Macro

[Vivek]

Ron, Welcome and thanks for the shots.

I had a 50mm and 100mm Minolta macro (bellows) lenses a while ago (part traded them for a set of Luminars). They are great.

Unlike you, I like short WD lenses (especially for still subjects).

Jerry, I thought I will also take my latest macro lens for a spin.

Here is a test shot of a black pepper (Piper nigrum), the very thing that was the center of the spice trade.

Piper nigrum, ~2.5X, G1, reversed Pana 20/1.7, f/11, 1/6s.

 

[petermcwerner]

As laptoprob says, it has everything to do with capture and nothing to do with projection/viewing. So question 2 is out the window. I guess perhaps another way of looking at it, it is actually mainly an optical quality, and has little or nothing to do with even the sensor.

For question 1, Vivek's definition makes lens focal length irrelevant. All that matters is the size of the original object, and the size of the image being projected onto the sensor (which depends on focal length, subject distance, etc.)

This definition of the magnification factor seems illogical because it depends on sensor (or film) size, as I had explained in my previous message. It may stand mathematically but goes against all common sense. Where did you find this definition? Please give an exact scientific source citation. The formula of the magnification factor must be defined in some treaty on optical theory and we cannot re-invent it ourselves in this forum as it pleases us.

 

[Vivek]

Where did you find this definition? Please give an exact scientific source citation. The formula of the magnification factor must be defined in some treaty on optical theory and we cannot re-invent it ourselves in this forum as it pleases us.

Post #13.

Peter, It is alright if you have doubts and such. Referring to standard photography text books would clear them up. If you need, there are always more advanced ones (as the Kodak publication and such). No one here has invented these. Yes, there is no need to reinvent the wheel.

 

[madmaxmedia]

This definition of the magnification factor seems illogical because it depends on sensor (or film) size, as I had explained in my previous message. It may stand mathematically but goes against all common sense. Where did you find this definition? Please give an exact scientific source citation. The formula of the magnification factor must be defined in some treaty on optical theory and we cannot re-invent it ourselves in this forum as it pleases us.

Vivek's definition is pretty much standard (sorry I don't have a link.) I am by no means an expert, but here is why I would say sensor size doesn't matter.

A lens projects an image onto a sensor. The image has a certain size, that is what is important. If take a photo of a peppercorn that is say 2mm in diameter, the magnification factor is based on the size of the peppercorn in the image projected by the lens. So a 35mm true macro lens is a macro lens, regardless of whether the camera attached is 35mm film, 35mm full-frame digital, 1.6x crop digital, or a Micro 4/3 camera.

Now of course there are a lot factors that influence resolution, quality, and other characteristics of the final image that you record to film or digital. But that is a separate issue than what Vivek describes as macro (1:1 or greater magnification) photography.

When discussing equipment, we never talk about macro cameras, only macro lenses. So the definition of macro here is necessarily about the optics, and none of the rest. That doesn't mean you can't take a great close-up with a 'non-macro' (less than 1:1 magnification) lens.

 

[madmaxmedia]

Actually, Wikipedia (FWIW) describes it very well, as both a definition and as a general term:

Macro photography is close-up photography. The classical definition is that the image projected on the "film plane" (i.e., film or a digital sensor) is close to the same size as the subject. On 35 mm film (for example), the lens is typically optimized to focus sharply on a small area approaching the size of the film frame. Most 35mm format macro lenses achieve at least 1:2, that is to say, the image on the film is 1/2 the size of the object being photographed. Many 35mm macro lenses are 1:1, meaning the image on the film is the same size as the object being photographed. Another important distinction is that lenses designed for macro are usually at their sharpest at macro focus distances and are not quite as sharp at other focus distances.

In recent years, the term macro has been used in marketing material to mean being able to focus on a subject close enough so that when a regular 6×4 inch (15×10 cm) print is made, the image is life-size or larger. With 35mm film this requires a magnification ratio of only approximately 1:4, which demands less of lens quality than 1:1. With digital cameras the actual image size is rarely stated, so that the magnification ratio is largely irrelevant; cameras instead advertise their closest focusing distance.

 

[petermcwerner]

Thanks to all who helped to clarify the confusion about the magnification factor. I think the following paragraphs give a good summary of the confusion about the terminology.

