How to avoid Star Trails with the '500 Rule'

Due to the rotation of the earth it appears as though the stars are moving through the sky in long exposures. Star trails can be a desired effect when done for much longer exposures, but in this case we want points of light to represent how we see the stars with our eyes. To achieve points of light you can use a simple rule, it's often called the '500 rule'.

Badlands Milky Way Pano

500 Rule: 500 divided by the focal length of your lens = the longest exposure before stars start to trail or blur (in seconds)

For example; let's say your taking a shot with a 24mm lens on a full frame camera. 500 / 24 = 21 seconds, which you can round to 20 seconds. 

The example above was taken with a 14mm lens on a full frame camera, at 90 seconds you can see the blur of the stars, but at 30 seconds the stars are nice sharp points of light.

You may see this as the 600 rule, I personally do not believe this is the best approach as you will have a small amount of trail using 600. If you never intend to print your images very large then you can use this number to capture a bit more light and nobody will know any better. Smaller prints or web sizes will not show this small trail, but large prints will. This is your choice, but we do not know what the future holds so you should consider starting with 500, and with newer sensors like the Sony a7S you could with a higher ISO and instead use a 400 rule to ensure your prints have no trails.

Math and sleepless nights do not mix (I've learned the hard way) so here is a handy cheat sheet you can print out and keep with you.

  Seconds Before Stars Blur
Focal Length Full Frame Nikon 1.5 Crop Canon 1.6 Crop
10 n/a 33 31
14 36 24 22
16 31 21 20
20 25 17 16
24 21 14 13
28 18 12 11
35 14 10 9
50 10 7 6
70 7 5 4
85 6 4 4

Note that I did not round these numbers, you do not have to use the exact number, and I would round down, for example for 18 seconds would round to 15 rather than 20. It is possible to use the exact number if you have an intervalometer; simply set your shutter to BULB and set your intervalometer with these settings: Delay-0, Long-18", Intvl-1", N-1. This will take 1 shot that is 18 seconds long.

Follow this simple formula and you will be well on your way to creating images like the one below.

Oxbow Bend Reflections

There has been some discussion on various social networks as to why those with higher megapixel cameras can see star trails when using the 500 rule. The problem comes when viewing raw files at specific zoom percentages. What you see is dependent on the amount of megapixels. In the example below I zoomed in to 400% to show an extreme example of this. The D700 appears to have no trails and the 5D MKII appears to have not insignificant trails (both were taken at 14mm, 30 seconds). 

Here's where things get interesting. I opened both files in Photoshop and re-sized them to 24x36. With the playing field leveled we now have a 1/16" star trail in both files! 

What's the takeaway? First off, megapixels have no effect on the 500 rule. When you print, the star trails will be the same size. What it really comes down to is how big you are going to print and what the viewing distance is. This will determine how long your trails can be, sorry I don't have an answer for this. Can you perceive a 1/16" trail on a 24x36 print? I highly doubt it. A 60x90 print will have 3/32" trails, this is getting to be a decent size. But, how close should you be viewing a 60x90 print? not the same distance as a 24x36. Ultimately it's up to you, the artist to decide what is acceptable. I'm content with this length of trail and will be sticking with the 500 rule for now.




Prime Time! - Lenses for Night Photography

I'm often asked what the best lenses are for night photography, my recommendations may be a pleasant surprise to your wallet!

What do you want in a lens for night photography? The most important factor is how much light a lens will let in so we can shoot at lower ISO's, this means apertures of 2.8 or greater (1.4 being preferred). Most zoom lenses only go to 2.8, while this perfectly okay for night photography, it's not the ultimate lens to use. Most zoom lenses in the 2.8 category cost anywhere from $1500 to $2500 a piece.

Enter the prime lens, a prime is a fixed focal length that is designed to have much larger apertures. If you have looked into the major manufacturer's primes (Nikon, Canon, Zeiss) you may be thinking I'm crazy right now because they are expensive! Anywhere from $1000-$2000 each. I wasn't about to pay these prices, so I went on a search for lenses with the ultimate quality to price ratio.

In this search I've become a huge fan of Rokinon lenses, these are also branded under Samyang, ProOptic, Bower. They are all the same lenses, just with different names. Rokinon seems to be more common in the US and are usually cheaper.

These following lenses are relatively cheap compared to the pro series Nikon or Canon lenses

Rokinon 14mm 2.8
Rokinon 24mm 1.4
Rokinon 35mm 1.4

BorrowLenses has the following Canon cinema lenses available to rent. Cinema lenses have the same optics but the aperture is measured in T stops rather than F stops, but they perform the same.

