Macro Lens Questions?

[Ron Kruger]

I've shot a good number of macro images over the years, but never gave the differences in macro lenses much thought. In fact, this is the first time in 30 years that I've been without a macro lens and I'm considering buying one.
I'm not talking about brands here, but focal lengths and general aspects.
What are the differences in the magnification between the various focal lengths, both fixed and variable?
Would I get greater magnification with a 100mm than with a 50mm?
Are fixed focal lengths generally better for a macro?
Like general photography, do faster lenses give better DOF to macro?

[mjs1973]

Good questions Ron. From what I have seen, most true macro lenses are fixed focal length, but I'm sure there are some zooms as well. The term "macro" seems to have turned into a marketing buzz word for lens makers to slap onto a lens that will focus closer than other lenses. A lot of times a lens that says macro on it, is not a true macro lens. A true macro lens will give you a 1:1 ratio (life size). The optics on true macro lenses is generally very good. When shooting at life size, you are going to have a pretty shallow DOF. If you want a lot of DOF, you're going to want to stop down, so I don't know if having a fast lens is really all that important. The big plus for a fast lens IMO is that you will get a much brighter image in the VF and it will make it easier to focus.

As far as the focal length goes, it really depends on your style, and what you want to do. A macro lens that gives you a 1:1 life size image is going to be the same whether it's on a 50mm, 100mm or 200mm lens. What is going to change is how close you have to be to that image to get that 1:1 ratio. To get a life size image with a 50mm lens, you're going to have to be a lot closer than you would if you used a 200mm lens. If you want to really get a tight shot on your subject, and get rid of FG & BG elements, a longer lens would be better. If you like to show a wider view of the subject, a shorter lens would be a better choice. Along lens will give you a greater working distance when it comes to shooting things like insects or small critters that you can't get real close to.

This article has some good info on choosing a macro lens.

http://www.outdoorphotographer.com/h...our-macro.html

[Sushigaijin]

Mike pretty much covered the field.

I'd consider bokeh quality to be just as important as sharpness in a macro lens because MOST (by pixel volume) of your shots will be OOF. Shorter lenses often have busier bokeh than long lenses...

Focal length should probably be determined by subject. For me, a 100mm (=) made the most sense because I care most about shooting snakes. I want to be close enough to wrangle the subject, far away enough to not spook it, and have enough magnification to get a head-shot or a full-body. Any shorter would force me to be too-close, any longer would just give me eyeball shots.

I'm now considering a 300 (=) because it will give me a little more working distance with bugs. Where I need to be hands-on with snakes, the bugs just get mad if I try to move them

I don't think a 200 (=) would have been a good all-rounder, I do think that I'd rather have two lenses than one.

[Ron Kruger]

Thanks for the input, both of you.
Most of what I've owned have been 50mm macros, but I did have a 35-70 Nikor macro, and although they were good lenses, I was thinking a really fast macro in 50mm (I'm familiar with the macro distance) would give me more light-gathering capabilities, and therefor more DOF. I need to get a standard lens to replace the cheap kit lens that came with my camera, anyway, but wasn't sure I wanted a 35mm or a 50mm or a 14-55mm. The link MJ provided convinced me to go with the 50mm. (For maximum quality and light-gathering capabilities, with this switch from Nikon film to Pentax digital, I've decided to go with all fixed lenses and just move my lazy bleep back and forth.)
DOF, to me, is the biggest problem with macro, because I'm concerned with making illustrations, not "art," and years ago I began carrying a hand mirror in my camera bag, and when I wanted a macro, I'd hold it off to the side so that the sun reflected directly upon my subject, flooding it with light and giving me enough light for a better appature (more DOF) and still enough shutter speed for hand-held.
Macro before was sort of a toy, an accessory I rarely used, but this time I want to create some really stunning macros.

[OldClicker]

Now you're in trouble. Macros are more addictive than birds! - TF

[Ron Kruger]

I was shopping around a bit. Pentax doesn't make a macro faster than f2.8, but I did find a Ziess 2.0 for over a grand, and a pretty fast Sigma macro for a little over $300.
Ziess is some of the best glass in the world, but I don't know that I can justify that much for a macro lens. Has anyone here experience with the Sigma macro?

[freygr]

With Micro Photography the DOF is a problem. The faster the lens is the smaller the DOF will be. To get good DOF you going to be stopped down to f 11 or greater. The shorter the focal length of the lens is the greater the DOF you will get.

