diffraction

Color Seascapes: Cozumel, Mexico

El Mirador, #18. Cozumel, Mexico, 2017
El Mirador, #18. Cozumel, Mexico, 2017

 

Sorry about the lack of posts of late. We have been spending a lot of our emotional capitol recently and decided to drop off of the grid and out of the social media gerbil mill for ten days or so.

It was refreshing.

Enthused by a new environment, I did hoist my sleepy fanny perpendicular on nearly every morning in search of interesting sunrise sites, the above being one: El Mirador on the windy (Caribbean) side of the isle.

Some photography tips for this and other spots on Cozumel:

–First and foremost, the east area of the island, which I found most interesting, is theoretically off-limits before 6a.m. and after 7p.m., which will be a problem during certain times of the year for a photographer looking for good light. In the dark wee hours, you may run in to some reflectors stretched across the road next to a smallish warning sign that states the hours of access. (The sign actually says you can’t go into the southern and eastern areas between 6a.m. and 7p.m., but that is clearly a mistake.) It is easy enough to drive

Check Point. Cozumel, Mexico, 2017
Check Point. Cozumel, Mexico, 2017

around the reflectors–they were unmanned when I encountered them–and continue on your way, but you could be taking a risk. The reason for the restriction (according to three different locals we asked) was that contraband and drug shipment activities were at one time an unpleasant reality in the relatively unpopulated areas (not so much now, apparently) and the local authorities didn’t want tourists inadvertently walking into some sort of Breaking Bad business transaction on one of the desolate beaches. I am not sure what the police would do if they found you and your tripod there outside of the posted hours but an educated guess would be that it would likely involve a fine. In my case, typically passing the check point at 5:40a.m. and arriving at my chosen photo op spots by 6a.m., I saw absolutely no one. YMMV!

–You will need a rental car (or scooter) to get out east and back during the “golden hours” of sunrise/sunset. We rented a car and had no close calls with other vehicles, people, iguanas, or crocodiles, although you have to be very alert when driving anywhere near San Miguel–motorcycles and scooters, like buzzing locusts, are everywhere. Note on car rental: The initial price will look very, very cheap. You’ll need to add on all the different required insurance policies, so you’ll likely end up paying $300.00 or even more for a week with a small economy car. It is worth it, though, if you need the photographic flexibility.

–Remember all the usual salt water/beach precautions: Be careful about sand and salt spray getting in and on your equipment. Bring cloths to clean things up and for wiping off lenses. Many folks will use a clear filter to protect their lenses in these conditions. Take great care when changing lenses–reminder: the east side is the windy side.

–The rock around El Mirador and on the southeastern side of the island is SHARPLY sculptured limestone. If you fall on it, you could stab yourself to death, poke an eye out, bust a kneecap…or, at the very least, come up very scraped, bloodied, and humbled. So, wear some good shoes–and watch your step.

–Be ready to fill a memory card or two as you experiment with different wave combinations and shutter speeds. I tried everything from longer 30-second exposures with my 9-stop ND filter, to exposures short enough to freeze the water motion. I tended to prefer the 2-second to 1/8 of a second range because of the wonderful water effects this would often create. (The above image was shot at 1/4 second and f/22. Yeah, yeah, I know…diffraction and all. It does indeed have a negative effect on sharpness but I’m OK with it.)

–Expect to do a fair amount of cloning in post-processing due to the amount of trash that collects along tide line on top of the algae. Or, alternatively, you could just fill up a few bags with trash before you shoot.

–Other spots to consider: the tide pools at Chen Rio at Kilometer 44, and the interesting blow holes at Kilometer 32. El Mirador is at about Kilometer 34.

–In a future post, I’ll show one or two before and after post-processing comparisons using my raw files. You will see that I did a fair amount of lifting of shadows and dropping of highlights, cloning out of trash and water droplets, contrast and saturation increases, horizon straightening, and so on…to turn the images into what I saw on that morning!

Here are some examples of what I came up with on the different mornings I shot along the east coast…

First, here is an example pre-sunrise image. Sometimes there is very nice light, with more subtle colors, before sunrise, so plan accordingly. I liked arriving just as first light was approaching. This gave me time to play with longer shutter speeds (8 seconds in this case) as well as scope out the area:

El Mirador, #1. Cozumel, Mexico, 2017
El Mirador, #1. Cozumel, Mexico, 2017

 

Here is another pre-sunrise photograph taken on a different morning, this time with Venus above and also reflected in the foreground pool. I only saw the planet’s reflection later, during post. If I had noticed at the time, I would have moved slightly right so as to put the reflection just slightly to the right in the water. This was a 20-second exposure and the naked eye saw much less light than what you see here:

