Today I am proud to release a new book aimed squarely at beginning astrophotographers who want to know what astrophotography objects they can image with their equipment.
From the webpage:
Are you interested in astrophotography objects in the northern hemisphere?
Do you need good information on astrophotography objects that can help you as a starting point?
Taking images of astrophotography objects that are millions of miles from Earth is about as complicated as it sounds and when you start out you will find it hard to target the right ones.
Size, brightness and type are just a few of the more common considerations, but there are many more that relate to the type of equipment you have to hand and what the best tools for the job will be.
Now, with 50 Best Astrophotography Targets for Beginners, you have a handy information guide that will provide the starting place you seek, with information on:
How to get started
Tackling close astrophotography objects like the sun and moon
What the targets look like
The best time of the year to shoot them
How big the targets are
How to find them
What the images look like straight out of the camera
And much more…
Once you have mastered the techniques needed to take stunning photographs of these amazing beginner astrophotography targets you can move on to further reading on the subject, but making sure that you are taking quality images of some of these is the first step.
Designed with the novice in mind, 50 Best Astrophotography Targets for Beginners provides good, clear information in an easily understood format, allowing you to take the photographs you’ve always wanted to take. It even includes photographs that realistically shows you, as a beginner, what you can expect to achieve. There are no NASA or Hubble images in this book!
Aimed specifically at the beginning astrophotographer using a camera such as a DSLR in the Northern Hemisphere, this is the book you have been looking for.
Get a copy today and see how it will improve the way you take amazing shots of the heavens that will impress and delight friends and family alike!
The book is available today in both print and Kindle editions.
When I first started writing books I thought setting up a forum for support of the books would be a good idea. Unfortunately I never really kept up with it and soon it fell by the wayside. It soon broke to the point that new users could not even register. Sad.
Recently I have had some people ask me what happened to the forums and so I decided to put in some work and get them back up and running. After many upgrades, head pounding, and new additions, the new and improved astrophotography forum is ready for action.
While originally intended to support my books, since my books are primarily aimed at astrophotography, that theme will permeate the forums making them mostly an astrophotography forum. This should be pretty obvious with the big moon phase at the top right of the screen!
Of course there is a set of astronomy forums in there too. Even though most of my work has been with a DSLR, and most of my books cover that form of imaging, this is not just a DSLR astrophotography forum.
Since allans-stuff.com is one of the leading astrophotography websites today, it just made sense to have its own astrophotography forum where you can not only discuss the techniques presented in my books, but general imaging topics too.
So if you have any comments, suggestions, ideas or corrections about any of my books, or want to talk about astrophotography, astronomy, or any other subjects really, head on over to the forums. If you have any problems getting signed up, use the contact form here on allans-stuff.com to send me a message and I will get it straightened out for you.
Hop on over to the AS Forum and post up some astrophotography pics!
A while back, a customer who goes by Brucer on Amazon, suggested I add more data to the web page for Long Exposure Astrophotography so people who bought the book would have more astrophotography data to practice with. I thought that was an excellent idea but was crazy busy at the times.
I have found some time to add a little to the website so I am please to announce I have uploaded additional astrophotography data including lights, darks and bias files that I used to process my images of M16 the Eagle Nebula, M22 cluster, IC281 the Pac Man nebula, and NGC6992 the Eastern Veil Nebula.
These are the exact same raw files I used so you can see the end results I came up with on my website. That gives you something to shoot for!
Although I can not always fulfill every request, I really love it when people give me suggestions to help other readers learn astrophotography and I do what I can. If you have any ideas, suggestions or requests, please do not hesitate to use the contact form or drop by the forums and let me know.
Do you want to learn how to take photographs of an exciting Solar or Lunar Eclipse? Do you have the right equipment for the job? Do you want to know ALL the tips and techniques needed to make this a success?
A total Solar Eclipse is an incredible sight to behold. It is one of nature’s most awe-inspiring events and has been the subject of amazement, wonder and fear throughout the ages.
But they don’t come around very often. In fact, the last total solar eclipse in North America was 40 years ago. In 2017, however, you will have another chance to witness this rare phenomenon as another total solar eclipse will occur on the 21st August. The total solar eclipse 2017 is something to not be missed!