Rokinon 14mm T3.1
Rokinon 24mm T1.5
Rokinon 35mm T1.5

I will also throw in the Nikon 50mm 1.8G, since Rokinon does not make a 50mm. Why not the 1.4 version you ask? Aspherical lens element, that's why. This was the first 50mm released that has an aspherical element, so what you say? This type of lens reduces coma dramatically, the other factor to consider when picking a lens for night photography, which I'll explain next.

I know what you gear heads are thinking; I want the highest quality lenses out there, I only buy the manufacturers lenses because they're the best! Hold on there buddy, there's a reason I recommend these lenses. You may have heard of Coma if you're a real pixel peeper, but most people have never heard of it, and for most photography it's not something to worry about. When it comes to night photography though, coma is especially important. Below is an extreme example of what coma does to stars near the edge of the frame when shot wide open. This was taken with the Nikon 50mm 1.8D which does not have an aspherical element. Those are supposed to be points of light, not streaks!

Surprisingly the Nikon and Canon versions of the 24mm 1.4 have terrible coma as well. Here's a comparison of the Canon 24 1.4 and the Rokinon 24 1.4, from what I've read the Nikon is even worse than the Canon. These lenses are around $2000! You can buy the entire lineup I listed above for the price of this one lens!

The great news about Rokinon; almost no coma. The Image below is a 100% crop from a corner taken with the Rokinon 14mm at f2.8

And the Rokinon 24mm at f1.4. The slight blur is from being just out of focus, don't rely on infinity with this lens, it's not accurate and you need to manually focus.

The quality of these lenses continues to pleasantly surprise me.

If you're on a budget or just getting started, I would recommend the Rokinon 14mm 2.8 for shooting meteor showers, timelapse and wide views of the milky way. Next, I would get the Rokinon 35mm 1.4 if you're interested in doingpanoramas or tighter shots of the milky way.

One thing to note; the Rokinon lenses are all manual focus, a big reason for their lower cost. The good news? You can't auto focus in the dark anyway! The best way to focus at night is using live view, zooming in on a bright star and manually focusing.

Another lens I should throw in is the venerable Nikon 14-24 2.8, a phenomenal lens for Nikon or Canon (with an adapter). If you have the means, or just happen to have this lens already you certainly don't need the Rokinon 14mm. The Nikon has very little coma and is probably the greatest wide angle ever made. The Nikon 24-70 2.8 is also a great lens if you already have one, I wouldn't pick it up specifically for night photography though as it does have a decent amount of coma and is only a 2.8.

I've been asked for recommendations for cropped sensor cameras. I only have second had experience with these lenses, so you may want to do your own research. First up is the

Tokina 11-16 2.8, Nikon Canon Sony I've heard only good things about this lens

Nikon 35mm 1.8g - Since this has an aspherical element it should perform well, but I have no experience with it.

External Power for a Nikon D700

After my first successful attempt at shooting the Perseids meteor shower I became addicted. I have shot 2 other meteor showers since then and have more planned for the future. Photographing a meteor shower can put quite the stress on your camera, especially the battery. Cold conditions in the mountains and taking continuous 30 second exposures for an entire night eats them up quickly. I was able to change the batteries easily enough because I have an MB-D10 battery grip that holds an additional battery. But this required me to change out the battery every 2 hours which made for a long night, plus I had to borrow extra batteries to make it through the night. 

I decided there must be a better way, I knew of the EL-5 AC adapter which allows you to hook up your camera to an AC power source. Since I obviously cannot plug in to an outlet in the mountains I figured a jumper box with an outlet would do the trick. After researching this further I realized that this was not the optimal solution, the conversion from DC to AC, back to DC is extremely inefficient, plus lead acid batteries are very heavy.

I finally came across this article DSLR Battery Hack for Timelapse that hacks up a cheap EN-EL3e to attach an external battery through this shell battery. This was a great idea and I almost ran with it, but I thought there had to be an even better way. The DC plug on the D700 was taunting me, surely if I hooked up the battery to this I would be set, but a thorough Google search returned nothing, I couldn't find anyone who had done this before. I was scared to fry my baby, I forged on though.

The standard Nikon EN-EL3e has 1500mAh. When shooting the Perseids meteor shower I went through 5 batteries in 8 hours. So I'm assuming 1.6 hours for 1 battery in the cold.

