's an example: A penny is about 19mm in diameter. The sensor on a DSLR with an APS-C size sensor (the vast majority of DSLRs) is about 14mm tall by 22mm wide (roughly). That means that at 1:1 scale, a penny would not completely fit within the frame of the sensor. The width would fit with a tiny bit of room to spare, but height-wise the penny would be slightly cropped. So that's pretty close.

Canon (and as far as I know, _only_ Canon) actually makes a special purpose macro lens that can do 5:1 scale (image on sensor is up to 5 times larger than the subject is in real life.) That's the MP-E 65mm. The "catch" is that this is a special-purpose macro lens. Nearly all macro lenses can also be used as ordinary prime lenses (they're not just for macro work exclusively). They focus from that very close 1:1 scale distance out to infinity. But the MP-E lens from Canon can _only_ do macro work. It's near-focus is 5:1 scale and it's far focus is 1:1 scale.

There are many zoom lenses which also claim to be "macro" zooms. This is the "marketing version" of macro and not what a purist would regard as a macro. These lenses usually can only focus to maybe 1:3 or 1:4 scale.

When you get really close to a subject for that minimum focusing distance, the shadow of your lens, camera, or even your body might be altering the light on the subject. For this reason, longer focal length macros are usually preferable. A longer focal length also means that if you are trying to take a macro shot of a skittish critter, the critter might not run away when the lens looks like it's so close that it's about to be squashed.

True macro lenses are prime lenses with very close minimum focusing distances, but ALSO they usually have particularly good resolving capability (the "MTF" score of these lenses is usually very high.)

2 - Get extension tubes

Extension tubes really are just "tubes". It's a barrel that mates onto your camera body (where the lens attaches) and then your lens mounts to the other end of the barrel. The reason it's called a "tube" is because it doesn't contain any glass. It's completely hollow. It's job is to move the entire lens farther away from the camera -- thus changing the back-focus distance on your lens. By doing this, the "closest focusing distance" of your lens will be reduced -- but the catch is, so will the "farthest focusing distance". In other words, you will find that your lens can no longer focus all the way out to "infinity" when it's mounted to the extension tube.

The extension tubes only technology is that they do pass-through the communication pins so your lens and camera body can still communicate, and the better ones actually report that they are present (so the camera knows there's an extension tube in use.) Apart from that, the air inside brand 'a' is generally just as good as the air inside brand 'b' (as there are no "optics" in these things, image quality will never be a question of "which one is best".

Since you can put an extension tube on any lens, and "any lens" usually doesn't have optical quality quite up to the standards of a good macro, you might notice that the detail isn't quite as good IF you are a pixel-peeper. However... there are a LOT of "macro" photos that you've undoubtedly seen in your life with astonishingly high quality that would have been photographed with a relatively ordinary lens... and an extension tube.

Extension tubes come in various lengths and are also sometimes sold as "sets" (the longer the tube, the more it reduces the minimum focusing distance. You can "stack" them.)

Extension tubes are not particularly expensive.

Some people will use a true macro in combination with extension tubes for even closer macro work.

3 - Get Close-up diopters

Close up diopters look like filters. They "screw on" to the filter threads on the end of your lens -- just like you'd do to attach a polarizing filter, neutral density filter, or any number of other filters (e.g. UV filters... which don't actually help because all digital cameras already have an internal UV filter, but that's a different thread.)

The diopter works quite a bit like attaching a magnifying glass to the end of your lens. In fact... it's so much like attaching a magnifying glass to the end of your lens that it even has the same problems you would have it you _really_ attached a magnifying glass to the end of your lens.

They work and they're probably the least expensive way to get "close-up" shots. They come in different strengths and you can even "stack" them for stronger levels of power.

But there is a downside to these. A lens element, by itself, looks like a magnifying glass. If you look at the cross section of the lens shape, the center is thickest and it tapers to a thin edge. That tapered shape means that as light passes through the lens surfaces it will bend. The refraction is desirable because that's what magnifies the image. But along with "diffraction" you also get "dispersion" ... "dispersion" is what a prism does when you shine a white light through it. It splits the light into a rainbow spectrum. Different wavelengths of light will diffract by different amounts such that no all "colors" actually focus at the same distance from the lens. The dispersion is almost non-existent in the very center axis of the lens, and very strong at the outermost edges. That means you'll see color fringing (color fringing is called "chromatic aberration" or just "CA" for short) in the details near the edges of your frame... objects in these areas of the frame will have a reddish glow (or "fringe") on one side and a blueish "fringe" on the other.

Hold a magnifying glass over a piece of fine newsprint in a nice brightly lit area and you'll notice that the print in the center of your magnifying glass looks large, sharp, and good. But at the edges of the view the text is beginning to distort, you see "color" (red & blue) even though you know the newspaper is really black & white.)

All lenses technically have this problem, but the reason you don't usually notice it is because lens makers arrange the elements within the lens into a configuration known as an "achromatic doublet". The doublet configuration tends to greatly reduce the level of CA.

Canon actually makes two different close-up diopters that are quite a bit thicker and they actually contain multiple elements (they actually have achromatic doublets in them.) They give the very best image quality you can get from a close-up filter... but they're not cheap. I bought one for my Canon G1 X (a high end point & shoot) and I seem to recall it was about $130 for the close-up diopter (not a set.) That's _very_ expensive for a close-up filter (which are usually less than $25).

