canon rf 100-500mm f/4.5-7.1l is usm lens, please explain, setting focal distance range

[ahardy]

I have they canon rf 100-500mm f/4.5-7.1l is usm lens. Can someone explain the  "settng focal distance range".

I am photographing wildlife ie moose, bears, wild horses. I am having trouble with clarity of the animal at a distance. I read the manual and I'm still not sure if I should use "full" or "3 meters to infinity". I had it on the latter, and feel like thats not working. I have been on a good tripod, and hand holding with shutter speed up to 1200. Appreciate any advice. Alicen

[Anonymous · Accepted solution]

If your subject is further than 3 meters away, setting the lens on 3 meters to infinity will help the lens focus more quickly. If closer than 3 meters, then set it to full so the lens can focus closer than 3 meters. If set it to full and you shoot a subject farther away, it may take a little longer to obtain focus, but should work. Full gives you the full range of focus for the lens, without concern on your subject distance.

The focus limit switch just limits the range of focus distance to enable quicker focusing.

[rs-eos · Accepted solution]

If what you're photographing will always be 3 m (approx 10 ft) away, then set the lens to "3m to infinity".  By restricting the range, that will help achieve focus more quickly.

You'd set it to the full range if you'd end up taking photos where subjects could be at varying distances, to include down to about 1 m (3 ft) which is the minimum focusing distance.

Can you further explain what is not working?  Do you have example images you have taken?   Can you estimate how far away your subjects were?

[Anonymous · Accepted solution]

If your subject is further than 3 meters away, setting the lens on 3 meters to infinity will help the lens focus more quickly. If closer than 3 meters, then set it to full so the lens can focus closer than 3 meters. If set it to full and you shoot a subject farther away, it may take a little longer to obtain focus, but should work. Full gives you the full range of focus for the lens, without concern on your subject distance.

The focus limit switch just limits the range of focus distance to enable quicker focusing.

[ahardy]

ok thanks! better explanation than the manual. 

 I live in Wyoming. Pretty bear aware. My question is: at a distance of ie 100-200 yards and the lens at 500mm, is it better for a sharpest photo to use "3 meter to infinity" or use the "full" setting that also has a focal distance to 500mm? My foreground and background are pretty sharp, but the bear or other large animals are soft. I think it is the law of physics (too far away) but wondering which setting to use on the focus limiter. thanks! 

[rs-eos · Accepted solution]

If what you're photographing will always be 3 m (approx 10 ft) away, then set the lens to "3m to infinity".  By restricting the range, that will help achieve focus more quickly.

You'd set it to the full range if you'd end up taking photos where subjects could be at varying distances, to include down to about 1 m (3 ft) which is the minimum focusing distance.

Can you further explain what is not working?  Do you have example images you have taken?   Can you estimate how far away your subjects were?

[ahardy]

 I live in Wyoming. Pretty bear aware. My question is: at a distance of ie 100-200 yards and the lens at 500mm, is it better for a sharpest photo to use "3 meter to infinity" or use the "full" setting that also has a focal distance to 500mm? My foreground and background are pretty sharp, but the bear or other large animals are soft. I think it is the law of physics (too far away) but wondering which setting to use on the focus limiter. thanks!

[ahardy]

thanks again, never shooting less then 3 meters with this lens. So sounds like 3meter to infinity will focus faster! I live in Wyoming. Pretty bear aware. Mostly at 100-200 yards and the lens at 500mm  My foreground and background are pretty sharp, but the bear or other large animals are soft. I think it is the law of physics (too far away). ALICEN

[ColinBROWN]

I just say stay more than 3 metres away from the bear for safety reasons, when it comes to the EVF focal distance scale. I am not expert on wildlife photography, but I just have an inkling that my advice makes sense. 

[ahardy]

yeah, I live in Wyoming. Pretty bear aware. My question is: at a distance of ie 100-200 yards and the lens at 500mm is it better for a sharpest photo to use 3 meter to infinity or use the "full" setting that also has a focal distance to 500mm? thanks 🙂

[shadowsports]

Hi ahardy,

RS-EOS & 5DIV (Ricky and Bob are both so wonderful!) 😎

The RF 100-500 has a MFD (minimum focus distance) of 2.95 ft (a little under 3ft) at 100mm.  This means it cannot focus on a subject closer than that.      Lens|-----3ft----|subject .  The MFD increases as you increase FL (focal length). 

If the subject is at or beyond this distance, no problem.  If the subject is closer than 3ft, the subject will be blurry (not in focus)

Focal distance range     

Full (Basically) 3ft to Infinity.  This tells the lens it will be looking for subjects between 3ft and infinity.

3 meters to Infinity (Basically) 9ft to Infinity.  This setting does two things.  It tells the lens it will be ignoring subjects between 3-9ft.  It also changes the logic the lens uses to acquire focus on subjects at greater distances. The MFD still varies based on the set focal length, but the lens doesn't do the full focus "pull" from blurry to sharp when it being told to lock its focus on a distance subject.    

As the guys pointed out above, the lens is able to acquire focus faster (more quickly) if it knows it should not be looking for subjects closer than 9ft.  Remembering that the lens cannot focus on a subject closer than its MFD of approx 3ft. at the minimum FL.    

"Its not "better" per se to use 3m to infinity on distance subjects, this setting just allows the lens to focus more quickly.  The same focus will be achieved, it might just take a micro second longer if full is used.  The latter is a focus acquisition (speed) performance improvement, not an image sharpness improvement.  

The performance enhancement is different based on the focal length you have set.  Try setting your AF to a single focus point.  Use the focus limiter switch to improve focus speed on subjects at greater distances.

Go ahead and experiment.  I think after a few shots you'll see what we mean.  

[rs-eos]

Thanks, Rick!   Yep, agreed that the range will not have any impact on sharpness or other quality aspects in the photos.  It's just there to improve speed of acquiring focus (effectively a hint for the lens).