Enough with the noise, fuggedaboudit

I was fortunate enough to capture this image of the Manhattan skyline recently from the "Top of the Rock" (Rockefeller Center) in New York.  The observatory at Top of the Rock has a strict rule prohibiting tripods so I took this hand held.  In low light shooting hand held, you will probably have to boost your ISO quite a bit, even if you open your aperture.  For this shot
I opened up to f/4,  set my shutter at 1/30 sec, and boosted my ISO to 1250.  58mm zoom, full frame sensor.

Looking at the image at 100%, there's an obvious noise problem.  For those of you not familiar what noise is, it is similar to grain in hi speed film.  But in my opinion, it's worse because it looks more like annoying TV static.  Film grain is viewed by some to be a pleasing texture and hi speed film is sometimes used on purpose for that reason.  It's all opinion so come to your own conclusions.  I was lucky to have taken a steady shot at 1/30 sec at 58mm, most likely thanks to my IS lens.  DSLRs are getting better and better at shooting in low light with very low noise.  My current camera is a Canon 5D Mark II, which is a lot better in low light than my old 5D.  A 5D Mark III or Nikon D800 would probably produce no noticeable noise at ISO 1250 (understatement) if you can afford one of those.  There is help though with software in noise reduction in post especially if you shot RAW.  Photoshop has noise reduction capabilities, and there are dedicated noise reduction programs like Neat Image that work well.  However my new noise reduction process solution of choice is in Lightroom 5 and I will explain the steps here.  The problem with previous noise reduction solutions for me is that it blurs the details it bit too much.  This solution is really slick though at reducing noise and retaining detail so please read on.

In the Develop module, go to the Details panel.  Zoom to 100% by simply clicking on your image and pan to an area of your image showing a good sample of your noise problem (typically more in dark areas).  Then slide the Luminance slider to the right until the noise level is acceptable to you.  You can see above that I slid mine to 60, and the noise is essentially gone.  But also notice the loss of detail.

Now for some simple math.  Subtract your Luminance value from 100.  In my case 100-60=40.  If your Luminance value is 70, then you'd end up with 30 etc.  Above I'm moving the Sharpen slider to 40 from my subtraction equation.  This brings back some detail but also brings back some noise.  Hang on though for what makes this solution awesome.

Hold your Alt key (or Option key if you're on a Mac) and slide the Masking slider to the right until a mask of your details shows up.  Let go of the key to see the results and tweak as needed.  Basically in my example, the sky and darker areas without much detail are black while building edges and details are white.  This is a mask that applies to your sharpening.  So anything in white gets the sharpening treatment added earlier and therefore helps preserve details.  Anything in black gets none of the sharpening and gets none of the sharpening treatment and therefore all of the noise reduction.

Here is my result after setting my Masking slider to 61 and letting go of the Alt key.  Much less noise than the original image and much of the detail is retained.

Here you can see the original image compared to the processed image.  Not perfect but much improved and the best solution that I know of so far.  If anyone has a better one, please let me know and let's share ideas.  It's still noticeably a little blurry but keep in mind that this is a 100% crop of a 21mpx image and even though I shot with quality glass, my aperture was f/4 and shutter at 1/30 sec hand held.  Not ideal for a deep depth of field or fast shutter speed.  I've printed it at 12x18 and am very happy with the sharpness.  In fact I can't see any softness or noise at all in the print.  Maybe I'll have a more modern low light performer next time and shoot this at something like f/11, 1/60 sec, and push the ISO much further with zero noise.

If you're a Photoshop user, the Camera Raw adjustments are almost identical to the Develop Module in Lightroom.  This process would not quite be possible in PS 6 because it lacks the sharpening mask feature.  I'd guess that Camera Raw in PS CC does have this feature but I can't confirm this.  If you know whether or not it does, please share.  With an older version of PS, you could of course do this in a round about way by creating a mask and using it to combine layers.  But so slick with the Alt/Option mask feature.  Look around for other features in the Develop Module that do helpful things when moving sliders with Alt/Option held.  Very useful.

A couple final notes.  The upper most level of the observatory does have some flat masonry surfaces that you could rest a camera on, but it was closed for renovation on this trip.  I have done that on a previous trip though.  The no tripod rule also applies to the Empire State Building observatory which is currently the only other rooftop observatory in Manhattan.  One World Trade Center (the tallest building in the background of my image, and also the new tallest building in the US), will have an observatory in 2015.  Can't wait!