<![CDATA[Telescope FAQs - Knowledgebase Articles]]> <![CDATA[How do I align my Schmidt-Cassegrain telescope’s (SCT’s) corrector plate and secondary?]]> Alignment of your secondary relative to the corrector plate and to the primary is important to the proper optical performance of your scope. There are two ali]]> <![CDATA[What is backlash and how can I adjust it?]]> Backlash is play in the drive gears. All telescopes have some backlash, as gears can’t be too tight, preventing the motors from turning. Backlash causes]]> <![CDATA[How far can I see with a telescope?]]> The farthest you can see in the sky with your telescope will depend on its ability to gather light and where you observe.

The most dis]]> <![CDATA[How do you determine a telescope's magnification?]]> The magnification of a telescope changes as the eyepiece is changed. Magnification can be calculated by dividing the focal length of your telescope by the focal length of the eyepiece.
To correct an inverted image, you will need a 90-degree star diagonal. When a 90-degree star diagonal is used, the mirror flips the image over, giving a right side up but reversed left to right image. You ]]> <![CDATA[Why can't I see anything in my telescope when I have the moon centered in the crosshairs of my finderscope?]]> Most likely your finderscope needs to be aligned with your main telescope. I]]> <![CDATA[I have a 60mm refractor with a focal length of 900mm. Why can't I get a clear image when I try to use my 2x Barlow lens with my 6mm eyepiece?]]> It’s because you’ve exceeded the practical limits of magnification for your telescope. These are determined by the laws of optics and the nature of the human eye. As a rule of thumb, the maximum ]]> <![CDATA[Why don't the images I see through my telescope look the same as photos I see taken with the same type of telescope?]]> The reason photos look better than what you see with the unaided eye is due to the camera’s ability to store light continuously as long as the shutter is open.

TNOTE: These instructions are only for the NexStar hand control with versions HC 4.0 and higher. You cannot flash upgrade older hand controls. The newer NexStar+ (NexStar Plus) hand co]]> <![CDATA[Improving GOTO Performance]]>  There are a number of techniques you can use to improve the accuracy of your GOTO telescope’s performance. Plus functions that are av]]> <![CDATA[How do I connect a single-lens reflex (SLR) camera to my telescope?]]> To connect an SLR camera to your telescope, you’ll need two accessories: a T-ring and a T-adapter. The T-adapter system is a worldwide standard 42mm thread to connect cameras to other devices.
 <![CDATA[Where do I find infrared (IR) and ultraviolet (UV) transmission and reflection data for Celestron products?]]> We don’t have the data for regions outside the visible spectrum, since our products are marketed for amateur astronomy.

Please g]]> <![CDATA[My scope has a donut-shaped spot in the center of my mirror. Is it a problem? Do I need to clean my mirror to remove it?]]> The donut ring is used for collimation (alignment) of your reflecting telescope’s optics and doesn't interfere with scope operation, as it's in the shadow of the secondary mirror. It’s placed aro]]> <![CDATA[I upgraded-reflashed my hand control and now I’m not getting the control functions for my mount, but for another mount. What happened? How can this be fixed?]]> You probably flashed it with the wrong version of firmware, one for another mount. When you do this, you may get the telescope model displayed correctly when your scope is powered up, but a completely differ]]> <![CDATA[Why does there appear to be a black circle in the middle of my image when I look at a star or planet?]]> If you can see the shadow of the secondary mirror (the black circle) and spider vanes in the eyepiece, the scope is not focused.

As you move the focuser, the image should get smaller until you re]]> <![CDATA[I hibernated my GOTO mount. When I powered back up and woke up the scope, it did not point as accurately as before. What gives?]]> The hibernate mode allows you to retain the alignment of your scope when it’s completely powered down. However, it’s not perfectly accurate and the accuracy decreases with the amount of time the ]]> <![CDATA[Why do I only see stars as points of light even when using my highest power eyepiece?]]> The ability to see details on an object ultimately depends on how far away it is and how big it is.

Stars are so very far away that they will never show a real disk or ball shape in a telescope. <![CDATA[Which screws are safe to remove for mounting an accessory finderscope on my Celestron Schmidt-Cassegrain telescope (SCT)?]]> There are three things to be careful about when turning or removing screws on your SCT tube. First, you must identify the screws holding the rear and front cells to the tube. Second, the threading of any new]]> <![CDATA[Can my NexStar hand control be repaired instead of replaced?]]> In some circumstances, your Celestron NexStar hand control can be repaired instead of completely replaced.

Here is a summary of rules experts recommend for safe shipping of fragile optics and electronic equipment. 

 <![CDATA[Why won’t my image erecting eyepiece or image erecting diagonal always give right side up images with my scope?]]> Image erectors won’t work in all circumstances.

