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.
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
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:
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:
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:
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:
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):
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:
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.
If you own a DSLR and think you might need a new paintbrush (that is, a new lens), don’t discount third party lenses. True, there are some real rotten apples out there amongst these “non-Canikon” brands, but there are some with excellent reputations as well.
If you looking for a new lens, stop and read what I wrote about lens buying on the FAQs page first (scroll down to #4), then continue on…
A short list of third party lenses with good reputations:
—Tamron SP AF 17-50mm f/2.8 XR Di-II VC LD Aspherical (IF) – Helluva title, eh? I used this with my Nikon D90 as my walk-around lens and it is a nice one for a crop factor DSLR. It has Vibration Compensation (VC) and is fast, so it is handy for low light conditions. Image quality is very good. About $650.00.
—Tokina AT-X Pro 11-16mm f/2.8 DX II – Never owned this one, but was tempted because I like the super wide look now and again. It has a narrow range, but very often, when you go wide, you take it to the max and zoom range becomes less relevant. A fast 2.8 lens built for crop factor cameras. About $450.00.
—Sigma 35mm f/1.4 DG HSM – An extremely fast lens with excellent sharpness and bokeh, from what many reviewers say. Works on both crop factor and full-frame DSLRs. About $900.00.
—Tamron SP 24-70mm f/2.8 Di VC USD – The only, fast, medium-range zoom for full frame cameras that comes with Vibration Compensation (VC). Image quality reputed to be very good. I went with the Nikkor version and, since I do most of my work from a tripod, I haven’t missed the image stabilization feature, but you may have other needs. About $1300.00.
—Sigma 150mm f/2.8 EX DG OS Macro HSM – A fairly heavy lens for both crop factor and full-frame. Excellent bokeh and sharpness. I have the older version without Optical Stabilization (OS), but am on the tripod mostly. I like that I can stand off a bit from macro subjects and it doesn’t seem to suffer too badly from diffraction even when I stop down to the ridiculous–like f/29! About $1100.00, but you can get a good used one without OS for about $550.00-$600.00.
This is just a partial list of third party lenses that I see getting fairly constant good reviews–and two of which I have used. You’ll have to do your own research to find others that might interest you.
One note of caution. If you buy mail order, be sure to check out your lens thoroughly once you get it as quality can vary significantly from copy to copy–perhaps more so with third party lenses. If you buy locally, you may be able to compare several different copies on your own camera right in the shop. Check sharpness as best you can at all f stops and at various distances and in varying lighting situations.
I like lists and organization…so, one of the things I do rather anally is keep an annual list of my “keepers”. Usually, it totals around 600 images over twelve months, of which maybe ten or twenty qualify as “pretty good” (IMHO). The interesting thing, though, is what I learn from looking at the patterns that emerge, as these lists include all the metadata (and some other variables I track) from each photograph.Here are some conclusions from my 2013 list:
–I shoot about 90% in black and white and about 10% in color, (Actually, I shoot 100% in color as this statistic just reflects the post-processing conversion rate.)
–I often forget to change my ISO from the previous shoot. That is, I’ll find myself in broad daylight, on a tripod, shooting a landscape at a ridiculous ISO, like 3200–my setting from the cathedral interior I was shooting the previous day. Dang, follow the checklist, man!
–I almost never use flash. Note to self: learn to use both on-camera and strobe flash better, especially fill flash.
–A good 60%-70% of my images are shot from a tripod, regardless of shutter speed. On the tripod, I always use mirror lock-up along with a delay to allow the camera to become still after pressing the shutter (I use the remote only for bulb-type exposures).
–I am getting much better at including the ISO in the same cross check as aperture and shutter speed. I used to just keep my old camera on the base ISO almost all the time as it was too noisy if I moved much above that. However, with these new generation cameras (examples: the Nikon D800, Sony A7r, Canon 5DMKIII), I freely move between 100 and 3200 ISO as the situation dictates–ISO 100, generally, when I am outside in decent light, or anytime on a tripod…ISOs 200 to 800 when I am handholding and walking the mountain trails or the city sidewalks…ISOs 1600 and 3200 for indoors, handheld shots, or for the night stars. I could probably even push it to 6400 and be OK in some situations. I do this manually, preferring not to set up the auto ISO function in the camera. Being free to move up and down the scale is all quite liberating. I just need to remember to reset the dang ISO when I change situations (see first bullet)!
–Generally, I am pretty good at picking the right aperture for the depth-of-field required–and I use aperture priority almost exclusively (on a rare occasion, I go full manual). This is important because of the balance I need to find between getting sufficient depth-of-field and avoiding the effects of diffraction. With the 14-24, this is not really an issue as f/8 will often get most everything in focus and avoid the heaviest diffraction effects. But, this is often a player with the 24-70 when the diffraction-inducing f-stop of f/22 might be required. (All this depends, of course, on whether or not a super sharp image is actually a requirement–many times it isn’t.) Note to self: practice focus stacking…shoot three images (at, say, f/5.6), focused at the fore, middle and backgrounds, then combine them in Photoshop.
–My two most often used lenses are the 24-70 f/2.8 and the 70-200 f/4. They get about 40% each of the total, while the 14-24 f/2.8 picks up the remaining 20%, or even less.
–It’s interesting to see how often I am at either the shortest or longest end of the focal length of a given zoom–this happens maybe 25% of the time.
–The good images often come in bursts. Looking at the numbering, I see that I might have three, four, or even a half-dozen “keepers” within a 30-frame range…then I’ll go 150 or more frames without a decent photograph. Maybe this indicates that sometimes I am “in the zone”, and sometimes I am not–or I’m experimenting and things aren’t working.
–I need to get a lot more critical at culling out the good images from the great images. In 2014, lets see if I can cut the “keepers” list in half!
So, maybe take a look at your metadata trends and see if they might be telling you something important.
Sometimes, as a change of pace, I’ll grab a tool I don’t often use: my macro lens. It is enjoyable to flip the switch wired to my photographer’s eyeball and start “seeing” the tiny details in that micro-world that always surrounds us.
I chose the Sigma 150mm f/2.8 lens for several reasons: its good reviews as a sharp, top quality lens, it will work with both full-frame and crop-sensor bodies, it’s a fast lens, and it gives you some stand-off when trying to stalk shy insects. It is, however, a fairly heavy, large hunk with a relatively large price tag for the newer version which has image stabilization. (I have the older, cheaper version without stabilization and generally use it on a tripod, so lack of I.S. isn’t important to me.)
Playing with depth of field…the above was shot at f/2.8 to isolate one or two of the spiny tufts.
You’ll have to analyze your personal macro wants and needs, then decide which macro tool would be best for you.
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.
Yesterday I posted a photograph which was actually a collection of images that created sort of a loose story line which I called “Shadow Play”. The above photograph is one of the individual photographs from that collection–and I’m going to make an example out of it! You see, as I was looking at the metadata of this and all the other shadow images I noticed something: they were all shot at f/16. (Click here to see why I thought that was a big deal.)
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.
2016 Black & White Magazine, Spotlight Award Winner! (Issue: June, 2017, #121)
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