Handicapped Astronomy
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I want a Telescope
Time for a new Telescope
Eyepieces and Filters
Observing Session Basics
Book Reviews
Free Astronomy Software
Our First Night Out
Orion SpaceProbe 130ST First Light
Handicapped Astronomy
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Handicapped Astronomy
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Telescopes And Disabilities
Everyone wants to start with a telescope. I urge you to not skip the steps listed on the previous page. Following these guidelines will ground you and help you look realistically at how well you can make this hobby work for you. It will also help you better understand your needs when shopping for a scope. If you haven’t read the first page go back and do it now. If you are ready to consider a telescope the following page will help you explore some options.
Since I made book recommendations in the earlier sections, I’ll mention another one by Phil Harrington. Star Watch breaks the night sky up into seasons then explores what to look for, where to find it, and what to expect to see. I take this book in the field with me when I observe.
Once you narrow down your choices for a scope, if you haven’t done so already, you should consider getting a star atlas. There are several good ones available. The one I recommended earlier is the Pocket Sky Atlas because it is compact yet very usable. A free option is one of the charts listed on my software page.
Ok, let’s talk scopes. Since you are reading this it suggest you like to do your research before jumping into something. It also implies you are willing to take advice. I implore you do not buy your scope at a toy or department store unless you first check out reviews of that particular model. Most toy store scopes are just that – toys. They do more to discourage people away from astronomy than to encourage them. The lenses are plastic or poorly ground and the mounts are horrible. You will be sorry.
Occasionally around Christmas you might find a package deal that actually is not too bad optically, their weakness is they usually suffer from being poorly mounted. So check out what others think online first. A quality telescope doesn’t have to cost a lot more than the super store scope but you will probably have to order it online from a reputable dealer.
Besides price and quality there are other considerations the physically challenged need to consider before buying. There is no point getting a scope home only to find you are unable to handle it yourself. The store or dealer isn’t likely to fully understand the obstacles you must overcome to observe. So that you will know what to watch out for, from someone who understands, let’s look at some of the different types of telescopes and see their strengths and weaknesses from your perspective.
My reviews are based on assuming the observer is wheelchair bound or is unstable while walking, has limited upper body strength and carrying ability, and limited range of motion while seated. Each person is different so consider your own situation as you read.
Dobsonian Not The Best Choice
Most astronomers will recommend a 6 or 8” Dobsonian as a great first scope, and it is, but probably not for those with mobility issues. In fact it encompasses almost everything you should avoid! Trust me, I’ve got one and I know what I am talking about. A Dob is a long tube with a mirror in one end and an eyepiece sticking out the side on the other end. It is supported in the middle by a Lazy Susan type base. It is elegant in its simplicity but is not a good choice for most handicapped astronomers. Let’s go through the problems so we can better understand.
Dobsonians are often recommend because they are relatively inexpensive, simple to operate, and big. The first two are great advantages but the last is a deal breaker. Usually, aperture rules in astronomy, big is better. However, big translates into heavy and awkward to move. If you can’t move it you won’t use it. Carrying 35-40 pounds across the yard may be an easy task for some folks but it is asking way too much of most with disabilities. Even if you take the tube off the base it is still difficult to maneuver. Strike one. You should consider something lightweight and portable.
Dobsonians sit very low to the ground. This works well for most people to use in a sitting position. Which all sounds well and good except that an 8” scope moving from near horizon viewing to straight overhead causes the eyepiece to move upward and back around 18”. That is a lot of movement. In a wheelchair consider if you have that much mobility. If you are not in a wheelchair using a dob can cause back, hip, and knee strain. Strike two. You need shorter eyepiece travel and better height adjustment.
In order to observe something you must be able to find it first. That is the purpose of the finder scope. On a Dobsonian one must contort oneself over the top of the scope in order to view through the finder. Near the horizon this is hard enough. When attempting to locate something directly overhead it is near impossible for all but the really limber as you have to nearly stand on your head. Strike three.
There are some small tabletop and lap versions of the dob that might work for you but I can’t comment on the quality or usability as I have never seen or used one personally.
Finder Solutions
The finder issue can be addressed in a number of ways. Some solutions will prove to work better than others.
Many people replace the stock finder with a right angle correct image finder, also known as a RACI. This means you no longer have to contort yourself to look through the finder. There is a trade off here. While seeing through the RACI finder is substantially easier, knowing what you are looking at is a lot harder. Essentially you are looking around a corner at a tiny piece of the sky and trying to figure out what star is in the finder.