The orientation of the image pr]]> <![CDATA[My image shifts when I’m focusing my Schmidt-Cassegrain telescope (SCT) and after I get a great focus, the focus will change. What is happening?]]> All Celestron SCTs and some of our Maks adjust focus by sliding the primary mirror along a set of nesting baffles inside the main tube. This is done by an arm to one side of the tube that is fixed to the mir]]> <![CDATA[What is field rotation? How does it affect my scope’s viewing and imaging?]]> Field rotation is the apparent rotation of a celestial object in the field of view of a telescope during the course of the night. All objects in the eyepiece field or on the camera’s image will move in]]> <![CDATA[How do I remove the optics from the optical tube assembly (OTA) of my Schmidt-Cassegrain telescope (SCT)?]]> Most of the time you would never need to remove the optics from your OTA. However, if the scope is old and dirty, the corrector plate broken, you want to line or paint the inside of the tube, modify the t]]> <![CDATA[My GPS-equipped scope is showing the wrong time information. How do I correct this?]]> Your scope will display the Universal Time given by the GPS satellite system unless you set the correct time-site information.

Yes.

The GPS feeds its signal to your scope’s mount, providing it with the time and site information it needs as a part of the alignment pro]]> <![CDATA[I’m looking at my Celestron scope and it has a serial number on it. Can you tell me the model, type and year it was made?]]> No, we cannot.

Though many of the products we’ve made have serial numbers on th]]> <![CDATA[Does the stated payload weight of my Celestron mount include the counterweights?]]> No. The payload weight does not include the counterweights.

The payload weight is defined by Celestron’s engineering department ]]> <![CDATA[How do I use the setting circles on my Celestron German equatorial mount?]]> When you look at your equatorially mounted telescope, you’ll notice dials on both of the axes of the scope. These graduated circular scales are the sett]]> <![CDATA[What is LST? Where do I find it in my GOTO scope’s menu?]]> LST refers to the local sidereal time, which is the right ascension (RA) that is on the meridian at your observing location. Objects with RAs equal to the LST]]> <![CDATA[When I use IDENTIFY with my GOTO scope, what is it showing me?]]> MENU – IDENTIFY displays the angular distance (degrees, minutes, seconds) from the center of the eyepiece field to objects that are in the database of your scope’s hand control. You can then perf]]> <![CDATA[My cordwrap was turned on before I updated my alt-azimuth GOTO scope’s hand control. Now it’s off – what happened?]]> Cordwrap safeguards against your scope slewing more than 360 degrees in azimuth, which can spiral your power and accessory cables around the b]]> <![CDATA[Where can I download the unified ASCOM drivers for Celestron?]]> Please go to this web page on the ASCOM Initiatives website:

We have no stated operating temperature range. 

We know from experience that our]]> <![CDATA[I’m using rechargeable batteries with my Celestron GOTO mount and the mount won’t power up even though the batteries are new and fully charged. What’s the problem?]]> Most likely it’s because the NiMH (nickel metal hydride) or Ni-cad (nickel cadmium) batteries just aren’t providing enough voltage because of their chemistry.

Celestron]]> <![CDATA[How do I do a GOTO or alignment on the sun when it does not appear in the SOLAR SYSTEM list?]]> Once you have your solar filter over the front of your scope, you can safely point it at the sun. However, as a safety feature, the sun does not appear in the hand control unless you enable it.

Go]]> <![CDATA[My NexStar hand control displays “Offset Too Large” when I’m trying to change my scope’s alignment. What does this mean? How do I fix the issue?]]> It means your SYNC operation has failed.

SYNC is a function to improve accuracy over a specific region of the sky. It’s great for tasks like constellation tours. To use it, select a star or ]]> <![CDATA[My refractor shows color fringes since it’s not an apochromatic design. Is there any filter or way to reduce these fringes?]]> Many refractors are two-element conventional achromatic designs, which leave what’s called residual color. This means the designs don’t fully remove all the color left over from dispersion of lig]]> <![CDATA[I want to use SAO stars with my GOTO scope. What do I need to know?]]> Celestron hand controls have a STAR button that directly accesses SAO (Smithsonian Astrophysical Observatory Catalog) stars in the scope’s firmware database. You can also find these stars by pressing LIST then scrollin]]> <![CDATA[I cannot get the USB – RS232 Converter Cable #18775 drivers to install on my computer – help!]]> Try disabling your antivirus software temporarily while you are installing the drivers. Often these programs will think the new driver is a virus attacking your operating system and block the installation. <![CDATA[I need a case or bag for my scope and I can’t find it on your website. Where can I find them?]]> Celestron no longer carries cases, etc. for all the telescopes and tripods we sell.

There are several other companies that have products useful for storing and or transporting your astronomical]]> <![CDATA[Is there any way to run Celestron’s Window-based drivers and software on Macs?]]> The drivers and software used with most Celestron products are (as of Fall 2009) not compatible with Mac operating systems.

