Query about relation between Field of view and reproduction ratio in macro lenses.

[LukaviZ]

Hmmm.. while doing random reading about various macro lenses, i suddenly pondered about the following, and did a search online, but couldnt seem to find a clear defined answer:

Aside from working distance, what differences are there between a 50mm, 100mm and 180mm macro lens at the same reproduction ratio (ie, 1:1)?

at normal usage, we understand that fov is different at the various focal lengths, but at 1:1 magnification, does it differ at 50mm and 180mm?

 

[daredevil123]

Different focal lengths at same magnification will give you different working distance. But at same magnification you get same fov irregardless of focal length.

 

[GRbenji]

Different focal lengths at same magnification will give you different working distance.But at same magnification you get same fov irregardless of focal length.

FOV depend on lens' focal length, and fov doesn't change whether subject is nearer or further with the same lens. Hence FOV cannot be the same for different focal length even at same magnification.

In fact your 1st statement answer the 2nd. The shorter FL requires nearer distance to get same magnification because of the wider fov.

 

[LukaviZ]

im still pondering about what other differences aside from working distance...

i do recall that at 1:1 magnification, it should look the same size across various focal lengths, but what else changes as a result of different working distances...? bokeh quality? compression? anyone done any testing before on this...?

 

[ZerocoolAstra]

im still pondering about what other differences aside from working distance...

i do recall that at 1:1 magnification, it should look the same size across various focal lengths, but what else changes as a result of different working distances...? bokeh quality? compression? anyone done any testing before on this...?

the bokeh is probably dependent on the individual lens design instead of the focal length.

DOF would still be a function of focal length and camera--subject (ie. focusing) distance.

 

[Huge Mouth Photos]

confused. any visuals to illustrate the explanation?

 

[daredevil123]

FOV depend on lens' focal length, and fov doesn't change whether subject is nearer or further with the same lens. Hence FOV cannot be the same for different focal length even at same magnification.

In fact your 1st statement answer the 2nd. The shorter FL requires nearer distance to get same magnification because of the wider fov.

Yup... my mistake on the use of the term FOV. the FOV is the wideness (angle of view) of the lens, and that never changes on a fixed focal length lens.

View of subject in viewfinder was what I was trying to say. And then I realized ya, that is the same meaning as magnification.

THanks for pointing that out bro.

 

[daredevil123]

confused. any visuals to illustrate the explanation?

actually quite simple.

assume shooting a dragonfly. On a 60mm macro lens, you have to be quite close to the subject to fill 2/3 of the frame. With a 200mm macro lens, you position your camera a lot further away from the subject to fill 2/3 of the frame.

That is the difference in working distance. That with a longer lens, you can be further away from your subject, giving your more room, and less chance to disturb/scare your subject.

 

[henry soh]

Each lens is designed differently from each other to serve its purpose. A 50mm lens from one brand is designed differently from each other to serve different purposes. Magnification changes from 1:1 to 1:2 at 50mm, 100mm etc in certain types of lenses. Looking at the functions of each marco lens based on its design rather than general statements.

 

[An drew]

This is taken from Canon Lens Chart. It shows the angle of view for the different macro lenses. Maximum magnification will be at the closest focusing distance.

While the magnification may be the same with different focal lengths, e.g. 1:1, the perspective would be different since the distances to the object are different.

 

[An drew]

confused. any visuals to illustrate the explanation?

See post number 8 at this link.

http://www.pentaxforums.com/forums/pentax-slr-lens-discussion/65043-50mm-macro-vs-100mm-macro.html

 

[LukaviZ]

thank you so much~ that was exactly what i was asking about~ =)

was deciding whether to get a short macro or not.