Home News Buyers Guide About Advertising
 
 
 
   
Results 1 to 7 of 7
  1. #1
    Join Date
    Apr 2007
    Posts
    2

    Newbie - how does sLR compare to Optical zoom?

    Hi All!
    I know nothing about photography so I am hoping someone can help. I currently have a Sony Cybershot DCS-P71 that has 3x optical zoom. My wife wants to get an SLR (in particular, a Nikon D40) that comes with an 18-55mm zoom lens.
    What I am trying to figure out it - how can I relate an 3x optical zoom to an SLR? If I was going to get a non-SLR camera, I would now go for a 10x optical zoom. So how can I figure out which SLR's would give me the same as a non-SLR 10x?
    Thanks!
    Trey

  2. #2
    Join Date
    Feb 2006
    Location
    Des Plaines, IL
    Posts
    9,554

    Question Optical Zoom of a DSLR? I suppose, but why?

    You can divide the longest focal length by the shortest and have a pretty good idea of it for any zoom lens.

    (longest focal length/shortest focal length)

    You mentioned the 18-55mm ... fine, let's use it for your example.

    55 / 18 = 3.05x optical zoom

    Select the TAMRON 18-250mm lens and you get the widest optical zoom available, today, on an interchangable lens.

    Let's do the math ...

    250 / 18 = 13.9x optical zoom.

    More often it will be determined by how wide the lens will go. If you take a 70-300mm lens, which is a very common telephoto and do the optical zoom calculation on it ... you get:

    300 / 70 = 4.3x optical zoom

    When it comes to DSLRs ... this optical zooming means very little, because you can CHANGE to a lens that gives you what you want. With a point & shoot (P&S) ... it's one lens to do everything, so you are kind of stuck. You had better have some serious optical zoom range.


    I hope this helps you out.

    EDIT: After I thought about this a little, I figured it might be better for you think of lensing as to its typical use ... and not optical zooming, as determined by its focal range.

    for APS-C sensors
    10-24mm is considered Ultra Wide-Angle - used for taking large groups or little groups very, very close.

    18mm-35mm is considered Wide-Angle, but at decent distances

    17-50mm is considered a short utility range. It covers wide angle, normal, and creeps in on short telephoto in one lens. (Good choice)

    18-200/250mm is considered an UTILITY lens, which is what you would want if you could only carry one lens for all aspect photography. These can range from $300 - $500, and deliver a rather good image in daylight. It's telephoto effectiveness lessens with limited light. Defintely best used in combination with an external flash, indoors.

    50-150mm is considered to be a short telephoto. You'd use something with this range for subjects 20 feet or further away from you, when you need to get tight.

    (high end) 70-200mm is considered to be the most desired lens choice at f/2.8, for it's performance indoors. This would be an "across the room" lens, when you need reach and have a limited light source. These usually are quite pricey.

    70-300mm is considered a standard telephoto and outdoor lens. If it focuses fast, this would be the lens you'd take to the ballpark to snap lil' Joey snagging that fly ball in Right field. A very cost-effective choice for most folks.

    200-500mm is considered to long telephoto, usually for taking images of birds or relatively distant subjects, that will not allow you a close vantage point for a better shot.
    Last edited by DonSchap; 04-22-2007 at 09:05 AM.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  3. #3
    Join Date
    Feb 2006
    Posts
    301
    Digicams as well as the xzoom number also show the range of the lens in 35mm(film) equivalent terms.

    For the Sony 'cam its a 39mm - 117mm lens.

    Quoting in terms of the 35mm equivalence is easier to compare than simply quoting a X zoom number, indeed as Don shows above the zoom figure is a simple ratio..

    So while your 39-117 lens is a x3 zoom so is a lens going from 20-60, or 100-300, however the 100-300 for example has nearly 3 times the "reach" as your camera, ie it gets you a lot closer ...

    The Nikon d40 has a sensor just like your Sony 'cam which is smaller than than the sensor (film) used in 35mm slrs , so it has a so called crop factor.

    Slr/dslr lenses are always quoted in 35mm terms, so a 18-55mm lens when placed on a Nikon d40 which has a crop factor of x1.5, you actually get a field of view as if the lens was 18x1.5 - 55x1.5 , ie as if the lens was a 27mm-82.5mm lens.

