FOV matching calculator, is there one?

[Rick Burnett]

I'd like to find a tool that I can put in a focal length and then have it give me the distances I'd have to move to get the same FOV with other lens. Or, an equation for it.

I understand that the flattening of the image will be different, which is what I want to study with all my different lenses.

So I'd like to put in 30mm then change to my 50, then 85 and walk backwards from my objects and look at them with the same approximate FOV.

Thanks!

 

[David Battistella]

Artemis director viewfinder for iphone is a pretty solid tool.

David

 

[Rick Burnett]

Thanks for the link. That is pretty cool. Might have to try that out when scoping out locations.

However, I am thinking I am just going to need to write my own spreadsheet or something. After looking at it closer, it's a pretty simple calculation. As long as I know the subject distance from the camera, and I convert focal lengths to angles, I can work backwards from that to determine the movement required. Just some trig.

 

[Rick Burnett]

So using some trigonometry and the handy SOHCAHTOA trick I learned back in junior high I was able to at least calculate some information. The sensor size doesn't really matter since it is constant with all the lens, but I did choose to use the diagonal of APS-C that I have which is 26.82mm

So, for the comparison, I put in a 30mm lens and chose an object at 5 feet away. To have the objects at 5 feet have the same size on the sensor, these are the calculated positions I'd have to move from the object if I changed my lenses:

11mm needs 2.75 feet
30mm needs 5.00 feet (the start basis of all the calculations)
50mm needs 7.76 feet
85mm needs 12.8 feet
100mm needs 15 feet
150mm needs 22.4 feet
300mm needs 44.6 feet

I had never done the math before, but now, the whole flattening of longer focal lengths is much easier to actually conceptualize because when you look at the angular value of focal length, if you pick two distances from the camera, you can effectively calculation how that area changes in size with respect to what the camera sees on the sensor. You could actually calculate very easily the rate of contraction of further images knowing the angle.

For me this is important for our fight scene filming. The longer the lens, the closer hits/kicks look and it really sells the scene a lot more. I think I might setup a test scene with some manequins and actually do these and post them so people can really see how either a dialog sequence of a fake punch will look at different focal lengths but the same FOV of the subject.

 

[Tom.Wong]

you gonna test out macro telephoto lenses too? could give you something closer to what you are looking for, 100 mm macro canon L is an amazing lens.

 

[Rick Burnett]

Might not be a bad idea. My next lens purchase is going to be an 85mm F1.4. There are a variety of brands so not sure which one yet.

I am probably going to ask my local camera shop if I can do this test at their store and use some other lens I don't have. I've bought quite a bit from them, so they'll probably be inclined to let me

 

[David Battistella]

Might not be a bad idea. My next lens purchase is going to be an 85mm F1.4. There are a variety of brands so not sure which one yet.

I am probably going to ask my local camera shop if I can do this test at their store and use some other lens I don't have. I've bought quite a bit from them, so they'll probably be inclined to let me

My Nikon 85mm is a very sweet lens.

david.

Let me know if you are going to share the spread sheet.

David

Also.

iSee4K has a FOV calculator built in.

 

[Alexander Ibrahim]

Might not be a bad idea. My next lens purchase is going to be an 85mm F1.4. There are a variety of brands so not sure which one yet.

I am probably going to ask my local camera shop if I can do this test at their store and use some other lens I don't have. I've bought quite a bit from them, so they'll probably be inclined to let me

My favorites tend to be Zeiss.

Zeiss ZF.2 or Zeiss ZE if you are shopping for an SLR lens.

I really like the Zeiss 85 CP as well, but that is PL mount. Note I said CP, not the CP.2. The Zeiss CP 85mm is an f/1.4 t/1.5 lens, while the CP.2 is an f/2 t/2.1 lens.

I don't have a tremendous amount of experience with higher end PL mount Zeiss lenses, but I do love the 50mm and 85mm master primes.

I'm a big fan of the 85mm lens, and I'm a bit upset that Cooke & Leica don't have one. They both have 75mm, which I could probably use more easily more often... but I always prefer to rearrange things to work with the 85 if practical. That, and I think that 75mm to 100mm is too big a jump in a lens lineup- but hey those companies will probably do fine with or without my business.