5 Tips to use an Telescope with an Equatorial Mount (the easy version)

In past entries in this blog we have discussed the merits Equatorial Mounts vs Altazimuth mounts on telescopes, but we never actually went into much detail on how to properly use one of these mounts. Here are some basic hints for a beginner first trying to use an equatorial mount. Note that this are not hints for precision alignment – they are strictly for the beginner so they do not get overwhelmed! Speaking of which

1) Keep you mount setup as simple as possible at first.

Look at telescope instructions for equatorial mounts and you’ll see a lot of information on adjusting setting circles, using a polar axis scope, and other heavy duty details. Here’s a hint: If you don’t plan on doing astrophotography or long, long viewing sessions you don’t need all of that setup! Here is what you need to do:

Telescope Tips: Finder Scopes vs. Red Dot (Reflex) Finders

Aiming a telescope is tricky: It sees only a tiny portion of the sky, it might not be in focus for what you are looking at, and slight bumps can throw off your aim. That is why most telescopes come equipped with some kind of aiming device to help you find objects in the night sky. In the past this was almost exclusively with a Finder Scope – a little, low poweder telescope on top of the main telescope’s optical tube with a cross-hair that was used to aim.

FINDER SCOPES

The design of these little telescopes would vary from 20mm to 50mm in diameter, and the power was from 5x to 9x, typically. The holding bracket originally

would be two metal O-Rings with three thumbscrews each to adjust the aim of the finder scope. More recently that design would be replaced with a single ring with two thumbscrews and a spring bracket. Those were the good ones, anyway. Cheaper telescopes would often have a plastic 5x finder scope with a single holding bracket with

Not a good sign.

three plastic thumbscrews that would often frustrate new telescope owners as this mount is clunk and hard to control and the optics in the finder scope were poor.

This frustration would lead to a buig change in smaller telescopes around 10-15 years ago as they switched from cheap finder scopes to using reflex finders.

 

REFLEX FINDERS

Reflex finders, or red dot finders involve no magnifying optics. Instead the reflect finder has a window that you look through and a red dot is projected to show where the telescope is aimed. Adjustment is made by two knobs. This was much easier to deal with fot new astronomers as the main frustrations with cheap f

inder scopes were mostly alleviated by using a red dot finder. But unfortunately they were replaced with new issues. The first being that all too often the new astronomer would leave the Red Dot Finder on after the viewing session was over, which would drain the battery. Long term storage would also be an issue as many would forget to remove the battery and they might leak acid onto the electronics.

The final issue was that once the astronomer gains some experience they will not be able to use the Red Dot Finder for a technique that is ued by more advanced astronomers to find objects: Star Hopping. This is where the viewer jumps from star to star in the field-of-view of the finder scope to get towards an object they are seeking such as a small nebula or globular cluster.  The technique involves having one bright known star that is near another known star (not as bright) such that they can both be in the field of view of the finder scope. That 2nd start is then centered in the finder scope and a 3rd star that is near the edge of the field of view is found and so on. It is a tricky technique to learn and unfortunately you can’t do it with a Red Dot Finder.

SO which to choose? Well, some do not:

More determined astronomers will actually have both designs on their telescope. A red dot finder to easy aiming along with a larger finder scope for close work and star hopping. This may not be an option for those using smaller telescopes as they have limited space for such extravengance.

Here is a summary of the main points along with some other advntages and disadvantages:

FINDER SCOPES:

Advantages:

• Have actual magnification
• Can be used to star hop
• Magnification gives a  better sense of where you are viewing
• Can be purchased as ‘right angle’ which makes using them on Reflecting telescopes easier

Disadvantages:

• Harder to use for new astronomers
• Trickier to align properly with the optical tube
• Cheap ones extremely hard to aim
• Need to keep clean

RED DOT FINDERS

Advantages:

• Easy to use, especailly for new astronomers
• Much easier to align with the telescope

Disadvantages

• Batteries can be drained if you forget to swithc off
• Batteries can leak in long term storage
• No magnification means no star hopping

Have fun viewing whichever you use!

www.spectrum-scientifics.com

Telescope Tips: Dark Skies – The Philadelphia Region

When selling a telescope to a customer, we often give advice on how to view in light polluted areas. Simple stuff such as selecting your targets, using filters, etc. Often we asked “is there anywhere I can go and get away from the light pollution?”

The answer depends on your answer to ‘How far do you want to drive?’

One thing we have in our telescope section is a version of this light pollution map on the wall:

Telescope Tips: The Standardization of Telescope Eyepieces

When you get down to it, a telescope is optically made up of two parts: The objective lens or mirror and the eyepiece. There are other optics involved, of course (a secondary mirror is rather critical  in a reflector telescope), but for the most part it is the part you aim at the sky and the part you actually look through. We are going to discuss the latter today.

We’re not going to discuss the various types of eyepieces, that would involve several posts on its own. But we will discuss the issue of eyepiece size, and how compatible they are with other eyepieces.

So if there is a good guideline with regard to telescope eyepieces it is this:

Telescope eyepieces are remarkably standardized, very few other products work with other brands as well as telescope eyepieces!

