Macro photography: Understanding magnification (2024)

An 18 mpx APS-c sensor would capture exactly the same image magnification as a 10 mpx.

If you make an 8 x 12 of the full frame at 300ppi, both prints would yield exactly the same magification. The 10mpx will yield an 8 x 12 at 300ppi without uprezing. To make a print from the 18mpx you will have to toss some pixels away by downrezing the file size.

The 18 mpx will yield a print up to 11 x 17 without uprezing. The 10 mpx would have to be uprezed slightly so there would be some loss of details but would yield a print of exactly the same magnification.

Beyond 11 x 17, both files will need to be uprezed to maintain 300ppi, so both files would be suffering a degradation of image quality at larger sizes.

While a higher resolution sensor might capture more detail per mm, that may not translate into more details in the final output.

Resolution of detail is a seperate charactoristic than magnification.

Dec 11, 2011permalink

Actually it does make sense! Creating an enlargement by cropping, either in post or with a smaller than full frame sensor, creates an enlargement of the subject but it does not increase the magnification. Cropping the subject, no matter how you do it, will not reveal additional detail that was not already there but increasing the magnification by projecting a larger impression of the subject onto the image plane can give you more detail...

Nov 10, 2021permalink

Larawanista

Ok I will pretend for a moment I understood the confusing magnification "rule" with respect to distance, sensor size, etc. Now back to simply trying to take good photos!

Dec 4, 2011permalink

Some may question why this information is even relevent. Well it's relevent in deciding which lens or accessories to buy to achieve the degree of magnification desired.

Once the equipment is in hand, you're not really going to think about it, your just going to use what you've got.

Of course it''s really handy to know exactly how much magnification a so called macro lens is really delivering. It might be that the so called macro lens really isn't delivering the goods. I know I've got a few of those. I never purchased them with macro in mind. If macro capability were something I was looking for in a lens then I certainly want to know exactly how much magnification the lens is really delivering before making my purchase decision.

I use a number of different close up photography tools including reversal rings, extension tubes, etc. By using the methods described in the article I can determine the exact magnification that each method is capable of delivering.

Dec 4, 2011permalink

tbcass

OK here's an analysis of the article from a former physics teacher. His use of the term magnification is misleading. True magnification only happens when the image on the sensor (or film) is greater than 1:1. When printed or viewed on screen the image is magnified in relation to the size on the film or sensor but in that case all viewed or printed images are magnified for viewing. When the resulting image as viewed is larger than life then magnification results. Other factors such as pixel count, lens quality and Monitor size have to be considered because there is the issue of effective magnification where the amount of detail retained has to be taken into account. Magnification without retaining a corresponding amount of detail is useless. Sorry to be picky but I had to get that off my chest.

Dec 3, 2011*permalink

As I mentioned in an earlier reply, in macro photography perspective is very important. Just blowing up an image shot from a distance does not give the same result as actual close up photography.

And while longer focal legnth macro lenses allow a longer working distance they do not provide the same perspective as a shorter focal legnth macro used very very close.

I always make the distiction between in camera magnification and post production magnification by refering only to the former as magnification, the latter is more appropriately described as "enlargment"

Dec 4, 2011*permalink

olyflyer

Magnification can be negative as well. 1:100 is also a magnification, just like 2:1. In the former case the magnification is 0.01 times the original size and in the later case it is two times. As a former physics teacher you should know that.

Dec 5, 2011permalink

You are confusing magnification, which is fixed at the time an image was taken, with creating an enlargement which is done after. Making the subject look larger in the frame, after the shot was taken, will not reveal additional detail that was not already in the photo. But increasing the magnification before the shutter is pressed can allow for more detail to be resolved...

Nov 10, 2021permalink

Weia

I do not use magnification, I only need to know how to measure the length of say an insect under certain standardized circ*mstances. With a Sigma 150 macro on Olympus E-3 at closest focus I have 210 pixels for a millimeter. With a 2x extender it becomes 428 pixels to a millimeter.

