Tag Archives: experience

Commentary, Locations, Popular

Photographing the Moving Rocks at Racetrack Playa

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(Note: Originally posted in January, 2008.)

Earlier this week I posted an older photo from Racetrack Playa at Flickr and got a lot of comments and a few questions. In response, I said that I would post something here about this location – so here goes…

The Racetrack Playa is in Death Valley National Park in south-eastern California. The Playa is the site Death Valley NP’s famous moving rocks (a.k.a. “sliding rocks”) phenomenon. Rocks, some of which are television-sized, have left tracks behind them as they have traveled across the surface of the playa. (See a post from earlier today for one photograph – there are more in the Death Valley section of my Gallery.)

No one has actually seen the rocks move, but there has been a lot of speculation about the process by which the rocks manage to travel across the playa. I’m no expert on this, but here’s some of what I’ve heard. First of all, while you are free to have a different opinion, I’m not convinced that aliens did it. (Though it would be a heck of a good joke on us.;-)

One theory involved a combination of wind and water. While you might wonder how water could play a role in a dry place like Death Valley, it most certainly can. In fact a playa is a feature formed when water washes sediment down from surrounding hills into a lower basin. The water spreads onto the playa and drops its load of sediment. When the water dries it leaves behind an extraordinarily flat surface. The thought was that rocks sitting on a very slippery surface of the playa might be moved by strong winds. Observations tended to make this scenario unlikely. For example, it was calculated that the winds necessary to move the largest rocks would have to be several hundred miles per hour. It gets windy there, but not that windy.

A refinement of the theory adds ice to the mix. Imagine a thin layer of water on the playa with the slippery surface underneath. Now freeze a thin layer of ice on the top of the underlying water in this shallow “lake.” (And, yes, it very definitely gets cold enough there to freeze water.) Now the winds would not have to work directly on the rocks themselves, but could instead act on the whole frozen surface, much as they act on the arctic ice pack. As the ice moved, the rocks embedded in the ice would be dragged along. This seems to make sense given the observation that groups of rocks often follow parallel paths across the playa surface.

The rocks seem to come from a low rocky hill at the south end of the playa. While they can be found in many other areas of the playa, the greatest concentration is near this formation.

Access to the Racetrack Playa is typically by way of an awful 27 mile gravel road that starts near Ubehebe Crater. (I’m no expert on desert travel or on these roads, so consult the Park Service for current and more reliable information if you go.) The road has been badly washboarded every time I’ve been on it – some people are so distressed by the conditions on the road that they turn around after a few miles of driving. For most drivers this makes for very slow going and it can take up to about two hours to get out to the playa. I met one driver of a very large truck who was convinced that “once you get above 30 mph the road smooths out.” I don’t recommend that approach. Slow and careful is probably a lot safer, especially for those without extensive experience driving roads like these. I know that I sit back and take it slow.

The last time I checked the Park Service recommended a “high clearance vehicle” for this road, and I concur. I have seen some vehicles without such clearance and it seemed to be pretty rough going, not to mention that you increase the risk that the undercarriage will be damaged by rocks. (If it has rained or snowed, all bets are off. Best to stay away. You certainly aren’t going to walk on the playa when it is wet anyway, are you!?)

Soon after you pass Teakettle Junction you will catch your first view of the playa ahead and/or to the left. You still have a ways to drive before you arrive at the playa and drive along the right side. You’ll want to keep going if you plan to see the best rocks, though it is worth stopping at the Grandstand, a large rock formation in the playa not far from where it starts. I’ve had good luck photographing this feature during the late afternoon.

Continue on to pull-outs near the far end of the playa for closest access to the rocky hill and the largest number of moving rocks. You’ll need to leave your car and walk a good distance out onto the playa. (Don’t even think about walking on the playa unless it is completely dry. Foolish and inconsiderate visitors have done so, and their footprints mar the scene for years afterwards.) Before long you’ll start to see the rocks. One plan is to head for the low hill where the rocks originate and then explore outwards from there.

There is a small “camping area” a short distance beyond the end of the playa. It is very primitive, consisting of little more than a couple of wide spots in the road and one dilapidated outhouse. There is no water whatsoever. I have camped there and it is very quiet and peaceful. I’ve also see people sleep in their cars back at the turnouts right at the playa.

My ideal trip works something like this: Go during the cool season. Almost no one would want to try to visit this place in the summer. Most visit in late fall, winter, or very early spring. My visits have all been during the first week of April. Drive out to the playa in the afternoon, arriving a few hours before sunset. If you have time, stop to photograph the Grandstand in the afternoon light. Then head on down to the south end of the playa and figure out where you’ll sleep that night.