Here's a list of the items you'll need:

Wasabi Power Battery - $28.99
This is a high capacity battery for a Canon camcorder that puts out the same voltage as the D700's battery, I wanted the voltage to be the same so I didn't have to put a regulator in the mix. Here's the cool part; 8500mAh. That's nearly equivalent to 6 EN-EL3e batteries! It should last for a little over 9 hours in cold conditions. Also the power to weight ratio is much better. An EN-EL3e weighs 2.8oz and the Wasabi with the plate and cord weighs 11.5oz. So the EN-EL3e is 535mAh/oz and the Wasabi is 739mAh/oz. This battery alone may be a great option for the ultra lightweight backpacker going on a week or 2 long trip.

Nikon EH-5 ebay knockoff - $16.00
This is a super cheap knock off of the Nikon EL-5, don't waste your money on the Nikon version, all we'll be doing is cutting off the wire to use the proprietary plug to connect to the D700.

Pearstone Compact AC-DC Charger - $24.95
A charger for the new battery.

Pearstone Battery Adapter Plate - $4.95
This is just a dummy plate I found that will hold the battery when shooting and make the connection to the battery.

Total Cost - $74.89

Versus 1 D3 battery (EN-EL4a) which costs $109 and only has 2500mAh, since the EN-EL4a replaces the battery in the MB-D10 grip you would have a total of 4000mAh, still less than half of just this one battery.

The beauty of this setup is that I can still use my EN-EL3e batteries in the camera and the MB-D10, so with the new battery I have a total of 11,500mAh! Nearly 12.5 hours of shooting!

Eventually when I get a D800 I will add the Nikon EP-5B because they decided to omit the DC jack. Or I will build my own version of this with a cheap hacked up EN-EL15. The unfortunate part of this is the need to use one of the battery slots, either in the camera or in the grip, meaning less overall power. I may play around with wiring it directly to the battery and leave the cells in place so that battery can still be used.

On to the instructions....

The first step is to pop off the back of the Adapter plate, cut the wires off of the small circuit board inside (cut as close to the board as possible) and strip back a small portion of the wire. (Sorry I don't have any pictures of the build because I was in a hurry to shoot meteors!)

Next, grab the EL-5 and cut off the wire that comes out of the 'black box', leave a little to spare if you ever want to use the AC adapter. Strip back the covering, you'll find wire just under the black covering, this is the ground wire. There will be another white coating below this, strip this back to find your positive wire.

Now you will need a soldering iron preferably or you may be able to get away with wire connectors that you can pick up at any auto parts store. Solder together the positive wire from the EL-5 cable to the red wire in the adapter plate and do the same for the ground wire to the black wire on the adapter. Put some heat shrink tubing or electrical tape around these connections. You can drill a hole in the adapter for the wire to exit from and put the back plate back on.

That's it. Make sure your new battery is charged and slip it in the adapter. Plug the wire into the DC port on the D700. Suddenly you have all the power you'll ever need. The only downside is you can't see how much battery life is left.

I tested this out on the Orionid meteor shower and shot for 6.5 hours, I still had life left in the new battery, but I don't know how much was left. I'll need a longer night to know for sure.

Overall I'm incredibly happy I built this, I'll also be using it for milky way shots and for timelapses. It's lightweight and small enough to take along for hikes. I may even take this backpacking so I can do night timelapses without the fear of having no batteries for the rest of the trip!

Keywords: BatteryD700batteriesmeteor showernight photographynight tutorialsnightscapestimelapse

Nature Photography Tools for Predicting Weather

Creating nature photographs that really stand out takes more than just leaving the house on a nice day and hoping to get lucky. Dedicated nature photographers must research and plan from a host of variables that will make or break a great shot.

Weather is the biggest thing new nature photographers miss out on, they will wait until the weather is 'nice' to go out shooting. I will let you in on a secret, dramatic weather creates dramatic photographs. If there are thunderstorms get out there, if there's snowstorms get out there (as the storm is coming in or just after the storm clears you will have dramatic light) on overcast days go shoot waterfalls or macro, white puffy clouds make for great black and white, about the only time I don't go out is on clear sky days. While most people love clear skies, it is the most despised thing of nature photographers, these are great days for sitting inside and editing images...or just be like a normal person for a day, leave the gear behind, and go out to enjoy it...yeah, that's probably not going to happen. If I'm on a road trip and the skies turn clear for a week I will refocus my energy on night photography since clear skies are desirable to see the stars.