But now something very strange. At a holiday I did not want to carry too much so only took my 18-180. At close focus and f=180 it uses only 53 pixels to a millimeter. I bought a 5 diopter close focus lens and it became 107 pixels to a millimeter. But in the field strange things happened when focusing so I did new tests and found out I had to move backwards and to focus on infinity to have the biggest magnification! Now it is 190 pixels for a millimeter. Completely contrary to expectation, unexplicable, but very useful for identifying small insects! Of course the optical quality of the combination is not extremely good.
Just to let you know. Maybe I should buy a close focus lens for the Sigma too.

Dec 2, 2011*permalink

BenFrantzDale

You say "This relationship isn't linear, i.e. if I get a 1:4 magnification from a shooting distance of 40 cm, I won't necessarily get a magnification of 1:2 (twice that) from a shooting distance of 20cm."

That's only sort of right. You should be precise about the "shooting distance". The only sensible distance is the distance from the subject to the entrance pupil (which is almost always inside the lens). In an ideal camera in which you can change the lens power while maintaining the pinhole geometry (e.g., an adjustable-power lens at the aperture), then halving the distance from the subject to the entrance pupil will exactly double the magnification.

In reality, the details of how the lens focuses will affect things, so the distance from the projection center to the sensor may change.

PS,
The illustration at the top with the red and blue ray bundles should show an aperture. As illustrated it's beyond telecentric -- the entrance pupil is beyond infinity.

Nov 30, 2011permalink

(unknown member)

I've read similar articles before and came away understanding a portion of what was written.

This article is written so clearly and succinctly that I understand the subject a lot more clearly.

Very well conceived and written.

Thank You

Nov 30, 2011permalink

Second example: I take again a Sony A77 (24 megapixel APS-C) and a Konica-Minolta Dynax 7D (6 megapixel, APS-C).I put the same macro lens with magification 1:1 on both cameras and take a picture of the ruler at maximum magnification. I will end up with 2 pictures that show the same: 24 mm of the ruler. However, when I crop the A77 picture down to 6 megapixel, I suddenly have again 2 pictures with the same resolution of 6 megapixel, one showing 12 mm and the other 24 mm of the ruler.

Would it be a good idea to start using a kind of "35mm equivalent magnification factor" by involving the sensor size, just like is is done for the focal length? So a 0.5x lens would have a 0.75x "35mm equivalent" magnification on APS-C.

Nov 30, 2011*permalink

No, that would be a bad idea, just as using 35mm focal length equivalences is a bad idea.

Dec 1, 2011permalink

Why is this a bad idea (in both cases, so for the magnification and the focal lenght). It is common practice for the focal length everywhere to compare lenses on small sensor, 1", (micro) 4/3, APS-C and Fullframe cameras.

Dec 1, 2011*permalink

No, that is a really bad idea. As the magnification goes up the depth of field goes down, getting enough good light to expose the scene becomes more difficult (less surface area reflecting light back into the camera), and even the 1/focal length rule for hand holding a lens breaks down. Impossible to have a conversation about macro without a fixed, easy to understand, definition of what it is. The fact that you cropped a photo and can see fewer millimeters does not change the magnification.

Nov 11, 2021permalink

The whole magnification thing has become a mess. In the old days, it all just depended on the magnification factor of the lens. Now sensor size and resolution also play a role.

First example: I take a Sony A900 (24 megapixel, fullframe) and a Sony A77 (24 megapixel, APS-C). I put the same macro lens with magification 1:1 on both camera and take a picture of the ruler at maximum magnification. I will end up with 2 pictures that are both 24 megapixels, but the A900 picture shows 36 mm and the A77 picture shows 24 mm of the ruler. This should both be called 1:1 magnification?

Nov 30, 2011*permalink

Yes. The ruler method of determining magnification is based upon the size (width) of the imaging media. In your case the A900 full frame size is 36mm wide and the A77 APS-C size is 24mm. If yiou were shooting 4x5, then you would see 5 inches of ruler, 2 1/4 film? You'd see 2 1/4 of ruler....and so on.