This may seem a bit odd to a person used to other products. After all the parts of a Ford car will likely not fit in a Toyota. But one shouldn’t think of it in those terms, think instead of a DVD player or Blu-Ray player. There are plenty of brands to choose from, but they will all play DVDs, or Blu-Ray (of course, a regular DVD player won’t play Blu-Ray discs, so our metaphor might actually carry better than we think at first – read on:)

So in discussion of actual eyepieces, there are 3 sizes to deal with – barring a few very rare exceptions. Those sizes are .965″, 1.25″ and 2″. All the sizes refer to the barrel end of the eyepiece. The have nothing to do with the length, diameter, or focal length of the eyepiece. The size is the diameter of the part that actually goes into the telescope.

So a little bit about those sizes:

0.965″ Diameter

This used to be referred to as the ‘Japanese Standard”. It has a barrel less than an inch in diameter (.965″ is equal to 25mm) and at one time was ubiquitous as most telescopes were designed and built in Japan. However, this size was generally seen as being inferior. You couldn’t but any decent amount of glass in it (needed for high-end eyepieces)  and even Japan started moving on to 1.25″ eyepiece designs. The eyepieces faded out slowly and few sellers still had them as of 10 years ago. However some legacy equipment, old telescopes in ‘Dad’s attic’, and low-end telescope lines appear now and then and require the old lenses to work (or an adapter) so they haven’t completely gone yet.

1.25″ Diameter

Even hand grenade sized.

Far and away the most popular diameter these days. The 1.25″ used to be moderate-to-high end, but now even most beginner telescopes use this standard. It wouldn’t be too far out to suggest that 95%+ eyepieces today are this size. They come a wide variety of sizes and designs.

What this means is that if you have an eyepiece for a telescope that was made in the past 20 years, odds are it will work with almost any telescope that was built in the last 20 years. Even if they weren’t the odds are still pretty good they will be compatible unless the telescope was low-end and old.

2″ Diameter

The high end of eyepieces, these are gaining in popularity as they make for very comfortable viewing. The large glass apertures mean less struggle to center your eye along with optical comforts. 2″ eyepieces are gaining in popularity but will not likely surpass the 1.25″ as the standard as they are a) too bulky and heavy for smaller telescopes, b) hard to design for shorter (higher magnification) focal lengths.

Other designs – Occasionally, some obscure telescope maker tries to reinvent the wheel and makes a telescope that uses some kind of proprietary eyepiece. This never succeeds but does result in some odd telescopes and eyepieces rolling around the marketplace. They are extremely rare, however, so don’t worry too much about buying one by accident.

So when you get down to it, it is fairly amazing that telescope’s use so much of the same standards. Especially given that no national or international standards were ever officially set such as happened with microscopes. In the end, it is probably simply a matter that no vendor ever wants to have to tell a customer that the $500 worth of accessories are now useless. You might get away with that in a large, everyday-use market like computers (at least over a period of a few years you can), but not with a hobby like astronomy.

Want to buy telescope eyepieces?

www.spectrum-scientifics.com

Astronomy Hints #18: Do I need a red light flashlight?

There are many factors that can effect the quality of a telescope session: clouds, turbulence, haze, light pollution, moonlight, and so on. Most of these the astronomer cannot do anything to change, but one of them – night adapted vision, you do at least have some control over. You cannot control everything your eyes do, but you can help them a lot.

Many beginning astronomers often make a common mistake of going from a brightly lit house with their telescope out into the darks skies and start viewing through their telescope immediately. This can be a bit unsatisfying if you are looking at dim deep space objects. The will be extremely faint simply because your eyes are not adapted to the darkness. This isn’t just about the pupils of your eyes dialating, either.

Astronomy Tips: Astronomy Smart Phone Apps Part 3

Its time to review some more astronomy apps for your smart phone!

Let’s start with this guy: Astronomy Calender

This little app is pretty much does what it says, albeit in a rather bare-bones format. You don’t get so much of a calender as you get a straight up listing of upcoming events:

Assembling the Orion SkyQuest XT8i Intelliscope Dobsonian Telescope – Part 2

OK, so we are continuing from Part 1 of this telescope assembly. Our base is pretty much together, but now we need to add the encoders. Here is where we shall see the major issues with the way Orion’s instructions are laid out.

First of all, as we mentioned in the 2nd to last paragraph of part 1, you have to stop working from the main instruction manual. There isn’t really an indication as to where you should do this, but if you continue to build your telescope you will need to unbuild it to attach all the pieces needed for the Intelliscope parts to be attached. In order to continue properly, you actually have to switch over to the manual that comes with the Intelliscope controller.

There was a time when there was good reason for why this manual was separate from the main manual. Orion originally sold the Intelliscope with and without the Intelliscope controller. Four years ago they ended that policy since the “Classic”  SkyQuest was still available. Now all the Intellscopes come with the Intelliscope Controller, so there is no legitimate reason to confuse the customer with different manuals. Especially ones that have errata and parts for versions of the Intelliscope that have not been made in 7-8 years.