Confused By Pixel


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Apr 13, 2004
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#1
Hello...
I am not new to SLR, but I do not consider myself a pro either.But I am really considering in selling off my Nikon FM2 and my 3 lenses to upgrade to digital SLR.

After "site surveying", I am considering in getting the Nikon D70.But since the day digital cameras appear in Singapore, I am still baffled and confused by the pixel thing. I know a few basic thing about pixels, but with the current market, the manufactures are selling their cameras with higher and higher pixels.

My questions are:

1) At how much resolution can a picture be developed (blown up), eg., for 1024 by 980 blown up to 16R without graininess, or should i say pixelation?

2) I have read that newer models will come with 7 or 8 megapixel, so will that be a necessary factor in getting a digital SLR, rather than the light sensors and other functions?

3)Why is it that a Nikon G lense of the new NikonD70, 17 - 80 mm is equivelant to that of a 27 - 105mm? I could not find any sort of explanation from any of the reviewing sites.



Please advise......
 

alexj

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Apr 10, 2004
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#2
1) Depends on the print resolution you're going for. Quality prints usually go at 300dpi (dots per inch). so a 5 megapix cam takes a picture about 2560 x 1920. divide each by 300 and u get 8.5 inches x 6.4 inches. (we're not taking into account of other factors, like poor picture quality and such, just the technical details)

2) sorry, not an expert in those areas.

3) digital cameras have a different size capturing area compared to a normal film camera which is 35mm.

so when u place the lense in, the 35mm's 27mm-105mm is equivalent to the digital's XXmm's 17-80mm. if i'm not mistaken, some digital slrs are 35mm, and they are workable with your film slr lenses.

maybe someone can help verify what i said in 3). hope that helps.
 

Feb 3, 2002
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#3
SlowShutter said:
2) I have read that newer models will come with 7 or 8 megapixel, so will that be a necessary factor in getting a digital SLR, rather than the light sensors and other functions?

3)Why is it that a Nikon G lense of the new NikonD70, 17 - 80 mm is equivelant to that of a 27 - 105mm? I could not find any sort of explanation from any of the reviewing sites.
Alex has answered Q1 so let me help with Q2 and 3.

2) Megapixels are important if you're looking at making really large prints (A0?); otherwise the current batch of DSLRs with a >6 MP sensor should be more than enough for the advanced amateur or professional. What you should look out for would be ease of use, AF speed, handling, etc.

3) CCD/CMOs sensors are pretty expensive - thus it's not really economically viable for the various manufacturers to produce 35 mm sized sensors. Most of these sensors are smaller and hence the resultant image is "cropped". The term used to describe this is Focal Length Multiplier (FLM). For the D70, the FLM is 1.5x, and thus the 17-80 effectively becomes 27-105.

Hope this helps. :)
 

kfeng

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Mar 7, 2004
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Inside the world of tech
#4
SlowShutter said:
My questions are:

3)Why is it that a Nikon G lense of the new NikonD70, 17 - 80 mm is equivelant to that of a 27 - 105mm? I could not find any sort of explanation from any of the reviewing sites.

Please advise......
For question 3. I believe the correct answer is to be found at nikon's website. Though not in a easy to find way...
The 17-80mm [DX] is equivalent to the 27-105 [35mm] because the picture angle they produce is the same.

To explain better, take i will use real lens example to show you.

Take the 17-55mm DX and the 24-85mm [35mm]. By multiplying the focal multiplier, you can get the 17-55 to become 25.5-82.5mm. Ok so the 25.5-82.5 can be approximated to 24-85mm lens. Now compare their picture angles obtainable from nikon's website. Both roughly have the same picture angle ... 79° to 28°50' (17-55) to 84° to 28°30' (24-85).

The focal multiplier is also used when you place non-dx lenses onto a nikon dslr. So a 50mm becomes a 75mm. (Its not exactly the same as a 75mm also, but i believe there are explanations on this on the net.)
 

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