Another option is to mount a zero power finder on the scope. The big names here are Telrad and Rigel. These don’t magnify the sky like a regular finder. Instead you locate a naked eye star within a red circle that is aligned to match your scope eyepiece view. Often these are used in conjunction with a RACI finder. You rough in your location with the zero power finder, then fine tune it with the RACI. This is a nifty idea but if you are using it on a dob it will again require contorting yourself to look into it.
My solution is to use a green laser pointer mounted along with the RACI finder. You align both with your scope and when the light beam is lined up with a star it will be in you field of view through the finder and the scope. Brilliant! Some people dislike lasers because they fear their misuse. Others discourage their use because of the potential of interfering with another observer’s astrophotography session. It is a very workable idea for you if you weigh all the other factors before proceeding.
A Refractor Also Has Problems
A Refractor is what most people think of when they picture a telescope. It typically has a long slender tube with an eyepiece on one end and a large objective lens on the other. They are supported in the middle on a tripod mount. A refractor is generally considered best suited for lunar and planetary viewing, where as the dob is designed more with deep space viewing in mind.
On the plus side if you choose a lightweight mount the weight issue is not so big a problem. If you turn a wheelchair sideways you can probably avoid the tripod legs and get to the scope to view. Because you are looking straight up the optical tube the finder contortions are not an issue. The legs on the tripod will be adjustable so the height of the scope can be raised and lowered for comfort.
For the physically challenged a standard refractor suffers at least one major problem mentioned previously with the dobs. The eyepiece travel is still going to be excessive. Many refractors come with a right angle eyepiece to make it easier to view at zenith. This can be rotated around the optical tube so it points up, down, sideways, or anywhere in between. This will help some but not enough. Raising and lowering the tripod as you change targets is not a practical solution. You can do it, but you will get tired of it real quick and it will mess up the polar alignment of the scope.
Newtonian More Of The Same With Complications
A Newtonian is essentially the same optical tube as found on a Dobsonian but instead of the simple dob base it is traditionally placed on an equatorial mount. They are great telescopes and an equatorial mount is an ingenious concept allowing you to track objects in the sky. But a Newtonian will usually weigh more than the same size Dobsonian because of the mount/tripod weight and the additional counterweights used to balance the scope. So you potentially have more weight, the finder issues, and the eyepiece travel problem. In addition an equatorial mount is difficult to learn to use. It also adds a new problem caused by the mount. As you point the scope the eyepiece and finder can rotate into impossible positions to use. The way this is overcome is to loosen the screws on the rings and rotate the optical tube in the mounting rings until the eyepiece is comfortable to use. Unless you know you can handle this scope, I would avoid it.
An SCT May Work If You Can Lift And Afford It
A Schmidt-Cassegrain Telescope or SCT for short is a catadioptric telescope, which is a combination of the reflector and refractor. It uses lenses and mirrors. This reduces the length of the tube considerably. The eyepiece is located at the bottom of the tube like a refractor. Every one of these that I have seen is on an Alt/Az fork mount. Essentially this is the same as a dob mount but smaller, more technical, and set on top of a tripod.
These scopes are very popular among the more experienced astronomers I know. Though having a narrower field of view than most Newtonians they are popular for planetary and DSO hunting.
On the plus side, there are no bulky counterweights to contend with. The tripod is height adjustable. The finder is a straight shot with no contortions – if you can reach it (I need some feedback from users to know if this is an issue). The biggest plus is the eyepiece travel is substantially reduced because of the short tube length. This coupled with the right angle oriented eyepiece that rotates around its axis, I believe, makes viewing possible.
The negatives are not small either. An SCT can be pretty expensive maybe way more than you would want to spend on a beginner scope, especially a computerized GOTO version. Weight is still a big factor. Most SCT observers have an 8-9 inch scope. The weight of the entire set up can be excessive. They come apart in three pieces – scope, mount, and tripod – but that may still be a substantial hurdle to overcome. If you have good upper body strength or help and a thick wallet, this scope may work for you.
Mak Attack Another Possible Option
Another type of scope is a Maksutov-Cassegrain also known as a Mak. The most popular version is the ETX models sold by Meade. You can find similar scopes sold under different names. They are a catadioptric scope with a refractor type lens on the front, a short optical tube and the eyepiece on the end. The objective lens generally limits the size of these scopes because big lenses are expensive. So they are portable making them a very usable possibility. Most of these I have seen are on an alt/az GOTO fork mount. Somewhat less expensive than a SCT, though remember they are also smaller in aperture, a Mak may still be a lot more than you want to spend on a beginner scope.
