Questions? (1.5x factor, and caculating zoom, Nikor 18-55?)

[Scott6]

I under stand how to caculate the 1.5X factor, what what exactly is it? what is is about DSLRs that give it 1.5x more?

And how to you caculate the "Zoom" for comparsion to a ultra zoom?
Max focal lenth/????


And last question is the D50 kit lens bad? I read a few reviews that said they reaally liek it, quiet, fast, sharp... but some seem to think I should go with a Sigma 18-125 and a body only D50. But I think its out of my price range like that..I can ge the D50 kit for $630 and that maxing out my budjet or $600..

[cdifoto]

I can answer the first 2 sections but I shoot Canon so I can't comment on the kit quality for Nikon.

The crop factor is related to the sensor size. The sensor of a full frame 35mm camera is 1.5 times bigger than that of the Nikon frame. Hence the 1.5. It means you don't make use of the entire image circle of the lens...you're *cropping* out the center portion.

Here's an illustration I just made up. Hopefully it helps.

http://i14.photobucket.com/albums/a304/cdifoto/cropexplained.jpg

As for the comparison to those all-in-one superzooms, you have to know the sensor size in the camera...or just look on the lens or the manual. They usually give their equivalent focal lengths somewhere since the actual focal lengths don't really mean anything.

[coldrain]

"zoom" isnot a quantity. It is justa marketing nonsense term. It is max focal range / min focal range.

Now onto crop factors. A 50mm lens is called a 50mm lens because its focal point is 50mm from the 35mm film. That creates a certain image impression, in how wide a part of the world you can see through the lens. A shorter focal point will give a wider view (wide angle), while a longer focal point will give a more narrow view (tele lens).

All this is in relation to a 35mm film. For a small sensor digital compact, the normal view will not be reached with a 50mm lens, but with a much smaller lens. With digital SLRs it gets a bit confusing. You still use 35mm lenses. But the film, or sensor, can be smaller than the 35mm film. With your Nikon the sensor is 1.5x smaller than the full frame film. So, it is like you are cutting parts from the edges of the film and end up with a much smaller view.

To understand how much smaller the view is, that is where the crop factor gets into play. When you apply it to a focal lenght, you get an idea of how the field of view will relate to the field of view of 35mm film cameras.

The 50mm lens will give a field of view of 50 x 1.5 = 75mm on the DSLR in comparisson to a full frame SLR.

[Scott6]

hmm, so why they hell did the shrink the sensor size? Is it just Nikon? why no full frame?

[cdifoto]

hmm, so why they hell did the shrink the sensor size? Is it just Nikon? why no full frame?


Because silicon is expensive to produce. Nikon relies on Sony for its sensors. They only have crop cameras. Canon makes its own sensors and has full frame available for the pro 1 series bodies, which you do pay a premium for.

[erichlund]

I under stand how to caculate the 1.5X factor, what what exactly is it? what is is about DSLRs that give it 1.5x more?

And how to you caculate the "Zoom" for comparsion to a ultra zoom?
Max focal lenth/????


And last question is the D50 kit lens bad? I read a few reviews that said they reaally liek it, quiet, fast, sharp... but some seem to think I should go with a Sigma 18-125 and a body only D50. But I think its out of my price range like that..I can ge the D50 kit for $630 and that maxing out my budjet or $600..
Others have basically answered your first questions. Question 3 is where you are trying to compare this lens to a 10X lens on an ultra zoom. The problem is, that says nothing about the starting and stopping points, and of course, with a dSLR, if you don't like the lens you have on, you can buy another that has the range you want. For example (and this will also highlight how to use the "crop" factor:
The 18-55 lens has a 35mm equivalent of 18*1.5 to 55*1.5 = 27 to 82.5.
The Panasonic has a 7.4 - 88.8 mm lens with a 35mm equivalent of 35mm - 420mm (for a crop factor of approximately 4.73). Now, you have a normalized range to make comparison: 27-82.5 vs 35-420. This may seem a big advantage to Panasonic, but the FZ30 cannot change lenses. Also, if you like to shoot wide angle, 27 is significantly wider than 35, even though the number differences are smaller. The wider you go, the more difference small changes in the numbers make. You can probably get an adapter to make the FZ30 go a bit wider, but you can change lenses to get MUCH wider on the D50. Same at the long end.

Something else to consider. Exceptionally wide zoom ranges come at a price. To create such a range, especially in a relatively compact design, means compromises in image quality. I have the 18-200VR. Nikon did a wonderful job with this lens, and it's the best of the three available (Sigma and Tamron make the others). But that doesn't mean it's Pro quality glass. There is distortion at the wide end. I haven't had a problem with ghosting or flare, but at least one review reports some. OTOH, it's a darn good, everyday, walkaround lens. But, if I wanted absolutely critical performance in this range, I would look to the 17-55DX and the 70-200VR. Those lenses provide outstanding performance within thier ranges.

All that said, the 18-55 lens is Nikon's economy product. It doesn't have the performance or features of more expensive glass, even in the same zoom range. When you go to the camera store, try the camera with that lens and the 17-55DX I mentioned (Don't ask the price). I think you will see a significant difference even without actually shooting the two lenses.

If you decide to go with better quality, there are a range of products for you to choose from. Nikon's 18-70 and 18-200 are good choices with superior quality and features to the 18-55. There are 18-125 and 18-200 lenses from Sigma and the 18-200 from Tamron. These are all good starter lenses.

As I said, I have the 18-200. I also have the 35mm f2 (nice color and contrast) and 50mm f1.8 primes. The latter is very inexpensive, and no Nikon bag should be without it unless you are going with a superior choice, like the 50mm f1.4 (a little faster, better color, contrast and bokeh, but only marginally, for a lot more money). I also have the 55mm AI-S f2.8 micro, but you would want the 60mm micro because the D50 cannot meter the old manual focus AI / AI-S lenses. Micro lenses (Macro in another brand) provide close focusing capability (think bug and flower pictures).

Cheers,
Eric

[coldrain]

The D50's kit lens isn't half bad.
It actually is better than the 18-70 kit lens from the D70(s). Most think it is worse, but that is only in build quality. The 18-55 has less vignetting and distortion, is surprisingly contrasty and quite sharp.

In its focal range it probably beats the 18-125 and 18-200 lenses from Sigma and Nikon.

[George Riehm]

hmm, so why they hell did the shrink the sensor size? Is it just Nikon? why no full frame?

The lowest cost full frame camera is from Canon in the 5D. List is $3299. The Canon 1Ds Mark II is next up at $8000. The canon consumer and prosumer cameras are APS-C size sensors at less than $1400.

Big silicon costs big bucks.

That's why the hell they shrink the sensor size.;)

[Scott6]

in that case im glad they shrank the size.. :)

Kinda like CPUs... but generally in CPU the less silicon the faster the chip..