By the time the light starts to become interesting you’ll want to be out on the playa, perhaps with a few shots already scoped out. Shoot like crazy for the next few hours as the sun drops and finally sets, continuing on after sunset as long as the light is interesting. Head back to your car and grab some dinner. (The last time I visited I met some fellow photographers and we had a great time sharing food and drink.) If there is a full moon (or maybe even if there isn’t) head back out to do some night photography. This is a wonderful place to photograph star trails, and there are a ton of interesting opportunities on full moon nights once the moon finally makes it over the ridge located to the east. Finally, completely exhausted, head back to your camp for the night.

Rise early the next morning – well before sunrise. You want to already be out on the playa before the interesting light starts. The morning lighting is interesting and somewhat challenging. All I’ll say is that there are mountains to the east that block the first light, yet the very earliest light will illuminate some interesting subjects.

Soon, most of the playa is in full sun. I generally shoot a bit more, but by this time I’m running out of gas – and getting hungry for some real food. I head back to the car, say goodbye to the playa and start the long drive back to the paved road that begins near Ubehebe Crater. (Don’t pass up on photographic opportunities as you drive this road though.)

Finally, a few random thoughts – some in response to questions I’ve received.

  • Someone asked how often the rocks move? I’m not sure but not often – the interval must be measured in years.
  • Someone else asked how they keep visitors from “tracking it up” when it is wet? Good question, and an important one to mention. There are footprints on the playa left by inconsiderate visitors who wandered about when the playa was muddy. Their footprints remain for years. If you visit when the surface is wet please do not leave tracks on the playa, even if that means coming back a different time. Fortunately, the road is so long and so bad and there are no services out there – all of which drastically limit the number of visitors. I’ve seen perhaps as many as 20 people out there at once, but on one other visit there were only two of us.
  • Another photographer asked about the effect of the eastern ridge on sunrise photography. I touched on that above, but there is indeed a very tall ridge to the east that keeps the area with the concentration of rocks in the shadows until later in the morning.
  • And what about the ridge to the west at sunset? There is also a large ridge to the west of the main part of the playa, and the road past the playa runs along its lower east edge. This feature casts a shadow on the northern portion of the playa well before actual sunset. My advice it to photograph there a bit earlier – I’ve had good luck photographing “The Grandstand” in the late afternoon. The sun hits the southern portion of the playa later in the evening since the valley opens to the west from there.
Commentary, Equipment, Popular

Lens Protection: Ultraviolet (UV) Filter or Lens Cap and Hood?

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(This has become one of the most-read articles at this site. For some reason, the question of whether or not it makes sense to add these little filters to your lenses generates a lot of interest… and sometimes a lot of lively debate. Portions are now a bit dated — the article comes from 2007 — but the general concepts discussed here still hold. From time to time I make small updates based on new information or questions that have come up. Note that there are links to a couple of related posts listed near the end of the article.)

Sellers sell, and some buyers buy, ultraviolet (UV) filters for their cameras. The main advantages are said to be twofold: some reduction of haze that is invisible to the human eye but which the camera purportedly might register, and some protection for the front element of your lens.

On the other hand many photographers wouldn’t think of putting an extra layer of unnecessary glass in front of their lenses. They would rather accept the (rather small) possibility of a scratch on the front element of a lens than possibly reduce the quality of their images, and/or they prefer to protect the lens by using a lens cap and lens hood.

I’m in the latter camp. I no longer use any UV filters* and I can think of darned few situations in which I’d want to use one. (One possible exception being the use of fully-sealed lenses on which the seal is completed by adding a front filter – and here only if I were to use the lens in an extremely hostile environment and with a fully environmentally sealed camera body.) My preference is to handle my camera and equipment relatively carefully, keep the gear protected when not actually using it, use a lens cap, and to almost always use a rigid lens hood.

Continue reading Lens Protection: Ultraviolet (UV) Filter or Lens Cap and Hood? →
Equipment, Reviews, Tests

Canon EF 24-105mm f/4 IS L Lens

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(Updated December 28, 2011.)

I have owned the Canon EF 24-105mm f/4 IS L lens since 2006. I originally picked this lens for several reasons:

  • On my full-frame cameras,  this lens covers a very useful range from fairly wide to slightly long, making it a very flexible and versatile lens.
  • The lens is quite sharp and has good contrast throughout its focal length range.
  • For its focal length range the lens is relatively compact. This is important to me since I frequently hike or backpack with photo gear.
  • The f/4 maximum aperture is generally sufficient for the kinds of photography I do.
  • The image stabilization (IS) feature is helpful for handheld photography and somewhat compensates for the f/4 maximum aperture.

