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01-22-2010, 11:40 PM   #1
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How do I know if a lens is a good macro

How do I know if a lens is a good macro other than if it says macro. What specs am I looking for printed on the lens. As I understand some just zoom close for focusing but some can just focus closer.

Sorry as Im sure this is a newbie question

01-22-2010, 11:50 PM   #2
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QuoteOriginally posted by MikesChevelle Quote
How do I know if a lens is a good macro other than if it says macro. What specs am I looking for printed on the lens. As I understand some just zoom close for focusing but some can just focus closer.

Sorry as Im sure this is a newbie question
Macro lenses will focus closer, and project the FOV onto the sensor/film at a ratio, usually described as 1:1, 1:2 etc. This is not the same as aperture, it's the ratio between the subject size and it's size as projected onto the sensor/film.

1:1 means a 1cm diameter circle is projected onto the sensor as a 1cm diameter circle.

1:2 means a 1cm diameter circle is projected onto the sensor as a 5mm diameter circle.

Etc.

ETA: There's actually a simple explanation here: http://www.tamron.com/lenses/fundamentals.asp just past the 1/2 mark down the page.
01-23-2010, 12:03 AM   #3
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If it's a zoom, it's not a true Macro.
A true macro is considered as one that gives you magnification of 1:2 or larger. Generally speaking you should only consider magnification of 1:1 . That means the subject will be life size in the frame at minimum focusing distance.

I don't think there is a bad macro, they are all pretty well designed and engineered.
Macros range from 35mm to 200mm and generally go up in price accordingly, the most common FL's are 35, 50, 70, 90, 100 and 105. When deciding on a macro it's good to know what you are planning on shooting mostly. If you want to do insects you probably don't want a 35mm, the smaller the focal length the closer the minimum focusing distance. So a 35mm would be good for static objects and things like flowers.
Probably the most popular are the 100/105 FL's because they are in the middle of the range and so can cover most eventualities.
01-23-2010, 06:24 AM   #4
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The problem really is that some of the lens companies have decided to refer to the ability to focus close with a lens as a "macro capability." Sigma in particular does this with their zooms, but they aren't true macro lenses and often they are softer when focusing close than at a distance.

As Gary says, with a true macro prime, the question is really the focal length. A longer focal length is more useful when shooting insects, but otherwise the photos you take will look exactly the same, with the same depth of field, etc. The difference is that with a 35mm macro, you have to be 3 inches a way from the thing your shooting.

01-23-2010, 06:34 AM   #5
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If it isn't a zoom and is called a macro you can be sure it is a good macro.
After that, it's a matter of deciding focal length, as this determines working distance.
Some less expensive macro lenses focus to 1:2 reproduction ratio. This does not mean they are not good macro lenses, but the manufacturer has chosen to put a short helicoid on and you will need an extension tube to hit 1:1.

I have yet to see a 1:1 macro lens that isn't a good macro lens, though some of them leave a bit to be desired at normal photography distances.
01-23-2010, 07:41 AM   #6
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True macros and AF

For doing true macros you don't need auto focus, often you are using a focusing rail to get the correct focus point so consider the older MF lenses they are a bargain.

Also from personal experience buy the longest macro lens you can afford. DOF is determined by apature not focal length in the macro world so you only gain benfits, i.e working distance (well at the expense of portability).
01-23-2010, 07:41 AM   #7
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My 50 that I got says 1:2 on it yet I do not feel that it has much marco capabilities. I cant get much closer than about 2 and a half feet.
01-23-2010, 08:31 AM   #8
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QuoteOriginally posted by MikesChevelle Quote
My 50 that I got says 1:2 on it yet I do not feel that it has much marco capabilities. I cant get much closer than about 2 and a half feet.
It will give you 1/2 life size.
This is typical of 50mm macro lenses.
Pick up a set of extension tubes to add to it's capablities.
If it's the Pentax 50/4 macro, it is a very good lens indeed at close distances, a little less good at distances ~10 feet or greater.
Don't think in terms of how close the lens will focus, this has no bearing whatsoever on whether or not it is a decent macro lens.
As an example, one afternoon we had a flock of either Monarch or Ambassador butterflies come through our yard.
I stuck a bunch of extension tubes onto my 300mm lens because they were being very flitty and I couldn't get close.
I found my best working distance to be ~15 feet, and with the rig I had set up, this gave me good shots of entire butterflies.

