Canon 100mm Macro Help.

[chachads]

Hello Friends,
I know that a Canon 100mm macro lense will provide a 1x (lifesize magnification) on a 35mm film camera. Does this mean that when mounted on a D30, it will provide a 1.6x larger than life magnification? Does anyone have any experiences with this lense, or are the answers guesses just like mine is?
Thank you,
Y. Chachad

Sorry, I accidentally posted this on the software forum, and did not get any comments

[Dick]

Yes, the 100mm will act like a 160mm lens. All the lens are magnifide by 1.6X.

What I can't answer for you is whether the closest focusing distance is extended.

[Inactive User 001]

A 100 mm lens is still a 100mm lens. The focus still occurs at the film plane (or at the sensor) and it makes no difference if that sensor is 2mm x 2mm or 35mm. The 100 mm lens has a 'field of view' equal to a 160mm lens on a 35 mm camera, and that is all.

[RichardtheSane]

I have the 100mm macro USM. To answer the question about minimum focus distance a little more simply that chet - the minimum focus distance will not change. all that will change is the field of view, giving the impression it was a 160mm lens.

[PacAce]

RichardtheSane wrote:
I have the 100mm macro USM. To answer the question about minimum focus distance a little more simply that chet - the minimum focus distance will not change. all that will change is the field of view, giving the impression it was a 160mm lens.

But you should still be able to get 1:1 magnification, right? You just have to be a little farther away, is that correct?

[DaveG]

PacAce wrote:
RichardtheSane wrote:
I have the 100mm macro USM. To answer the question about minimum focus distance a little more simply that chet - the minimum focus distance will not change. all that will change is the field of view, giving the impression it was a 160mm lens.

But you should still be able to get 1:1 magnification, right? You just have to be a little farther away, is that correct?


I've been trying to get my head around this point for the last few minutes. 1:1 means that if the subject was 1 cm long in reality it'd be 1 cm long on the negative (or CMOS).

If I was to photograph something 1 cm long with my 4x5 camera at 1:1, it'd be fairly small on the negative and wouldn't look like I was all that close. On 35 mm that same 1 cm subject would look much bigger. But this is just because I'm coming closer to filling the frame with 35 mm than with 4x5. On a 10D with the even smalller CMOS the 1 cm subject would look bigger still, but only because (once again) I've filled the frame more tightly.

So as near as I can figure, on a 10D the 100 mm macro will give you 1:1; you will get the perspective of using a 160 mm lens, and it will appear on a full framed "print" to be tighter than if you used a Canon film camera for the same shot.

[PacAce]

DaveG wrote:
I've been trying to get my head around this point for the last few minutes. 1:1 means that if the subject was 1 cm long in reality it'd be 1 cm long on the negative (or CMOS).

If I was to photograph something 1 cm long with my 4x5 camera at 1:1, it'd be fairly small on the negative and wouldn't look like I was all that close. On 35 mm that same 1 cm subject would look much bigger. But this is just because I'm coming closer to filling the frame with 35 mm than with 4x5. On a 10D with the even smalller CMOS the 1 cm subject would look bigger still, but only because (once again) I've filled the frame more tightly.

So as near as I can figure, on a 10D the 100 mm macro will give you 1:1; you will get the perspective of using a 160 mm lens, and it will appear on a full framed "print" to be tighter than if you used a Canon film camera for the same shot.


Dave, your reasoning sounds perfectly logical. A 1" object at 1:1 would be 1" no matter what format the image was taken on. So, I guess the only time anything would change, or need to change (like subject to camera distance), is if you wanted the image on your 10D sensor to look exactly like that on the 35mm negative, as in when duplicating a 35mm slide with the 10D.

[rdenney]

PacAce wrote:

Dave, your reasoning sounds perfectly logical. A 1" object at 1:1 would be 1" no matter what format the image was taken on. So, I guess the only time anything would change, or need to change (like subject to camera distance), is if you wanted the image on your 10D sensor to look exactly like that on the 35mm negative, as in when duplicating a 35mm slide with the 10D.



At 1:1, any macro lens on a 10D will take a picture of an object 15x23mm. A 100mm macro lens will be farther away from the subject that would be a 50mm macro lens (with the 1:1 converter), as long as both are focused at 1:1. Both would cover that same 15x23 field of view.

So, if you want to take a picture of something that is 24x36mm, then back up a bit and refocus. The magnification ends up being 1:1.6, and that's what the magnification scale on the lens barrel would read.

Macro numbers work differently than we are used to. We are accustomed to looking at things in terms of camera position first, and then selecting a focal length that provides the needed field of view. In copy work we start with the field of view and then select the focal length to provide a convenient camera position. People who shoot bugs know how big those bugs are, and they want them to fill the screen from as far away as possible--hence the popularity of long macro lenses.

If I wanted to take a picture of a 35mm slide on my medium-format camera, I could just rack out the bellow until that 36mm image filled my 56mm frame. The magnification would be greater than 1:1, or 1.56:1. Or, I could focus at 1:1, and the 35mm slide would make a 24x36 picture in the middle of my 56x56 frame. Macro in larger formats is fun, because you can take pictures of bigger things at macro magnifications.

Rick "who has a wonderful 105mm Nikkor enlarging lens on a medium-format bellows that he can adapt to a 10D if he needs more than 1:1" Denney