Tag Archives: high ISO

Top Ten Reasons to Do Night Photography

I presented this list the Palo Alto Camera Club recently. Much thanks to them for being a wonderful audience and for the opportunity for Harold Davis and me to speak.

Docked [C_050127+]

10. Night photography takes time so you get a free lesson in patience.

9. You can’t use the meter so you really DO have to learn how to take photos.

8. Lots of challenges to overcome = excitement for geeks and engineers (and some normal people, too).

7. You can refer to yourself as the CRAFTER of LIGHT (if you want).

6. The camera sees all: including colors at night.

5. Automation makes night photography almost easy.

4. An excuse to upgrade: I’ve GOTTA get better high ISO performance!

3. You have PROOF that you were behaving when you were out all night!

2. You don’t have to give up your day job to do night photography.

1. Is there a more fun way to meet people in the dark?

The Elusive Milky Way – How to Find It!

Last revised: May 9, 2017
Original Publish Date:  June 26, 2012

This is Part 1 of a multi-part series on finding and photographing the Milky Way.  From November through February it is impossible to spot the densest part of the Milky Way because the sun is hovering there. Read on for more information.

What IS the Milky Way?

Path of the Milky Way West-to-East

The Milky Way in Summer from Horizon to Horizon

We are located in a corner of the heavens of a galaxy we call “The Milky Way.” The Milky Way stretches all the way across the sky and some part of the Milky Way is present every night – indeed EVERY star you see in the sky is located within our Milky Way.   Most people, however, think of the Milky Way as the cloud-like stretch of stars from the constellation Scorpius (aka Scorpio) to the constellation Cygnus – particularly the part nearest to Sagittarius.  I’ll try not to be too poetic, but when you have clearly seen the Milky Way, it is hard to describe how awesome it is without breaking into song. In ideal conditions the diffuse light of the Milky Way can cast a shadow on the ground!  Unfortunately there is little chance that you will ever see that shadow because most accessible places in the world are mildly to HORRIBLY light polluted. Constellations that are found in the Milky Way include:  Perseus (off the bottom), Cassiopeia (near the bottom in the picture above-left), Lacerta, Cygnus (near the center), Aquila, Sagittarius, Ophiuchus and Scorpius (very top).  Those in the Southern Hemisphere will also find Norma, Circinus, Crux, and Carina.  There is a faint portion of the Milky Way visible in Puppis, Canis Major and the bow of Orion. Look carefully at the image above and you’ll see a bright “smudge” in the center of the bottom fourth of the image. That is one of our sister galaxies known as Andromeda. The galaxy gets its name from the constellation in which it is found.  With an unaided eye it is readily possible to spot Andromeda in a dark sky. With binoculars Andromeda is observable even in a suburban area. In the southern hemisphere two additional sister galaxies called the Large and Small Magellanic clouds are easily seen. On a dark clear night it is easy to observe the lack of stars in the broad band of wispiness that forms the Milky Way. But the dark void is not due to the absence of stars. The void is due to immense inky dust lanes that obscure the stars!

When to See the Milky Way

The sun is in the constellation Sagittarius in December so during November, December and January it is impossible to view the richest part of the Milky Way.  October and February are generally impossible, too. The optimum viewing time in the Northern Hemisphere is in the summer when the sun is on the opposite side of the sky. Unfortunately summer in the Northern Hemisphere is also when hot, stormy, cloudy weather is doing its worst and also when the nights are the shortest. Those in the Southern Hemisphere have an advantage – longer and cooler nights during winter mean the air is clearer. Using a simple tool called a planisphere it is easy to predict when and where to look for the dense part of the Milky Way. But what must also be factored in is the location and phase of the moon. The time of year and the direction of the least light pollution also frame the parameters for getting the best view of the Milky Way. Generally the dense part of the Milky Way is best viewed when it is as high as possible in the Southern sky. Facing south during April and May the pre-dawn hours are best. From June to early August the best time is near midnight, though the Milky Way will be visible almost all night. From Mid August through September the best time is soon after the sun has set and the sky has grown dark. Below is an illustration that may help you. It was created for 38 degrees North latitude, but will serve the middle of the United States, Southern Europe, Northern China, Japan, and any location at a similar latitude very closely.  The farther North you go, the lower in the southern sky the Milky Way will be.  If you live above 65 degrees north, you will never see the Milky Way core because it never rises above your local horizon. The circle in the image below indicates the star Alnasl in the constellation Sagittarius. Above Alnasl (the spout of the teapot) is the center of our Milky Way Galaxy.

