58mm 250mm ?

[Poider]

Hi, i am looking at different cameras and am a little bewildered by the mm numbers
I have a Nikon P100 26 x zoom at its most zoomed out the focal length is 5mm with a 35mm focal length of 26 at its most zoomed in the focal length is 120mm and a 35mm focal length of 678,
My camera says it is 4.6 - 120mm, so does that mean that a DSLR lens with the numbers 55 - 250mm would assumably have a zoom capability of just over twice the zoom power of my 4.6 - 120mm?
Peter

[OsmosisStudios]

Your P100 uses a very small sensor and is subject to what is called a Crop Factor. When compared to a 35mm reference (which almost all cameras use), you have to multiply the focal length by a certain amount (which is based on the size of the sensor) to get the equivalent focal length.

The P100 has a 4.6-120mm actual focal length, but because of the sensor it has an equivalent of 26-678. What that means is that your crop factor is somewhere between 5.2 and 5.6 (the lens is a weird design which causes this).

A 55-250 lens has a 35mm equivalent of 83-375 (on a Nikon/Sony body). So not at all the same range.

Cameras like your P100 are popular for this exact reason: they cover an incredible range in one very small package. To cover anything even remotely close to what you have, I'd need at the very least 2 lenses, likely 3 or more. And the body is bigger. So I'd have the same range, but a considerably larger package to deal with.

[Poider]

Thanks for that, If i purchased a nikon d3000 what lens would give me the same zoom as the p100?
Peter

[Aegea]

I don't think there is one lens that gives 26-678mm zoom. Any 600mm lens for a D3000 will be either VERY large and VERY expensive, or junk. Closest reasonable lens would probably be the 28-300. You could add a 2x teleconverter and get to 600mm, but that would give you f/11 at the long end. Not at all recommended!

[OsmosisStudios]

Originally Posted by Poider

Thanks for that, If i purchased a nikon d3000 what lens would give me the same zoom as the p100?
Peter

No such thing, though it's easy enough to figure out. The D3000 has a x1.5 crop factor, so to get 600mm all you'd need is a 400mm length lens.

So, worst case scenario, a 16-85 and an 80-400 would get you 24-600, but it'd be over two lenses.

Originally Posted by Aegea

I don't think there is one lens that gives 26-678mm zoom. Any 600mm lens for a D3000 will be either VERY large and VERY expensive, or junk. Closest reasonable lens would probably be the 28-300. You could add a 2x teleconverter and get to 600mm, but that would give you f/11 at the long end. Not at all recommended!

The 28-300 is probably the closest, but its most certainly NOT TC compatible. You'd also be starting with 42mm without the TC, which then becomes an 84 with the TC. That's missing out on the 26-42 range

[Poider]

ok thanks guys, you have helped me out a lot.
I think I will stick with the P100 for now, it has the zoom i want and it takes decent phtos, It has a manual mode, (albeit a little strange with the manual focus, through the use of a coupe of buttons), but apart from having interchangable lenses, I think i have enough for the time being.
Thanks
Peter

[Poider]

So having said all that, my wife bought me A Nikon D3100 for Christmas.
It came with the Lens kit of:

Nikon DX VR AF - S Nikkor 18 - 55mm 1:3.5 - 5.6 G and
Nikon DX VR AF - S Nikkor 55 - 300mm 1:4.5 - 5.6 G ED

We are going to the UK in July and Iam Wondering, shoudl I be Satisfied with the kit lenses and swapping and changing lenses to suit, or should I try to beg borrow and steal to get a 28 -300mm lens or even a 18 - 250mm lens that will cover all.
I still get confused looking at the lenses on offer.
For exampleformthe Nikkor website:

My Nikon DX VR AF - S Nikkor 18 - 55mm 1:3.5 - 5.6 G
is advertised as having 3x Zoom

AF-S DX NIKKOR 16 - 85mm f/3.5-5.6G ED VR
is advertised as having 5.3x Zoom
and the

AF-S DX NIKKOR 55 - 300mm f/4.5-5.6G ED VR
is advertised as having 5.5x Zoom

Maybe I am looking at it wrong but I interpret 3x zoom would mean that the object taken at normal perspective would be 3 times bigger in the view finder, EG: if I took a photo of a ruler and at the widest angle i had 30 cms from edge to edge then if I zoom in 3x then I would have 10 cms from edge to edge.
This seems logical but that means the bigger 55 - 300mm is only a little bit better zoom wise than the 18 - 55mm
But then the
AF-S DX NIKKOR 18 - 200mm f/m 3.5-5.6G ED VR
is advertised as having 11.1x Zoom.
If you could see menow with my tongue lolling out the side of my mouth and my eyes doing backflips you would laugh but I am thouroughly confused now.
Peter

[Aegea]

That's a good pair of kit lenses to start with, I think they will be just fine for a trip to Europe (my last trip a few years ago I just took an 18-55 and was perfectly happy). You seem to be a bit hung up on zoom range, which is not IMHO the most important characteristic of a lens. I'd say use them for a few months and then think about making changes. Really, going out with the lenses and shooting things, lots of things, is going to be much more informative than reading about it. Electrons are cheap, so use what you have and then decide what you might need.

[Poider]

It's not so much that I am hung up on zoom range, I like to take photos of G.A aircraft in flight and so get much better results with a larger zoom.
I am more or less trying to understand the ranges and the terminology about the zoom range, when I first asked this question I had a Nikon P100 and was thinking of getting the Nikon D3000, I have since been given a Nikon D3100. Osmosis Studies mentioned a crop factor of the P100.
As far as I can see the crop factor of the D3100 is 1.5, this makes the range of the kit lenses, 18 - 55 = 27 - 82.5 and the 55 to 300 = 82.5 - 450, I think I have it right.
Does the crop factor change with different lenses?
Last question... what does fast glass or fast lens mean?
Peter

[Aegea]

Crop factor can be confusing when thinking about lens focal lengths. Forgive me if you understand this stuff, but I'm going to start from the beginning. The focal length of a lens (say, 50mm) is an absolute physical characteristic of the lens. The crop factor is an absolute physical characteristic of the camera body (so it does not change for different lenses). The confusion comes when mixing the two.

Take a 50mm lens. Irrespective of what body the lens is mounted on, it's focal length will always be 50mm. However, for historical reasons, people like to relate lenses to how they would perform on a 35mm film body. On a full frame camera like a D3, a 50mm lens will give the same field of view as it would on a 35mm film camera, naturally. On a crop sensor camera like a D3100 it will give the same field of view as a 75mm lens would on a full frame body. Put that same lens on a 4/3 body with an even smaller sensor and it would behave like an even longer lens. A typical point and shoot camera might have a 3.2mm sensor, which gives a crop factor of more than 10, compared as always to 35mm film. So, yes, it is correct that an 18 - 55 on a D3100 is like a 27 - 82.5 on a full frame body, but this is only meaningful if you are used to shooting full frame.

Finally, fast glass just means a lens that has a wide maximum aperture - usually to f/2.8 or lower.

Hope this is helpful.