20mm for landscape

[Alaun]

...As a macro lens, reversed, it also offers 3.4x magnification (D810) and a 5.2x equivalent on the D500. ...

Just a little side note: I learned long long time ago, that -despite the size you print a picture- with macro and micro (or microscopy) pictures, you always refer to the magnification with respect to the film/sensor?

(At least in the scientific world  )

[David H. Hartman]

I would be good if people would forget this crop factor thing and just use lenses and learn what focal lengths do what on each format.

Dave

[JKoerner007]

This is overwhelmingly convincing. The images are excellent, but the AIS-lens is demonstrably a brilliantly versatile tool.

Thank you ... and, yes indeed, they are

I take for granted that the 24mm and 28mm AIS/AI-versions are similarly functional albeit with a little less magnification.

Yes, exactly. In fact, the second image (the fly) was taken with the 28mm; the first was with the 20mm. Effectively, AI-S lenses (reversed) provide the following magnification beyond a standard 1x macro:

• A 50mm f/1.2 AI-S lens reverses to:   1.1x ( = 32.7mm edge-to-edge sensor coverage)
• A 35mm f/1.4 AI-S lens reverses to:   1.8x ( = 20.0mm edge-to-edge sensor coverage)
• A 28mm f/2.8 AI-S lens reverses to:   2.1x ( = 17.1mm edge-to-edge sensor coverage)
• A 24mm f/2.8 AI-S lens reverses to:   2.6x ( = 13.9mm edge-to-edge sensor coverage)
• A 20mm f/2.8 AI-S lens reverses to:   3.4x ( = 10.6mm edge-to-edge sensor coverage)

The above figures represent a FF (FX) 36mm sensor.

However, in this case, I took the images with a D500 (DX), so I multiplied by a factor of 1.5. For example, when you put a 300mm lens on a DX, you now have a 1.5x conversion factor, which gives you an "effective 450mm of reach," due to the crop. So too does a DX 1.5 factor amplify macro magnification.

The first image (a tick) was taken with the 20mm on my D500 (which transfers 6.9mm edge-to-edge sensor coverage, or 5.1x) ... while the second (the fly) was taken with the 28mm on a D500 (which transfers 11.2mm edge-to-edge sensor coverage, or 3.2x). This is in comparison to a 1x (36mm) sensor coverage on an FX, charted above.

Interestingly, this possibility is an argument in favor of AI/AIS lenses over the more modern G and E versions.

We agree again ... which is why I shoot only AI-S lenses (with the exception of a super-telephoto). They're lighter, just as good IMO, and much-much more versatile

[JKoerner007]

Just a little side note: I learned long long time ago, that -despite the size you print a picture- with macro and micro (or microscopy) pictures, you always refer to the magnification with respect to the film/sensor?

(At least in the scientific world  )

My magnification figures had nothing to do with print size or film; they were based precisely on sensor coverage. (See above)

[Roland Vink]

Just a little side note: I learned long long time ago, that -despite the size you print a picture- with macro and micro (or microscopy) pictures, you always refer to the magnification with respect to the film/sensor?

Yes that's right. If an image of a bug projected on the film/sensor is the same size as the bug itself, the magnification is 1:1. If the projected image is only 1/2 the size of the bug, the magnification is 1:2, and so on.

It stands to reason that a bug projected 1:1 onto a m4/3 sensor will fill more of the frame than the same image projected onto an FX or medium format sensor. That's where the so-called "crop factor" comes in, but the magnification stays the same.

Of course when the same image is enlarged and viewed on screen or printed, the magnification is greatly increased.

[David H. Hartman]

Rehab Atriums shot hand held with a 20/2.8 AIS Nikkor...






I'll explain my technique better: I stepped back a little. Focused using live view. Stepped forward all to keep the camera about in the same place. Then I took the photos, free standing. Since the shutter speeds were very slow I shot several to get a few that were sharp. [I just checked the NEF(s): I shot three of the first one and two of the second. All were acceptably sharp. The 20mm lens is quite forgiving as the subject magnification is small.] This is the best I could do without a tripod. The use was a charities Face Book.

The focusing by Live View was difficult and focusing on the matte focus screen impossible. This series convinced me it was time to get a 20 or a 24 AF lens.

Dave Hartman

[Bjørn Rørslett]

To elaborate on what Roland wrote, magnification is a scale thus the *format* of the medium is irrelevant. A picture captured at 1.5X is 1.5X no matter whether it is done with a CX, m43, DX, FF, medium format, or even an 8x10". This is one of the fundamentals you quickly learn when you work different formats  (I've done all of those formats listed, by the way).

In scientific usage, a scale bar is more often used to indicate magnification as subsequent (secondary) magnification for printing etc. is self-explanatory.

[Alaun]

Yes, a scale bar and the magnification is given. Modern software even does this automaticly.