Now, with How to Take Pictures of an Eclipse, you can be prepared to capture this unique moment as well as other solar and lunar eclipses with information on:
¬The basics you’ll need to know
¬Getting the images you really want
¬What sort of camera to use
¬Using a telescope
¬And much more…
Capturing this amazing, once-in-a-generation event is something that you won’t want to miss out on and capturing the best shots of it is crucial when it comes to the bragging rights.
Now is the time to act if you want to be prepared for this spectacular sight. Get your copy of How to Take Pictures of an Eclipse now and make sure that you are ready to get the photographs that will amaze your friends and family and be the envy of all.
Pixel size, sensor size and many other factors seem to complicate our choices for cameras these days. Just when you thought cameras could not get any more complex with ISO range, well depth, and active/passive cooling I’m here to throw another wrench or several into the mix.
Lets start with pixel size or pixel measurement which should really be called photosite size. The actual sensor on a digital camera is made up of light detectors called photosites. These photosites are what create the pixels in the image. Each photosite measures the light hitting that sensor and generates a signal in proportion to the amount of light hitting it that is sent to the processor inside your camera.
fig 1: Illustration of how photosite size affects light collecting ability
As a general rule, the larger the photosite size the more light it can gather simply because the larger area will be struck by more photons. More light striking the sensor means a higher signal output by each photosite. This in turn means it will require less amplification (a lower ISO) to achieve the same results as a camera with smaller photosites. You could also say that at the same ISO the camera with the larger photosites could use a faster exposure.
Since you can collect more light with a larger photosite size that also means that you have a higher signal to noise ratio (SNR). This is particularly important in astrophotography because we are always shooting an extremely dark object (nebula etc) against a totally dark background (black of space). Since there is so little contrast or difference between the object and the background, it is important to have the highest SNR possible. The reasoning is that when there is a lot of noise, it is much more difficult to extract the signal.
Think of it as audio. When you are at a live concert the band is the noise, then you try to talk to the person next to you which is the signal. This is very difficult to do at a heavy metal concert (high noise) but far easier at a concert featuring an unplugged classical guitarist (low noise). Since in astrophotgraphy you are always shooting long exposures (compared to normal daylight photography) and using high ISO values when you can, there is a lot of noise injected into the images.
A larger photosite size will have lower noise primarily because the accuracy of the measurement from a light sensor is proportional to the amount of light it collects. In other words, if a sensor collects one photon over a one second exposure it will be dramatically less accurate than if it collects one hundred photons. This occurs because every photosite has an amount of noise that happens when the sensor is read (read noise) and a certain about of noise per exposure (shot noise). This amount of noise does not substantially change from a one second exposure to a two second exposure whereas the number of photos captured doubles. More photons collected means a lower amount of noise in relation to the number of photons.
Now to be technically correct, the amount of noise does change as the exposure time changes, but it does so far less than the increase in the number of photons collected. In fact, the signal is the squared amount of noise, or the noise is the square root of the signal, whichever is easier for you to remember. If the signal is 900 photons, then the noise is 30 which gives you a SNR of 30. Double the incoming light to get 1800 photons and you get a noise of roughly 42.5 and a SNR of about 42.5. As you doubled the light collected in this example, you increased the SNR which made it easier for you to pull really dark objects out of the muck.
The next effect of a larger photosite is in dynamic range. A dynamic range is basically the amount of difference between the darkest a sensor can record and the lightest. In a previous article I discussed full well depth as being the maximum amount of light a photosite can store and that is an important player in dynamic range.
fig 2: A six part gray scale representing a low dynamic range
In figure 2 above the numbers across the top represent percentages of saturation of a photosite. Since this has such a small dynamic range everything from about 19% through 33% all reads as the same color. This is not what you want in astrophotography where the nebula is almost as dark as empty space.
fig 3: A twelve part gray scale representing a low dynamic range
In figure 3 we see that there is far more definition so there are two different shades for objects in the same range of 19% through 33%. The higher the number of shades on this chart, the higher the dynamic range. More dynamic range makes it easier to separate nebulas and empty space.