[Sushigaijin]

The sigma macros are really good buys.

The 150/2.8 is widely regarded as very sharp.

The 105/2.8 is also regarded as very sharp, but it's not the flagship build quality that the 150 is.

The tamron 90mm is pretty popular among herpers, supposedly it is as sharp or sharper than the nikkor equivalent. I don't know if they make it in pentax mount, but it's worth looking at.

Personally I wouldn't worry that much about a faster max aperture than f/2.8. That's plenty of light gathering for a bright viewfinder. In the end the max aperture isn't all that important since you'll be stopping WAY down to get good DoF.

[Sushigaijin]

The shorter the focal length of the lens is the greater the DOF you will get.

This isn't true. Focal length doesn't have anything to do with depth of field, except when the subject distance is very close to hyperfocal distance. It's especially inapplicable at macro distances.

At 1:1 magnification, F/2.8 will ALWAYS give you the exact same DoF. Same for F/4, F/8, F/11, F/22 etc. Doesn't matter if the lens is 1000mm or 100mm. This is why F/stop is expressed as a ratio instead of an absolute aperture size. The same is true for less magnification also (except near hyperfocal distance). Same magnification, same F/stop, same DoF. The only thing that changes this rule is format size; the larger the format, the less DoF at any given aperture.

At hyperfocal distance (and near hyperfocal distance) the focal length effects the DoF, but not nearly as much as we are led to believe by the simplified interweb DoF tutorials. Focal length is a convenient way to think about DoF when shooting at low magnification levels but it is never applicable to very high magnification where DoF is critical and also a sliver.

Macro focal length mostly controls Field of View, which in turn effects how out-of-focus the out-of-focus parts are. OOF areas in with a wider FoV, like a 50mm lens, are not compressed and will look less OOF than the exact same framing at 200mm. Assuming the F/stop is the same, magnification is the same...you would of course have to step back to get the same magnification with a 200mm vs. a 50mm.

[mjs1973]

Ron,
Have you considered using extension tubes to turn your current lenses into macro lenses? I have an inexpensive set that I use on many different lenses to help me get closer. I will admit though, that I have the most fun with them when I combine them with my macro lens to get REALLY close.

[Ron Kruger]

Thanks for all the feedback and advice.
Mike, I have considered extension tubes to use with my 200mm f2.8. I tried them years ago, and decided the quality wasn’t acceptable, but Loupey’s experiments have changed my mind. Tubes would be a good way to get what I want, until I can afford a high-quality macro.
The only thing posted that I don’t agree with is some of the things said about DOF. Within a certain focal length, the faster the lens the wider the DOF for particular shutter speeds. If I want f/11 or higher for good DOF, I can shoot it with a much higher shutter speed using an f/2.8 lens, for example, than with an f/4. The light gathering capabilities of a lens doesn’t just affect the bottom end of the spectrum, but every stop throughout the range. Plus a faster lens allows you to use a lower ISO for better quality.
Faster lens: better DOF and better overall quality.

[Sushigaijin]

The only thing posted that I don’t agree with is some of the things said about DOF. Within a certain focal length, the faster the lens the wider the DOF for particular shutter speeds. If I want f/11 or higher for good DOF, I can shoot it with a much higher shutter speed using an f/2.8 lens, for example, than with an f/4. The light gathering capabilities of a lens doesn’t just affect the bottom end of the spectrum, but every stop throughout the range.
Faster lens: better DOF

Tubes are awesome, and at about $100 they are the best deal out there for macro on a shoestring.

Maximum aperture does not in any way effect the other apertures.

F/11 is f/11, regardless of focal length, max aperture, or magnification. The only elements that effect depth of field are magnification, f/stop and format (4/3, aps, etc), except when close to hyperfocal distance when focal length plays too. F/11 is the exact same exposure on ANY camera, any lens, and any focal length...Assuming of course same subject luminance.

You can use any ASA/ISO camera/lens combination and come up with the exact same exposure in the same circumstances. Try it yourself, it isn't a difficult test and it is pretty easy to do in real world situations. F/11 at 1/30s ISO100 will ALWAYS be exactly that, and at 1:1 magnification it will ALWAYS have the same DoF. With any camera, any lens...in the same sensor format, of course.

