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I have a Nikon P900 that I use mostly for birds. I find the 2000mm equivalent wonderful. At the long end it will only focus from 5 meters to infinity. At the short end (24mm) it will focus very close and make an nice large image, but if I try to get that close it scares the butterfly.

I got a +1 diopter close up lens. It works reasonably well but there are two problems. The first is that for butterflies getting with 1 meter is too close. I would like a +1/2 or even +1/4 but I can't find one. Are they available? I need a 67mm filter size. Being 2 meters away with the 2000mm zoom will get a nice size image. The second is that the autofocus is close but not correct. It seems to focus a little too deep when the close up lens is on. Any ideas?

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Regular (+1, +2, +3, +4, +5 and +10) diopters are available from low to reasonable price.

Special (+1/8, +1/4, +1/2, +3/4) diopters are available for much larger diameter lenses (so you'll need to step down) at prices ranging from a few hundred to twice that much, so that's probably cost prohibitive.

Schneider Kreuznach (B+W) makes high quality products, but the diopter you want is special order and for larger lenses used for professional cinematography.

A webpage with photos demonstrating the magnification effect of various regular diopters is available here: "Using Diopters - Close-Up Lenses".

Your difficulty is described in the DPReview Forum thread: "Help with close up zoom on Nikon Coolpix P900!" where Stephen Ingraham explains:

"As noted in other responses, the further you zoom in, the further you have to be from your subject for the camera to focus.

At full zoom (2000mm equivalent), you have to be 16.5 feet from the flower for the camera to focus.

At half zoom (1000mm) you have to be about 9 feet from your flower.

At 500-600mm equivalent (1/4 zoom) you have to be about 6 feet from your flower.

If you are closer, the focus will try ... but you will get a red square where the focus square is in the finder. That means the camera has not focused.

If you are the correct distance, or further, you will get a green focus square.

If you zoom while looking at the finder or the LCD, you can see were it goes out of focus when zooming in. Past that point it will not focus no matter what you do.

If you want to do close-ups, set the camera in Close Up Mode in the Scene modes ... it will zoom to the widest angle. That is where you can get closest to your subject. As you zoom in, you will see that the zoom indicator at the top of the viewfinder is green unit about 1/5 zoom, then it goes clear again.".

I think you are going to have to be satisfied with +1 diopter, use of the close focusing mode, reduced zoom, and some cropping; unless it's worth over a few hundred dollars to get these photos.

Be prepared to scare off a few bugs if you have to get the camera close and want to move around a lot. Placing the camera up close to a prime patch of flowers where butterflies land and triggering automatically (with a seperate trigger) in your backyard (over a period of hours or days) may be the only way to do it on the cheap.

Surprisingly bees are quite friendly and allow you to get closeups, if you'd be willing to switch from butterflies. This bee photo was taken from about 6" away, handheld.

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    Thanks much. I have the regular ones. It occurred to me afterward that aperture priority may be a good idea to get more depth of field. I have had the focus off with the +1 diopter lens – Ross Millikan May 20 '18 at 3:07
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You have discovered that the camera has limitations as to how close it can focus. Two countermeasures are available.

  1. You dismount the lens and remount it using a ring spacer. These accessories are called rings and tubes. Rings and tubes come in different lengths. They transform ordinary lenses into the realm of macro. Their chief disadvantage, the electrical and mechanical interconnection between camera body and lens is lost. You are on your own; you must manually adjust your lens. Some high-end rings and tubs maintain some or all of the interconnection.

  2. You mount a supplemental close-up lens ahead of your camera lens. These work like reading glasses in that they allow close focusing. Supplemental lenses likely induce some aberrations that degrade the resulting image. My experience is, they do quite well. The bad reputation they have acquired is worst then their bite. Quality supplemental close-ups are doublets that thwart the biggest complaint which is chromatic aberration (color fringing).

When you mount a close-up lens the diopter power expresses the revised close focusing distance when the camera is set to infinity, symbol ∞ (as far as the eye can see ). The problem is, the diopter power of a lens is likely an unfamiliar value. Eye doctors and opticians have adopted the diopter as their method to express the power of a lens to refract light. Happily we can convert diopters to millimeters or vice versa. Converting ½ diopter to millimeters: 1 ÷ 0.5 X 1000 = 2000mm. Converting 2 diopter to millimeters: 1 ÷ 2 X 1000 = 500mm.

Table of some diopter values to millimeters:

3d = 333mm

2.5d = 400mm

2d = 500mm

1.5d = 666mm

1d = 1000mm

0.75d = 1333mm

0.50d = 2000mm

0.25d = 4000mm

How to use these values: If you mount a +1d supplemental close-up, your camera when set to infinity ( ∞ ) focuses at 1000mm. This will be the maximum distance you can obtain focus. You can, using your focusing mechanism, get significantly closer. If you mount a +1/2d, customarily written as 0.5d, your maximum subject distance becomes 200mm.

How can you experiment and find out what power supplemental you need on the cheap. Since the diopter method is universally used for eyeglasses, you can go your neighborhood drugstore and buy a 0.5d reading glasses. Hold or tape one lens forward of your camera lens. Now you are close focusing using a 1/2d. If this works for you, you can search the internet for a close-up that fits your camera, with that power. Also, your local optometrist can supply you with a large 1/2d. Just remember, eyeglass lens are not highly corrected. They might just work but usually, we want a two element corrected supplemental.

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    Option 1 isn't an option in this case, as the Nikon P900 has a permanently-affixed lens. – mattdm May 19 '18 at 15:46
  • I am aware of the conversion between diopters and focal length. The weakest lens I could find was 1 diopter, which means I have to be within 1 meter. That is close enough to scare the butterfly in most cases, which is why I am looking for a weaker one. – Ross Millikan May 19 '18 at 19:02
  • @ Ross Millikan - Go to the drugstore, buy a .5d reading eyeglass, test to see if you like the results. Your local eye doctor can supply a .5 or .25. Best you test with lens from drug store. – Alan Marcus May 19 '18 at 19:44

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