Tag Archives: astrophotography

Simple Astro Processing Technique to Conquer Noise

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Is one of these your scenario?

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  • It’s really dark. The ISO is bumped up, the noise is screaming at you, but you REALLY want the shot.
  • The Milky Way looks SO gorgeous, you want to take it home with you like a trophy, but when you shoot short enough exposures to prevent smears, mostly what you get is noise.
  • You are surprised that you can faintly make out the Milky Way. You know your buddies will be jealous if you can show them a photo of the Milky Way that you took from IN TOWN. They won’t believe you!
  • You have a great star trail, but your foreground is not lit. The photo would sing if you could tease out that foreground – minus the noise, of course.

In the Star Circle Academy’s “Astrophotography 101: Getting Started without Getting Soaked” webinar we cover all the theory and equipment you need to take gorgeous photos of deep sky objects (nebula, galaxies):

Colorful Neighbor

But absent the fancy equipment, all you need is a wee bit of Photoshop skill to get a pretty compelling image. Less than 10 miles away from Palo Alto, California, with over 8 million households in a 50 mile radius I got the image you see below. I understand why you might not believe me.  Is it the most compelling Milky Way you’ll ever see – definitely not.

Urban Milky Way [C_036919-23PSavg]

Here is the best I could do with a single image from the same location:

Milky Skyline [5_006550]

After much processing it’s still noisy (grainy) and contrast poor.

We covered the processing technique in our Night Photography 150: Photo Manipulation I Webinar – among many other topics. Below is a 7 minute video describing how to do that simple astro photography processing.

If you think a webinar on photo processing would be of interest, join our Interest List for this or other topics and you’ll be notified when we schedule the next webinar. You can influence the topics we choose to cover by making your comments here.

Simple Astro Photo Processing in Photoshop CS5 from Steven Christenson on Vimeo.

NOTE: If the above says password required, enter scanp150 In the video, you’ll also learn how to constrain the healing tool, use curves, layers, and the history tool to undo inadvertant changes.

In our next installment, we will talk about how to get the Milky Way shots in the first place.  Camera considerations, settings, tradeoffs.

By the way, this image consists of a single sky shot and a multi-processed foreground using the technique described above. Click the image for further details.

South Side Truckin' [C_009842]

Astrophotography Equipment Recommendations – Beginner to Intermediate

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For basic astrophotography I recommend starting with a wide angle lens and a sturdy tripod.  That’s it. Go out there and get some Milky Way or starry sky shots. Take plenty and average stack them (after aligning them). More on this later.

To image things like the moon, planets, galaxies and nebula you’ll want to move up to a decent telephoto lens (200-800 mm effective focal length) and an Equatorial Mount.

Mounts

To my thinking there are 4 categories of mounts with their approximate prices and assembled total weight (excluding telescope or camera):

  • Light, single drive (e.g. the AstroTrac, $900, 15 lbs, or the Polarie)
  • Cheap ($189) and probably useless to decent but limited AstroView Equatorial $350, 26 lbs.
  • Mid-range, accurate with features like autoguide ports, and GoTo: Celestron CG-5GT, $690, 42 lbs; Orion Sirius, $1150, 43 lbs; Orion Atlas, $1400, 76 lbs. All are heavy!
  • High end: A hefty hunk of metal with a hefty price point: e.g. Celestron CGE Pro, $4,400, 154 lbs.

In the examples I’ve shown mostly equipment from Orion for three reasons:

  1. I have Orion equipment and they have a local store.
  2. They have a good reputation for being helpful and consumer friendly
  3. Their website makes comparisons easy!

The Portable Solution

The best portable solution is clearly the well made AstroTrac with the power cable, finder scope (upper right) and the drive at the bottom.

To use this you need several other bits and pieces shown here excluding a standard camera tripod.

It’s a well engineered, portable system. All the gear together (including tripod, drive, camera, telephoto lens, batteries, etc) is about 16 pounds – meaning you can carry it with you. The next closest equatorial drive solution is about twice that heavy.

The cost is a minimum of $680 for the drive, polar scope and power cable. But you’ll need some additional head components (about $210), a power supply of some kind ($30) and perhaps a sturdier tripod. The total outlay will be under a thousand making it comparable to the low end of the mid-range mounts.

PROS: The AstroTrac is easy to set up, and relatively easy to align if you use the geared heads and the polar scope. You can pack it in a suitcase or a backpack and take it on an airplane!

CONS: More expensive than a single drive equatorial mount. Only drives one axis (all that is generally needed). Maximum tracking time is about 2 hours. Repointing the camera may misalign the drive. Need to build or buy a 12V battery pack (though this is easy to do). Need to learn your sky to find things.

The Equatorial Mount

Go cheap, go big, go fancy… but you’re not going light.

The AstroView - which I have - requires drive motor(s) for another $130 or so bringing the total outlay to about $380. It's carry weight is about 35 pounds if you include the camera, and all accessories including counter weights.

PROS: Inexpensive, includes polar scope, lighter of the many mount options, can support modest refractor or small reflector. Tracks well.

CONS: No guide port, limited to about 12 pounds of capacity, no "GoTo" option so you have to learn your skies to use it well. Tripod is thin aluminum. It's sturdy but may not hold up to extended use.

A step up from the entry level mount would be something like the SkyView Pro ($850) It includes a "GoTo" computerized control which is a great help to the novice and helps you with alignment routines. I'd probably opt for the Orion Sirius ($1150) however as it supports 10 more pounds (30 total) and for that extra $300 bucks you also get a polar scope, the ability to use a decently large telescope and fancier drive options. A highly recommend mount is the Celestron CG-5GT at about $690 add $50 for a polar scope. All of the GoTo mounts will "slew" (move rapidly and accurately) from one object to the next and you can enter the object into a keypad to get there. Save even more money by using your computer instead of the "GoTo" unit.

Attaching A Camera to A Mount

If you opt for a telescope mount, you will want to consider using a ball head for maximum ease of pointing the camera. However you CAN attach the camera directly to the dovetail bar and use it just like a telescope (with limitations on the field orientation). Here I have used a ring collar that couples my telephoto lens to the ball head. This allows me to rotate the camera to change the frame without having to repoint. It's also better balanced.  There is enough room on the front of the dovetail to put another head and another camera.

I even "cheated" and am using a camera as a counter weight - see it hanging there in front of me?

Telescopes

If you decide to up the ante, here are a few commendable small, light refractors. None are "top of the line", but I've had some pretty good success with the ED80. It's biggest weakness is that it comes with no mounting bracket, and the focus mechanism is not the "dual speed" (fine focus) option that seems to help fine tune things. I did find that I could mount the ED80 on my scope without mounting rings by attaching it to a Vixen-style dovetail bar and a 1/4" 20 cap screw. A hex bolt would work fine, too.  I drilled out one of the threaded holes in the dovetail bar.