[Ron Kruger]

Thanks, Eric. I don't really disagree with that, but...
What I'm trying to say is that a f2.8 lens at f/11 and ISO100 will let me shoot (guess guessing) at 1/250 sec., while an f/4 only allows 1/30 sec. under the same lighting conditions, which permits the shot to be taken hand-held and ensures a sharper image. That's what I mean by: "The light gathering capabilities of a lens doesn’t just affect the bottom end of the spectrum, but every stop throughout the range." It's all about available light and how much of that light enters through the lens.
The faster the lens the more latitude I have for using a f/11 or higher appature under various light conditions and still be able to use a higher shutter speed for sharpness.
The lower the light the more a fast lens pays off, especially if I'm shooting living creatures that might move slightly.
I've come to these conclusions from experience, and compensated before for not having a fast macro lens by flooding the area with sunlight by using a hand-held mirror to greatly increase f-stop, shutter speed--and DOF.
Now, if I'm wrong about all this, I'll gladly accept it being explained to me, and I'll happily buy an f/4 for a couple of hundred dollars, instead of a f/2.0 for a thousand dollars.

[freygr]

This isn't true. Focal length doesn't have anything to do with depth of field, except when the subject distance is very close to hyperfocal distance. It's especially inapplicable at macro distances.

At 1:1 magnification, F/2.8 will ALWAYS give you the exact same DoF. Same for F/4, F/8, F/11, F/22 etc. Doesn't matter if the lens is 1000mm or 100mm. This is why F/stop is expressed as a ratio instead of an absolute aperture size. The same is true for less magnification also (except near hyperfocal distance). Same magnification, same F/stop, same DoF. The only thing that changes this rule is format size; the larger the format, the less DoF at any given aperture.

At hyperfocal distance (and near hyperfocal distance) the focal length effects the DoF, but not nearly as much as we are led to believe by the simplified interweb DoF tutorials. Focal length is a convenient way to think about DoF when shooting at low magnification levels but it is never applicable to very high magnification where DoF is critical and also a sliver.

Macro focal length mostly controls Field of View, which in turn effects how out-of-focus the out-of-focus parts are. OOF areas in with a wider FoV, like a 50mm lens, are not compressed and will look less OOF than the exact same framing at 200mm. Assuming the F/stop is the same, magnification is the same...you would of course have to step back to get the same magnification with a 200mm vs. a 50mm.

I'm sorry that you don't think the laws of physics don't apply to micro photography. The shorter the lens is the more DOF it will have in micro photography distances no mater what. 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.

[freygr]

Thanks, Eric. I don't really disagree with that, but...
What I'm trying to say is that a f2.8 lens at f/11 and ISO100 will let me shoot (guess guessing) at 1/250 sec., while an f/4 only allows 1/30 sec. under the same lighting conditions, which permits the shot to be taken hand-held and ensures a sharper image. That's what I mean by: "The light gathering capabilities of a lens doesn’t just affect the bottom end of the spectrum, but every stop throughout the range." It's all about available light and how much of that light enters through the lens.
The faster the lens the more latitude I have for using a f/11 or higher appature under various light conditions and still be able to use a higher shutter speed for sharpness.
The lower the light the more a fast lens pays off, especially if I'm shooting living creatures that might move slightly.
I've come to these conclusions from experience, and compensated before for not having a fast macro lens by flooding the area with sunlight by using a hand-held mirror to greatly increase f-stop, shutter speed--and DOF.
Now, if I'm wrong about all this, I'll gladly accept it being explained to me, and I'll happily buy an f/4 for a couple of hundred dollars, instead of a f/2.0 for a thousand dollars.

I don't see how an F2.8 lens is not faster than a F4 lens unless there is a problem with one of the lenses.

[Ron Kruger]

Good point, FRY:
"I'm sorry that you don't think the laws of physics don't apply to micro photography. The shorter the lens is the more DOF it will have in micro photography distances no mater what. 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."
Another thing I have considered is buying a little P&S Sony specifically for macro work. I can get a good one for less than the cost of a good DSLR lens, and I've seen some amazing results from P&S macros on other sites.
As long as I've got a megapixel range of 8 or above, the only problem I can image is having to get so close to the subject that I might block some of the light.
What do you think?