Like most lenses, this one has a “personality” that gives it particular strengths and weaknesses relative to the individual photographer’s work and working methods. My extensive experience with the lens convinces me of the following:

  • Resolution is very good when the lens is used with care. Sharpness is excellent throughout the focal length range, being best in the middle portion as expected. Sharpness can diminish a bit at the long end compared to, say, 50mm – but this is usually not a reason to switch to another lens except in those cases where I have plenty of time to do so.
  • Vignetting (corner light falloff) is certainly noticeable at f/4 and especially so at the shortest focal lengths. For most of my photography this is not an issue since I most often shoot at smaller apertures. However, I do shoot the lens at f/4 and wide angle focal lengths. In these cases a) the vignetting is actually a nice effect with some subjects, b) it can be corrected easily and pretty much automatically in post when necessary.
  • Barrel/pincushion distortion is mostly not an issue, though the lens does produce noticeable barrel distortion at 24mm. Here the situation is somewhat similar to that with vignetting. In most cases, I don’t even notice the barrel distortion in actual photographs. I do notice it in photographs that have lines parallel to and close to the edges of the frame. When necessary, I let my raw conversion software (ACR) apply an automatic correction and the image lines up nicely and still has very good resolution.
  • There is a false notion that this lens is not sharp at 24mm. This is incorrect. I think that this rumor -which is what it is – got started on internet discussion boards where people morphed the descriptions of the vignetting and barrel distortion into “poor performance at 24mm” and then further to “must not be sharp.” This is simply wrong. Sharpness is fine at 24mm.
  • Handling is great. Compared to the lens sometimes cited as an alternative, the 24-70mm f/2.8 L, this lens is more compact and a bit lighter. The lens is solidly built and the controls are accessible and easy to use.
  • Over time any lens can go out of adjustment and require service. If you use your lenses a lot, you will eventually discover this truth. In my experience, two particular issues might eventually come up with this lens. First, I notice and others have described the development of “zoom creep” after a time. The tension on the zoom mechanism seems to loosen and if you point the lens straight down it may “zoom out.” Second, although I have only my own experience to go on here, I have a slight suspicion that the lens may be a bit more susceptible to going out of adjustment with rough treatment compared to some other Canon zooms. After a few years of being banged around on the trail, mine had to go in for adjustment of a focus issue on one side of the image. After adjustment it came back working great.
  • While a f/4 zoom is generally not going to be a super bokeh lens (though there are exceptions), this lens does OK. It can produce slightly “busy” bokeh at some middle apertures. Surprisingly, it produces very nice bokeh when used with an extension tube for macro work. (In fact, for hand held photography of things like wildflowers, extension tubes attached to this lens with its IS feature can work very well.)

The dimensions of the lens are similar to, but slightly larger than, my 17-40mm lens. However, the 24-105 is noticably heavier, though not enough so to compromise its use as a walk-around lens. Speaking of which, it is regarded by many as a nearly perfect lens for this role on full-frame bodies. In fact, I’ve had great success using it for street photography!

On a 1.6 crop factor body it is less useful as a single lens solution than it is on a full frame body, since 24mm is not all that wide on this camera. (It is roughly equivalent to a 38mm lens of a full frame body which is only moderately wide.) I did use it on a cropped sensor body for about a year when I first purchased it. In practice, I found that I tended to switch back and forth between the 24-105 a wider zoom a lot. Unless you are not fond of wide angle shooting or you like to switch lenses a lot, there can be better solutions for use on cropped sensor bodies. The following are a couple of other lenses to consider if you shoot a cropped sensor body: Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens or
Canon EF-S 17-55mm f/2.8 IS USM Zoom Lens. (The links go to site sponsor B&H Photo.)

My article on backpacking photography discusses how I combine the 24-105 with other lenses to produce a very viable and reasonably light backpacking kit.  In a few cases I have gotten along quite nicely on pack trips with just the 24-105 , though in most cases I combine it with the Canon 17-40mm f/4 L and/or the Canon EF 70-200mm f/4 L for more flexibility.

Bottom line: I’m quite happy with the EF 24-105 f/4 IS L lens. Color and contrast are great and it is very sharp for a zoom. The zoom range is excellent on a full frame body and might be useful for some shooters even on a 1.6 crop factor camera.

