Working Distances for Macro lenses

I am trying to decide which macro lens to purchase-- the Canon EF 100mm or the EF-S 60 mm.

Could someone with experience please tell me the approximate distance from the end of the lens to the subject at 1:1 magnification for each lens?

Thanks in advance.

Hank

I had to get out my 100mm macro to measure this by checking the lens and found I am about 4 inches from the end of the lens to the subject which is already close enough. I have the older non USM lens though and I don't know if the newer one is any better than that. The key problem with any macro like the 60mm is that you often end up covering the light source with your body or the camera because you are so close to the subject.

On Canon's website it shows the minimum focus distance of the 60 is 0.2m, while the minimum focus distance for the 100 is 0.31m.

rklepper wrote in post #9019113
On Canon's website it shows the minimum focus distance of the 60 is 0.2m, while the minimum focus distance for the 100 is 0.31m.

That is the minimum distance from the sensor.

The EF-S 60 Macro has a WD (lens to subject distance or working distance) of 94 mm at 1:1, the EF 100 Macro of 149 mm.

BTW, this makes the EF-S 60 effectively a 50 mm lens at 1:1, and the 100 Macro a 70 mm at 1:1, both due to the IF mechanism.

Kind regards, Wim

The subject-to-focal plane distance is typically 4*FL for 1:1 size.

Hi Wilt,

Wilt wrote in post #9019380
The subject-to-focal plane distance is typically 4*FL for 1:1 size.

Yes, but the OP is asking for the distance from the end of the lens to the subject, IOW WD, not the focusing distance.

Kind regards, Wim

wimg wrote in post #9019392
Hi Wilt,

Yes, but the OP is asking for the distance from the end of the lens to the subject, IOW WD, not the focusing distance.

Kind regards, Wim

I know, Wim. I was merely providing pertinent information about 1:1 shooting regardless of the lens itself (and the physical length of that lens in front of the body)

Wilt wrote in post #9019449
I know, Wim. I was merely providing pertinent information about 1:1 shooting regardless of the lens itself (and the physical length of that lens in front of the body)

Unfortunately, with these two lenses the formula is not straightforward, due to the fact that both have IF - the FL changes when focusing closer, even if it is relatively little .

The MFD of the 60 is 20 cm, hence the FL at that distance, for 1:1 is 5 cm or 50 mm . For the 100 Macro, it is 31 cm, hence the FL being 77.5 mm at MFD.

Kind regards, Wim

wimg wrote in post #9019500


Unfortunately, with these two lenses the formula is not straightforward, due to the fact that both have IF - the FL changes when focusing closer, even if it is relatively little .

The MFD of the 60 is 20 cm, hence the FL at that distance, for 1:1 is 5 cm or 50 mm . For the 100 Macro, it is 31 cm, hence the FL being 77.5 mm at MFD.

Kind regards, Wim

I think that macro lenses which change FL internally make it unnecessarily difficult to achieve a specific size of reproduction at the focal plane.

Wilt wrote in post #9019512
I think that macro lenses which change FL internally make it unnecessarily difficult to achieve a specific size of reproduction at the focal plane.

ROFL!

Fortunately Canon does provide us with the MFD, so we can still calculate what the true FL is, and that means we can also calculate the absolute minimum WD ever .

Kind regards, Wim

Wilt wrote in post #9019380
The subject-to-focal plane distance is typically 4*FL for 1:1 size.

At the risk of hijacking the thread, it's a good time to ask a question that's been niggling for a while.

Given the impressive MFD of the 300/4 IS, I'd expect the native magnification at this distance to be much higher...why isn't it?

Bob

Any certain mm at any certain MFD yields any certain mag. ratio. It is what it is. The 300/4 L IS is kinda of a hidden gem in the macro world though. Add an ext. tube, maybe a 1.4x TC, monopod and you have the best rig for butterflies, dragonflies and many flowers - at a very practical working distance!

Hi Bob,

Long time no see .

Canon Bob wrote in post #9019548
At the risk of hijacking the thread, it's a good time to ask a question that's been niggling for a while.

Given the impressive MFD of the 300/4 IS, I'd expect the native magnification at this distance to be much higher...why isn't it?

Bob

This is because of the lens formulae, which depend on FL.

a) 1/f = 1/(image distance) + 1/(object distance)
and
b) M = (image size) / (object size) = (image distance) / (object distance)

where f equals FL, and M equals magnification, and object distance and image distance are both calculated or measured from their relative focal or nodal points, IOW,

c) (total distance from image plane to object plane) = (image distance) + (object distance)

At 1:1, image distance equals object distance, otherwise it wouldn't be 1:1 after all, so when you substitute, you get
1/f = 1/(object distance) + 1(object distance) = 2/(object distance)

Work this out and you get object distance equals 2X FL, and similarly image distance also equals 2X FL. Substitute in c) and you find that at 1:1 the distance from image plane to object plane equals 4X FL, or 1200 mm. However, the back focal or nodal point needs to be 600 mm away from the image plane or sensor, and the front focal or nodal point also needs to be 600 mm away from the object plane.

In short, in order to achieve such magnifications with a 300 mm lens, you need it fitted in a tube that allows for roughly 300 mm of extension, making it quite a contraption.

This, BTW, is the reason why it is advisable to use a close-up lens with a long lens for macro type work. A close-up lens maintains the same light level as a lens without one, unlike a lens tube extension, it also gives you an additional benefit: the longer the lens, the more additional magnification you get.

The additional magnification with a close-up lens equals (FL main lens) / (FL close-up lens).
Using a 500D, achromat close-up lens (very good close-up lens), which has an FL of 500 mm (2 dioptres), you will get an additional 300/500 = 0.6X magnification above and beyond what the 300 is already capable of. The disadvantage being of course that with the lens at infinity you already get 0.6X magnification extra as a minimum too, hence no infinity focus possible when mounted.

However, this is a very compact and high quality option for chasing butterflies, photographing flowers, shooting small lizards, dragonflies, scorpions etc, without cramping their space, or when you don't want to come too close . This is done a lot mostly with the 300 F/4L IS and the 100-400L IS, where the 100-400 obviously is more flexible (0.2X to 0.8X additional magnification just by zooming).

Kind regards, Wim

Thanks for the explanation Wim...never did get the chance to buy you dinner and I've retired now (and emigrated to France).

Incidentally, I use a 500D with the 300/4 and think it's a very usable setup. Initially, I sold my 300/4 when I got the 300/2.8 but then realised what I was missing in the portability and close focussing stakes....so had to replace it again.

Bob