Macro Lens Questions?

[Ron Kruger]

With an f/2.8, the light gathering capabilities of the glass not only allows you to shoot in lower light than an f/4, it means that f/2.8 also require less available light to achieve an f/11setting for an equal lumance and shutter speed. =light-gathering capabilities.

[SmartWombat]

A small Canon P&S like the G9 might be useful, because it works with the Canon flash range. So you could use the macro ring flash or macro twin flash with a Canon SLR as well as a Canon P&S.
I use the 580EX and 580EXII because the G9 supports the ETTL metering/control options of the flash.

But you're right about the problem of getting too close to the subject with a P&S camera.

[Ron Kruger]

Yes, f/11 is f/11 is f/11. But the amount of light the glass gathers determines how much luminance is required to reach f/11. So while the amount of light being permitted through an f/11 appature is the same for a f/2.8 AND a f4, how much available light it requires to achieve an f/11 is not the same between a f/2.8 and a f/4. Gathering more light doesn't just allow one to shoot in lower light condtions, but to make more use of available light throughout the f-stop range.

[Ron Kruger]

What is the megapixels of that G9, Wombat, and what is the price range?

[OldClicker]

"If someone had two lenses of the same focal length, but different f-stop ratings, and they shot both those lenses in appature preferred, set on f/11, under the same lighting conditions, their camera would choose a different shutter speed for each lens.
Similarlly, if they set them both on shutter preferred, their camera would chose a different apparture for each."

I just did it. Camera at ISO= 400.

Aperture Priority: 35-70 f/4 @ 50mm & f/11= 2 sec. 28-75 f/2.8 @ 50mm & f/11= 2 sec.

Shutter Speed Priority: 35-70 f/4 @ 50mm & 2 sec= f/11. 28-75 f/2.8 @ 50mm & 2 sec= f/11.

When you used a separate light meter, it gave you the ISO, f-stop and shutter speed, correct? No matter what body, lens or film - it worked.

TF

[Ron Kruger]

"Aperture Priority: 35-70 f/4 @ 50mm & f/11= 2 sec. 28-75 f/2.8 @ 50mm & f/11= 2 sec.

Shutter Speed Priority: 35-70 f/4 @ 50mm & 2 sec= f/11. 28-75 f/2.8 @ 50mm & 2 sec= f/11.

When you used a separate light meter, it gave you the ISO, f-stop and shutter speed, correct? No matter what body, lens or film - it worked."

Thanks, Clicker. I stand corrected. And you may have saved me some money.

[Ron Kruger]

So what I'm getting out of all this, is that for the best macro shots, what I need is not a fast lens, but a shorter, like 35mm, fixed macro lens?

[Loupey]

There is a reason why manufacturers don't make true macro lenses faster than f/2.8 - there is no need.

Shooting high magnifications at apertures wider than f/2.8 would produce incredibly ridiculously shallow DOF. Since macros need DOF (i.e. stopping down), there is no reason to make a "fast" macro other than to help with focusing.

[Loupey]

Ron, simply put, macros come in three flavors: short (50mm~60mm), medium (80mm~105mm), and long (150mm~200mm).

Each has its own merits. There are a lot of variables as to when each is "better" than the others - many of these have already been thoughtfully discussed by others here.

[Loupey]

The small sensor higher end PS will always have better DOF at the same framing comparted to a DX or FX sensor DSLR camera, due to the shorter focal length of the PS lens.

Keep in mind that the shorter focal lengths of the compacts are relative to the small size of the imaging sensors.

PS cameras typically have lenses in the 7mm~14mm range. So the effect can be replicated if you put a fisheye lens on an SLR and take a PS section crop of the image. One can then see why it is that one must get so close with a PS to get a decent subject size - and why the angle of view differs.

