Tag Archives: astrophotography

Simple Astro Processing Technique to Conquer Noise

Published: Jun 20, 2012
Last Updated: March 5, 2017

Is one of these your scenario?

  • 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.

ALSO NOTE: Advanced StackerPLUS has a built in averaging operation. You just feed it the images. It does NOT do auto alignment, however.

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]


We have another video tutorial that uses some similar processing techniques:

12 Minute Star Trail using Advanced Stacker PLUS version14D from Steven Christenson on Vimeo.

Astrophotography Equipment Recommendations – Beginner to Intermediate

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.


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, the Polarie or the SkyTracker)
  • 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?



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.


If you are thinking of going in all at once, various vendors offer bundles that might interest you.  Here are some examples from Orion (www.telescope.com)






Resources for Astrophotography

Original Publication: Oct 12, 2011
Last Revised: Nov 9, 2017

Local Stores (San Francisco Bay Area)

Orion Telescope Center

10555 S De Anza Blvd
Ste 105; Cupertino, CA 95014
(408) 255-8770

Mon-Sat 10 am – 5:30 pm
Sun 12 pm – 5 pm

Equipment Recommendations

There is a lot of gear out there and a lot of thought about what is good / better / best.  For the purpose of my recommendations I’m assuming your interest is primarily Astrophotography and primarily based around using a telephoto lens or a small/lightweight telescope attached to a DSLR. Of course you might succumb to a small telescope. Most of my recommendations are based on personal experience. Some are based on observations of people much wiser than me.  If you decide to get a mount, here are representative alternatives.


Before we dive into conventional mounts, however, lets take a look a well featured, light-weight solutions.

Approach A: Good, Light and Portable


AstroTrac TT320X-AG – photo from AstroTrac site.

Since, portable, inexpensive and stable do not all fit into the same category the best solution is the AstroTrac. It is light, well made and moderately priced (from $546 to $1,959 depending on the package – not including shipping). You will be limited to using the AstroTrac with a telephoto lens on a camera unless you buy some dubious additions to turn the AstroTrac into a big scale solution – but since you’re reading this that is probably what you intended anyway. Be sure to get the Polar Scope as it is difficult to align without it! This mount will track at Lunar, Sidereal or Solar rate!  While $546 might sound expensive, for the light weight versatility it’s hard to beat. For a video and more information, see the manufacturer’s page.

Pros: Total schlep weight (tripod, heads, polar scope, battery, AstroTrac) is about 12 pounds (less if you have a lighter tripod); setup is pretty easy; accurate tracking;  maximum load is 33 pound; stops automatically to prevent damage.

Cons: Limited weight; repointing at a different object may compromise the alignment;  2 hours tracking before reset; single drive solution.

Orion Astrophotography Bundle

A possible solution – much cheaper at $180 but also with very significant limitations is the Orion Astrophotography Bundle.  It is a light weight, low load mount with a single axis drive and no alignment scope. At 14 pounds assembled and a load of up to 7 pounds it’s not bad for very wide field astrophotography – but it will never take more than a single camera load. I DO NOT recommend it. For why, please see my review.


Another product that has caught my eye is the Polarie device.  Imagine a device about the size of  a DVD slip case only about 3 times as thick.

Polarie Device with Polar scope (image from Amazon) – requires TWO heads and a tripod.

The Polarie device costs about $400 USD, but that doesn’t include the possibly unnecessary polar scope – which is an extra $250 – or a tripod rig to set it all on.  Like the Astrotrac, Polarie is light and portable and runs on conventional batteries.  A competitor is the iOptron Skytracker. Very similar features to the Polarie with a few advantages and disadvantages. The Polarie is a miss, mostly in that the scope is expensive, and requires removing the whole face. Once you put camera gear on it, the distribution of weight changes enough that the alignment via the scope is useless.  It didn’t do a good job managing my Canon 50d with a 70-200 mm lens.

iOptron Sky Tracker

iOptronSkyTracker (requires head, tripod)

Of the Polarie and the $400 Sky Tracker, I prefer the Sky Tracker. It’s better thought out.  The down side is you’ll need to remove the head from your tripod and put this in it’s place then put the head from the tripod on the face of the Sky Tracker.

