100mm f2 on 40D

[joseph_gledhill]

Just received my 40D + 50mm 1.4 lens which I will use for general portraits.

With the crop factor, I was delighted to see how close I can frame a shot. I

can fill the frame with something the size of a CD. However, for occasional

"close up" photography, the working distance is to small (casts shadows and can

be intimidating for insects). Glad I never brought the 60mm macro. I always

thought I would have to buy the 100mm macro but was always reluctant to do so

(do not want the size or weight - IMHO). I have always been keen on the 100mm

f2 (had it for film). If this gets me close enough (for something the size of a

peacock butterfly) then that is good enough for me. The lens is small, sharp,

light, portable and gives a good compression and bokeh effect. If I bought the

100mm macro my worry is I would rarely use it at "macro" distances. So, my

question is, the 100mm f2 has a magnification of 0.14x. With a crop sensor,

what sort of field of view/effective magnification could I achieve? Would it be

more than the 50mm on a crop? (If so, that will do me). Sorry, I don't know

how to work that out. Thanks.

[JohnMWright]

Other things being equal, if you double the focal length you double the magnification. To achieve the same magnification, a 100mm lens will be twice as far from the subject as a 50mm (again, other things being equal).

 

Not all lenses share the same designs however. Internal focusing lenses actually shorten the focal length while focusing closer. I don't know offhand if the 100mm f/2 uses IF. The 100mm macro does.

 

If you can, go to your local photo store and try one. If they don't have the f/2, try another to get an idea about working distance and magnifications, etc.

[rainer_t]

Technical data about the lenses can be found at....

 

http://www.canon.com/camera-museum/camera/lens/ef/standard.html

 

So, the 100/2 reaches 0.14x magnification at 90cm focus distance, and the 50/1.4 reaches 0.15x magnification at 45cm focus distance.

 

The sensor of the 40D is about 21mm horizontally. (21mm/0.14=150mm ... 21mm/0.15=140mm) Both lenses (each used at its minimum focus distance) will project an object that is about 15cm long so that it fills the frame horizontally. But with the 100/2 your working distance is bigger.

[neil fraser]

Joseph,

 

You mentioned that you were reluctant to buy the 100mm macro as you believed that you

would rarely use it at macro distances but dont forget that the lens is an excellent 100mm

lens in its own right. It focuses to infinity so can be used on your camera as a regular non-

macro 100mm lens.

[tommyinca]

"my question is, the 100mm f2 has a magnification of 0.14x. With a crop sensor, what sort of field of view/effective magnification could I achieve?"

 

The same size obeject will fill the frame of an 35mm full frame with a magnification of .14x * 1.6 = 0.224X

 

"Would it be more than the 50mm on a crop?"

 

No, it will be a little bit less, 0.01x less. This mean the object has to be 1/4 mm bigger to fill the screen.

[arie_vandervelden1]

One thing you could do is buy a 100/2 and a Kenko extension tube set. Extension tubes allow you to focus closer at the expense of losing distant focus. You'll be able to fill the frame with a medium-sized butterfly. You can also put the extension tube set on your 50/1.4 and you'll be able to get 1:1 or pretty close to it - i.e. fill the frame with a subject 20 mm across.

 

A tube set will also work on a Canon 70-200/4 - this would allow you to choose your focal length for even more control.

 

Another option is Tamron 90/2.8 - it is much lighter than Canon 100/2.8

[lester_wareham]

For what you describe you would be best to get the 100mm macro which will be better corrected at closeup distances unless you have an overriding need for the extra stop of the 100mm f2.

 

0.14X is not a lot of magnification, many routine lenses will go to 0.24X.

 

On APS-C 0.14X width of focused frame is sensor_width/magnification

 

so 22mm/0.14=157mm fairly large.

 

First time I have heard of someone going for a non-macro lens for closeup.

[hjoseph7]

I heard the 100mm f2 and the 85mm f1.8 are practically the same lens. Is this true ?

[bobatkins]

No, but they are quite similar...

[yog_sothoth]

IMHO the 100mm 2.8 macro is one of Canon's best lenses. I use it and the 180mm macro at work, and I prefer the 100mm if I can get close enough to my subject.

[canfred]

Better than extension tubes are the type of close up lenses like the Zeiss Proxar or Leica Elpro. depending on the filter thread in your lens you will be able to fit and use one on any lens. Not sure if there is Canon but perhaps Bob is? As a rule macro lenses do not perform well at distance and extension tubes do not that well for close up.

[jimstrutz]

In case anyone wants a graphical representation of how close they both can focus...<div></div>

[canfred]

Here is a 90mm with close up lens number 3.

Full frame 40D the screen raster interferes with colour.

[mark u]

Butterfly lens: 300mm f/4 + 1.4xTC + 12mm tube gets you to just under half life size (e.g. ~5cm/2 inch wingspan) from a bit over 1m.

 

Jim's illustrations serve to show a small difference in field of view at close focus, but the field of view depends on the size of his monitor.

 

With an EF 12 tube, the 100mm f/2 will go from 0.13-0.27x magnification at working distances (front of lens to subject) of 829-445mm; with the EF 25 you get 0.28-0.42x at 401-309mm (just over 1 foot). The 100mm f/2 is better than the 85mm f/1.8 for use with tubes because the magnification coverage is not gappy. Subject sizes are of course sensor size (~22.5x15mm) divided by magnification.

 

There are plenty of threads that discuss macro lens alternatives in the archives.