The Milky Way as seen from Mid-Northern Latitudes

The Milky Way as seen from Mid-Northern Latitudes Facing South. Click for a larger illustration

 

Month Best Time (Local Time) Moon Phase*
  January IMPOSSIBLE
  February Difficult. Before sunrise (late February only) 3Q to New
  March Difficult. Before sunrise New to 1Q
  April 4 AM to Sunrise New to 1Q
  May 3 AM to 6 AM New to 1Q
  June 10 PM to 2 AM New
  July Sunset to Midnight 3Q to New
  August Sunset until 10 PM 3Q to New
  September Sunset until 9 PM 3Q to New
  October Difficult: Sunset (early October only) 3Q to New
  November IMPOSSIBLE
  December IMPOSSIBLE

*1Q means first quarter moon (half full). In its first quarter the moon rises around noon and sets near midnight. 2Q is a Full moon. Nearly full is called a Gibbous. It is nearly impossible to see the Milky Way when the moon is near full. 3Q is the third quarter (also half full) moon which rises near midnight and sets near noon. New means the moon rises and sets very near the sun. Includes a slender crescent phase, too.

Where to See the Milky Way

Central Nevada, Eastern Utah. Montana. In short, remote areas far from city light pollution afford the best view. But if you know what to look for and when and where to look you can spot the Milky Way from many places throughout the world. Or you can wait for a massive regional blackout. I have seen the Milky Way very clearly from the top of Mission Peak in Fremont, California – an area with over 8 million people in literally every direction. However that glimpse required that the entire Bay Area be blotted out by low, heavy fog. My perch was above the darkness blanket that the fog provided. Yosemite National Park is still mostly dark despite cities like Fresno that are doing their best to ruin the darkness. As Numerous at the Grains of Sand Anywhere along a remote area of the coast far from cities there is a chance to see the Milky Way. For example, I spotted a washed out Milky Way just 8 miles north of Santa Cruz, California.  A long exposure and some photo editing improved the view.  If you get farther away from civilization the results can be much more spectacular as you see here. Finding somewhere in the country where it is truly dark, like the Black Rock Desert in Nevada, or White Mountain in Central, Eastern California the Milky Way reaches its most inspiring awesomeness. If you live outside the United States, do not despair, you have a good chance of seeing the core of the galaxy from anywhere south of 55 degrees northern latitude. Above that latitude the core of the Milky Way will never rise above the horizon.

How do I See the Milky Way

Visor View [C_033780]I know what you’re thinking: don’t I just “look” in the right direction? The answer is no! It takes your eyes 15 to 20 minutes to see their best in the dark.  Any bright light source in the direction you look will diminish the view. Running out of a well-lit house, or jumping out of a car where you’ve spent the last 15 minute driving with the headlights on will make the Milky Way far less awesome.  Avoiding ALL light and shielding your eyes from anything you can’t avoid will help a lot.  Do you see the Milky Way in this photo from the top of Clouds Rest in Yosemite? I promise you it is there. It juts out above the Yosemite Valley near the center of the image. Here is a view from the wilderness in Yosemite.

Lost in Yosemite [C_033706]

Can You Help Me Find the Best Time Where I Live?