In all these cases the ratio of the projected image size to the actual subject size is 1:1.

If you were to shoot a 1:1 image on 35mm film and then on 4x5, the size of the subject would be exactly the same on both films. The 4x5 would show much more space around the subject but the actual subject size would be identical.

Therefore a subject 10mm wide would be 10 mm wide on both the 35mm and 4x5 film. If both images were exposed on the same film, say tri x, and printed without changing the enlarger height, they would both yield images of the same size and same grain.

Things get a bit dicey with digital because of the variable in pixel counts.

Nov 30, 2011permalink

Continued...Remeber that magnification ratio is a the realtionship between the actual subject size and the size of its image at the focal plane. It make no difference what kind of media or what size media it is projected upon.

However, the charactoristics of the capture media will have an effect upon the degree to which the image can be enlarged. This is true for both film and digital. It's a matter of resolution.

The advantage with film is that even at a relatively small print size like 8x10, a super fine grain film like Tech Pan would look smoother and sharper than the same image shot of tri x.

But at 300 DPI, image shot on a 10mpx sensor would yield a print of 8x12 without interpolation, wearas the image shot with an 18mpx sensor would yield a print of 11.5 x 17.25. At 8x12, the 18mpx image would actually have to be downrezed. At that size the 10MPX image would contain as much detail as the 18mpx. But at larger sizes the 18mpx would have more details.

Nov 30, 2011permalink

Part three...if the pixel density of the full frame and APS-c frame are the same, and the full frame image was cropped to match the APS, the resulting image size would be the same.

But in your case, the pixel density of the 24mpx APS-c is greater so you would be able to get a greater degree of enlargement at 300DPI.

Remember, image magnification is the charactoristic of the lens. How big an image we can get from the captured image is the degree of enlargment, not magnification.

In a nutshell, magnification is the degree of image magnification at the focal plane and is not dependent upon the media it is projected upon. Enlargment is the degree magnification of the captured image and is dependent upon the resolution of the capture media. Makes no difference whether it's film or digital, same rules apply. The size of the media is irrelevent.

Nov 30, 2011permalink

Last words....Using the same lens at it's closest focusing distance, the size of the subject at the focal plane would be the same on both the full frame and APS-c . If the subject fills the frame at 1:1 on the APS-c camera, the full frame will capture a wider field of view and have more space around it, but the magnification will still be the same.

Macro photography is more than just a matter of magnification, it is also a matter of perspective. Just enlarging a piece of an image that was shot from a distance will not yield the same kind of image as on that was shot close up. Likewise using a longer macro lens that allows a greater working distance from the subject will not yield exactly the same image as using a shorter lens very close to the subject. It's a matter of perspective.

Nov 30, 2011permalink

Thank you for your clarification. BTW, I am really looking forward to the next articles about this very interesting subject.

Dec 1, 2011permalink

olyflyer

EXX, sensor size plays no role in magnification. It is about the relationship between the object and the image. That relationship is the same regardless of sensor size. If your object is 1 mm in size and the magnification is 1:1 then the recorded image is 1 mm is 1 mm on an FF sensor as well as on an APS or FourThirds. That's what 1:1 magnification is.

Dec 5, 2011permalink

Yes, they are both 1:1 photos! You are seeing a life size representation of the subject in both images...

Nov 11, 2021permalink

madeinlisboa

"The problem, however, is that a regular lens will not be able to focus at such close distances". Unless you reverse them ;)

Nov 30, 2011permalink

Prashant Bande

Great article.....

Nov 30, 2011permalink

Dan Tong

Excellent article as usual.

Thanks!

