someone with the nikkor 70-200mm VR2 ..little help?

Qarik

regarding the the magnification loss at closer distances..I would like to see the closest head shot you can get on that lens.

So at 4.6 feet and 200mm..how tight can you get? I know it is about 135mm equivalent..but what does that look like on a human face? Does it fill up the sensor? I would like to see this on FX.

I don't have lens in the 135mm range to try and duplicate this either.

Thanks in advance!

Qarik

Qarik wrote:

regarding the the magnification loss at closer distances..I would like to see the closest head shot you can get on that lens.

So at 4.6 feet and 200mm..how tight can you get? I know it is about 135mm equivalent..but what does that look like on a human face? Does it fill up the sensor? I would like to see this on FX.

I don't have lens in the 135mm range to try and duplicate this either.

Thanks in advance!

bump

okay..next best thing..can someone with a zoom in that range take a head shot at 4.6 feet and 135mm?

ziggy53

Qarik wrote:

bump

okay..next best thing..can someone with a zoom in that range take a head shot at 4.6 feet and 135mm?

Most zooms will have a similar problem with mis-reporting the focal length at close focus. You will get a more accurate estimation of FOV using a 135mm prime lens at that distance.

I have some family stuff going on so it might take some time but I can do that test for you maybe later in the week. Perhaps someone else can help, but in the meantime a 135mm prime has a FOV angle of 10 degrees on the vertical dimension of a FF image. You should be able to calculate the dimensional FOV for any distance.

To find the height of the FOV/AOV of 10 degrees at 4.6 feet, divide the known angle (10 degrees) in half, find the tangent of the resulting angle (5 degrees in this case, so the tangent is .09). Multiply the tangent by the distance to the subject (4.6ft x .09 = half the height) and then multiply that by 2 to get the full image height for the scene.

The image width would be that result times 1.5 (since the image aspect ratio is 3:2, or the image width is half again wider than it is tall.)

For:

Lens with AOV "A" (in vertical degrees)
Distance to subject "D"
And you want to find the scene height "H"

Formula: H = 2 x (D x (tan(A/2)))

Now you know how to calculate the dimensions of a scene if you know the AOV and the distance to the subject. This formula only works for an AOV of less than 180 degrees, but that should cover most needs.

(Can someone double-check my math please.)

Qarik

ziggy, I have a masters in engineering degree from cornell..but that makes my head hurt.

BUMP.

ziggy53

Qarik wrote:

ziggy, I have a masters in engineering degree from cornell..but that makes my head hurt.

...

This is exactly the same engineering problem as finding the height of a building knowing your distance from the building and the measured viewing angle of the top of the building, except that this time we also want to know the depth of the basement beneath the building, which (fortunately) is the same as the height.

The important geometry for your purposes is in this single paragraph:

ziggy53 wrote:

To find the height of the FOV/AOV of 10 degrees at 4.6 feet, divide the known angle (10 degrees) in half, find the tangent of the resulting angle (5 degrees in this case, so the tangent is .09). Multiply the tangent by the distance to the subject (4.6ft x .09 = half the height) and then multiply that by 2 to get the full image height for the scene.

This is your only equation (if my math is correct):

2 x (4.6ft x .09) = visible height in ft.

If you turn the camera to portrait mode you should multiply the above solution by 1.5 for the visible height.

Qarik

okay I found this in the DPreview of the lens. This is the tightest headshot you can get with the lens. The red box represents what you can get with the older lens. Note the "model" has child sized head according the reviewers.

This is not objectionable to me.