It seems that the Nikon P900 is the flat earth conspicist's favourite camera, yet it is unclear why. Perhaps it is the zoom ratio of 83X that attracts them.
First the specifications:
Lens - 4mm - 357mm and Vibration Reduction
zoom ratio - 4.3mm x83
35mm equivalent - 24mm - 2000mm
Aperture - f2.8 - f6.5
CCD - 16 megapixels - 5.6 crop
image size - 4608*3456
Autofocus
Manual focus - by stepper motor, not true manual as it has no focus ring on the lens.
At first glance the spec looks pretty impressive. It is obvious that the FEr is going by the zoom ratio, have often seen FErs comment it is the most powerful camera on the market. Which it is not, it does have the longest zoom ratio, but that means nothing in terms of reach.
I think it is obvious that the FEr is thinking that the 83x zoom refers to magnification. Not so. Zoom ratio is based on its shortest focal length (4.3mm) to its longest focal length (357mm). Focal length is the important factor here and this camera has mediocre focal length. If we were to compare it to the human eye we get a better understanding of its actual magnification. The human eye is estimated to be the equivalent of 50mm, so a lens with a focal length of 100mm could be considered to be a 2X magnification. This system is used to categorise optical equipment such as binoculars and spotting scopes. You may see the designation of 8X - 50 quoted for a pair of binoculars which means 8X is the magnification factor (400mm) and the 50 refers to its front objective lens diamater (50mm). Objective lens is also a crucial factor.
So comparing it in terms of magnification, at its longest focal length it equals X7.4
Another factor to take into account is the sensor crop factor, this is comparing the sensors physical size compared to the industry standard sensor size of 35mm (or 135 standard), the crop factor for the P900 is 5.6, the sensor being not much bigger than a finger nail. This is the factor that gives it an apparent focal length range of 24mm - 2000mm. Basically this means that the camera crops an area that is 5.6 smaller than a 35mm sensor. Sensors this small will have inferior focusing and noise performance over a full 35mm sensor. However, it does give an impressive image size of 16 megapixels 4608*3456.
So how does it compare to other cameras. I can only compare it directly with my camera and lens setup as I do not have the P900 (nor would i want to) or another superzoom point and shoot.
I have DSLR camera bodies with interchangable lenses. My main camera is the Nikon D600. This has a full 35mm sensor of 24 megapixels. My back up camera is a Nikon D7100 again with 24 megapixels, but it is a 1.5 crop factor. I mostly use 2 lenses, a Sigma 150-600mm 4x telephoto zoom and a 600mm F4.
Putting the 600mm F4 lens on the D7100 gives an equivalent focal length of 900mm, but with its sensor size of 24 megapixels being a third more pixels than the P900.
I also have a Skywatcher 200p Newtonian reflector telescope, with a focal length of 1000mm F5. I use the DSLrs in conjunction with barlow lenses of 2X and 4X, giving me an effective focal lengths of 3000mm and 6000mm.
One more factor needs to be addressed in these comparisons is aperture. Aperture refers to the size of the opening of the cameras or lens diaphragm iris, these are refered to as F stops, the lower the number, the wider the aperture. This controls how much light is let through to the sensor. The factors are not measured in sizes but in ratios and this is important as the front objective lens influences this.
Once again, I will compare the P900 against my equipment. The P900 is quite a small compact point and shoot camera, in a line up of the P900 - D7100+600mm - D7100 + telescope the P900 has the smallest objective lens, the the 600mm and then the telescope at 200mm. The P900 is going to let the least amount of light in to the sensor.
So why is this important, it is because it seems that FErs seem to think this camera will outperform other cameras and telescopes. Obviously it is not. It is quite good for photos/videos of the moon and I have seen some good results. But when it comes to the stars and planets it just does not cut it, it has not been designed for astrophotography, telescopes are. This is due to the objective lens size, you need as much light in as you can get for stars etc, and the telescope wins hands down, 200mm against,what, a few milimetres.
There are a lot of videos posted on YouTube showing stars and planets that are more like 'rippling orbs'. They are all out of focus, the poster is adamant that that is what they really look like.There are lots of images of the stars, planets and other celestial objects taken by astronomers professional and amatuers alike, using equipment made for the job. However, the average FEr seems to think they have discovered that they are all wrong over 500 years of the telescope, and the P900 shows this. Its a complete myth. Quite simply put, it is not up to the job, and while the FEr continues to have this arrogance they will never know their mistakes, as per rebelwithoutapause who has been told numerous times, but insists he is right. SMH
. Personally I think this is one of the most comical, laughable claim from FErs, it is just plain stupid
So why is it doing this. Light, or lack of. Cameras focus by 2 methods, phase detection and contrast detect. Phase detection is used exclusively by cameras with optical view finders as they are in DSLRs, contrast detect is used by electronic viewfinders and LCD screen on point and shoot types, contrast detection is also used by DSLrs as well. Any autofocus camera is going to have serious issues with dark subjects and night time. There simply is not enough light to focus on. DSLRs and some point and shoot cameras overcome this by using infra red emmiters, this is generally only useful in short range photography, ie at night, with portraits. A quick burst of infra red is emmited and the bounced back light helps to focus. But a single star, planet in a black sky, no chance. Manual focus is the preffered method for astrophotography, or alternatively you could autofocus on something large and bright more than say a kilometer away (as that will put it in the range of infinity) or even autofocus the moon, then switch off autofocus and do not refocus. The moon will be at infinity and then so will the stars (this is not guaranteed, there remains an issue of not enough light)
Th resulting 'rippling orbs' is simply refracted light caused by the aperture diaphraghm scattering the light onto the sensor, we refer to this as 'bokeh'. Here are 3 videos showing this effect.
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