Two primary things affect dynamic range, the ISO and the well depth. Since a larger photosite size or larger sensor size typically has higher full well capacities and also require lower ISO values for a given exposure, they tend to have far superior dynamic ranges.
fig 4: Dynamic range and SNR by ISO for a Nikon D7000 DSLR
In figure 4 we see how the dynamic range (DR) and SNR both drop as the ISO increases. The D7000 camera used above is what is typically called a crop sensor (APS C sensor size) camera which typically has substantially smaller photosites compared to a full frame sensor camera. To get a general idea you could say that the dynamic range of a crop sensor camera at ISO 800 is 10.75 and for a full frame camera is 11.75 at the same ISO. While this is a massive generalization (and really wrong 99.9% of the time) it does give you the right idea.
This sounds great! Are there any down sides? Maybe.
One argument for smaller photosites is that they capture more detail. This stands to reason since the same amount of light would be spread across more photosites on a smaller sensor and therefor more pixels. It would simply be a matter of more pixels in the same image meaning more detail. True enough.
The opposing view is that in most cases people do very little enlargement by cropping an existing photo. This means that a photo taken with a 20MP (mega pixel or million pixel) full frame camera would have the same detail as a photo taken with a 20MP crop sensor camera. Also true.
Another concern is that crop sensor cameras have a crop factor built in. This means if you shoot a full frame image with a 50mm lens and then put that same lens on a crop sensor camera what you wind up with is the photograph looking like it was shot with up to a 75mm lens. This is because the lens puts the same size projection of light at the sensor plane (where the sensor is) and if you have a smaller sensor, less of the image appears on that sensor. This makes the image appear to be zoomed in.
While the image being zoomed in has no real bearing on the image quality, it can really throw a wrench into things when you bolt that camera onto a telescope. An object that fit perfectly on your full frame camera’s sensor now spills over the edges on the new crop sensor camera you just bought.
The last and probably most important factor is that a larger photosite size or a larger sensor size typically cost more money. This money could be spent getting something with a better cooling system or some other feature. Only you can decide where to spend your finite resources and which features are more important than others.
So what does sensor size have to do with anything other than maybe having a crop factor? A larger sensor simply has more room for larger photosites, or a higher number of smaller ones as compared to smaller sensors.
I hope you enjoyed my article on pixel size and sensor size!
My most popular DIY project which I think is now in at least two of my books is this one. Since so many people enjoy it I thought I would post it on the blog for everyone to use. Remember that this is primarily for inspiration and not really meant to be a recipe for one that will work with your scope.
Well since I have started really working on my post processing I have noticed the need to start shooting flats. The problem is, you must shoot flats without moving the camera, scope, focus, anything. This means they have to be shot on site, right before or right after shooting your lights.
There are a couple of problems with that. All the designs I have seen are large boxes, I don’t want to carry around a large box to the dark site and besides, something that large might disturb the dust bunnies and mess up the whole idea of flats. Next problem is if anyone else is there, flicking on a light could get me shot (this is Texas here, heh). So what do I do?
First thing I do is come up with a list of what it needs to be able to do, so here goes:
1) It must be easily portable, small and light. Anything heavy can mess up the scope’s setup.
2) It must be reasonably accurate. The light must be uniform in illumination.
3) It must be reasonably inexpensive, the EL panels I have been looking at run about $100, lets keep it under that.
4) It must be usable when other images are right next to me, no light leaks.
5) It must be servicable, meaning I can repair it, replace things, etc.
Off to Home Depot I go! I know they thought I was some terrorist getting bomb supplies, I walked up and down every isle grabbing weird items, putting others back, fitting things together that were completely unreleated. Boy did I get some weird looks! After about an hour I left with this:
This was two 4″ PVC sewer pipe connectors, a 6″ flashing connector for I think a stove exhaust vent, a can of PVC glue, two translucent lids, a 6″ plastic floor drain grill, and a bag of bolts.
Next stop, Radio Shack!
Here I found 4 white 3v LEDs, 4 LED mounts, a rocker switch, a 4 AA battery holder, and a project box. Next stop, Wal-Mart!
Left to right we have a box of male and female electrical connectors, some styrofoam plates, glue and some velcro.