Though Celestron provides no support for these work]]> <![CDATA[What do I need to connect my hiking or other GPS to feed time-site information to my Celestron GOTO telescope?]]> There are a number of ways to hook up a GPS you already own to one of Celestron’s current generation of NexStar telescopes.

The first way is ]]> <![CDATA[How can you track satellites with a Celestron GOTO telescope?]]> Celestron does not have any functionality directly in the NexStar GOTO firmware to calculate satellite positions and track them with the mount.

 <![CDATA[Can all named stars listed in the hand control be used for alignment?]]> No. Only stars brighther than or equal to magnitude 2.5 (bright stars) can be used for alignments with Celestron’s NexStar computerized mounts.

Even though there are about 250]]> <![CDATA[The alignment pin in my new Fastar-equipped SCT is at the 11 o'clock position. Isn't it supposed to be at the 3 o'clock position as viewed from in front of the telescope?]]> For newer Celestron Fastar-equipped SCTs, the alignment pin can be in any orientation. 

Older Celes]]> <![CDATA[I want to use 2” eyepieces with my Schmidt-Cassegrain telescope (SCT) and or Maksutov (Mak). Will there be vignetting from the telescope optical tube assembly (OTA) itself?]]> Vignetting is normal in any real optical system. Some light must be blocked because of off-axis distortions or aberrations from the optics themselves. Glare and reflections from inside and out]]> <![CDATA[How do I quickly start my Celestron telescope? Can I use previous alignment information?]]> If you want a fast start for your scope to track without bothering to go through the entire alignment routine, there are a number of functions available. It depends on what Celes]]> <![CDATA[I have my Celestron GOTO Alt-Az scope on a wedge and the hand display shows a slew limit warning. What’s wrong?]]> Probably nothing.

Slew limits are designed to stop your scope from either hitting itself, an attached accessory like a camera or poi]]> <![CDATA[What dovetail bars are used with various Celestron mounts?]]> The most common dovetail bar size in the telescope market is the Vixen-style bar, which is 1-3/4” wide. This is the size used with the dovetail clamp on the Advanced GT (CG-5) mount. It is also used with the LCM, SLT, SE ]]> <![CDATA[How do you stop a GOTO slew in progress? Is there a better way than turning off power or pulling the power plug?]]> Interrupt the mount’s GOTO slew by pressing any arrow key. The mount will halt the GOTO in progress.

Since this is a regular h]]> <![CDATA[What is seeing? How does it affect my observing and astrophotography?]]> Seeing is the term astronomers use to describe the stability of the atmosphere for observing. Seeing significantly affect]]> <![CDATA[What problems are possible when using a dovetail-equipped telescope tube designed for one mount when it’s used with another mount?]]> The dovetail bar (sometimes called a rail) is one of the great ideas in small telescope design. With the clamp on the mount and a bar on the tube, telescopes (OTAs) and mounts ca]]> <![CDATA[What is the size of the threading holding the visual back to my Schmidt-Cassegrain telescope? Is it the same for all Celestron SCTs?]]> The baffle lock nut is the back end of the C8 and C9.25 and it is a 2” x 24 thread.

On the C11 and C14 (and the EdgeHD 9.25), there is a reducer plate on the back over the b]]> <![CDATA[Operating System Compatibility Guide]]> CELESTRON PRODUCT  -  OPERATING SYSTEM COMPATIBILITY QUICK REFERENCE
Current Products October 2010

Currently we have no experience or support on interfacing with devices like iPhones and other smart phones, iPads, ]]> <![CDATA[What are the optimum back focus distances for Celestron’s Schmidt-Cassegrain (SCT) telescopes?]]> The back focus distances are as follows:

<![CDATA[What is precession? Do Celestron mounts correct for it?]]> Precession is the movement of the north celestial pole (NCP) among the constellations over long periods of time. It’s caused by external gravitational forces from the]]> <![CDATA[My new Celestron Schmidt-Cassegrain telescope (SCT) has a knurled ring on the secondary cell. Does this mean it’s Fastar equipped?]]> Knurled rings on the secondary cells of SCTs no longer mean the scope has a Fastar-Hyperstar compatible secondary cell.

Synta and Celestron are putting knurled ]]> <![CDATA[What screws are used for the C11 optical tube assembly (OTA)?]]> On recent C11 OTAs, the corrector cell and the mirror cell are held on by M4x10 screws. These are nutted. Typically there will be 4 on the corrector cell and 7 on the mirro]]> <![CDATA[What is the outside diameter and weight of the C6 optical tube assembly (OTA)?]]> It is approximately 7” OD. The OTA weighs approx 8 lbs.

]]> <![CDATA[What is the size of the screws for the corrector plate retaining ring for the C925?]]> There are six of the screws on a C925. They are M3 x 0.5 x 14.

]]> <![CDATA[What are the sizes of collimation screws on current production Celestron Schmidt Cassegrain telescopes (SCTs)?]]>