Oh, that brings up the fact that any focal length can be used for macros. I've used 17mm (on dSLR) up to 600mm. Knowing how and when to use the tools available to you is the "black art" of shooting macros

[freygr]

I sure hope someone figures this out 'cuz I'm totally in the dark but my amateur common sense says that f/whatever has the same dof, no matter which lens its in.

No the focal length and aperture BOTH determine the DOF. Check out this page link: http://www.cambridgeincolour.com/tut...h-of-field.htm

At the bottom of the page is a DOF calculator.

[freygr]

Ron Kruger, If you going to get a PS for micro work just remember you need manual focus and aperture priority settings at a minimum! Finding PS with manual controls is going to hard to do as those are options which are not being put in PS anymore.

This link is for movie makers but it shows the DOF and lens focal length relationship: http://www.mediachance.com/dvdlab/dof/index.htm

and this link is for 35mm film: http://www.tutorial9.net/photography...n-photography/

If you have a Palm device check out this download: http://dofmaster.com/download_le.html

[Sushigaijin]

Laws of physics, as concerned to macro photographers.

so that for a given magnification, DOF is independent of focal length. Stated otherwise, for the same subject magnification, all focal lengths give approximately the same DOF. This statement is true only when the subject distance is small in comparison with the hyperfocal distance, however.

Source, under "close up"

http://en.wikipedia.org/wiki/Depth_of_field

So lets recap: A fast lens only gathers more light when it is stopped wider than a slow lens, and macro photography depth of field is governed by sensor size, magnification, and aperture only...not focal length. We don't have to worry about hyperfocal distance because macros are usually telephotos. A 200mm macro lens' hyperfocal distance at f/8 and 200mm is something like 425 feet. I don't think we're going to be taking too many macro shots at 425 feet. This is also why telephotos all perform similarly at high magnification - the difference in DoF between a 100mm lens and a 400mm lens is negligable at most reasonable working distances.

Oh, and here's a quote from Freygr's link for moviemakers concerning DoF:

On the image above we use same three cameras, all f/2.8 and each moved further back and zoomed-in so the subject appear the same on each viewfinder. The DOF doesn't change, because it doesn't depend on the focal-length (opposite what many people think). It depends only on F-stop (aperture) and that stays the same. However, thanks to the perspective, longer distance from object also virtually shortens the DOF. Zooming-in may look like it produced shallower DOF but any other distances are shortened as well so the image is loosing its depth.


Edit: OOOh almost forgot, I thought of this on the way to work tonight...The reason that macro lenses often have magnification scales drawn on them is so that you can figure DoF easily at a given F/stop...

[Ron Kruger]

Thanks, Frey. Good link.
Though I admitted I was wrong about how faster lenses work, I have a good understanding of DOF. One new and interesting thing I did learn from this article, however, was about "distribution of depth of field," and how that varies with focal length.
The chart, for instance, shows a wide variance between the in-front and behind range of "acceptable focus" between short and long focal lengths. Very interesting.
Loupey makes an excellent point as well about sensor size on P&S cameras, so I'm probably going to settle on Pentax's 35mm, f/2.8 macro (which also will have many uses in my non-macro shooting). And, because 35mm in digital is equal to about 50mm in film, I should be able to maintain the same distance from the subject as I've found acceptable with 50mm film cameras. Right?
I've always thought that the best way to focus macro is upon the front edge of the subject, but according to the chart listed (I'm pretty certain the chart was for film focal lengths), 50mm affords the most evenly distributed acceptable focus front and rear, with only slighter more acceptable focus behind than in front of the subject, so focusing on the front edge always leaves some wasted space of acceptable focus in front of the main subject and what I want to do is capture as much of the subject as possible in focus.
I had a certain procedure I developed for shooting macro: Because the focus is so critical, and the DOF so narrow, I developed a habit of sort of bracketing my focus. Once I got the focus where it seemed clearest on the front edge, I would snap a shot, move my head back just slightly without touching the focus ring. Snap another shot. Move my head just slightly again. Snap another shot.
Then I'd settle again on what appeared to be the sharpest focus, snap, move slightly closer, snap, move closer, snap.
That way I always came out with one that was perfectly focused, though I couldn't remember if it was the first or the sixth shot by the time my Kodachroms came back. Since learning about the range from this article and chart, I figure it was probably the fifth or sixth shot taken when I moved my head closer and eliminated the wasted focal space in front.
So, what I plan to do now, based upon this new information, is focus on about the center of my subject and bracket my focus both ways as I did with film.

