how to pick a digital camera?

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Tom of the Woods
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how to pick a digital camera?

Post by Tom of the Woods » February 1st, 2017, 4:09 pm

I have a little pocket camera so that's not the focus. I'm looking at "mega zoom" digital cameras. Is there a tradeoff point between more magnification but a lower megapixel "rate" vs less magnification but higher megapixel "rate"?

The two cameras I'm considering are a 16 mp camera with an 83x top magnfication vs a 20.1 mp camera with 60x magnification. I realize there can be other factors, but if all things were equal ... ?

The context of the question is photographing wildlife and fairly extreme distance. There's a high ridge overlooking a few year old fire scar. The closest part of the burn is about a mile away and 1400 feet down. The center is about 2.5 miles away and 500 feet lower.

There's no practical way to get closer without being embedded so deeply in the terrain and patches of brush that the wildlife likely can't be located to be approached. It's "go long or stay home."

Any guess which camera would be a better choice?
- Tom

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jdemott
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Re: how to pick a digital camera?

Post by jdemott » February 1st, 2017, 5:45 pm

Yes there is a trade off, but like all things in photography, it isn't as simple as that.

Start with the zoom numbers. A camera that covers the focal range 50 to 100mm would be 2x, and a camera that covers 25 to 100mm would be 4x, but both of them would have a top focal length of 100mm and so would be identical for purposes of zooming in on distant subjects. The advantage of the 4x camera in that case would be for wide angle shots--very useful sometimes but not for the use you're asking about. What you want is a lens with the highest focal length rating (ie. 500mm is better than 400mm) to give you the greatest reach. Don't count any claims for "digital zoom."

More megapixels record more detail--in theory if you had many many megapixels and an excellent quality lens you could take a photo with a fairly wide focal length and see the same amount of detail as a much longer focal length lens with very few megapixels. The difference between 16 and 20 megapixels would be very slight so I wouldn't worry about it much. Also, other things being equal, more megapixels equals more noise (visual static).

My suggestion is to look at reviews of superzoom cameras on Digital Photography Review (dpreview) and go with what looks best. Don't be swayed totally by manufacturers' claimed megapixels and lens numbers because quality of sensor and lens will affect quality of the image. Also, if you want to get the best images from extreme distance, you MUST have a tripod or something to keep the camera dead steady--image stabilization is great but far from perfect. Beware of camera automatic settings that will bump up the ISO to give you a fast enough shutter speed to take extreme zoom shots--you will get an unusable noisy photo.

Tom of the Woods
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Re: how to pick a digital camera?

Post by Tom of the Woods » February 3rd, 2017, 3:36 pm

Thanks ... looks like I have some reading to do.

It looks like some "same words" mean different things regarding photography optics and hunting optics .. my specialty .. creating confusion in discussion.

When when say "4x", in hunting optics, we mean it gives the apparent distance as 1/4th what the naked eye sees, so my 12-40X spotting scope "brings things 40 times closer" (relative to the naked eye) when cranked clear up.

Correct me if I'm wrong, but it appears that when a photographer talks about 4x, they mean the top magnification is 4x as strong as the bottom, but it says nothing at all about how strong the bottom magnification is. So ... ?? ... you have to look at focal length to get an absolute magnification?

Or have I just missed the boat in a different direction yet?
- Tom

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jdemott
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Re: how to pick a digital camera?

Post by jdemott » February 3rd, 2017, 6:06 pm

Yes, you've got it. I hadn't picked up on the fact that you were using scope terminology--it's confusing. In photography, the x factor has come to be used as a multiplier from the lowest focal length to the highest. What you need to pay attention to is the longest focal length, but even that can be confusing.

In digital photography, particularly consumer digital cameras, focal lengths of lenses are usually expressed in terms of the focal length that would be equivalent to the type of lens used on a 35mm film camera. This is because the magnification of the photo is a function of both the focal length of the lens and the size of the sensor--and there are many sizes of sensors in use. Old fashioned 35mm film gives us a standard size reference. So, what you will usually see in camera reviews and advertisements (and on internet discussion boards) are the standard focal lengths, like 28 to 200mm. But the focal length printed on the lens will often be the actual optical focal length, say 7 to 50mm. A Nikon P900 advertised as 83x, has a 35mm standard focal length of 24 to 2000mm but the true optical focal length is 4.3 to 357mm, which wouldn't give you any basis for comparison.