El Mirador, #30. Cozumel, Mexico, 2017
El Mirador, #30. Cozumel, Mexico, 2017

 

As the Sun comes up, your shutter speed will have to get shorter (unless you use filters), but this is a nice opportunity to try to catch waves in flagrante delicto, as in the following three examples–two into the sun, and one away. In the last, a half Moon happened to position itself nicely in the blue between the high clouds:

El Mirador, #7. Cozumel, Mexico, 2017
El Mirador, #7. Cozumel, Mexico, 2017

 

El Mirador, #40. Cozumel, Mexico, 2017
El Mirador, #40. Cozumel, Mexico, 2017

 

El Mirador, #42. Cozumel, Mexico, 2017
El Mirador, #42. Cozumel, Mexico, 2017

 

Another option for a completely different mood and look is to throw on a 9-stop filter and go for a long exposure–30 seconds at f/11 in this case. These filters are so dark you have to frame and focus first, then put the filter on for the shot:

Chen Rio, #5. Cozumel, Mexico, 2017
Chen Rio, #5. Cozumel, Mexico, 2017

 

The opposite extreme is to stop at least some of the water motion. Here, at the blow holes at Kilometer 32, I used 1/200 and f/11 with full morning sun. I wasn’t quite successful in capturing the partial rainbow that would fleetingly appear through the mist (sorta seen below the Moon):

Blow Holes, #2. Cozumel, Mexico, 2017
Blow Holes, #2. Cozumel, Mexico, 2017

 

Finally, if you are stuck at “home” maybe try shooting the pier right next to your hotel as I did here. The near full Moon helped by adding a nice center-o’-interest with an anchored boat and dock light on the left as secondary tidbits. This was a 25-second exposure at f/22 but done sans filters as it was still quite dark out (well, with moonlight). The slow shutter smoothed out the sea (and blurred a few clouds) and the small aperture helped bring out the star effect on the Moon and the pier lights:

Moon Over the Pier. Cozumel, Mexico, 2017
Moon Over the Pier. Cozumel, Mexico, 2017

Getting a sunburst (Howdja do it?)

Sunburst, Sunlight Spire, #3. Needle Mountains, Colorado, 2014
Sunburst, Sunlight Spire, #3. Needle Mountains, Colorado, 2014 (with the Nikkor 14-24mm f/2.8 wide angle zoom lens set at 14mm and f/22)

Someone asked me this question recently, so I thought I’d answer it here.

A simple way to do it…

1) Use aperture priority and set your f-stop to somewhere between f/16 and f/22. The higher the number, the smaller the hole and, thus, the sharper the sunburst. Consider that these small apertures will also introduce a bit of softness to the overall image via diffraction (but, IMHO, not too much for most purposes). Experiment with varying f-stops to see the different effects you’ll get with the burst.

2) Place an edge of the Sun’s disc behind an object–leaf, rock, building, bear, clown, person, whatever. If you don’t do this–if you have the entire Sun’s disc in the image–you may get more of a blobbish kind o’ sunburst, although it can still work. Hiding a part of the disc enhances the sharpness of the effect. Experiment with varying “bites” out of the Sun, then select the best image later in post-processing.

3) Know that each lens will yield a different effect. For example, my 14-24mm f/2.8 wide angle zoom (as in the above example image) gives much sharper bursts than my 70-200 f/4 telephoto. Generally, straighter blades in the lens diaphragm = sharper rays, while rounded blades = softer rays. Often, older lenses, with their straight blades, give very good results. Practice with all your lenses so you can learn their characteristics. (NOTE: In lenses with an odd number of blades, the number of rays in the sunburst will be exactly double the number of diaphragm blades.  If the lens has an even number, the ray count will be equal to that number.)

4) You’ll need to watch your histogram and/or the blinkies in the LCD as the correct exposure may appear very dark. Know that the sunburst itself will blow out a bit, and that’s OK. The rest of the image should not typically have any blown highlights (unless there are reflections or specular highlights somewhere). Also, the shadows will likely be well to the left on the histogram, but they should not be slammed entirely against the left wall–that is, they should be mostly recoverable in post. Consider trying different exposures.  If you use base ISO (typically 64, 100 or 200), the shadows can be recovered with less noise.

5) Capture raw files for max ability to manipulate them in post.

6) In post, you will likely have to move the Shadows slider right–maybe all the way–to recover the detail in what will initially look like an underexposed image. Moving the Highlights slider left can adjust your sunburst a bit, reducing an excessive blob effect–experiment. A combination of increasing exposure and reducing the highlights can also help. Increasing Clarity slightly is another way to brighten up the darker areas–but don’t overdo it. Finally, depending on your camera’s noise-in-the-shadows capability, you may need some noise reduction.