The faceplate only “locks down” via that single screw. I found it sometimes slips. Also there is a little slop in the gearing. The good news is that unlike the Polarie with its expensive polar scope, you can actually mount your camera ON the face and make sure there is room to also use the scope to accurately position things.

There is a newer Sky Tracker Pro available which is more like a “real mount”. Haven’t investigated that much.

The advantage of the SkyTracker over most solutions is that it is light and easily portable.

A Canon 50d with a 70-200mm lens was more than it could manage well.


iOptron Sky Tracker Pro

We have no experience with this unit, however one of our workshop participants managed to make it work well. iOptron Sky Tracker Pro (no experience)



There is even a new contender rising in the KickStarter arena… it’s called Astro: Time-Lapse Motion Control.  It’s not clear if it will be accurate enough to track at sidereal rate, but I am hopeful.

It’s not designed for astrophotography, but if the rate can be set precisely enough, and a simple alignment done it may work quite well.  It does have a built-in intervalometer, though and as you can see it’s quite compact.

NOTE: I purchased one and found it disappointing.


Approach B: Good, Economical

The next bump up in capability is the Orion AstroView Equatorial mount ($250) to which you must add the single or dual drive ($140, recommended) motors for a total outlay of about $390. It’s carry weight is around 31 pounds including batteries but it can handle 12 pounds of payload and you may not need to use all 12 pounds of counterweight. Orion does have mounts in between, but I say skip ’em.  The disadvantage here is that it really can’t take a telescope, there is no autoguider port, and no “GoTo”. But it does come with a polar alignment scope. Tracking accuracy at sidereal rate is pretty good. I haven’t pushed the mount beyond 450 mm so I can’t make final conclusions. One advantage over a normal “tripod” is that the extra weight makes this solution much more stable than a conventional tripod. The latitudes range for use is 18-63 degrees. With some finagling I was able to physically get the angle down to 0 degrees – but you can’t track the RA axis at that angle. Two more drawbacks are that the tripod is lightweight aluminum square tubing with a plastic clamp – it’s begging to fail from overtightening, and the drive motor connectors stick out like sacrificial lambs begging to be broken off when placed down on a hard surface incorrectly.

Approach C: Serious Astrophotographer

Once you move up the value chain you will want to get a “GoTo” scope. This moves you from the $400 neighborhood to the $1400 address which gets an Orion Atlas EQ-G that can support 40 pounds of payload, and costs about 80 pounds in back buckling schlepping to move it around (22 pounds are counterweights).  The good news is a modestly sized telescope can go on this thing – you could even give your toddler a ride. The bad news is there is still plenty you’ll want to buy: an autoguider… and perhaps even a telescope. If that’s where you want to go, perhaps the best bet is the even stronger solution, the Orion Sirius EON 120mm EQ-G GoTo APO at $2800.  None of the above  include an autoguider, or the few miscellaneous parts you’ll need to attach your camera.   If you want a slightly less expensive, lighter system the Sirius mount isn’t a bad deal.

If you KNOW you’re going to put a immodestly sized scope on your mount, you might find yourself in the $4,000 district where a forklift or weightlifting team can help you move the apparatus around. Trust me, $4,000 still isn’t the penthouse suite!

Approach D: Insanely Serious Astrophotographer

Actually I can’t recommend anything in this category because it enters a realm where I’m not willing to go financially. For a down payment on a house you can get a large refractor (or reflector), massively accurate GoTo mount with autoguider, a high-end imaging camera, and a wheelbarrow full of accessories. Names like Losmandy, Takahashi, AstroPhysics and others rule this realm.

Polar Alignment

  • http://www.astronomy-pictures.com/Imaging-Tips.htm#zero
  • http://www.petesastrophotography.com/polaralignment.html
  • http://www.astronomy-pictures.com/Zeroing%20it%20in.%20Using%20a%20DSLR%20or%20CCD%20to%20Align%20Your%20Scope.pdf