For your purposes in comparing cameras, use the 35mm film standard. In those terms, 500mm will always give you 25percent more magnification than 400mm. As a rule of thumb you could estimate that a 50 mm lens is approximately equal to zero magnification. I.e., a 50 mm lens gives you a field of view similar to the human eye. With that reference, you could say that a 200 mm lens is similar to a 4x scope. But the analogy is somewhat misleading because with a photo you can always enlarge the image digitally (i.e. zoom in). The limit to your ability to enlarge the image digitally, of course, is the number of megapixels, which is why the megapixel rating is a relevant number also. (note that a 6 MP sensor might be 2000 by 3000 pixels while a 12 MP sensor might be 3000 by 4000, so a doubling of the pixels does not double the resolution in either direction, which is why I said that the difference from 16 to 20 MP isn't great). If you had enough pixels, the focal length of the lens wouldn't matter for your ability to magnify. Photographers are more accustomed to thinking of focal length as determining field of view, not magnification.

I'm sure you know that distances over a mile are really long for photographing wildlife. You might want to go to a camera store and ask to take the camera outdoors and take a shot of the most distant object you can see to be sure the camera will do what you want. I've found that stores will let me bring a memory card and take shots with different cameras to take home and compare.

Hope this helps, rather than adding to the confusion.

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Re: how to pick a digital camera?

Post by pcg » February 5th, 2017, 5:55 pm

One of the most important things you need to look at it is how much light you can gather - i.e. f-stop of the lens at high magnification.

To get proper exposure you are going to have to balance ISO, f-stop, and shutter speed. Wildlife is generally most active in low light - dawn/dusk. To get more light you can raise ISO (introduces more noise), lower shutter speed (lose ability to capture a sharp image of a moving object), and lower f-stop. The latter is what photographers most often bump up against because telephoto lenses with low f-stops are very expensive.

I would do some research and determine a maximum ISO, maximum shutter speed, and minimum f-stop for your intended application, and then go shopping. Be aware that small (sensor smaller than full frame) cameras may offer very high ISO options, but they you pay dearly for that in terms of noise. In general, the small sensors on consumer-grade zoom cameras are very noisy at ISOs above a few hundred.

More fundamentally, instead of comparing pixels to magnification, I think you should compare pixels to lens quality, i.e. sharpness of the lens. Once you get up around 12 MP or greater, you are going to start to see the diffraction limits of low quality glass. You can add all the pixels you want, but unless you are using a very sharp lens they aren't going to help.

A serious wildlife photographer, which I am not, will have a full-frame or larger sensor camera body so they can take pictures in low light. Then they couple that with a telephoto that is as high a quality (sharp glass) and with as low an f-stop as they can afford. Typically the camera body will cost substantially less then the telephoto lens and the total is many thousands of dollars. I'm not trying to discourage you - just trying to make you aware of the limitations of a consumer grade zoom camera for taking wildlife photos at long distances. In bright daylight yes, but in low light very difficult.
Last edited by pcg on February 6th, 2017, 9:13 am, edited 1 time in total.

Tom of the Woods
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Re: how to pick a digital camera?

Post by Tom of the Woods » February 6th, 2017, 8:19 am

That's good info.

Light conditions shouldn't be an issue. I'm trying to photograph something specific. I don't know what it is yet, that's part of the puzzle. I've heard its vocalization twice, 6 weeks apart, 2-1/2 miles apart. Once was a late morning in mid July, the other was in early September right at noon. USFS has a couple other reports of the same sound from early afternoon.

I love puzzles, I'm neurotic, compulsive, obsessive about puzzles. I want to know what that was. I want its picture.
- Tom

Tom of the Woods
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Re: how to pick a digital camera?

Post by Tom of the Woods » June 14th, 2017, 7:02 am

... and I bought the Nikon P900. There's a high peak 5-3/4 miles from my front door. I set up the camera on a tripod and cranked it up to max optical zoom. The picture was a bit blurry since I had to trigger by hand, didn't have an I.R. "trigger" yet, but the picture was good enough to see a person up there, probably not quite good enough to recognize an individual by facial features, but ... good. More practicing to come!! :)
- Tom

Lurch
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Re: how to pick a digital camera?

Post by Lurch » June 14th, 2017, 7:36 am

I might also suggest once you get a couple models you are interested in, head over to http://www.dpreview.com/ and do read their reviews and comparisons

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adamschneider
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Re: how to pick a digital camera?

Post by adamschneider » June 14th, 2017, 9:13 am

Tom of the Woods wrote:... and I bought the Nikon P900.
That thing is insane. And I've mostly heard good things about it. Its sheer physical size is the biggest downside.

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rainrunner
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Re: how to pick a digital camera?

Post by rainrunner » June 14th, 2017, 1:41 pm

Tom of the Woods wrote:... and I bought the Nikon P900. There's a high peak 5-3/4 miles from my front door. I set up the camera on a tripod and cranked it up to max optical zoom. The picture was a bit blurry since I had to trigger by hand, didn't have an I.R. "trigger" yet, but the picture was good enough to see a person up there, probably not quite good enough to recognize an individual by facial features, but ... good. More practicing to come!! :)

Use the two second delay when using a tripod so you don't get camera shake of pressing the shutter button.
The mountains are calling and I must go.
John Muir

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