In short, no. Please read through the comments for many such questions and answers. It’s impossible to cover information for everywhere on earth, but our notes here cover all the general concepts. Moreover, the moon phase is different so even though the Milky Way may be glorious this year on say August 8th, next year the moon may be full and obscure your view. Also, weather conditions may affect your view, so do not neglect that variable!

How Do I Photograph The Milky Way?

Cameras are getting better all the time, and there are some nifty tricks you can use to make a compelling photograph of the Milky Way even if your camera is not the top heavyweight performer in the gear smack down.  We’ll cover cameras and techniques in installment 2 of this series!

Famous III [C_035478]

Trouble with Long Exposures – Part 2 of 2

In the previous article I discussed 4 of the 6 most common problems that occur with long exposures.  Those problems are:

  1. Poor Focus
  2. Dim Stars (low contrast)
  3. Strange Colors
  4. Purple or Pink Glow

In this installment we tackle these two issues

  1. Gaps in Star Trails
  2. Lots of Noise (Colored Speckles)

Gaps in Star Trails

To oversimplify a bit there are four causes for gaps in star trails created from successive exposures:

  1. Camera limitations
  2. Camera or intervalometer misconfiguration
  3. Processing choices
  4. Weather conditions

Camera limitations: I described this issue in my article “How long does a 30 second exposure take?”  All the Canon cameras I own – including the top of the line 5D Mark II require 32.8 seconds to complete a single 30 second exposure. Well there you go: almost 3 seconds of time where there is no exposure. This problem can be compounded by two common misconfiguration blunders:

  • Failing to allow enough time between exposures when using an intervalometer. Or using the wrong drive mode on the camera.
  • Failing to turn off long exposure noise reduction.

To avoid intervalometer misconfiguration I operate in either continuous exposure mode or bulb mode. I use continuous exposure mode when my exposures will be many and a maximum of 30 seconds – e.g. when trying to capture meteors or planning for a time-lapse animation. In continuous exposure mode I set my intervalometer with a start delay and then program an exposure time of several hours… AND I put my camera in Manual, high-speed continuous exposure mode with a typical exposure of 30 seconds. You do not really need an intervalometer for this – a locking cable release is sufficient.

When I operate in bulb mode, I try to get a moderately long exposure. Usually in the 4 to 10 minute range depending on the sky conditions. In this setup it is very important to put the camera in Bulb exposure and program the intervalometer to leave a 3 second gap between one exposure and the next. I have recently discovered, however that the Canon 5D Mark II will work with my intervalometer set to 1 second intervals. That’s goodness. I am still trying to work out whether the problem is due more to the timer or the camera. I do know that in continuous exposure mode all my cameras require 32.8 seconds per each 30 second exposure. Failure to allow a long enough pause between exposures can cause unexpected results.

Photo 1: For the first half of the evening I mistakenly left long exposure noise reduction on. The result was that half of my shots occured at every-other eight minute intervals.

The “dotted lines” in the circle above were caused by leaving on long exposure noise reduction. The result was that the intervalometer timed an 8 minute exposure, waited three seconds and then pressed the shutter for the next 8 minute exposure. However 3 seconds after the exposure completed it was still doing long exposure noise reduction so that cycle was skipped until the intervalometer released the shutter for the next 3 second “off” interval.

I have gotten into the habit of setting my exposure length to 3 seconds less than what I want… e.g. 9:57 for a 10 minute exposure. I then set a 3 second inter-shot interval. I used to set a 10 minute exposure plus a 3 second gap – but the predictability of starting a new exposure every 10 minutes makes it easier to monitor what is going on.

Another cause for gaps: changing the battery. I can offer the following important tidbits when you need to change the battery.

  • Do not wait for your battery to be exhausted. A partial exposure may not stack well or be completely written to your card. Battery exhaustion will likely occur at an inopportune time.
  • Have everything at hand in advance of the change. For example, keep the battery in your front pocket where your body heat will keep it warm.
  • Practice a battery change BEFORE you start your exposures. Only by practice beforehand will you be able to discover that the battery compartment is blocked by your tripod, or impossible to reach, etc.
  • When you DO change batteries beware! Your camera settings may change dramatically!