Related:

This lens is available from site sponsor B&H Photo, and your purchase though links at this site help support the blog. If this information was useful to you in making your decision, please consider purchase through the following link: Canon 24-105mm f/4L IS at B&H

Other gear mentioned in this article, with links to B&H:

G Dan Mitchell Photography
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Text, photographs, and other media are © Copyright G Dan Mitchell (or others when indicated) and are not in the public domain and may not be used on websites, blogs, or in other media without advance permission from G Dan Mitchell.

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Equipment

Lowepro Slingshot 200 AW

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(Note: I originally wrote this piece when I was using a smaller cropped sensor Canon DSLR. I’ve left much of the write-up as it was originally, but I have added/adapted to reflect additional experience with this product with my full-frame Canon 5D.)

Finding the right bag to carry photo gear is very difficult for me, and I hear I’m not alone. In general, my needs fall into three categories:

  1. Small bags and pouches that can hold individual pieces of gear. For example, I carry my camera in a small chest-mount bag when I backpack.
  2. Large backpack that can handle major amounts of photo gear, a tripod, and additional equipment for hiking and/or travelling. (As I write this, I’m still looking…)
  3. A bag that will hold all the gear I need but which provides easy access without the need to remove the bag.

I think I have finally found the answer in the third category in the Lowepro Slingshot 200 AW. This bag rides over one shoulder like a backpack with only one strap, which allows it to slide forward into a position at my side or in front of me where I can access my gear without taking the pack off. (For me at least, this maneuver requires a quick tug to loosen the strap since I pull it relatively tight while carrying the pack on my back.)

A large zipper flap provides access to the main portion of the bag. Attachment straps keep it from accidentally opening too far and spilling equipment on the ground. When theese are undone and the pack removed, it opens twice as wide to provide even better access. Removing this pack is easier than removing a regular backpack since there is only one strap and it can easily be loosened. A lighter secondary strap can be unstowed and attached across your chest to provide a bit more stability and security when desired

(The following is from the original post, written when I was using this bag to carry a lightweight setup based around a cropped sensor camera. Though it is now dated, I’m leaving it here since it may be useful to some photographers using similar gear.) The bag easily handles my 350D with a 17-40mm lens attached, my 70-200 f4, and my 50mm f1.4 – all with the hoods – plus my 17-85mm EF-S, and still have a bit of room left over. I’m quite certain that I could replace the 350D with something like a 20D or 5D and still fit everything in. My tripod is the only thing that won’t fit in or on this bag, so I carry it in a separate bag over my other shoulder.

My primary camera these days is a Canon 5D, and my default lens is most often the EF 24-105mm f/4 L IS. With the hood reversed this combination will fit into the main compartment in the lens down position, with enough space on either side for my EF 17-40mm f/4 L (with hood removed) and EF 70-200mm f/4 L (hood reversed) – a snug fit but entirely workable. I can add my 50mm prime below the UWA lens, but here things start to get a bit tight. But, keeping in mind that I have larger bags for those times when I really want to bring everything along, the Slingshot is perfect for carrying “just enough gear” and being able to travel a bit faster and lighter.

A good sized upper pocket can carry some additional “stuff.” For example you could fit an additional lens or an external flash in this pocket. I often use it for “odds and ends,” including lens/sensor cleaning supplies, wallet, cell phone, iPod, and so forth. (When I fly and pack a set of tripod legs in my checked luggage I use this upper pocket to carry my ballhead.) An additional smaller pocket on the back of the pack is handy for items like memory cards, batteries, filters, and business cards.

I have no major complaints about this bag. However, I could wish that the main compartment provided just a little more flexibility for carrying extra lenses. A few more velcro attachment points would do the trick.

The waterproof cover is pretty useful, at least in light rain. The pack is short enough (just barely!) so that I can wear a fanny pack from The North Face below it. This lets me carry a couple water bottles, some extra clothes, and some food for hiking. Alternatively, I attach a Lowepro accessory water bottle carrier to one of the attachment points on the side of the Slingshot and forego the fanny pack.

Update 8/26/08: Lowepro produces a variety of Slingshot bags. For some time smaller Slingshot 100 AW and the larger Slingshot 300 AW have been available, and recently the Slingshot 350 AW was introduced – the latter bag appears to be even a bit larger and to provide space for carrying a laptop, which should make it quite useful for folks flying with camera gear.

G Dan Mitchell Photography
About | Flickr | Twitter | Facebook | Google+ | 500px.com | LinkedIn | Email

Text, photographs, and other media are © Copyright G Dan Mitchell (or others when indicated) and are not in the public domain and may not be used on websites, blogs, or in other media without advance permission from G Dan Mitchell.

(Basic EXIF data is available by “mousing over” large images in blog posts. Leave a comment if you want to know more.)