4 - Get a Reversing ring

I've never done this particular method so I can't speak to all the ins and outs of it. But a reversing ring lets you mount a lens to your camera BACKWARDS. On the front of your lens, you'll notice you have filter threads (the diameter varies by the lens, but most lenses have them.) The back of your lens has the mount required to attach to your camera body. The reversing ring lets you attach the lens backwards. It's a simple ring which attaches to your camera body on one side, but the other side of the ring has "filter threads". You screw the ring onto the front of your lens, and then attach it to your camera.

As the lens is mounted backwards, there is no communication with the lens and body. You cannot control aperture. The lens will not auto-focus. You have to control the exposure using only shutter speed & ISO and focus the lens manually.

The reversing ring is cheap.


No matter what you get... get a tripod. The depth of field can be so incredibly thin that if your body moves so much as a millimeter between the time you focus and the time you shoot (something which is extremely likely if you're a living-breathing person) you'll get soft focus on your intended subject. People who regularly shoot macro also buy a focus rail.

 

[cgipson1]

Tim.. nice write up!! :thumbup:

 

[Theninjaseal]

Thanks, Tim. You included some information I hadn't heard before. One more question I think, Would it be bad to use a film SLR lens with m4/3 tubes? With an adapter ring, of course.

 

[bratkinson]

Tim -

Thank you for the very informative writeup. I've never been much of a macro shooter, and your clarification of 'true macro' versus 'marketing version' macro cleared up some of my misconceptions.

About the only thing I can add, from personal experience, is to absolutely avoid the cheapo screw-on macro lenses...unless one actually -wants- fuzzy pictures. Mine fell apart the first time I unscrewed it from the front of the lens. Too often, I learn things the hard way...<groan>.

 

[480sparky]

A couple things that haven't been touched on:

Close-up work produces razor-thin depths of field, even when lenses are stopped down to minimum. This is where focus stacking can help you. It's a method similar to HDR, but you change the focus point of each frame, then 'stack' them with special software that will utilize the in-focus portion of each frame into one.

The diffraction created by closing the aperture down is sometime greatly magnified when shooting macro. I realize it's tempting to stop the lens all the way down for maximum DOF, but it can easily backfire. I know for a fact my 28mm lens, reversed on a bellows/extension tube, produces best results at f/8. I can see a markedly poorer image quality even stopping down to 11 or opening to 5.6. Outside that range, I know I shouldn't even bother. Each lens will have it's own unique characteristics, however, and some produce stellar results at f/16 or 22 while being dismal at f/8. So it's a matter of taking several test frames and making the call.

When using a reversing ring, the focusing ability of the lens is lost. Focus is achieved by moving the camera.

Many think the ability to 'get close' is measured by the distance from the lens to the subject. While in general, getting closer means the subject is enlarged in the viewfinder, macro photography is based on reproduction ratios, not subject-to-lens measurements. Reproduction ratios means the relationship between the actual measurement of the subject compared to the measurement of the projected image of the subject. Let's say you have an object measuring 1mm across. If the projected image of the subject on the film/sensor measures 1mm, you have a 1:1 reproduction ratio. If it's projected at 2mm, you have a 2:1 ratio. If you can increase the projected image to, say, 8mm, you have an 8:1 ratio. If your projected image is only 0.5 mm across, you have a 1:2 ratio.

Reproduction ratios are not dependent on any 'crop' factors of a digital camera. A 10mm object projected across 10mm of sensor is still 1:1, regardless of the camera being 'full frame' or 'crop sensor'.

An some cases, you can get so close to the subject it's impossible to light. So do some research online to avoid buying a set-up that can end up with this result. In fact, it's physically possible to create a condition where the point-of-focus is inside the lens itself. Rare, but is truly achievable.

Some other gear considerations: A focus rail. The usually come in two flavors, 2-way and 4-way. A 2-way rail will give you the option of moving the camera/lens combination either forward/backward or side-to-side, depending on how you install it. A 4-way rail gives you both directions. Once you start magnifying so much, physically moving the tripod becomes problematic.

Geared tripod head. Again... once you start getting into high magnifications, a ball head or other 'normal' type of head makes fine, small adjustments insanely difficult.

Ring light. When all else fails for lighting, a ring light can 'save the day' when your lens is very very close to the subject.

 

[Lenschecker]

I go for the extension tubes. It's a good middle way between costs and quality, I think.

 

[Theninjaseal]

Thanks everyone for the help. I ended up getting a nice-ish macro filter (4-element Opteka) along with some tubes. I found a Nikkor 75-200 that blends really well with my macro conversion lens. Gladly, I've gotten back in to the macro world.

I'd thought about focus stacking on a fundamental level, but I've never heard the name for it. Could someone point me towards what you think is the best software for it?

 

[Overread]

Focus stacking hasn't really got a "best software" option. There are a range of options from free through to commercial and each different stacking program works in slightly different ways and has different ways to adjust the results. The end result is that each one has a certain area of stacking where it will work better than the others; but these differences are almost impossible to shoot for; thus you can't tailor your shooting to a specific software suit.

As such focus stacking is one area where it becomes beneficial to gather up a few different programs and learn to use them; because a stack which fails with one can work really well with another. This is generally one of the few times in editing where owning cross brand different packages for the same application can produce a very noticeable difference in the results (many times things like different sharpening, noise reduction, RAW processing etc... software options have only very marginal differences in results and many of which are impossible to see on normal outputs).


Combine ZP is the newer freeware software option.
Photoshop CS5 has a focus stacking code built into it
Helicon Focus and Zerine Stacker are two of the popular commercial stacking programs (both have demo modes available at no cost).

Personally I would start with Combine ZP and then move on from there, unless you have a copy of photoshop. Helicon and Zerine I would also make an aim to purchase (Helicon also has some additional features which come with it which can help as well as some remote control options for some cameras).