[JKoerner007]

To elaborate on what Roland wrote, magnification is a scale thus the *format* of the medium is irrelevant. A picture captured at 1.5X is 1.5X no matter whether it is done with a CX, m43, DX, FF, medium format, or even an 8x10". This is one of the fundamentals you quickly learn when you work different formats  (I've done all of those formats listed, by the way).

In scientific usage, a scale bar is more often used to indicate magnification as subsequent (secondary) magnification for printing etc. is self-explanatory.

Technically-speaking, you're correct: a 300mm lens is a 300mm lens ... but we still call it an "effective reach" of 450mm on a DX ... even though we're still shooting a 300mm lens.

By the same token, you're right: a 20mm AI-S lens, reversed, only offers 3.4x magnification; a 28mm only 2.1x magnification.

I tried to say "an effective" 5.1x and 3.2x ... to reflect the 1.5x crop factor of the DX ... but at the end of the day the magnification of the lenses are constant, yes, regardless of the sensor size.

[Bjørn Rørslett]

And to round off this sub-topic; primary magnification is at the recording medium. Anything later is secondary magnification and thus sooner or later one runs into the danger zone of "empty magnification". Meaning one gets a "bigger" picture, but no more detail. Very easily done if the capture format is small.

[David H. Hartman]

To elaborate on what Roland wrote, magnification is a scale thus the *format* of the medium is irrelevant.

And so 1:1 (life size) is not very impressive on 6x6 and if shooting bees the whole swarm (well not quite ) can be captured on 4x5...

I was disappointed with 1:1 on 6x6 but not surprised. I knew what to expect since 6x6 was my third format. My first lens for 35mm achieved 1:1 with the included extension tube.

Dave

[Bjørn Rørslett]

On 8x10", life-size meant you captured almost the entire face of a person. However, depth of field was severely limited as it was set by the magnification, but the large format allowed diffraction-prone apertures (f/32, f/45, etc.)  to be used as the secondary magnification would be small. Still, the price to be paid was the need for light.

[JKoerner007]

As the saying goes:

• "A man with one watch know what time it is ... a man with many watches is never sure."

If you shoot across multiple platforms, the phrase 1:1 can become meaningless.

Since the vast majority of macro is taken with DSLRs, "the standard" 36mm sensor is a helpful anchor point.

Since magnification is what helps frame the shot, next to the size of our macro subject, the question of whether to shoot 1:4 or 4:1 is only meaningful if we have a reference point of 36mm as the standard.

A 9mm subject is 1/4 the size of a 36mm sensor, so we need to be at about 4:1 to 'fill the frame' with such a tiny subject.

If we think of a 20mm AI-S lens as a fixed "3.4x" magnifier, we can run into trouble

While that may be the perfect magnification to shoot a 9mm subject, on an FX ... giving me a bit of room on either side ... that same 20mm AI-S lens, on a DX, will only allow for 6.9mm edge-to-edge sensor coverage, so it will be too close on a DX.

This is why (compositionally) I prefer to think of a 20mm as 5.1x on a DX, 3.4x on an FX. (It may not be technically-accurate, but  if we think of the differences in magnification that "switching cameras" brings, we make sure to use the right tool for the job.)

More succinctly, the 20mm lens would make sense for a 9mm subject on my D810, but it would be amplifying the subject too close on a D500.

[Bjørn Rørslett]

There isn't such a thing as "meaningless magnification". Not for the primary capture. The entire imaging chain might run  into empty magnification, though, if one is careless.

In fact magnification is a primary parameter for a host of other characteristics regarding the photo, its depth of field, the maximum resolution to be attained, exposure time, and so forth. Scientific photography without paying proper attention to magnification, however, easily defeats its purpose by the introduced ambiguity.

[JKoerner007]

There isn't such a thing as "meaningless magnification". Not for the primary capture. The entire imaging chain might run  into empty magnification, though, if one is careless.

Please read again. It's not the magnification that's meaningless, it's the phrase "1:1."

The "introduced ambiguity" is precisely differing sensor sizes.

If all sensors were 36mm, then the phrase "1:1" would always mean filling a 36mm sensor with 36mm of subject.

However, because 1:1 on a 24mm sensor means something different from 1:1 on a 17mm sensor, the confusion comes not because the magnification has changed, but because of the different framing requirements.

I suppose what I am trying to illustrate is lens magnification alone can't help you compose a shot; but lens magnification in relation to your sensor-size is the way to consider macro compositions.

E.g.,:

1:1 (or 1x) = 36mm on an FX ... 24mm on a DX ... and 17mm on a Micro 4/3rd.

The phrase "1:1" is therefore meaningless ... unless it's considered within the context of sensor size.

If you have a 9mm subject, you'd want to have about 10-12mm of room to frame it.

3x magnification would make sense for a 36mm sensor, but 2x magnification would make sense on a DX. You'd want less than that on a micro 4/3rd.