I need a macro lens but am overwhelmed by info....

07/13/2011 10:17:05 PM · #12

Originally posted by GeneralE:

It seems intuitive to me that the ultimate comparison would be how large the subject ends up when printed at some standard resolution (e.g. 300dpi).

Yes sir, that would compare apples to apples.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

07/13/2011 10:11:08 PM · #13

Originally posted by kirbic:

Originally posted by james_so:
Does using a crop sensor change the macro ratio of a lens in a similar way to which it affects the [equivalent] focal length?

No, it does not. It crops the image, though, so at 1:1 you can fit in an object about 23mm long across the width of the frame, whereas on a 35mm camera you could fit a 36mm object. That said, here's a thought exercise:
1.) Shoot the same object with each camera at 1:1
2.) Blow up the resulting images to 240x360mm(about 9.5x14 inches)

The total magnification on the shot taken with the APS-C camera will be 360mm/23mm = 15.65
The total magnification on the shot taken with the 35mm camera will be 360mm/36mm = 10.00

In other words, the APS-C camera appears to give more magnification (and actually does, for the same print size), but the magnification from object to image on sensor is the same.

When you printing the image, resolution becomses relevant, and it seems to me that it's not only the size of the image projected onto the sensor, but also on the number of pixels on the sensor (pixel density). It seems intuitive to me that the ultimate comparison would be how large the subject ends up when printed at some standard resolution (e.g. 300dpi).

Mike

Canon EOS-5D Mark II

Tamron SP 24-70mm f/2.8 Di VC USD Canon Mount

07/13/2011 09:55:12 PM · #14

Originally posted by spiritualspatula:

Originally posted by mike_311:
hijack alert...

when using a cheap reversing ring how does one control the aperture of the lens?

Using the aperture control ring, if it has it. If it doesn't... you can wedge it open by operating the lever manually and sticking a piece of paper or something into it. Obviously the wedging method is not so accurate.

ETA: Oh yeah forgot those Canon's have no lever.... here's the go around for that...
"there's no aperture lever on Canon lenses and as the electrical contacts are broken by mounting the lens backward the only way to stop down is to use the depth of field preview button to close the aperture, and then with the button held down remove the lens. The aperture should remain stopped down."

thank you that worked. now to get a ring...

Bear_Music

Samsung Galaxy S21, S21+, S21 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

07/13/2011 08:47:11 PM · #15

Originally posted by mike_311:

hijack alert...

when using a cheap reversing ring how does one control the aperture of the lens?

Bubble gum.

R.

spiritualspatula

Panasonic LUMIX DMC-LX100

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

07/13/2011 08:46:49 PM · #16

Originally posted by mike_311:

hijack alert...

when using a cheap reversing ring how does one control the aperture of the lens?

Using the aperture control ring, if it has it. If it doesn't... you can wedge it open by operating the lever manually and sticking a piece of paper or something into it. Obviously the wedging method is not so accurate.

ETA: Oh yeah forgot those Canon's have no lever.... here's the go around for that...
"there's no aperture lever on Canon lenses and as the electrical contacts are broken by mounting the lens backward the only way to stop down is to use the depth of field preview button to close the aperture, and then with the button held down remove the lens. The aperture should remain stopped down."

Message edited by author 2011-07-13 20:49:20.

Mike

Canon EOS-5D Mark II

Tamron SP 24-70mm f/2.8 Di VC USD Canon Mount

07/13/2011 08:39:05 PM · #17

hijack alert...

when using a cheap reversing ring how does one control the aperture of the lens?

Sigma 30mm f/1.4 EX DC HSM for Canon

07/13/2011 08:29:50 PM · #18

Originally posted by james_so:

Does using a crop sensor change the macro ratio of a lens in a similar way to which it affects the [equivalent] focal length?

No, it does not. It crops the image, though, so at 1:1 you can fit in an object about 23mm long across the width of the frame, whereas on a 35mm camera you could fit a 36mm object. That said, here's a thought exercise:
1.) Shoot the same object with each camera at 1:1
2.) Blow up the resulting images to 240x360mm(about 9.5x14 inches)

The total magnification on the shot taken with the APS-C camera will be 360mm/23mm = 15.65
The total magnification on the shot taken with the 35mm camera will be 360mm/36mm = 10.00

In other words, the APS-C camera appears to give more magnification (and actually does, for the same print size), but the magnification from object to image on sensor is the same.

Message edited by author 2011-07-13 20:30:25.

james_so

Canon EOS 77D

07/13/2011 07:23:49 PM · #19

Does using a crop sensor change the macro ratio of a lens in a similar way to which it affects the [equivalent] focal length?

Bear_Music

Samsung Galaxy S21, S21+, S21 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

07/13/2011 06:55:58 PM · #20

True macro lenses are basically an evolutionary step away from copy lenses, with which you (GeneralE) are presumably very familiar. They're characterized by an extremely flat field and absolute edge to edge sharpness, because their heritage is the copying of documents and artwork for reprographics...

R.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

07/13/2011 04:59:35 PM · #21

Originally posted by kirbic:

Optically, all the add-on close-up lens is doing is allowing the lens behind it to focus closer. It's like reading glasses for your camera lens.

Thanks -- presbyopia is a condition with which I'm all too familiar ... :-(

07/13/2011 04:35:05 PM · #22

Optically, all the add-on close-up lens is doing is allowing the lens behind it to focus closer. It's like reading glasses for your camera lens. Literally. Pun intended.
The optical design of macro lenses is as varied as the design of other specialty lenses. There are few, if any common traits. That's especially true because lenses on cameras with small sensors yield macro-like images at magnifications as small as 1:5.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

07/13/2011 03:51:22 PM · #23

I'm not so concerned with the definition, but with the physical/optical difference between the two types of lenses. There may be none, other than one contains multiple elements and goes on a lensless-SLR body, while the other uses the camera's built-in lens as one component to "build" essentially the same thing as the macro lens.

It seems like the main difference between these and "regular" lenses is that the minimum subject distance is markedly reduced for any given focal length. My 436mm zoom would normally require the subject to be a minimum of five-six feet away to be able to focus; with the adapter lens it can get as close as a foot or so.

But I also have two "macro" settings built-in; with the "SuperMacro" setting I can use the 36mm end of the zoom lens to focus at 0" ... that must be doing something different than the external lenses. :-(

07/13/2011 03:28:18 PM · #24

Originally posted by GeneralE:

Can anyone explain the difference between a "macro" lens and a "close-up" lens?

The traditional definition of "macro" is a magnification equal to or greater than 1:1. In other words, the image of the subject, projected on the sensor, is life size or greater.
Today, that's a horrible definition. It means that if I shoot at 1:1 with my 5D, I can get a subject 1.5 inches long (36mm) in the frame, but if you shoot at 1:1 with your S3 IS, an object only 5.8mm long will fill the frame.