[mjs1973]

TBecause the focus is so critical, and the DOF so narrow, I developed a habit of sort of bracketing my focus. Once I got the focus where it seemed clearest on the front edge, I would snap a shot, move my head back just slightly without touching the focus ring. Snap another shot. Move my head just slightly again. Snap another shot.
Then I'd settle again on what appeared to be the sharpest focus, snap, move slightly closer, snap, move closer, snap.
That way I always came out with one that was perfectly focused, though I couldn't remember if it was the first or the sixth shot by the time my Kodachroms came back. Since learning about the range from this article and chart, I figure it was probably the fifth or sixth shot taken when I moved my head closer and eliminated the wasted focal space in front.
So, what I plan to do now, based upon this new information, is focus on about the center of my subject and bracket my focus both ways as I did with film.

Ron, there are programs out there that can combine all of these "bracketed" images to increase your DOF. There is a program called Helicon Focus that does a very nice job of this. Photoshop CS4 also has this feature in it but I can't get it to work on my machine.

Here is a link to a thread that I posted a while back showing some images that I used the Heliocn Focus software on.

Helicon Focus, it's like HDR for DOF

[Sushigaijin]

I've seen some really neat stacked-focus shots. One person regularly stacks 100+ frames into a single shot!!

And Ron, standard focus always places ~ %30/70 front/back depth of field. So for any given depth of field, %30 will be in the foreground and %70 in the background. I'm not totally sure if this is what you are talking about now, but it is an industry standard and has been around a long time...That applies to all focal lengths, all depth of fields (except hyperfocal, where everything is sharp from half the hyperfocal distance to infinity)

[Ron Kruger]

Thanks, Eric, but you might what to check out the link Frey posted.
And, thanks a bunch, Mike. I'm going to have to check out Helicon, and Outdoor Photographer too.
Not long ago I sent a query to Popular Photographer. The editor liked the story idea, but wanted to see the illustrations first. Makes sense. But, because they only paid, if I remember right, $250 tops for articles and NOTHING extra for pix, I didn't send him my best stuff. He said all the pix were really good, but they didn't make him go WOW.
Normally, I don't talk back to editors, but I did email this one back because I was sure I'd never deal with them again, and I explained that I can get at least four times what they expected to pay for "WOW" pictures, and don't have to write a story as well. Such is this business.

[Sushigaijin]

Hi Ron, I did check out Frey's link...the only thing I could find in it about Depth of field distribution is this line:

It’s important to know that the depth of field is greater behind the object than in front of it. If you want to photograph, let’s say 20 kids standing in a line, and you want as many of them as possible to be in focus, but you’re unable to have a small aperture, you should focus on the 6th-7th kid in line, which would balance the field of focus about right (depending on your distance to the kids). If you would focus on the 10th kid, that is the one in the middle, the first few kids would be more out of focus than the kids at the back of the line.

Which says exactly what I said: 30/70. Well, it actually says 6/14, but the ratio is the same. If there's something I'm missing, post a quote please!!

Oh yeah, you can also double check the 30/70 rule by using the depth of field chart on older manual aperture lenses. They are usually marked with a scale. You can see that the distance becomes more compressed as the focus extends towards infinity, at a rate that equates to 30/70.

[Sushigaijin]

The thing that a 50mm "normal" lens DOES do is eliminates the perspective distortion that you get in wide angle and telephoto lenses.