Nov 30, 2011permalink

Renard DellaFave

All I want to know in the end is maximum pixels-per-inch (or resolvable lpi at best aperture) I can get of the subject, and at what distance that happens. I can see why magnification exists as a figure, now, though, since it's the only number that ignores the camera and just talks about the lens. Seems odd to me since it has been 15 years since I had a lens that wasn't integral to its camera.
The use of "1:1" as anything special seems kind of like it only is for te same reason the year 2000 was special.

Nov 29, 2011permalink

It's somewhat arbitrary, but it's also not arbitrary. For a simple lens, it is macro if the lens is as least as close to the subject as it is to the focal plane. For a non-macro lens, it is always closer to the focal plane than to the subject. The lens is exactly half way between the focal plane and the subject at 1:1.

Of course, the lenses we use are not simple lenses, so the actual situation varies from this by lens design.

Dec 1, 2011permalink

liviutza

I understand most conventions around macro photography and do quite a lot of macros myself, but with the advent of various-sized systems, compacts and zooms macro conventions could really use a serious revamp
For example, a 1/2.5 sensor compact fits in the frame the same subject as a full-frame with 100mm macro. FoV aside, for the user and even for practical purposes the final image produced by the two ensembles is quite similar in terms of reproduced subject.
I used a number of close-ups platforms from the specialist MP-E 65 lens from Canon to compacts, and I am trying to focus on what the used system allows me to frame rather than ratio. In this respect I would rather think of "how many millimeters will my camera/lens fit in how many megapixels". Only downside of this is that on interchangeable lens cameras the body is also a factor to take into account, but i see it as more useful reference, especially for compact cameras that deliver quite stunning close-ups at their closest focus

Nov 29, 2011permalink

NJani

Dear Author,
Sorry to say but your article in some points is not correct. To put things into perspective let's talk about what the magnification ratio means.
The magnification ratio is not depends on sensor/film size. It depends only on how the lens magnifies the subject. The ratio stands between the subjects real size (lifesize) and between the subjects projected size what you will get on sensor/film. The magnification ratio 1:1 (AKA lifesize) means that the subject will occupy the same physical size on the sensor/film as it's on size. If the subject is 1cm x 1cm size, it will occupy on sensor/film 1cm x 1cm territory if the magnification ratio of the lens is 1:1. No matter how big is the sensor/film. If you use smaller sensors/films and will make prints with the same size (for eg. A3), of course you will get virtually bigger enlargements of the same subject but it is only because the smaller sensor/film does cropping. But the subject on all sensors/films will occupy the same size.

Nov 29, 2011permalink

Are you serious? Have you read the article?

Nov 29, 2011permalink

NJani

Sorry, not all! Started to read and scrolled down the screen. Stopped at dragonfly and read the notes below it where you wrote: "sensor is 22mm wide, so the magnification ratio is 22mm/60mm, approximately 1:2.7." That was the point what I misunderstood. Now a read the article and have to say that it is absolutely correct. Sorry about my post, hope you can forgive.

Nov 29, 2011permalink

Michael Gunawan

Dear NJani,
which part of the article makes you think that Erez didn't say exactly what you're stating ?

Nov 29, 2011permalink

anthonyGR

Why would he read the article before responding? this is the internet.

Nov 30, 2011permalink

DanCee

typical shout first before reading...

Nov 30, 2011permalink

probert500

An apology was proffered - why would this be responded to in such a rude way -oh it's the internet. Gee I'm stupid like a fox.

Dec 1, 2011permalink

hammerheadfistpunch

one question i have with magnification and macro is its benefit for portrait work and video interview. I was going to get a 45 mm macro for video interview but is there any reason to get a 1:1 lens for that type of work when a non-marco of the same focal length will do, i have heard conflicting information. whats the benefit?

Nov 29, 2011permalink

Macro photography lighting tips

The only difference between a macro lens and a non-macro of the same focal length is the macro lens' ability to focus from a much shorter distance.
Many use macro lenses fro non-macro work because of their image quality, which is almost always fantastic.

