Dec 132011
 

Ever thought “This is a beautiful moon tonight, let’s take a photograph?” If  you did, you probably ended up with one of two results: 1. The moon is totally blown out. 2. You see the moon but everything else is pitch black. Why is that? It turns out your eye is a much better camera than your DSLR, at least as far as dynamic range is concerned. While your eye sees the moon with its surface structure, it still perceives the surroundings are doused in a gentle light. Your camera sees a sun light object, the moon, which wants to be photographed at 1/125 and f11 or so (remember sunny 16 rule!), while the night scene won’t show up unless you open to f2.8 and crank up the ISO. Now you can “cheat” and photograph the moon, then come back and photograph the night when the moon is no longer in the picture, and then “photoshop” the moon into it. That actually works pretty well at times, and you can make the moon look bigger than it is, which helps if you photograph with a wide angle lens where the moon usually looks like a small bead on the sky.

 

The following images were shot with a Nikon D7000 and the 24-70mm f2.8 lens.

 

D7000, 24-70mm lens, Moon

Short exposure - moon appears "normal", most everything else is black.

 

D7000, 24-70mm lens, Moon

Long exposure - moon appears "sun-like", everything else is well visible.

 

Here is another approach: what you need is a tripod and photo-processing software that can do HDR (high dynamic range) or, if you are patient and meticulous, you can use something like Photoshop Elements or other software that you can layer several images together.

 

The principle in HDR imaging is that you take several pictures at different exposres and them combine them to extend the dynamic range of the camera. A usual DSLR has a range 11-12 “stops” (see the Lens chapter for what a stop is), i.e. it can “see” a difference of factor 2~12, which is 4096. That may seem like a lot but isn’t really that much. The human eye is capable of dynamic range of ~30 stops or factor 1,000,000,000, although not at the same time.  However at night, especially when our eyes have adjusted to it, we do much better than DSLRs! However when photographing a stationary subject, we can under- and  overerexpose an image to “gain” dymnamic range. For example if ausual scene meters at 1/250 , ISO 100 and f8, we can see “into the shadows” that the DSLR normally just records as  black by exposing  at 1/4, that is 6 stops overexposed. Of course most of the scene will be blown out, just pure white. One can either selectively combine parts of the two images to piece together an image which shows a well balanced scene, or one can use software to combine the information of the image into a “HDR” image.  The short version is that HDR “squeezes” mutliple images at different exposures into one and creates thus an artifically large dynamic range (i.e. if you use 3 images, each one stop over and underexposed, dynamic range increases by 2). HDR images can look pretty natural but often take on a flat, artificial look (we are nou tsed to seeing all that dynamic range projected onto a monitor or printed on paper which clearly does not have the same range). Some people like it, some don’t.

 

D7000, 24-70mm lens, Moon, HDR

HDR image of the scene, the moon is still blow out and has a weird shape

I did this with the moon lit scene, but even though I bracketed the exposure 5 stops, the moon is still blown out. I then took an additional picture which was underexposed by ~ 11 stops, giving me a passable image of the moon. I cut out the moon from the underexposed image and pasted it onto the HDR image. That clearly looks weird and needs some work.

 

D7000, 24-70mm lens, Moon, HDR, postprocessed

Pasting the moon into the HDR picture looks unnatural, at least initially

 

So using the pasted moon as a guide, I made a selection just the same size. Then refined the edge (feathering, some expansion) and then cut it from the background image, basically creating a while circle the same size as the “transplanted moon” while hiding the top layer than contains the moon.

 

D7000, 24-70mm lens, Moon, HDR, postprocessed
Making a selection of the size and shape of the moon
D7000, 24-70mm lens, Moon, HDR, postprocessed

Making a selection slightly bigger than the moon, which is used as a guide

Nikon D7000, 24-70mm lens, Moon, HDR, postprocessed

Cutting out the selection

I then make the top layer with the moon visible again. Changing the blending mode of the top layer to “Hard Light” and adjusting opacity as needed, the results becomes more acceptable.
Nikon D7000, 24-70mm lens, Moon, HDR, postprocessed
What is left to do? Fcat is when the shutter is open for 15 seconds or more, the movement of the start becomes apparent as little liner trails. Furthermore, times elpases between exposures and the HDR process adds extra stars to the trails:
Nikon D7000, 24-70mm lens, Moon, HDR, postprocessed

Star trail

However this is easily remedied by the clone tool, making sure to catch every one of them:
Nikon D7000, 24-70mm lens, Moon, HDR, postprocessed, photoshop
Then all what is left to do is to adjust the Hue (initial images were shot with Auto White Balance, which turned everything olive green-brown). A blueish tint makes for a convincing night scene. Voilà!
Nikon D7000, 24-70mm lens, Moon, HDR, postprocessed, photoshop

The final image

 

Once you get  a hand of it, these type of images can be processed fairly quickly. Here is anither scene from the night after. This adds a bit more challenge as the moon is no longer full, the water is quite still, and thus the reflection has to be worked on, too.  It also shows you what HDR does to the bright Xmas-lights of the house on the right side. Tonin gere ws split, with the house retaining the original wighte balance and the rest being toned bluish,

 

 

 

 



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  One Response to ““Making of an Image” Tutorial – Moon Photography/HDR”

  1. I don’t think I could ever get such fabulous pictures! Love them! Great tutorial!

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