Now its time to start working on stuff. The first thing I needed was a Proof Of Concept. For this I put things together and mounted it on the scope with just some clear tape and used one of those battery powered lights you press down on the top to turn on. That gave me my first flat:
This clearly shows I need flats. This image has been stretched and desaturated, it was brown (used an incandescent bulb). Next was to test out the batteries and LEDs:
Good! Now I know I can get them all lit up. Lets mount the battery pack to the top of the project box with hot glue:
Now we drill holes in the project box, four large ones for the LED mounts and two (well, four now cause I goobered!) smaller ones to bolt the project box to the drain grill:
Now we bolt the box on the grate and install the LEDs:
Now I open the package of velcro and take the fuzzy strip and run it around the inside of the 6″ metal connector, on the opposite end of where it will mount to the drain grill as this will protect the paint on the outside of the dew shield. Next we glue the two 4″ sewer pipe couplers together and mount them inside the 6″ metal connector:
Here is the outside view:
After a little wiring, we cut the paper plates into two circles for difusers, here is the first one installed:
So I turn on the lights and there is a problem, the light is nowhere near even enough to take a flat:
But I am not as stupid as I look! (or feel sometimes), I had actually planned on this and so I install the second difuser in it’s place four or so inches in front of the first diffuser and I get this:
HA! Nice even illumination! Lets put it on the scope:
And take a flat to see how it works:
So a little information:
Size = 7.5″ diameter x 10″ tall/long
Weight = 2lbs 4oz with batteries
Cost = $60 buying everything except a little wire and solder
Time to construct = About 3 hours
Exposure for about 40% sat on histogram = ISO800 1/60th sec
Now since the light goes down the inside of the sewer pipe couplers, to leak out it would have to come back up the outside of the couplers, curve around the end of the scope, and go down the metal coupler on the outside. I don’t see much light doing that. After dark tonight I will give it another test and let you all know how it goes.
The difference between DSLR and CCD astrophotography cameras is pretty immense. Most people when searching for astrophotography equipment for beginners choose DSLR astrophotography because they either already have one or they are far cheaper to start with. When you go from DSLR astrophotography to a monochrome CCD you lose live view, but gain chip cooling. You lose color but gain sensitivity. You can lose pixels but gain resolution. Wait a minute! How can you gain resolution if you lose pixels? Easy, you no longer have the Bayer matrix turning every four pixels into one so your monochrome CCD in effect has four times the stated resolution. Yeah, I know it isn’t that cut and dried, but seeing the images from both it sure starts to ring true. Here is a DSLR astrophotography image of M8 taken with a 16.7MP Nikon D7000, 36 300sec lights and 25 darks:
I always thought this was a pretty good image for unmodified DSLR astrophotography, and it is.
Once I decided to switch to CCD astrophotography I started looking for a camera trying to find the best CCD camera for astrophotography. Out of all the choices out there for astrophotography CCD cameras I picked an Atik 383L monochrome as it fit my needs and budget the best. Now here is the same target, same telescope, same mount, same capture software, same processing software, but with only an 8MP monochrome CCD shooting through a 6nm Hydrogen Alpha filter. That’s right, HALF the resolution:
Something else I forgot to mention, this is only 4 480sec exposures and 4 darks. Yep, one fifth of the total exposure time and about one sixth the number of darks. I don’t even know what to think except CCD astrophotography rocks. Why exactly was it I waited so long to go monochrome? I have no idea.
So now the thing that people always bring up when looking at monochrome CCD astrophotography is to shoot narrowband or RGB with filters on monochrome takes three times as long because you have to shoot through three different filters. True enough, but when I can get results like these with one fifth of the total exposure time, even if I have to shoot through three filters it still works out to less time exposing to get better images. I am still working on combining the Ha, OIII and S2 together to make a single color image and unfortunately the night I took this image I did not get enough usable OIII or S2.
Sure there are lots of things still to work out when switching from DSLR astrophotography to shooting CCD astrophotography but with a start like this it sure looks promising.
Stay tuned for the results of the first color combination coming soon!
I hope you enjoyed seeing the Difference between DSLR and CCD astrophotography!