When you deal with the reduced field of view sensor in digital, you have a unique situation which has no film counterpart. This is one reason why there is so much "confusion" in the digital/film world about the term "magnification."

Typically, people coming from a film background want to think of a reduced field of view sensor as identical to a simple film "crop" to like proportions. But it's decidedly more than this, which is why sports photographers love the crop factor sensor because it lets them shoot with much less glass and get equivalent results. The "magnification" is real, but it's not "optical" magnification, it's digital magnification made possible by vesting the full resolution of the sensor sampling "within" the reduced field of view.

Lenses of a given focal length seem to produce greater magnification on crop-factor cameras than they do on full-frame cameras. It should be noted that the lens casts the same image no matter what camera it is attached to, and therefore produces the same magnification on all cameras. It is only because the image sensor is smaller in many DSLRs that a narrower FOV is achieved. The end result is that while the lens produces the same magnification it always did, the image produced on small-sensor DSLRs will be enlarged more to produce output (print or screen) that matches the output of a longer focal length lens on a full-frame camera. That is, the magnification as usually defined, from subject to focal plane, is unchanged, but the system magnification from subject to print is increased.

We could discuss semantics all evening and agree or not, but the end result is that with the reduced field of view sensor there are advantages both to macro photography and to telephoto photography.

How we choose to "define" these differences is generally at the heart of most disagreements. Ideally we would have terms specific to the actual process, but at this time we must use the language of optics and physics in a rather unusual way. The important thing is not to get bogged down in semantics and insist on a rather limited and stringent use of terms like magnification and the "proper" definition of 1:1, etc. The important issue is to understand the process rather than agree or disagree with the verbiage.

Let us remember Viveks' question that started the whole discussion: “Any idea on the magnifications? Do you really think it would be 1X or over that?” I think this formulation is no longer meaningful in the digital age. A small sensor camera will hardly ever be able to produce an optical magnification factor of 1:1. It would probably be more meaningful to talk of the process or system magnification factor or of the FOV.


Sources:
Crop Factor, in Absolute Astronomy Encyclopedia ,
Understanding Magnification factor, zoom range and focal length range of a lens ,
Understanding the DSLR Magnification Factor, by Nick Rains

 

[madmaxmedia]

Yeah, I would agree that magnification is not so meaningful in discussing photos. It is meaningful in discussing glass.

 

[Vivek]

A small sensor camera will hardly ever be able to produce an optical magnification factor of 1:1.

Confusion is only on your part.

So, what would you tell Panasonic when they brand their 45/2.8 Macro as capable of going to 1:1 magnification?

 

[petermcwerner]

Confusion is only on your part.

Even the Astronomy Encyclopedia has an article on it.

So, what would you tell Panasonic when they brand their 45/2.8 Macro as capable of going to 1:1 magnification?

That they talk meaningless marketing lingo. on the same level as when cell phone cameras proudly brag about 12MB sensors

 

[Vivek]

I tried to help you Peter.

I do not know what Astronomy encyclopaedia says or some guy's book on DSLRs says (depends on how you read it, I suspect) but what you say here about magnification factors is simply untrue.

 

[petermcwerner]

I tried to help you Peter.

And I am grateful to you. This does not mean that we must agree on everything.

 

[Vivek]

One more learning experience for me. I think I will leave the explanations (of any sort) to others from now on. Sheer waste of time.

 

[pellicle]

Vivek

One more learning experience for me. I think I will leave the explanations (of any sort) to others from now on. Sheer waste of time.

it can be, however I would say that many years ago I learnt quite a bit from lurking in threads on various usenet groups. It is possible (however remote looking at the posts I see) that someone in the future may find your post from a google search and find value in the simplicity of:

If an object of 17.3mm wide fills the frame in your G1 (horizontal) then the magnification is 1X.

so don't be too discouraged. In teaching (and I am not a good teacher) presentation style is important ... as is patience.

