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I have a P900 that I use for birding. It's great for carrying around and not so great when (as usual) the light is low. I'm considering using an alternate set-up, for example a D500 coupled with a fixed 300mm prime lens. Or maybe I should go with a 400mm lens. Or a 500mm. Or something else.

Here's what I would like to be able to do but can't: I would like to be able to look through my P900, zoom out, and know when I reach the equivalent of a 300 mm fixed lens. Then I could look through the viewfinder and assess whether 300mm is sufficient, or instead whether I should be looking at a 400mm outfit, or a 500mm, or what have you. I could solve this problem much more easily if I had a 300mm lens (or 400, or 500) handy -- just try to replicate in the P900 the image you see in 300mm lens. Alas, I am currently overseas with no such resources available.

Stated differently, is there a way to glean a fixed lens equivalency from any P900 setting or photo data? I tried looking at photo metadata (specifically, the "focal length" field) from my P900 using Photoshop but couldn't figure it out. I also searched the display settings in the P900 in hopes that I could see the equivalency displayed as I zoomed in an out, but no such luck.

  • How do you know how far you are zoomed in? I didn't see any scale on the lens in the pictures. – Orbit Jul 27 '18 at 15:45
  • Evidently there is no way to know. That's the problem. The only way to know is after the fact, examining the EXIF data. – Chris Jul 28 '18 at 4:30
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The Nikon P900 sports a zoom lens 4.3mm thru 355mm. Nikon advertising claims this lens yields the equivalent of 24mm thru 2000mm. When taking equivalent, they are making a comparison using the venerable 35mm film camera as “standard”. They do this because the 35mm film camera has been with us for nearly 100 years and most of us “gray hairs” know how a 35mm film camera preforms.

When making this comparison we calculate a magnification factor, most often called a crop factor. Nikon has already published that when this camera is set to 4.3mm (its minimum zoom), it functions the same as a 35mm film camera with a 24mm lens mounted. Thus the magnification factor is 24 ÷ 4.3 = 5.58. Working this problem using the 2000mm equivalent --- 2000 ÷ 355 = 5.63. Seems we get two different answers however they are close so let’s average and deciare 5.6 as the real magnification factor.

So you want to know when you zoom and achieve the equivalent of a 300mm lens? We divide 300 by 5.6 = 53.6. That’s the answer, when your metadata reveals the actual focal length was about 50mm or perhaps a little more (53.6mm) then the angle of view delivered will be the equal of a 300mm lens mounted on a 35mm film camera.

Hope this helps.

P.S. The P900 sports a 1/2.3 image sensor. This data is cryptic – the dimensions are in inches and describe the diameter of the silicon chip that was used when making the imaging chip. This data dates back to the diameter of early image tubes used in TV cameras of a bygone era. In other words the data is not current. The P900 image chip yields an image size 4.55mm height by 6.17mm length. To work the magnification factor we find the diagonal (corner to corner measure) = 7.66mm. Now we find the diagonal measure of the 35mm film camera image which measures 24mm height by 36mm length. The diagonal measure = 43.2mm. Now we divide 43.2 ÷ 7.66 = 5.6 the magnification factor.

  • Perfect! Thank you so very much! If I could just figure out how to assess when I zoom to ~80mm while I am taking the photo I'd be all set, but nonetheless this is so helpful. Very grateful! Chris – Chris Jul 28 '18 at 1:20
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Your P900 has a cropped sensor with a crop factor of about 5.6X.

That means your P900 at about 53mm will give the same angle of view (AoV) as a 300mm on a 35mm film camera or a full frame digital camera.

The Nikon D500 you are considering has a crop factor of 1.5X, so a 300mm lens on the D500 will look like a 450mm lens on a FF camera.

To see how a 300mm lens would look on 1.5X cropped body Nikon D500, you need to use your P900 at about 80mm (actual focal length) or at 450mm 35mm equivalent focal length.

Is there a way to set my P900 at the 80mm zoom mark? I can't find any way to do that other than perhaps by taking a photo, uploading it to a computer, and checking the focal length metadata -- that is, after the photo has been taken, not while the photo is being taken.

I doubt it. If there are no markings on the zoom ring or displayed by the viewfinder/LCD then probably the only way is to use the EXIF data to see the focal length used.

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    A tip of the hat to Michel Clark --- He picked up on the fact that you also have a D500 and that you want consistently between the P900 and D500. He is correct -- you set the P900 at actual 80mm zoom mark --- This will match the D500 with a 300mm mounted. – Alan Marcus Jul 27 '18 at 18:58
  • Thank you so much! Is there a way to set my P900 at the 80mm zoom mark? I can't find any way to do that other than perhaps by taking a photo, uploading it to a computer, and checking the focal length metadata -- that is, after the photo has been taken, not while the photo is being taken. – Chris Jul 28 '18 at 0:58
  • @Chris I doubt it. If there are no markings on the zoom ring or displayed by the viewfinder/LCD then probably the only way is to use the EXIF data to see the focal length used. – Michael C Jul 28 '18 at 1:01
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In answer to the question is there a way to set my P900 at the 80mm zoom mark, yes there is, simply go to menu, zoom memory, click on, then click to the right, this will reveal all this memory settings,if you click all of these then when in program mode and you zoom in or out it will indicate the zoom setting at the top of the viewfinder or rear screen. Hope this is of help it certainly was for me when I discovered it by accident.

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