This website is purely focused on enjoying my hobby, sharing what I learn and can pass on and documenting my latest journey into Astronomy.
All work here is the property of Mark Abraham and is Copyrighted and may not be reused without my written permission.
As I move along I will be documenting some information. People ask me why I do this, the truth is it helps me remember and organize thoughts and information that I can easily refer to later when needed. I reference this information all the time and use it to also answer questions in helping others.
Choosing a Mount
Its amazing what one forgets in the course of 10 or more years. Its also amazing how once you start to relearn how much you can start to recall.
Regarding choosing a mount, my advice is the same as many others, don't skimp on it as it will be your greatest source of regrets if you do, cause you to waste time and waste money.
Think ahead! You may only want a refractor now, however, the hobby is addictive and your sure to want a larger heavier OTA in the future!
But a mount used, buy it from someone reputable, and buy one that has excellent resell value. Don't be tempted by cheap offerings and ignore the warnings of those who traveled the trail before you. This is the hardest advice to follow as you'll surely be tempted by smaller and lower cost options.
Research, research and research some more for your mount and take note on INTERNET astroimaging forums of the success and failures.
Look at the photographic weight capacity and not the mounts rated capacity. Most often a mount with a 60lb load rating will only be good for a 30lbs astro imaging platform.
Make sure service will be easily accessible and affordable and that there is
Choosing an OTA
Once you have chose your mount you’ll want to choose an OTA. You’ll be tempted again possibly to pick something that may be more difficult to image with that could lead to a very frustrating and negative experince.
A good used Refractor is a great starting place. See if you like the hobby and then work your way up!
Faster scopes will generally also have wider fields of view. You can go to we website like this and enter in your camera and OTA and get a FOV. This requires you also have a camera in mind, however, it may help you choose a good camera scope combination.
A tip that should help you is to setup FOV rectangles in your planetarium software. If your just trying to choose an OTA and camera then I reccomend you try a wide combo, something like an F6 Refractor and SBIG 8300 CCD Camera and create a FOV display. Then create a second with a F11 SCT and the same camera. This will allow you then to look at some objects you want to image and see ahead of time what things will look like, whether your setup is going to crop the objects your interested in, and see ahead of making any purchases.
Be sure to consider the weight of the OTA you choose and all the additional accesories you’ll add to support it, dove plates, cameras, dew straps, Focal reducers, Extensions tubes to ensure your mount can support your planned payload.
Choosing an a Camera and Guider
The camera you use is going to have a large impact on your imaging setup. If you go with a DSLR then you'll likely have a nice large chip and thus a larger FOV, however, unless the DSLR has been modified, it wont be cooled and will be less sensitive (meaning it will take longer exposures to get same results as a dedicated CCD camera). Dedicated CCD Cameras have cooling circuits that drop the CCD Chip to colder temperatures and reduce the noise in images.
One factor people tend to miss is that a larger chip could also result with some challenges. You may experience vignetting where the light can't evenly cover the whole CCD chip depending on what scope and chip combo you choose. You can compare chip sizes here to start to research the topic.
I recommend you read these websites thoroughly before making any decisions.
Some CCD Camera options including built in guide chips, or offer Off Axis Guiding accessories.
Off Axis verses Separate Guide Scope
There are pros and cons each way. A separate guide scope may offer a larger FOV and thus broader range of guide stars to choose from. In older cameras with the guide chip built in the chip sits behind the filters if your are going to image LRGB and thus will be impaired by them and less sensitive. This can cause problems if you don't have a bright guide star in your FOV for the desired target. Also, a built in guider will have an even smaller FOV than the primary imager, this also reduces your odds of finding a suitable star to guide on. The flip side of this is that if you use a separate guide scope, its not likely going to match the resolution of your primary OTA, especially if your using a longer focal ratio set of optics. What this translates to is that the wider FOV sees less movement than the higher resolution view and so the guider may show round stars while the shorter OTA will see much more movement yielding elongated and blurt stars.
You can setup a FOV indicator in your planetarium software as suggested above for your guider as well to get a sense of each option you choose. A guide camera can have a smaller FOV and keep your weight down as well. This is another factor to consider in choosing cameras, a seperate guide scope is how it will impact the total weight and payload for your mount.
You need to add up all the weights of all the accessories you mount on your imaging OTA because your mount has to carry and support it all successfully.
QE (Quantum Efficiency)
Each camera will have a Quantum Efficiency rating. The higher the QE percentage the shorter the exposure needs to be as compared to a camera with a lower QE.
Larger pixels tend to have better QE. There is a trade off though that may be worth considering. If you plan to print and display your final images, then fewer pixels will require you to upscale your image more which will result in a loss of quality. The more you upscale an image the faster the quality deteriorates. If you plan to only display images on websites or computing devices with moderate resolutions such as 1600 by 1000 then you'll have much more of a 1:1 ratio of scale and the images will look like they do on your screen after processing them. If you want to make a gallery size print of 20x16 then you'll be upscaling a lot and this is where 6MP cameras or better will help considerably.
Study up on all this as its very important in matching your expectations for your images.
Your Overall AP Platform
Your building a system when you are planning and pulling all this together. You will quickly get in trouble if you are just trying to buy the best equipment available for any one aspect of your Astro Photography platform. You can buy the very best of everything and have a bad mismatch and cause yourself tremendous frustration as well as loose a lot of money.
Pay close attention to other AstroImagers mix of equipment. Cloudy Nights is a great place to interact with other astroimagers and ask questions.
Your budget should include consideration for any software you may need, Focal Reducers, Filter wheels if your using a mono CCD. Don’t forget filters, they can add a significant cost!
You’ll need software to integrate all the parts of your system. This in itself is a huge topic I will come back to after I complete my integration on my own new AP Platform.