See Also

Nov 29, 2011permalink

Ashley Pomeroy

Assuming you're talking about the Leica/Panasonic 45mm macro for the four-thirds system, it won't hurt, and indeed that lens would be pretty good in that role (assuming you're shooting with the camera on a support). Having said that, you won't need or use the macro range unless you're testing the subject's iris response, and in practice a zoom will probably be more useful. Nonetheless that particular lens would be a good choice - and it can't *hurt*. Sadly there's a dearth of good portrait lenses for micro four-thirds, although conversely there's a huge surplus of old 35mm 50mm f/1.8s and f/1.4s you could adapt, if you don't mind manual focus.

Nov 29, 2011permalink

PicOne

Another common use for macro lenses for non-macro work is that these lenses tend to provide a flatter field of focus than non-macro lenses with less distortion, and as such are optimal for eg. artwork reproduction uses.

Nov 29, 2011permalink

wkay

What's the point of this whole article? Seems to be some sort of vague engineering discussion. If my subject fills the frame, focuses, and gives me a pleasant compostion, what the h do I care what the magnification is? Am I supposed to be taking critical measurements off the image for scientific purposes? I'm sure there are better tools for that. And who on earth needs to Tweet or Facebook this? My life is going fast enough, I dont need to waste any more of it on frivolties that I already am. Sorry to carry on, but these DP 'tutorials' are just proving a general waste of time as they are just superficial overviews that dont provide sufficient info to really improve my skills.

Nov 29, 2011permalink

ryansholl

I hate it when life is going so fast that I don't have time for articles such as this, but not quite so fast that writing a post to complain about it isn't worth my time. It's a strange conundrum, eh?

Nov 29, 2011*permalink

TomCreek

I've used a Canon autobellows going on 30 years now, and continue to use it with my now EOS system. I use macro lenses on it, non-macro, and even a bellows-only lens. I know the potential magnification with some of these is well beyond 1:1, but I've never bothered to look at the scale or calculate the magnification. So you can be into macro without the scientific/technical end. Oh by the way I'm an engineer, but as you say, all I care about is the composition. Be gentle though because a growing segment of the population gets off on metadata and technical details, as evidenced byt the large segment that is Tweeting and posting on FB meaningless krap.

Nov 29, 2011permalink

StephenSPhotog

I'm happy to tell you that you have successfully missed the point. Congratulations!

Nov 29, 2011*permalink

sacundim

"If my subject fills the frame, focuses, and gives me a pleasant compostion, what the h do I care what the magnification is?"

So if your subject won't fill the frame in sharp focus, how do you suggest we approach the matter?

Nov 29, 2011permalink

JWest

@sacundim - get a bigger subject.

Dec 1, 2011permalink

jcmarfilph

Oh take note that my HS10 + Raynox DCR-150 can fit in 9mm in the frame so technically magnification ratio is bigger than 1:1 of this article but when computed based on your formula it will only be *1:1.46. =D

Nov 29, 2011permalink

Chris Savage

The sensor in your HS10 is only ~ 6mm wide so if you're 'fitting in' 9mm your magnification ratio is indeed only ~ 1:1.5

Nov 29, 2011permalink

jcmarfilph

But in real-world, it will produce bigger magnification lthough you can crop the DSLR to match that result. I'll be doing a comparison between a DSLR with 55-250mm and my HS10 soon.

Nov 29, 2011permalink

Rachotilko

Sorry for off-topic, but :

has anybody else found that dpreview's forum message index froze 7 hours ago ? All posts are 7 hours old or older. Or is it my brower playing some nasty game with me ?

Nov 29, 2011*permalink

(unknown member)

My biggest wonder about macro is this:

How on earth do you get something such as an insect to stay where you want it to be whilst you set up the shot?!

Nov 29, 2011permalink

How am I supposed to keep you reading these articles? ;-)

Nov 29, 2011permalink

Daniel Lowe

Superglue!
Works a treat (bug doesn't work afterwards)

Nov 29, 2011permalink

Oy vey...