You will not see as deep as in a monster dob. So what! As I said before, if you can’t move it you won’t use it. It is interesting that the more you observe the more your eyes become trained therefore the more you detail you will see.
I have even seen them on tabletop mounts, which might be ideal for a wheelchair with a desktop tray. This might be a really good choice for a physically challenged individual including a child. Again the downside is cost.
A Rich Field Scope An Affordable Possibility
I currently own a Newtonian known as a short tube. The optical tube at 24” is about half as long as a normal scope. This is also known as a rich field telescope or RFT. These scopes are designed to give you a wider view of the sky. The trade off is that it is difficult to get high magnification. They are not great for high detailed planetary observing but I am mostly a deep space observer anyway. Fortunately most observing of many DSO’s is done at low power.
From my research it appears the lower quality RFT Newtonians have a lens built into the focuser similar to a Barlow that bends the light to focus at the shorter focal length of the scope. This lens in turn can cause distorted views. The better quality RFT’s use a parabolic mirror designed specifically to focus the image at the shorter focal length. Don’t worry if that does not make sense right now. Just trust me and look for a model with the parabolic mirror. They are a little more expensive than the Barlow version but it is not wasted money. This does fall in the price range of a good beginner scope.
The eyepiece travel is reduced to about 9”, which I find comfortable. I overcame the finder problem by adding a green laser pointer. The awkward rotation of the eyepiece due to the eq mount is easy to overcome by measuring the circumference of the optical tube and buying a couple sweeper belts at Wal-Mart. Putting one on either side of the rings allows you to keep the screws loose enough to rotate the tube easily without the tube sliding out of the rings.
The whole set up weighs about 29 pounds. The scope itself only weighs 7 pounds. The counterweight is 5 and the tripod/mount is 17. That is considered pretty light but is still a lot for me to handle. I have to take it apart or get help to move it. That coupled with the difficulty I have using an equatorial mount makes this still not ideal but usable for me. Remember though I am not in a wheelchair.
More discriminating users dislike my mount (an EQ2) because they say it is too wobbly. Well so am I so I have learned to work with it because that is the acceptable trade off to keep the weight down. Besides I use it with the legs all the way retracted and most people would extend the legs and that would add to the shakiness of the mount.
I like my scope so my current goal is to replace the eq mount with an alt/az mount. I have been researching and for about the same money as I would spend on a basic manual alt/az mount, I can get one with GOTO and tracking! Even better it requires no counterweights and weighs only 10 pounds. That will reduce the weight around 12 pounds to about 17 total. Woo Hoo! The mount I am looking at is an Ioptron Smartstar E also known as the cube. This is their low-end model but even their higher end mounts are reasonably priced. This addition should eliminate all my observing problems. If and when I save up enough for it I will write up a report on how it works.
The only other obstacle I can think of that might affect someone that is a wheelchair observer is whether the tripod would allow close enough access. I do not recall ever having to straddle the legs on my current tripod so I am relatively comfortable saying you can position a chair to view through this scope.
A Rich Field Refractor Definitely Doable
The final type telescope to be mentioned is the one I believe is the most likely candidate to consider. It is the short tube refractor. It is the lightest and most portable of all the scopes. As with all RFT’s it is intended to give a wider view of the sky at relatively low magnification. Still it will take you far deeper than standard binoculars. I have seen tripod mounted GOTO versions and tabletop versions. I have never seen it done but with an adapter plate one could be mounted on a parallelogram mount. This is a very versatile and affordable option. With a tabletop version there would be no weight problem or height adjustment issue. No matter how it is mounted the eyepiece travel is extremely minimal. There is no finder problem, as these usually don’t have a separate finder although you could add a laser.
Final Thoughts
I mentioned using a parallelogram mount with the short tube refractor but you could probably mount most of the other type scopes this way. Universal Astronomics makes a mount that is ideal for wheelchair usage. They would be an excellent source of information of what would be required to mount your scope. Remember though that a parallelogram mount requires counterweights, so the heavier the scope the more the counterweights. Make sure you don’t exceed your ability to transport the equipment.
Before you buy a scope find a local astronomy club and meet with them. Even if you have to drive a good distance this will be worth it. Tell them in advance of your situation, and your desire to see first hand the type scope you are considering. They will almost certainly be willing to help you out to see what will work. Good Luck and Clear Skies!
I hope this has been of help to you. Drop me a line and tell me of your experience. I would love to hear it and I just might learn something. If I have written something that is not correct please point it out to me and if you convince me I will get it changed.
Copyright © 2009 by Kevin Sluder
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