02-26-2019 04:33 PM
I don't know what you mean by "zoom power"
All that ratio means is the difference between the wide end and narrow end of the focal length.
It means so little that I hesitate to draw any generalities about it.
02-26-2019 05:40 PM
Ok, what I meant was the optical zoom capability of a lens to make the subject appear closer, whether it be 2X closer, 4X closer or pick a number closer. I saw that equation on the internet and it did seem a bit too simplistic to me.
02-26-2019 11:04 PM - edited 02-26-2019 11:04 PM
Yes, a 10x lens will decrease the field of view, and hence increase the magnification, a factor of 10.
But a 10-100 is very different than a 70 - 700.
02-27-2019 11:42 AM
"I recently purchased a Canon EOS Rebel T6, I would like to take close-up pics. of
birds from a distance of 20' to 25'. Will this lense do this ?"
Any lens will take a picture of a bird at 20 to 25 feet. The real question is how much of the photo do you want the bird to occupy? A small bird is always going to be small.
This is a Robin at around 30 feet but with a 600mm lens. I am using a FF camer though.
Here is a Ring Bill gull at around 50 feet with a 300mm lens.
What I want you to realize is the size of the bird and the distance and the resulting subject size in your picture it very important. My advice is don't buy the 70-300mm and look at one of the 150-600mm zoom lenses. It all depends on what you want your results to be.
02-27-2019 02:24 PM
The pic. of the robin is what I would like. As far as any lense will take a pic. at 20', I had a 55-250, it would take
a pic. but it would be what you see with the naked eye, very small.