Nov 29, 2011permalink

Cy Cheze

A shield bug is apt to sit still or move slowly. The robber fly may have to be poisoned and stuck on a pin. Looks like this polyoptic fly has some "lens dust."

Nov 29, 2011permalink

TomCreek

Freezing insects work, as does the chemical whose name escapes my brain, used to use in biology, which kills the insect. This is well known.

Nov 29, 2011permalink

All images in these articles were achieved WITHOUT ANIMAL ABUSE. I do *NOT* hurt, kill, maim, freeze, squash, glue, heat, refrigerate, skewer, disembowel or perform any other abuse on my subjects. I'll write about all my methods and techniques - I beg of you, please refrain from animal abuse until then.

Nov 29, 2011permalink

StephenSPhotog

Freeze it. It's just a bug.

Nov 29, 2011permalink

(unknown member)

Even to freeze it, you have to catch it!!

Also, how about if you want to photograph it flying? You can hardly toss it in the air with a cry of "Fly my pretty! Fly!" after you have frozen the poor thing!

Nov 29, 2011permalink

Erland Nielsen

If you want natural images, you don't catch the insects. It's quite simple. And if you hope to capture images showing behavior, it''s quite obvious.
Finding, approaching and photographing insects is something you learn by trial and error. It takes time, and more time.

Nov 29, 2011*permalink

Roman Korcek

@Erez Marom:
"please refrain from animal abuse until then"
And even during and after.

Nov 29, 2011permalink

TomCreek

Formaldehyde. That's the chemical we had in a small bottle with a dropper for insects in my biology days. It's also in photography chemical process and woodworking glues etc.

Nov 30, 2011permalink

David Pastern

One should NEVER freeze insects or arachnids or interfere with them in any way. Artie Morris doesn't tranquilise birds does he? Moose Peterson? John Shaw? nope. If you can't get the shot as is, then leave the insect or arachnid be. What you are suggesting is completely immoral and defeats the purpose of being a nature photographer in the first place.

re: the article - I guess from a technical point of view, it's nice, but it isn't strictly required knowledge from my experience imho. I've been shooting macro for near 10 years now, so I'm not exactly a newbie, so newbs may find this article of interest.

Dave

Dec 1, 2011permalink

DaveD64

So Erez, how did (do) you keep the "not dead" bugs so still?

Nov 1, 2015permalink

ptodd

I understand what magnification is; reassuring to have this knowledge consolidated.

What I don't understand is why '1:1' is so special? Using a smaller sensor, lower magnification ratios will yield essentially similar results (in terms of subject size relative to captured image, of course other variables like DOF will be different).

For example, why is it useful to the poster with an HS10 & close-up filter to directly compare the magnification ratio of their system to a user of a 35mm SLR? It seems to have little direct bearing on the subjects they will be able to capture or the images the will be able to produce. The magnification may be useful as an intermediate value for calculation, but why insist that only 1:1 is 'true macro', when for practical purposes the capacity of the system is so dependent on other factors?

I suppose the answer is that it is useful when comparing lenses of different focal length for use on the same size sensor (which in the old days was more fixed).

Nov 29, 2011permalink

ptodd

How long before we start having '35mm equivalent magnification ratio' like we have '35mm equivalent focal length' (rather than FOV which would actually be meaningful)... just to really arbitrarily obfuscate things for anyone learning about photography from scratch...

Nov 29, 2011permalink

I agree completely. On top of that, I never consider magnification in the field. I only try to achieve my desired composition, and so magnification is but a byproduct.
I only explained magnification because:
a) It's good to know what people are talking about and to solve misconceptions.
b) It's highly relevant for future technical discussions.

Nov 29, 2011*permalink

ptodd

That makes good sense, thank you for responding.

Certainly it is worthy of explanation; I can remember struggling a little with the concept at first, reading about it and understanding what was written, but refusing to take it on board because it seemed rather arbitrary... so months later, I'd see it mentioned again and think "surely there must be something more meaningful about this number that I haven't realised yet".