Processing choices you make when stacking the star trails also affect whether your gaps will be inconspicuous. Do not do any sharpening until you complete your stacking – and even then avoid sharpening the star trails themselves. The method used to stack trails is significant. However, I have observed that people do not notice gaps even in this image of 19 8-minute exposures printed out at 20×30 inches.

Photo 2: Even though it is composed of 19 eight minute exposures the gaps are never noticed even when printed at 20x30.

Weather conditions can also introduce gaps. In a truly dark sky where clouds are not lit by city glow, moonlight or twilight, clouds become “black holes” and block starlight. Low or fast moving clouds can obscure some, most or all of one or more images in the set. This can be perplexing if you happen to be sleeping during exposures which started and ended with clear skies.  Another problem is dew which may form a fog that diminishes or eliminates some or all of the exposures. Vigilance with a rag, the use of a hood or a dew heater are your only weapons against dew.

Lots of Noise (Speckled Colors)

I purposefully left the noise in Photo 1. It’s quite noticeable in the rock silhouette at the lower right and appears mostly as red specs. Annoying? Well, yes, but it is not the end of the world.  In order of effectiveness here are your best approaches to keep the noise manageable:

  1. Shoot at a lower ISO (100 or 200)
  2. Shoot and stack shorter exposures – longer exposures generate more noise.
  3. Capture the foreground and the star trails separately. A better lit foreground will exhibit less noise.
  4. Shoot during colder seasons – lower temperatures result in lower noise.
  5. Control stray light with a lens hood – and close or cover your viewfinder while exposing.
  6. Use high ISO noise reduction
  7. Use noise reduction post processing tools. Chrominance noise is usually most in need of correction.
  8. Use long exposure noise reduction.

Hopefully you noticed that long exposure noise reduction (LENR) is last on the list. If you are trying to stack star trails it is impossible to get continuous trails with LENR on. It is also the least effective unless you are only going to shoot one shot.

Before we go much further, it is worthwhile to note that there are 4 causes of “noise” and each has a different source. The random speckles are usually what is meant by noise. Those random speckles are created by heat, limitations in the electronics, and things as bizarre as electromagnetic phenomenon like sunspots. No kidding. True noise is by nature random and LENR can not do a thing to combat random noise except to diminish it by reducing the luminance of the offending pixels – which also reduces the sharpness of your image. But there are 3 other kinds of noise that are not random though often lumped into the same general category: hot/stuck or degraded pixels, local heat noise (sometimes called amp glow), and high ISO noise. LENR is effective for these because they are not random.

Hot or stuck pixels usually appear as bright pink, red, blue, green, white or purple spots. They are caused by either electronic problems on the sensor chip or by the dyes used to detect the color.  A pixel detects the intensity of the color red by use of a red dye (inkjet droplet) over a sensor site. If that red dye is insufficiently thick, or missing altogether then that pixel location will always read hot if there is any light falling on it – and if the problem is electronic it may read hot even if no light is striking it. Dead or degraded pixels are just the opposite. Too much dye or dead electronics at a pixel site. Degraded pixels are stuck black or darker than the surrounding pixels and are seldom if ever noticed in night photography.

Locally caused heat noise is noticeable in some cameras and is due to the heat of electronics in proximity to the sensor. In my opinion this problem is a design flaw in the camera. However this kind of noise is repeatable so LENR can help correct it. The “Pink or Purple Glow” that results from this flaw was discussed in Part 1.

High ISO noise has an understandable parallel in the world of audio. Take nearly any cheap radio. Turn it up. At some point the sound will become distorted and harsh. This harshness is because there are limitations in the signal, the amplifier circuitry and the speaker used to produce the sound.  Increasing the ISO in your camera is the photographic equivalent of the audio scenario.  At some point amplifying the light measurements made at each pixel makes the noise more obvious.