[Grandpaw]

Thanks, Eric. I don't really disagree with that, but...
What I'm trying to say is that a f2.8 lens at f/11 and ISO100 will let me shoot (guess guessing) at 1/250 sec., while an f/4 only allows 1/30 sec. under the same lighting conditions, which permits the shot to be taken hand-held and ensures a sharper image. That's what I mean by: "The light gathering capabilities of a lens doesn’t just affect the bottom end of the spectrum, but every stop throughout the range." It's all about available light and how much of that light enters through the lens.
The faster the lens the more latitude I have for using a f/11 or higher appature under various light conditions and still be able to use a higher shutter speed for sharpness.
The lower the light the more a fast lens pays off, especially if I'm shooting living creatures that might move slightly.
I've come to these conclusions from experience, and compensated before for not having a fast macro lens by flooding the area with sunlight by using a hand-held mirror to greatly increase f-stop, shutter speed--and DOF.
Now, if I'm wrong about all this, I'll gladly accept it being explained to me, and I'll happily buy an f/4 for a couple of hundred dollars, instead of a f/2.0 for a thousand dollars.

Ron, if you are shooting in the F11 range on a F2.8 lens or an F4.0 lens it is the same thing. I see no advantage of one over the other as far as DOF. F11 will use the same ISO and shutter speed settings with either lens. The faster lens will only come into play when you need more light and you pass the ability of the slower lens. If you are using the smaller openings to get greater DOF the speed of the lens won't come into play, Jeff

[OldClicker]

It is my understanding that a 300mm f/4 and a 300mm f/2.8 will provide the same amount of light and require the same shutter speed unless you go below f/4. This is why we use f-stops instead of actual aperture size. - TF

[Frog]

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.

[Ron Kruger]

We certianly have a wide range of understandings of DOF, as well as how shutter speeds and f-stops relate to each other.
This is the way I see it, without interjecting the variables of focal length, ISO, etc:
The higher the number, or smaller the appature, the wider the depth of field, regardless of the focal length. Admittedly the DOF on a longer lens is going to be narrower than for a short lens, but the same principle applies to all.
Apparture and shutter speed are like a teeter tater: Raise one side, and the other has to go down, or vice versa, to achieve proper exposure.
The range of the teeter tater is determined by the light gathering capabilities of the lens. If the lens is fast, it will permit a higher shutter speed for the same f-stop reading than a slower lens, simply because it is gathering more light to work with. That's why fast lenses give us much sharper images than slow lenses, and I don't see why the same principles wouldn't apply to macro.
I'm not saying that a faster lens has any more DOF at f/11 than a slower lens, just that when the lens is faster, you can achive a much higher f-stop for a given shutter speed, and thereby have more choices as to bumping the f-stop for more DOF or bumping the shutter speed for more clearity.

[OldClicker]

"If the lens is fast, it will permit a higher shutter speed for the same f-stop reading than a slower lens, simply because it is gathering more light to work with. That's why fast lenses give us much sharper images than slow lenses, and I don't see why the same principles wouldn't apply to macro."

This is where I disagree. The f/2.8 lens does NOT get more light than the f/4 lens unless you set it at f/2.8 (or less than f/4). The ability to go down to f/2.8 is what makes it 'faster'.

Also, a 'fast' lens is a lot more expensive than a slower one and usually has much better optics which may give better sharpness.

TF

[Ron Kruger]

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.

[Ron Kruger]

Good point, Clicker: "Also, a 'fast' lens is a lot more expensive than a slower one and usually has much better optics which may give better sharpness."
When one buys a fast lens, along with better light-gathering capabilities, you're also getting better glass, more finely ground and better coated. Agreed.
But isn't it the glass itself that lets in more light, and wouldn't that let in more light through the range of the f-stops?

[Ron Kruger]

An appature is the size of the opening that allows light through, designated by the f-stop scale. The size of that opening per f-stop desigination doesn't change between different cameras or lenses. The amount of light, however, reaching the appature is determined by the quality of the glass in the lens, or the lens' light-gathering capabilities.
If you have better glass, letting in more light, it doesn't just let in more light at f2.8 appature, but at f11 as well.

[Loupey]

If you have better glass, letting in more light, it doesn't just let in more light at f2.8 appature, but at f11 as well.

Well, no.

Ron, as Sushigaijin, Grandpaw, and OldClicker have been trying to tell you, f/11 is f/11 is f/11.

Consider this thought experiment: you have two lenses - a 200mm f/1.8 and a 200mm f/4

Set each at f/11 - the SAME AMOUNT OF LIGHT will come through. The exact same shutter speed will be used.

Otherwise, utter chaos will envelop the universe.