  4. #4
    Join Date
    Mar 2007
    Posts
    1,923
    I did the same thing, more or less - I spent years with a 3x zoom point-and-shoot, and have just upgraded (finally!) to a D40. The zoom is almost the same with the 18-55mm kit lens, but there is this to consider as well: the 6.1 MP SLR sensor, which is much larger than a point-and-shoot and therefore captures more detail, will allow you to display your pictures at a larger resolution with better detail than any point-and-shoot.

    And, as Don mentioned, interchangeable lenses mean that you are never tied down to a particular zoom length - adding the Nikkor 55-200mm telephoto lens will give you the equivalent of 18-200mm, about 11x zoom, a nice range. There are two 55-200mm lenses to choose from, a $175 non-image-stabilized, and a $250 VR (stabilized). The latter is a great deal.

    As for the choice of the D40, it's a fine camera. Limited a little by its so-called Achilles heel, the lack of an internal focus motor, but there are multiple lenses which will work fine regardless, and many of them are zoom lenses. The D40 also provides more information in-camera to familiarize new users with the settings and their effects. A great learner's SLR.
    Nikon D40 + kit lens

    Nikkor 50mm f/1.8 D AF(...or not)

  5. #5
    Join Date
    Jul 2005
    Posts
    6,590
    Quote Originally Posted by fionndruinne View Post
    I did the same thing, more or less - I spent years with a 3x zoom point-and-shoot, and have just upgraded (finally!) to a D40. The zoom is almost the same with the 18-55mm kit lens, but there is this to consider as well: the 6.1 MP SLR sensor, which is much larger than a point-and-shoot and therefore captures more detail, will allow you to display your pictures at a larger resolution with better detail than any point-and-shoot.
    This is not true (at all).
    In fact, most DSLRs get less detail from the same amount of pixels than a good compact digital camera. The DSLRs give a much softer photo. It does depend on the lens used in the compact digital though.
    And use the term compact digital, not point and shoot. The D40 is a point and shoot DSLR. The difference between sensors has an impact on noise performance, especially at higher ISO settings. Not detail.

    Look for instance at the review samples that show the same subject from Jeff Keller's reviews.
    One example:
    Nikon D40 6.1mp DSLR:
    http://www.dcresource.com/reviews/ni...w/DSC_0076.JPG
    Canon SD550 7.1mp digital compact:
    http://www.dcresource.com/reviews/ca...w/IMG_0061.JPG

    You can say a lot about both photos, but not that the digital compact shows less detail. And notice the Nikon trademark aliasing problems in the pointy roof tiles, where the yellow and blue bands are camera induced (aliasing), and the Nikon trademark strange patterns within these colour bands.
    Attached Images Attached Images  
    Last edited by coldrain; 04-22-2007 at 08:00 AM.
    Canon EOS 350D, Tamron SP AF 90mm F/2.8 macro, Sigma 18-50mm F2.8 DC EX, Canon EF 70-200mm f/4 L USM, Tokina AT-X124 Pro 12-24mm F4, Soligor 1.7x C/D4 DG Teleconvertor, Manfrotto 724B tripod, Canon Powershot S30

  6. #6
    Join Date
    Apr 2007
    Posts
    2
    Thanks! A lot of good info! Much appreciated.
    Trey

  7. #7
    Join Date
    Mar 2007
    Posts
    1,923
    Geez, you like to be difficult, Coldy.

    I've never seen aliasing in my shots except when they're not displayed at full size, which leads me to believe that those D40 shots aren't at full size themselves. Doesn't look like just 1MP's difference in size, either.

    You're generalizing a lot, and in most point-and-shoots noise is much worse than any DSLR, thus displaying at higher resolutions means dealing with that problem. Soft details can usually be fixed with sharpening to suit the eye better - that's much harder to do with noise reduction, which loses a lot of detail.

    And, of course, your anti-Nikon phrases like "Nikon trademark aliasing" are ridiculous, but that's your trademark. It'd be great if you could provide objective info for people without steering them towards your own pet beliefs.
    Nikon D40 + kit lens

    Nikkor 50mm f/1.8 D AF(...or not)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •