Focal Length Diffrences

Dexter247 · 21 Jul 2013

I am wondering if any one can help i am trying to decide between the sigma 120-400mm and the 150-500mm lens. I am trying to find a couple of images that demonstrate the difference in the focal length. What I'm looking for is two photos taken from the same position one at 400mmm and the other at 500mm so i can determine if the 500mm has enough extra reach to warrant the extra cost.
I hope that makes sense

sk66 · 21 Jul 2013

Do you have a zoom lens? If so, pick a FL and then a second that is 25% longer (i.e. 100mm/125mm). That will give you a "relative comparison."

The diff between 400/500mm is not much; ~10% increase in subject size.

sk66 · 21 Jul 2013

FWIW, I choose to use a 400mm f/2.8 instead of a 500/600mm f/4.

HoppyUK · 21 Jul 2013

Tamron focal length comparator widget https://www.tamron-usa.com/lenses/learning_center/tools/focal-length-comparison.php

sk66 · 21 Jul 2013

A quick search found this post comparing 300/400/500 on 1.6/1.3 format canon bodies.

But you also need to keep in mind that the Sigma's tend to have rather significant "focus breathing" and are really only giving the advertised magnification when focused @/near infinity. So some comparisons may not be "accurate."

Dexter247 · 21 Jul 2013

Thanks for that guys, seems there is not a lot of difference between 400 and 500mm in reach and I am leaning towards the 120-400mm lens as it it is a little faster at F4.5-5.6 against f/5-6.3 not a lot I know but every little helps, and for the difference in price I can get a decent tripod something I also need.

artyman · 21 Jul 2013

It depends on what you are shooting, for me it's birds and I want every bit of mm focal length I can get. The 150-500 is a great lens and I wouldn't worry about the f5.6 against the f6.3 as in real life it is insignificant in my experience.

sk66 · 21 Jul 2013

Dexter247 said:
Thanks for that guys, seems there is not a lot of difference between 400 and 500mm in reach and I am leaning towards the 120-400mm lens as it it is a little faster at F4.5-5.6 against f/5-6.3 not a lot I know but every little helps, and for the difference in price I can get a decent tripod something I also need.

I wouldn't be as concerned about aperture since they are both going to require good light. I'd be more concerned with max IQ since you will likely be doing a bit of cropping; depending on the subject.

I once owned the 50-500 and I thought it quite descent.