Perhaps the relevance of the '35mm equiv' aspect could be further emphasised to better avoid the misconception that it is meaningful to use this number as an absolute comparison between systems with different sensor sizes.

I look forward to the future discussions.

Nov 29, 2011permalink

_sem_

> What I don't understand is why '1:1' is so special?
Because most (D)SLR macro lenses reach 1:1 at close focus, and because specific macro issues (thin DoF, loss of light, etc) show up to such extent that one can't just ignore them as with lower magnification close-ups. And, one needs special equipment to magnify more than 1:1.

I think an article like this is pointless without an example with compact cameras (small sensor, preferably several sizes). Which would show that frame coverage (in mm) or "equivalent" optical magnification is more useful than the "naked" one.

Nov 29, 2011permalink

Chris Savage

"What I don't understand is why '1:1' is so special?"

To you or me it probably isn't.

Many technical fields of photography -- engineering, biology, archaeology spring to mind -- rely on being able to make direct size comparisons of subjects.

Nov 29, 2011permalink

Mostly Lurking

Why 1:1 is so special is because that is the minimum magnification that can truly be called a 'macro'. Here are the definitions:
>10:10, normal photography.
10:1 to 1:1, close-up photography. (Yes, there are over-laps.)
1:1 to 1:10. macro photography.
1:>10 micro-photography.

Nov 29, 2011permalink

@Mostly Lurking, your information is incorrect and/or includes typos. In general, A:B is macro if A is greater than or equal to B. You say 1:1 to 1:10 is macro photography. That is incorrect. It would have been correct of you had said 1:1 to 10:1.

Not sure what 10:10 is supposed to be. Usually, one of the numbers is 1. It doesn't need to be, though. It's just a ratio, which can also be expressed as a number. A 1:1 macro image and a 1X macro image are the same thing. A 3:2 macro image, 1 1.5:1 macro image and a 1.5X macro image are all the same thing. The image is 1 1/2 times the size of the subject.

Dec 1, 2011permalink

Maxim Ge

I think that the claim "Sensor size does not alter magnification" is arguable. To be more exact magnification definition itself does not quite fit the "real world".

You define maginifcation as "simply the relationship between of the size of the (in-focus) subject's projection on the imaging sensor and the subject's size in reality". I think it has to be coupled with crop factor.

Consider an example. You have a frame 24x36 and make a photo where subject size = 18mm, projected size is 36 mm, so maginification is 2:1, that's correct, but remember - we see that 18mm subject takes the entire frame.

Now we take a tiny camera with crop = 18 and make a photo where subject size = 18mm and projected size is 2 mm. Magnification = 1:9 ? But we continue to see that 18mm subject takes the entire frame.

So 2:1 and 1:9 give same result - strange, isn't it?

I think that crop factor should be added to magnification definition, in this case both considered pictures would have same magnification.

Nov 29, 2011permalink

It may seem strange, but that doesn't change the fact that magnification ratio is just a definition, and that's exactly how it's defined. This definition is required for other discussions, and believe me, nothing will ever change it... :)
Indeed, in order to fill the frame with a compact as compared to a FF camera, significantly different magnifications are required, but when you think about sensor sizes, it makes sense.

Nov 29, 2011permalink

Maxim Ge

Agree, but if we define magnification this way than thesis "macro photography means shooting at a magnification ratio of at least 1:1" looks a little bit strange. Compacts give significantly lesser magnification still they shoot macro ( so they have 1:1 being multiplied by crop factor).

Nov 29, 2011permalink

zebarnabe

That kinda troubles me as well... usually one should talk about certain terms in 35mm film equivalent due to the lack of better standard. Even in modern days most people know what the size of a negative film frame is.

With that in mind a 35mm equivalent 1:1 macro shot would mean a 36x24mm rectangle filling the frame (aspect ratios aside - take the diagonal of the frame as a measure) no matter what the sensor size or lens focal length/focus distance, the given magnification definition given on the article is correct though.

