macro lens ratio question

[PEACHMAN]

I am trying to understand Macro lens work...I don't seem to get the ratio thing...It seems the perfered for macro is 1:1...I assumed this means a prime lens? I also assumed the magnification ratio was arrived at by dividing the long focal length by the short of a specific lens..ie a 70-200 would be 200 divided by 70...this appears to be a wrong assumtion as the division equals 2.85 , where as the lens is rated as 1:3.9 ??? anybody know where I can find some good reading to understand this???? (I already tried SEARCH here..) and am I correct in assuming the 1:1 ratio is in fact perfered?

[basroil]

the magnification is always given as the maximum magnification of the lens. @ 1.4m, the canon 70-200 @200mm has a magnification of just about 1:5 (5x smaller than real life). 200/70 is just the zoom range, which has nothing to do with manification. 1:1 or a number like 5:1 is better than 1:5 (basically 5 is better than 1/5). hope that's easier to understand.

:quick edit: all magnification ratios are given as the image size on a 35mm film compared to the image size in real life. crop bodies screw up the ratio quite a bit, so don't bother figuring out the corrected ratio unless you want a headach first.

[J Rabin]

Peachman:
"If" I understand your question, the lens manufacturer published ratio only has to do with the ratio of the size of the image on the sensor or film versus it's real size.
It has NOTHING to do with lens focal length. It's a function of the optical design of a lens. A macro lens enables us to focus closer, usually by moving rear lens elements away from the sensor/film plane.

Different focal length macro lenses affect subject working distance (and thus also angle of view, depth of field, and out of focus background blur) more than anything else.

Riccardo Polini in Italy maintains a very nice tutorial on this:
http://xoomer.alice.it/ripolini/Close_up.htm

The maximum magnification reproduction ratio is independent of the APS-C digital SLR field of view crop factor.
1x magnification, or 1:1, or life size reproduction all mean the same thing.

An APS-C dSLR does enable us to fill the frame with a higher pixel density at life size, so the same benefits accruing to telephoto APS-C sensor photography accrue to macro photography: capturing more detail. But you are NOT changing the reproduction ratio. [I've probably stated this badly, but you'll figure it out.]

"1:1 magnification is 1:1 irrespective of format. You don't get 1.6:1 by slapping a macro on a 20D as opposed to a 5D. At 1:1 a 5mm long stick will occupy 5mm of sensor no matter what format, it does not occupy 8mm on a 20D. However, what you can gain on the 20D is working distance. You can shoot an object 1.6x further away than with the 5D and get the same FOV and improved DOF as you are now shooting a smaller magnification. You will get the 1.6x magnification factor though if you made a print of an image taken of a subject using the same macro lens at the same distance on a 20D and 5D."

Jack

[basroil]

i stand corrected then... either way, most lenses are not true macros even if they say macro. and the only lens from canon i know of that has higher than 1:1 is the MP-E 65mm lens. as for 70-200, i'de assume you are talking about the 70-200 from sigma (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=435163&is=USA&addedTroughType=categoryNavigation) which is not a true macro lens, rather a closeup lens that provides 1:3.8 (.4m difference in focusing distance between the 70-200 f2.8 and sigma's "macro" gives you a big difference in magnification), which is far from the 2.8 in your calculations.

[theJingster]

not only is 1:1 magnification preferred for macro photography, but it's the actual definition. most "macro" designated lenses are not, in fact, true macro lenses. they just offer an unexpectedly closer focusing distance for its focal length but offer magnifications of 1:3.8 (ie: sigma 24-70 EX DG macro). this means that the actual object is 3.8 times larger than its picture taken at the closest focusing distance.

re: macro photography (http://en.wikipedia.org/wiki/Macro_photography)

[YosemiteJunkie]

am I correct in assuming the 1:1 ratio is in fact perfered? 1:1 is life size where 1:2 is half life size. Jump on the 1:1
That's one of the reason I love my Sigma 105. It has the 1:1

[PEACHMAN]

1:1 is life size where 1:2 is half life size. Jump on the 1:1
That's one of the reason I love my Sigma 105. It has the 1:1I must be thick, or maybe it's this Vikiden I'm taking for my back...so far the only thing I am actually comprahending is 1:1 is life size on the sensor...1:2 means it will be 1/2 size on the sensor...what I just don't get is why a lens that is 200mm has an image 1/2 the size of a 100mm lens:o...Go ahead, roll on the floor laughing at my ignorance, but trying to understand lens work has always been like trying to understand how there could be no end to the universe,,,both things give me a head ache...I will go to the threads you all have provided and try to get a better understanding of the basics here and marvel at how some of you have such a good grasp at all of this..."Viva la point and shoot",,,Thanks all, for the attempted help...I'll be back!

[ron chappel]

It's all about close focus ability.
Any lens can do 1:1 (or better) if it has the mechanical ability to focus close enough.You can experiment with this by simply holding a lens -any lens- in front of the camera.As you move it further from the camera it will focus closer and closer

So basically any lens can be made into a 'macro' lens by designing into it a longer focus throw.
Of course there is abit more to it than that -for example the proper macro lenses have their optics designed to work best at these very close distances while a normal lens is optomised more for distant subjects

[YosemiteJunkie]

I must be thick, or maybe it's this Vikiden I'm taking for my back...so far the only thing I am actually comprahending is 1:1 is life size on the sensor...1:2 means it will be 1/2 size on the sensor...what I just don't get is why a lens that is 200mm has an image 1/2 the size of a 100mm lens:o. Me either. I just know that those shots taken with my 105 is much much better than those taken with the 70-300 for macro, (both are Sigma) and that the 105 is rated at 1:1 and the other at 1:2.
I have now resolved myself to the fact that I am going to be selling the later (it's a great lens for the far reaches) and get ahold of the 70-200L then either the 16-35L or 17-40L. then the EF 300mm f/4.0L IS.
Hmmm. Can you get L fever without ever owning one yet?

