Advice Centre by Photography Experts (Part 7) - Cropping to create close-ups & Moody skies

6/13/2012 9:27:17 AM

What influences lens size?

My Nikon 50mm lens is a lot smaller than my brother-in-law's Sigma 50mm. Why is that when they both have the same focal length?

Description: Nikon Lets Slip New 50mm ƒ1.8G Silent Wave Lens

Nikon Lets Slip New 50mm ƒ1.8G Silent Wave Lens

Focal length is only one factor that influences the physical size of the lens, and it's not the main one. The maximum aperture also plays an important role because the larger the aperture, the bigger the lens has to be to accommodate that aperture. A 50mm f/1.8 lens will be physically smaller and lighter than a 50mm f/1.4 and that, in turn, will be much smallerand lighterthan a 50mm f/1.2. Allied to maximum aperture is optical design; the wider the maximum aperture, the more glass elements there tends to be in the lens, which also increases size and weight.

Finally, if the lens has any specialist characteristics this also results in a size increase. Is the Sigma 50mm a basic standard lens or a macro version? That could also explain the size difference.

Cropping to create close-ups

I enjoy shooting close-ups of everyday objects and have been thinking about buying a macro lens. But they're expensive, and I don't have cash to burn, so I'm wondering if I could just crop the shots taken with my 50mm prime lens. Printed to A4 or viewed on-screen, will I really notice the difference in quality? My DSLR is a 16.2-megapixel Nikon D7000.

Description: Cropping to create close-ups

Cropping to create close-ups

It all depends how much you crop them. A proper macro lens allows you to focus very close and fill the frame with tiny subjects. At 1:1 (life-size) repro, you can fill the frame with an area the same size as your D7000's sensor, so around 25x16mm. Cropping an area out of a shot taken with a 50mm lens to match that isn't feasible as you'd be enlarging a fraction of the image area. However, for everyday details, cropping 50mm images to enlarge the subject is perfectly acceptable.

The output size of an image from your D7000 is approx 12xl6in at 300dpi. You could crop a quarter of that image and still have an output size of 6x8in at 300dpi. However, by interpolating the file you'd be able to print bigger than 6x8in - easily up to A4 at 300dpi and bigger if you dropped the print resolution to 240dpi or even 180dpi. All you do to interpolate is go to lmage>lmage Size, enter the new dimensions of the image, click on Bicubic Smoother at the bottom of the window, then click OK.

For images to be viewed on your computer screen or put online, you can crop in closer because screen images only need to be at 72dpi. So, if you enlarge one of your 50mm images to 100%, crop an area that measures only 4x3in (Vi6th the total image areal), then convert the cropped image from 300dpi to 72dpi - it would measure around 16xl2in and look great on screen.

Moody skies

I have a Nikon D3100 and have started shooting landscapes, but have been having difficulty getting to grips with the Bulb mode. Even using graduated filters I am struggling to capture moody, moving clouds and instead keep getting overexposed skies. What am I doing wrong?

Description: Moody skies

On most DSLRs, 30 seconds is the longest automatic exposure possible. To exceed this, you will need to use your camera's Bulb mode, allowing you to manually lock the shutter open. However, an exposure upwards of 30 seconds is normally only possible in low light. If you are getting blown-out results, too much light is reaching the sensor. You could try using a lower ISO and smaller aperture to help rectify this, but I suspect you are simply trying to achieve an exposure that is too long for the conditions. Try waiting until the twilight hours when light fades, or buy a solid Neutral Density filter. While a grad is designed to just hold back the sky, a solid ND will lengthen overall exposure. They are available in varying strengths, with a three-stop ND filter a useful buy. If you're wanting exposures of a minute or more, you will need an extreme ND such as Lee Filters' Big Stopper or Hitech’s Pro Stop, both of which offer ten stops of filtration. When shooting, review the monitor and histogram regularly to judge whetheryour exposures are correct.

  •  Pentax Q - The world's smallest MILC
  •  Create Your Own E-Books (Part 5) - Format Wars, Format Conversion & Apple Steps Forward
  •  Create Your Own E-Books (Part 4) - The EPUB Format & Introducing Sigil
  •  Create Your Own E-Books (Part 3) - The Amazon Effect & Kindle Tools
  •  Create Your Own E-Books (Part 2) - Creation Services
  •  Create Your Own E-Books (Part 1)
  •  World Wired Web (Part 2) - Windows 8 Flavours Unveiled
  •  World Wired Web (Part 1) - Cameras For One And All
  •  Predict The Weather (Part 3) - Understanding weather fronts
  •  Predict The Weather (Part 2) - Feathery storm clouds
  •  Predict The Weather (Part 1)
  •  Get To Know Your Camera (Part 3) - Histograms
  •  Get To Know Your Camera (Part 2) - Focusing
  •  Get To Know Your Camera (Part 1) - Camera icons explained
  •  Review: lcy Box Stand For iPad
  •  Home Security On A Budget (Part 3)
  •  Home Security On A Budget (Part 2)
  •  Home Security On A Budget (Part 1)
  •  Review: Nikon D4 – The master of the dark arts (Part 3)
  •  Review: Nikon D4 – The master of the dark arts (Part 2)
    Top 10
    Motorola RAZR MAXX - “Being The World’s Lightest”
    Nokia 808 Pureview
    Nokia Lumia 610 - Shines Out Of Low Segment
    Nokia Lumia 900 - The Brightest Star In Lumia Series
    One More Thing: Two New Ipods
    Sony Xperia P Review (Part 2)
    Sony Xperia P Review (Part 1)
    Onyx Calypso 9.7 Tablet
    Aesthetix Calypso Light Preamplifier Review
    Worthy Audio Block C-100 For Mid-Class CD Player
    Most View
    Android 4.0 Ice Cream Sandwich Guided Tour (Part 3)
    SharePoint 2010 : Operations Management with the SharePoint Central Administration Tool (part 6)
    Managing Browser Cookies and Other Temporary Internet Files
    The Best Time To Buy A Mac or iOS Device
    Shoot Your Best-Ever Portraits (Part 2) - Natural light setups
    iPhone 3D Programming : Textures and Image Capture - Fight Aliasing with Filtering
    Windows 7 : Keeping Your Family Safe While Using Your Computer (part 1)
    Playing In The Sandbox
    Windows Azure : Using the Storage Client Library
    The Language of Apple Platforms : Object-Oriented Programming and Objective-C
    SQL Server 2008 : Working with DML Queries - Using the INSERT Statement (part 2)
    Introduction to Xcode Simulator
    SQL Server 2008 : Performance Tuning - Using Dynamic Management Views
    iPhone 3D Programming : Adding Depth and Realism - Surface Normals (part 2)
    5 Beautiful Dock Speakers For Apple Devices
    Olympus VG-170
    Programming .NET Components : Building a Distributed Application (part 5) - Creating Remote Objects
    Windows Vista : Customizing Windows PE Boot Images (part 2) - Working with an ImageX GUI, Working with PEImg
    Which is the right router for you? (Part 3)
    Bose Introduced The Second TV Series