So for Peter I will attempt to augment Viveks correct assessment with:

keep in mind that your lens projects an image ... try it on a piece of paper with one. 1 to 1 (written as 1:1 often enough) means that the image projected onto the sensor (film or digital) measures one to one with the actual image. If I have a regular 28mm lens, place it 56mm from the sensor (say using bellows) any object in focus will also be 56mm from the sensor and be reproduced in the same dimensions as it has in real life

 

[pellicle]

Peter

I am getting a bit confused by the magnification issue. What is the meaning of at or above 1X Do you refer to the size of the image on the sensor of that particular camera? In that case the 1x would be different for cameras with different sensor sizes.

no, 1x would represent an increasingly smaller fraction of the image depending on sensor size. When I do 1:1 on my 4x5 inch sheet film it means that if I photograph a ruler that on the negative 1cm of the rulers markings will measure 1cm on the negative. If your sensor is only 1cm x 1cm its not a useful image I'll grant you.

confusion comes probably from the fact that any man and his dog calls closeup as macro and just looking at images people have often no idea what is happening.

Magnification is used distinctly from Enlargement where I take (say) a 36x24mm bit of film and make a larger print than a contact print ... common even if you're talking about "small prints"

With digital and often no concept of sensor size all of this becomes lost and people think that stuff like this:

is 1:1 ... when its just close focused ... the mother is about 2 or 3cm long

perhaps this is useful reading too

The image below was taken with 4x5 sheet film using a 90mm lens and it was extended to something like 140mm making it not quite 1:1. But if we pretend that it was 1:1 and if you took a small 36x24mm segment of that image (which is dimensioned at about 101mm x 127mm) you will get an increasingly small section and "what appears to be" in closer.

It happens that 35mm film / lens systems (and 4/3) can often render more detail per square cm of film than 4x5 can so you can then "enlarge" that segment better. If I was using my G1 with the lens at 1:1 I would likely see only the stamen in the flower there.

With a smaller sensor you can take the same "view" with much less magnification (and therefore enlarge it more). If you are not after "photo-micrographs" of your subject (eg the pepper corn above) then 1:1 is most often required with larger film formats. Of course it is interesting to pursue investigations of the micro world ... and small formats help that

HTH

 

[pellicle]

Peter

The important thing is not to get bogged down in semantics and insist on a rather limited and stringent use of terms like magnification and the "proper" definition of 1:1, etc. The important issue is to understand the process rather than agree or disagree with the verbiage.

not if you want to have a meaningful discussion ... if I say potatoe and you think cabbage we are going to have trouble cooking together...

just because kiddies on the net write in L33T does not make it English. r u kl3r on th@?

but I understand what you mean and it can be an impediment to a discussion if you simply get bogged down in detial.

but to address one of your questions, yes, small format cameras can get to 1:1 and it does have usefulness

 

[JerryMK]

Wow what a dicussion on magnification... If a picture is beautiful I love it.

 

[Vivek]

:ROTFL::cussing::ROTFL:

Actually, I think the smilies outdo any (of my) pictures. :scry:

 

[JerryMK]

 

[JBurnett]

As with MOST things these days, concepts and definitions can be skewed or muddied by marketing spin, and also by benign attempts to explain things in terms others will understand.

What I personally EXPECT:

a) 1:1 means that a 5mm long grain of rice is imaged 5mm long on my sensor or film. In other words, LIFE SIZE. This doesn't matter if I'm using a Point and Shoot, or a 4 x 5" view camera. If I could make CONTACT prints from any of these cameras, the image of the 5mm grain of rice would be 5mm long.

b) That a lens labelled as "macro" should provide at least 1:2 magnification (that is, the 5mm-long grain of rice is imaged 2.5mm long on the sensor or film). Bear in mind that this is just a long-standing marketing convention that I consider acceptable.

What I sometimes ENCOUNTER (and must interpret):

a) Marketing claims of 1:1 that are based on the "crop factor". The actual magnification is less.

b) Marketing labels of "macro" that are nowhere near 1:2 (e.g. 1:4, 1:6 or even less), or that are based on other criteria such as standard print sizes.

c) In addition to MACRO, the term MICRO has also be used to describe a VARIETY of magnifications (e.g. Micro-Nikkor at 1:1). As with MACRO photography, one must similarly look beyond the label.

 

[Ron Evers]

Vivek, that peppercorn shot of yours made me revisit my set-up to see if I could pull in the subject with more extension tubes on the 100mm. I have two sets of tubes & had all three of one set on for the first shot & decided to add a couple from the second set. I added another 32 mm of tubes that really hung the lens out a long way & took this shot still using the lens wide open @ f3.5. Still not as large an image as you got unless you cropped tour shot. I took the set -up down quickly for fear of doing damage to the lens mount.