[jsimon724]

True macro lenses have the ability to focus at very close distances and are designed to work well at those distances. Most are flat-field corrected, meaning if you are doing copy work (i.e. newsprint or similar) you will not have the field curvature that most lenses have and would cause the edges to appear out of focus.
Reproduction ratio refers to the size of the object you are photographing in relation to your photographic medium. Most macro lenses are 1:1 (or life-size) or 1:2 (or half life-size). For example, take a picture of a dime at 1:1 ratio, once with a film camera with slide film and then with a 1.6 crop digital. Compare the original dime to your processed slide, they will be the exact same size. View your digital file at the actual sensor size and again the dime will be the exact same size.
The only difference is that the dime takes up more of the frame in a cropped sensor than it does in a full-frame sensor or a frame of film, so it will appear larger. Reproduction ratio is the same in any medium, 1:1 is 1:1 in 35mm, medium format, sub-frame digital, or whatever.
And yes, most true macros are primes, although there are a few exceptions. Macros typically come in 50/60mm, 100/105mm, and 180/200mm ranges. Any of these can be capable of 1:1 reproduction, but the longer lenses will give you more working distance, useful for close-ups of critters.
Pick up a copy of John Shaw's "Close-ups in Nature". This will give you a good start in macro photography.

Jim

[pfogle]

The ratio is the image size on the left, which is usually taken as 1, and the size of the object you're photographing on the right.

So 1:5 means the object is five times bigger than it's image. When the object is twice as big as it's image (the image is half life size, in other words) the ratio is 1:2.

Life size, or 1:1, is the holy grail of macro - macro is usually from about 1:3 (one third life size) up to 6:1 (six times magnification). Of course, in a print or on a screen, the final magnification is much higher; the ratio only refers to the size of the image on the sensor/film.

[PEACHMAN]

This is like understanding electricity...when studying it I had this need to visulize the whole process...I did terrible at it until I just accepted the rules and applied them to the functions...then I did great...I think I will take others word for what works and apply it to my needs...I must say the thread to Polinis page is quite understandable and I'm plugging away at it..........Hey Yosemite...do you like that 70-300 sig as well as the 70-200 ? Have you had any chance to compare the two? Tried any TC's with it?

[PEACHMAN]

It's all about close focus ability.
Any lens can do 1:1 (or better) if it has the mechanical ability to focus close enough.You can experiment with this by simply holding a lens -any lens- in front of the camera.As you move it further from the camera it will focus closer and closer

So basically any lens can be made into a 'macro' lens by designing into it a longer focus throw.
Of course there is abit more to it than that -for example the proper macro lenses have their optics designed to work best at these very close distances while a normal lens is optomised more for distant subjectsHey Ron, just looked at your photo page....what are you guys doing down there...teaching horses to dance? Ridding steers from underneath? some cool shots there...!...PS, love those puppies..great shot...are they yours? What kind?.......My wife has an Ausie shepard...and my daughter has a blue Heeler....does that make us related??

[Papaw]

This thread starts with a good question that I have asked before and still don't understand and after reading this thread am even more confused.

[ron chappel]

LOL
Well as we both have dogs that DOES make us kind of related ;)
I've noticed there are dog people and non dog people with very few in between.

I think the ones on the photo.net site are from the last litter of border collies.
I may still have a couple of shots of border collie/kelpie cross pups on my dodo homepage site.
Best of all are the shots from the latest litter (just sold the last three today coincidentally :(:(:(:( ).Here are a couple of random pics -
http://members.dodo.net.au/~l8r_ron/images/pups36.jpg
http://members.dodo.net.au/~l8r_ron/images/pups11.jpg
http://members.dodo.net.au/~l8r_ron/images/pups37.jpg
http://members.dodo.net.au/~l8r_ron/images/pups40.jpg

You'll notice the addresses are the same but for the number.I actually have about 40 images there-just change the number in the web address to anything between 1 and 40 to see others if you want :)

The horses playfighting is a cool shot huh ,but it was a lucky one really.
I snapped it on the spur of the moment and it turned out way underexposed due to the bright background.Having the fill flash up didnt help.
So basically it's had truckloads of photoshop work to get it to that stage.;)

Hey i understand where you are comming from when you say you have to visualize this macro thing.I think i learn in a similar way.If i can think of good way of explaining it i'll come back and add more :)

[Dimitri_V]

This thread starts with a good question that I have asked before and still don't understand and after reading this thread am even more confused.

I totally agree here,very interesting subject.
Just got the canon 100 2.8 macro and all these things are openning a new can of worms for me.
Like peachman,completely lost and feeling daft,but i suppose i shouldn`t feel like this because every question is easy if you know the answer.

Thank you guys for the links to tutorials,i will too try to get my head around them.