Go Back   Steve's Digicams Forums > Digicam Help > Newbie Help

Reply
 
Thread Tools Search this Thread
Old Mar 19, 2004, 6:25 PM   #1
Junior Member
 
Join Date: Mar 2004
Posts: 9
Default Tough question about zoom and pixels

Is it better to have more optical zoom, or more pixels for distant shots?

Lets say I have a 3MP digicam with a 4X zoom and I frame a shot at full zoom and snap a photo. Now, lets say I take the SAME shot with a 4MP digicam with only 3X zoom and I zoom it so that the previously framed shot ocupies the SAME NUMBER OF PIXELS (after cropping). The result is that I have 2 photos that are 3MP - one zoomed and the other cropped. All else being equal, will the resulting images be the same?

Tough to explain - hope you get the point of my question.

Jim H.
jhimmel is offline   Reply With Quote
Sponsored Links
Old Mar 19, 2004, 11:21 PM   #2
Senior Member
 
Join Date: Dec 2002
Posts: 5,803
Default

You'll have to search back a ways in the archive of this message board, but this topic was discussed at great depth a bit over a year ago. I honestly don't remember all the logic and math that was being tossed around.

What I do remember is that the resolution has to grow a lot faster than linearly to give you the same resolution after you crop. So optical zoom is (almost) always better.

But the real problem with your question is that "3x" and "4x" are marketing terms and are almost useless. A 30-60MM lens is a "2x" zoom, but so is a 100-200mm. So trying to do these calculations based on the "x" factor is impossible... they are not comparable. The only things you can compare are the 35mm equivalent focal lengths.

Eric
eric s is offline   Reply With Quote
Old Mar 20, 2004, 7:11 AM   #3
Junior Member
 
Join Date: Mar 2004
Posts: 9
Default

I understand the vagueries of 3X and 4X, I was just trying to simplify the question. The actual range is imaterial to my point.

I will try to search out the thread you speak of.

Jim H
jhimmel is offline   Reply With Quote
Old Mar 20, 2004, 7:21 AM   #4
Junior Member
 
Join Date: Mar 2004
Posts: 9
Default

Any tips on how to search out that thread? General search terms that seem relevant are pulling up thousands of threads.

Jim H.
jhimmel is offline   Reply With Quote
Old Mar 20, 2004, 10:22 AM   #5
Senior Member
 
Join Date: Oct 2003
Location: Indian Rocks Beach, FL
Posts: 4,036
Default

To answer your question, the images will be exactly the same if everything else is equal like lens quality and noise generated by the density of the CCD.

What everyone is trying to point out is that increasing optical zoom has a 2:1 advantage over increased pixels when you start reaching longer distances. In other words, doubling your optical zoom will give you twice as many pixels in a distant target than will doubling your pixels. You get to the point very quickly in the optical zoom verses pixels argument where the increased pixels can not generate the same number of pixels from a distant object as what an optical zoom will give you.
slipe is offline   Reply With Quote
Old Mar 20, 2004, 2:00 PM   #6
Senior Member
 
Join Date: Dec 2002
Posts: 5,803
Default

Thanks slipe, that says that I was driving at very well.

I just did some searching and I couldn't find it. I did find this one:
http://www.stevesforums.com/phpBB2/v...cal+zoom+pixel

but it isn't the one I was thinking of. The one I remember had lots of detail with the math of how sensor size growth adds pixels at a certain rate, but that optical zoom does it faster. It was a good thread.

Eric
eric s is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 8:14 AM.