Now it’s time to go out and practice!

 

Diffraction

Platge, Evening #1. Barcelona, 2014 (A long exposure at f/22)
Platge, Evening #1. Barcelona, 2014 (A long exposure at f/22)

With my old film camera, and with my first digital cameras, the Nikon D70 and D90, if I wanted everything in focus in a landscape image, I’d just set f/22 (aperture priority), focus on my foreground object (or no more than 1/3 into the scene), and let ‘er rip. It seemed to work just as fine as a frog’s hair.Enter the newer generation of digital cameras, such as my current Nikon D800. With these much more capable machines, you’ll hear the term “diffraction” sprinkled throughout conversations that focus on (sic!) image quality and sharpness.

So what is diffraction? I’ll explain it the way I think of it even though it might not be particularly scientific: When light passes through a hole, if the hole is big, the light passes through no problem. But, if the hole is tiny, the light tries to cram its way through and some of the beams get bent and scatter in the process. The effect in your image is that, with a small aperture (say, f/22) there might be some softness to the photograph. At a larger aperture (say, f/5.6) you might notice more sharpness to the scene. This is all very subtle and is more noticeable in larger print sizes (say, 16×20 and up).

If you want to read a great explanation–much more scientific than mine, but still understandable–of diffraction , airy discs, and how it might affect your photography, see the Cambridge in Colour website. Of particular note on that website, are two little interactive sections (scroll down a bit on that link). In both, you can enter your camera model and the desired f-stop for some interesting visual feedback on what the image quality impact might be.

Five of my personal and very unscientific observations about diffraction:

1) Other factors tend to be much more important. For example, are you using…A stable tripod? Mirror lock-up? A remote trigger (or delay)? Good focus technique? A good quality lens? Proper sharpening in post?

2) For my 12×18 prints on 13×19 paper, it seems like f/22 has little noticeable negative effect–as long as I also pay attention to the laundry list of items in #1.

3) If I don’t need f/22 I don’t automatically set it, as I used to. Instead, I try to see if f/8, f/11 or f/16 will give me the depth o’ field I need. (A max of f/8 will often work, especially with very wide-angle lenses, depending on the scene.)

4) If I ever need to print larger than 12×18, I might consider the idea of focus stacking several captures all shot at, say, f/5.6.

5) If you honestly analyze your photography, how many of your images really rely on sharpness to be effective anyway? (The below image, for example, could have been shot with just about any camera at most any f-stop–the effects of diffraction on sharpness didn’t really enter into the equation.)

As a side note, I purchased the D800 as opposed to the D800e model partly based on what I read about diffraction. The “e” model apparently is slightly sharper than the “plain” model, but generally at the wider apertures (f/5.6 and wider). At smaller apertures (f/8 and smaller), this difference tends to disappear, and these are the apertures at which I find myself shooting at quite often.

The Cave Man. Barcelona, 2014
The Cave Man. Barcelona, 2014

May 2013 CNCC Meeting: Lessons Learned (Cliff DeJung)

Shadows and Arrow, Self-Portrait. Tucson, Arizona, 2013
Shadows and Arrow, Self-Portrait. Tucson, Arizona, 2013

At last night’s meeting our guest was Cliff DeJung, a talented photographer from Longmont, Colorado. His presentation on “How to Get Tack Sharp Images” went into more depth than I had seen before about this topic. Thanks, Cliff! Now, assuming you are wanting to get tack sharp images… click here for more info.

Wednesday Photo Critique #5, 12/19/2012

Ice #86, South Boulder Creek, 2012
Ice #86, South Boulder Creek, 2012

This week’s image for the Wednesday Critique is hot off the sensor–it’s from yesterday morning’s walk along the semi-frozen South Boulder Creek in Eldorado Springs Canyon.

And my standard call before I proceed: If you have been lurking about this web site and you’d like me to use your image for a Wednesday critique, just send me an e-mail (see Contact tab). That way, you can save me from critiquing my own images, which would be a welcome relief!

OK, back to the photo o’ the day…I have my critic’s hat on and I am pretending this is the first time I’ve ever seen this photograph…here we go…

The metadata: Nikon D90 (1.5x crop factor sensor) with Nikkor 70-300 f/4.5-5.6 zoom at 300mm, f/29, 1/2, ISO200, tripod, outdoor overcast light.

And following my 7-Step Critique Guide Click here for the entire critique! Click here for the critique! Click here for the critique!