National Weather Service

The NWS is the resource for weather prediction in my opinion, they have recently cleaned up their site to make it more user friendly, it used to be quite bad and why most people would gravitate towards other services. The NWS has some features that the others do not provide, first up is point forecasts, this means you can actually drill down to a specific spot on a map to get a forecast for an area. Go to the main site above, click on your region which brings up a regional map, click in the general area you want which will bring you to a forecast page, now to really get specific look for the google map in the right column and find the exact location you want, click that spot on the map and forecast page will change to this location. The NWS actually takes elevation into consideration which is critical if you're shooting in the mountains, I've found these forecasts to be surprisingly accurate.

The second feature they have is the hourly weather graph, when you're on the forecast page look for the hourly weather graph

This graph gives you a plethora of easy to digest information, take some time to learn how to read this and it will pay off bigtime. I've found the sky cover % to be especially useful

Clear Sky Chart - This is a great resource I mainly use for night photography to determine if the skies will be clear enough to see the stars at night, I've found it to be fairly accurate and use it during the day as well, but for the opposite reason; to make sure the skies will not be clear! This also has a great predictive satellite feature that many people probably miss; when you're on your forecast page you can click on one of the boxes for the hour your investigating and it will take you to a satellite image of the region, checking this 24 hours before you go out may completely change your plans!

Visible Satellite - This is a great detailed satellite view to help you see where the clouds are, scattered clouds are generally the best, but this really depends on what you're shooting. I also use this when storm chasing to spot overshooting tops which are an indication of a supercell that may develop a tornado.

Surface Analysis Map - This map shows current temperatures, dewpoints and wind speed/direction, which is good general information but I mainly use it for predicting where storms will be developing based on the dewpoints, Jeff Haby has a nice simple article explaining this in his Severe Thunderstorm Cookbook

Storm Prediction Center - The SPC is the resource to look to for severe weather, I check this site everyday to see if there will severe weather near my area

Graphical Forecasts - Another useful tool from the NWS, it gives good forecasts for a region rather than a specific area

Dark Sky Finder - This is specific to night photography to find dark skies which is incredibly important to actually see the stars!

Stellarium - Again night specific, I use this to determine when the milky way will be out and in the right position

The Photographer's Ephemeris - Last and certainly not least is TPE, this incredibly valuable tool will help you determine where the sun and moon are in relation to the landscape you're trying to photograph, much has been written on how to use this tool so I won't go deep into here.

This post turned out to be much longer than I thought it would, I have another post planned just for all the iPhone apps I use when in the field

 

 

Keywords: photographyweather

Comet Like Star Trails

UPDATE: Since I've written this my friend has produced a Photoshop script to automate this process, see the Waguila Stacker. If you prefer to do it manually or want a little more control, read on.

I've seen a few very unique images recently that turned star trails into what almost look like a sky full of comets, yet none of them shared their methods. This really disappointed me as I firmly believe that sharing knowledge helps us all improve together as a group. So without further ado, here is my method.

Close Encounters

First off the method for shooting is exactly the same as for making star trails, the key is to use the stacking method versus one long exposure. There is plenty of information out there so I won't be covering this; you can visit Steven's great site to learn more star trails and night photography

Next, we need to stack the images to create star trails, for this I recommend using Steven's Star Stacking Action, but we have to modify it slightly so we end up with the individual layers rather than a flattened image. After you install the actions, open the actions panel, expand Star Circle Academy Stacker, duplicate "Load and Stack in LIGHTEN Mode (Recommended)", in the copy of this delete the step 'Flatten Image'. Follow his instructions, the only change is when you are at the batch step you will select this copy of load and stack.

Now we have a bunch of layers that have their blending mode set to Lighten, I'm sure many of you have already figured out by now that all you need to do is change the opacity of each of these layers to be progressively more opaque. In my image I had 20 layers so I set each layer 5% apart; for example 95%, 90%, 85%, etc. This creates the trailing off that looks so cool. I've found that around (50) 30 second exposures looks very nice.

Finally to get the bright star with the spikes at the end of the trail I used the amazing plugin Star Spikes Pro which has an incredible amount of flexibility. I applied this only to the background layer (which I duplicated of course) I'm sure some won't like the spikes but I don't really care, this is art.

That's it! It's quite simple actually, the only thing that took a long time was cleaning out all the planes from different frames. I found that using layer masks and leaving all the layers on made this a lot simpler than trying to clean up each frame individually cloning because then you can see what effect it's having and you can be much less anal.

I hope this helps some of you out, and I want to see your results! I know I'll be putting this to good use in the near future as I plan to get out a lot more. Please feel free to re-share this and ask any questions.

 

Keywords: cometsgalaxymilky waynight tutorialspost processingstar trailsstars