Here's a hypothetical, given the same frame, composed with the subject at the same magnification - so a full body shot of a person in the field, with a bench about a foot in front of them, trees 20 feet behind, and mountains in the background.

Behind and in front of the subject, the rest of the things caught in the frame will relate to each other the same way that the eye sees; the trees will look the correct distance apart, the mountains in the background will look just as far away as they really are, and the bench in the foreground will still look the correct distance from the subject.

A wide angle lens sees WIDER than the eye can, so things fall away faster. The bench in the foreground would look farther away from the subject. The trees would look farther from the subject, and the mountains would be VERY small and look very far away...and, you will get a lot more background included...what used to be one mountain might now include the neighboring mountain.

A telephoto does the opposite, it's even called telephoto compression. the bench would look like it's within inches of the subject, the subject would look flat and two dimensional, and you might just get the brown on treetrunks in the background because the angle of view wouldn't include the mountains or the treetops.

Now, someone's going to say that the trees are going to be OOF because you're using a telephoto with a smaller DoF than a wide angle, even if you use the same F/stop. And the short answer is YES, that's true, to some extent....the wide angle's hyperfocal distance is probably only four feet or so from the sensor, so it is working with a different set of rules than the telephoto whose hyperfocal distance is about 200 feet. Since the wide angle is already at hyperfocal distance, everything in the frame will be in focus (from 1/2 hyperfocal distance to infinity). The telephoto, and possibly the normal (50mm) lens, are not going to be close to hyperfocal distance so the depth of field will be determined by sensor size, aperture, and magnification rather than focal length. If you have a wide angle that will focus very close, you can get the same DoF as a 300mm lens, same aperture, same framing...the trick is finding a subject that can be shot close enough to the sensor plane and away from hyperfocal distance. (small subjects, like macros).

[Grandpaw]

Not long ago I sent a query to Popular Photographer. The editor liked the story idea, but wanted to see the illustrations first. Makes sense. But, because they only paid, if I remember right, $250 tops for articles and NOTHING extra for pix, I didn't send him my best stuff. He said all the pix were really good, but they didn't make him go WOW.
Normally, I don't talk back to editors, but I did email this one back because I was sure I'd never deal with them again, and I explained that I can get at least four times what they expected to pay for "WOW" pictures, and don't have to write a story as well. Such is this business.

Ron, you say that you won't post your best stuff here and you didn't send this magazine your best stuff, I am curious and as to where "YOUR BEST" or "WOW STUFF" ends up at and where we can see it. You say you don't have a website like most pros and a lot of amateur photographers do so just where can we see your work that has been photographed and published over the last thirty plus years that you talk about? Jeff

[Ron Kruger]

Graphs don't copy, Eric, but you should be able to get it from this:
"Even though the total depth of field is virtually constant, the fraction of the depth of field which is in front of and behind the focus distance does change with focal length, as demonstrated below:

Distribution of the Depth of Field
Focal Length (mm) Rear Front
10 70.2 % 29.8 %
20 60.1 % 39.9 %
50 54.0 % 46.0 %
100 52.0 % 48.0 %
200 51.0 % 49.0 %
400 50.5 % 49.5 %

[Sushigaijin]

Oh, I see what you are looking at now.

There's a long and short to that scenario.

The ratio of the depth of field varies in relation to the focal distance, as well as focal length.

For most common shooting distances, where depth of field is a consideration, the ratio falls at (or close to) 3:7. This is at normal magnifications (not macro) and before lenses hit hyperfocal distance...obviously at hyperfocal distance the ratio is more like 1:9 for a wide lens and maybe still 3:7 for a telephoto. The closer the subject is to the camera, the more the ratio moves towards front focus. As the subject is moved farther from the camera, the ratio moves towards back focus. This does vary from focal length to focal length, but rest assured that in most shooting situations it is 3:7. This is where the common suggestion to shoot "a third into the frame" comes from.

At super high macro magnifications, it can be 7:3 or higher...but that's well on the other side of 1:1 magnification.