"(...) 22mm/22mm equals a 1:1 magnification ratio." in 35mm terms terms it would be 1.64:1 magnification ratio. If you simply say 1:1 the details about subject size are lost.

Nov 29, 2011permalink

sacundim

"I think that the claim "Sensor size does not alter magnification" is arguable. To be more exact magnification definition itself does not quite fit the 'real world'."

Indeed. I've long argued that it really makes more sense to talk about what I call the "print-to-life" ratio: the ratio of the size of the subject in the print (or computer screen) to the real-life subject. The print-to-life ratio is the product of what we may similarly call the life-to-sensor ratio (the traditional "magnification") and the print-to-sensor ratio (the traditional "englargement").

As to how to define macro photography, I think the best definition is simply photos of small subjects in the same size range as a coin.

Nov 29, 2011permalink

Mostly Lurking

That 'crop- factor' provides magnification is a fallacy, perpetrated by statements such as 'on an x crop factor camera, it's th same as a x mm lens.' If isn't the magnification they're talking about, it's the Field of View. The magnification is the same.

Nov 29, 2011permalink

kff

I expect a special AF macro software of cameras (firmware ... it is posible for Pentax K-5, K-7 etc.) for several macro shots with a good bokeh of fast lens and travelling AF points from the front to the back for compound exposition with choosing a range of blur field as bonus :)

... or Do You want to buy a special and an expensive macro gear for it and spend money and time with software in the computer, today?

Nov 29, 2011*permalink

OneGuy

A widely available parameter on a given camera is the 'minimum focusing distance.' Knowing the sensor size, can I calculate the (optical) magnification just from this parameter? Or do I have to use a ruler at that distance to get the object size?

I checked (quickly) DPR specs on Oly PM1 and did not find the optical magnification ratio (proportion) there -- only 'Live View Magnification." Is this the same thing? If not, what would be the benefit of including the optical magnification on the DPR spec sheet?

Nov 29, 2011permalink

J.K.T.

You'll need the ruler too. If you knew the focal length and the minimum distance, you could calculate the magnification. Unfortunately the given focal lengths are for infinity focus. The focal length at minimum focus can be (and usually is) different.

Nov 29, 2011permalink

gillbod

the minimum focus distance often doesn't give a good measure of magnification.

the problem is that the focal length changes during focussing. typically, focal lengths are measured at infinity. when you focus near by, the focal length is often less (sometimes much less) than the focal length at infinity. how much less depends on the design of the lens. this is the reason for the optical magnification appearing on many lens spec sheets.

Nov 29, 2011permalink

Indeed. That's also why macro lenses usually have a magnification scale alongside the focal distance scale.

Nov 29, 2011permalink

The sensor size is irrelevant. You can approximate the magnification from the focal length and minimum focus distance, but it's very important to know what the MFD is measured from.

At 1:1 magnification, a simple lens is exactly half way between the subject and focal plane. Additionally, the distance from the lens to the focal plane is exactly twice the focal length.

This information can be used to approximate the magnification, but lens design will generally affect this. Best is to do an actual measurement if the information is not readily available.

Dec 1, 2011permalink

elitver

thank you, great reading

Nov 29, 2011permalink

Debankur Mukherjee

Good Article......

Nov 29, 2011permalink

SemperUbiSubUbi

I should start by saying I have a very limited knowledge of optics - but the definition of magnification as size of the projection on the sensor over size of the subject seems strange to me. Surely pixel density must come into the equation? What if your sensor had a single really large pixel? If I print an image on a larger piece of paper - have I magnified it? I seems o me that what is spectacular about the picture of the bugs eye in the article is not the fact that the picture of the eye is larger than the eye of the fly - but that the detail on the picture at the size it is displayed is such that to the human eye it seems perfectly clear. It is not intuitive to me that magnification should be invariant to pixel density.

Nov 29, 2011permalink