Macro magnification ratio

[The Man from Mars]

I have a new Sony-E mount lens which boasts a 1:2 macro ration.

Now I mostly shoot flora with my macro lens, I've never really dug down on precisly how close it shoots. I assumed that a 1:1 macro meant you could photograph something the same size as your sensor. Curious to see how good the 1:2 claim is, I tried taking a close up shot of a ruler with manual focus set at min.

With the APS-C sensor, I would have expected, widthways, to be able to photograph down to 50mm, but the best I could get is 80mm.

Thinking they might be doing some correction, such as 1:2 macro equivalent, I stuck a full-frame 55mm micro Nikkor on the front with an adapter. Also that would only achieve 40mm. OK, so that is half the other lens, so the 1:1 macro does get twice as close as the 1:2.

But why not 25mm as I would expect? I then stuck the micro Nikkor on a FF Nikon, and I could shoot down to 60mm wide.

I'm baffled...what does 1:1 macro really mean?

 

[ishwanu]

I'm baffled...what does 1:1 macro really mean?

It means the image of the subject on the sensor is the same diameter as the subject itself. If you shoot a subject that's 10mm in diameter, the image of it will be 10mm in diameter.

1:2 magnification means the image on the sensor is half the diameter of the subject itself. If you shoot a subject that's 10mm in diameter, the image of it will be 5mm in diameter.

These things are true regardless of the sensor size. With a smaller sensor, the frame will be cropped, but the subject's image will be the same size.

 

[The Man from Mars]

That is what I had always assumed. So why will a 1:1 micro Nikkor not allow me to photograph a 25mm wide subject on APS-C?

And why only down to 60mm on FF?

 

[The Man from Mars]

Well here's the surprise, my micro Nikkor is in fact only rated at 1:2. I always thought 1:1 was part of spec to get 'micro' rating! It's actually performing better than spec, about 1:1.8, whereas the other rated at 1:2, but only an APS-C lens, seems to be considering an 'equivalent' macro ration.

 

[Leonard Migliore]

I have a new Sony-E mount lens which boasts a 1:2 macro ration.

Now I mostly shoot flora with my macro lens, I've never really dug down on precisly how close it shoots. I assumed that a 1:1 macro meant you could photograph something the same size as your sensor. Curious to see how good the 1:2 claim is, I tried taking a close up shot of a ruler with manual focus set at min.

With the APS-C sensor, I would have expected, widthways, to be able to photograph down to 50mm, but the best I could get is 80mm.

Thinking they might be doing some correction, such as 1:2 macro equivalent, I stuck a full-frame 55mm micro Nikkor on the front with an adapter. Also that would only achieve 40mm. OK, so that is half the other lens, so the 1:1 macro does get twice as close as the 1:2.

But why not 25mm as I would expect? I then stuck the micro Nikkor on a FF Nikon, and I could shoot down to 60mm wide.

I'm baffled...what does 1:1 macro really mean?

1:1 macro means that the image size is the same as the object size. 1:2 macro means that the image size is half the object size.

I have a 55mm Micro Nikkor and at minimum focus, I can get 68mm of ruler on a 35.9mm sensor,or a maximum ratio of 1:1.9. Since it is rated at 1:2, it's doing slightly better than specification, which is what I expect from Nikon.

If your Sony lens claims 1:2, you should indeed be able to put 50mm of ruler across a 25mm sensor. 80mm, as you have probably already calculated, is 1:3.2 which is way worse. It's even worse than a "crop factor" 1:2, which would let you put 75mm across the sensor. Maybe Sony should software correct the image by cropping it in the camera.

 

[ishwanu]

I have a new Sony-E mount lens which boasts a 1:2 macro ration ... rated at 1:2, but only an APS-C lens, seems to be considering an 'equivalent' macro ration.

Which specific lens is this?

 

[Interceptor121]

If this is a zoom lens it will only offer that ratio at a particular focal length

1:2 simply means your smaller frame width is 72mm

 

[AeroPhotographer]

In the ballpark of 1:1 the depth of field is damn shallow. And it diminishes with magnification squared. So 1:2 (or 0.5x) is the highest magnification that I wanted, even though my lens reaches 1:1.

I also have a Laowa 65mm which does 2:1 (2x). I tried it once on a dead aphid. That was too much.

A 1200 pixel wide image looks good on a laptop screen or an 8x10 print. A 1200 pixel image on a 61mp sensor is 4.5mm wide and on the screen or print about 250mm, so there is about 55x magnification from sensor to screen or to print.

The image below is 1205 pixels wide. The width at the subject is about 20mm and the magnification from 20mm subject to 250mm screen is a puny 12.5x. It's typical of my insect photos.

 

[UncleVanya]

What lens?

 

[Leonard Migliore]

In the ballpark of 1:1 the depth of field is damn shallow. And it diminishes with magnification squared. So 1:2 (or 0.5x) is the highest magnification that I wanted, even though my lens reaches 1:1.

I also have a Laowa 65mm which does 2:1 (2x). I tried it once on a dead aphid. That was too much.

Canon made a macro lens that started at 1:1 and went to 5:1. It was hard to use. For one thing, while the lens was specified as f/2.8, the actual aperture at 5:1 was closer to f/16. And, in fact, you had to use it wide open to avoid unsharpness from diffraction. The result of this was that your depth of field was around 50 microns, which is the same as nothing. If I wasn't shooting something very flat (fortunately, I tended to use it on silicon wafers, which are flat enough for anyone) I had to stack focus in 50 micron increments.

 

[AeroPhotographer]

What lens?

If you hover over a photo in a DPR forum, EXIF data appears. In the case of my bee, it's a 70-180mm f2.8. It should also say Tamron. I often shoot bees with telephoto lenses on extension tubes because they focus faster than macro lenses. I found that autofocus works well if the length of the extension tube does not exceed 10% of the lens focal length.

This approach is limited to max magnification of about 0.4x, which is fine with me and about right for bees.

 

[UncleVanya]

What lens?

If you hover over a photo in a DPR forum, EXIF data appears.

Not on mobile site. The mobile view excludes some functionality. I did test and in desktop mode in my mobile I can get the data to appear although it was a bit fiddly to get to work.

In the case of my bee, it's a 70-180mm f2.8. It should also say Tamron. I often shoot bees with telephoto lenses on extension tubes because they focus faster than macro lenses. I found that autofocus works well if the length of the extension tube does not exceed 10% of the lens focal length.

Interesting

This approach is limited to max magnification of about 0.4x, which is fine with me and about right for bees.

Thanks for the info.

 

[BubbaBob]

Micro is Nikon's term for macro. Really.

 

[UncleVanya]

Micro is Nikon's term for macro. Really.

Right. But some people are sticklers for the definition that macro STARTS at 1:1.