01-23-2010, 08:36 AM   #9
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Is that not the max aperture (lowest number)? From your signature, I assume it is but I might be wrong. Is it this one?

Last edited by sterretje; 01-23-2010 at 08:40 AM. Reason: Added url
01-23-2010, 09:01 AM   #10
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QuoteOriginally posted by sterretje Quote
Is that not the max aperture (lowest number)? From your signature, I assume it is but I might be wrong. Is it this one?
Good call. I bet his 50 is the f/2, not the f/4 macro.
If it is the macro, it will be either an f/2.8 or f/4 and will have macro indicated on the lens bezel.
01-23-2010, 03:04 PM   #11
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QuoteOriginally posted by Damn Brit Quote
If it's a zoom, it's not a true Macro.
A true macro is considered as one that gives you magnification of 1:2 or larger. Generally speaking you should only consider magnification of 1:1 . That means the subject will be life size in the frame at minimum focusing distance.

I don't think there is a bad macro, they are all pretty well designed and engineered.
Macros range from 35mm to 200mm and generally go up in price accordingly, the most common FL's are 35, 50, 70, 90, 100 and 105. When deciding on a macro it's good to know what you are planning on shooting mostly. If you want to do insects you probably don't want a 35mm, the smaller the focal length the closer the minimum focusing distance. So a 35mm would be good for static objects and things like flowers.
Probably the most popular are the 100/105 FL's because they are in the middle of the range and so can cover most eventualities.
I quoted this because that's the advice I would give. Zoom lenses with a close focus ability are just more flexibile zoom lenses, not really macro lenses. They don't really operate in the same predictable way that "true" macro lenses do.

With a real macro lens, you can start with your subject and work out what lens specs you need from there. Say you need to take a photo of a US penny. It's just a little bigger than the camera's sensor, so you want almost 1:1 magnification. It's not going to get scared if you get close, so you can go with a short focal length like 35mm. Longer focal lengths will make it easier to take the photo without your shadow looming over it, or use a flash. I could go on, but basically all your choices are guided by the subjects you choose.

It is a little confusing at first, because at times it seems like the opposite of how lenses work in non-macro situations. Here are some example photos that show some of what I'm explaining. In this first photo, I used a Tamron 28-300mm "macro" superzoom. I set it to 300mm and got as close as I could to the subject, the mirror from a Pentax SF1 film camera. I used f16 for decent depth of field.



You may think "300mm, that sounds like everything I'd ever need". But 300mm in this case is not a useful measure of macro ability. Magnification is everything. The next photo is the same subject and f-stop, as close as I could get the lens to focus:



For that photo, I used a Pentax-M 50mm f4 Macro, capable of 1:2 or half lifesize magnification. Here's another photo even closer:



That's with a Pentax-FA 35mm lens and a 25mm extension tube. I'm not sure what the magnification ratio works out to be. Working distance was almost touching the front element of the lens.
01-23-2010, 04:08 PM   #12
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QuoteOriginally posted by sterretje Quote
Is that not the max aperture (lowest number)? From your signature, I assume it is but I might be wrong. Is it this one?
That be her. I guess coming from the world of digital point and shoot, I am use to being able to get really close to a static object and having the ability to get the image in focus
01-23-2010, 04:11 PM   #13
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So if my 1:2 is indeed the ap (which it is) How am I supposed to know by looking at the lens if it has good macro cap?
01-23-2010, 04:13 PM   #14
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Nevermind, just realize I can look on the lense and the focus is marked by distance. Mine is 1.5 feet min
01-23-2010, 09:33 PM   #15
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Mike -got 2 questions for ya
1) what do you intend to shoot with a macro lens , let us know and maybe we can give a few suggestions of specific lenses to look for, your price range would help here too.
2) Whats in the Chevelle for a drive train?
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