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ETX-125 finder scope

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#1 NearVision

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Posted 05 March 2018 - 10:54 PM

Hi all,

I have a question or 2 to pose for thoughts, consideration, recommendations. I'm somewhat new to astronomy but have used a 35mm camera since the 70's. So I know how lenses work. At least on this planet. undecided.gif

 

What I'm running up against is finding things to look at. Here's what I mean. The ETX-125 has goto functionality and I use it, but it's often 'close' to what I want to see, but not in view of the scope. The finder scope that came with was worthless, so it  quickly got replaced with a Rigel QuikFinder. I bought the ETX used, so I don't think the finder was original.

But, what I'm finding now is that will the QuikFinder is great and really helps me zero in, I still have to be able to see at least a dim spot of light in the sky to use it.

 

I'm thinking that a 'larger' finder scope would help. By larger I mean something that would gather more light over a wider field of view. Just like a camera lens that is wider aperture and lower f-stop shows a brighter image in the view-finder.

 

What I looked at was the Meade LightBridge mini 82. It's an 82x300 reflector. What I planned on was to mount it on top or to the side of the ETX body and use it as a finder. I've looked at smaller finders 24 - 60mm, but I'm a little concerned that they mat not be bright enough for me to see.

 

I know that 82mm is huge for a finder and would probably end looking like the space shuttle on it's carrier 747 on a trip back to the cape. :)

My other concern is the weight and how that would affect the drive mechanism in the ETX.

 

What do you think. Am I barking up the wrong tree with a larger finder and just need to get familiar with where things are?

Will I really see the things that are too faint for my eyes to currently see?

Will the weight be a problem seeing as I plan to keep the QuikFinder mounted?

At this point I'm not real concerned with the quality of the viewing with whatever I end up with. If the edges are somewhat blurry or the color is shifted, it won't matter. it's primary use is to get the large scope centered.

 

Keep in mind that I need glasses to see anything more than a few feet away and have for over 50 years now so my eyesight never was the greatest.

And don't suggest a huge 'light bucket' with all the bells and whistles. While I don't mind spending money on quality, there are budgets and a wife to contend with.

 

So!

Thoughts. Comments. Suggestions. General laughterlol.gif confused1.gif confused1.gif confused1.gif


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#2 Augustus

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Posted 05 March 2018 - 11:07 PM

Why do you need anything more than the QuikFinder? The ETX has GoTo...........



#3 ShaulaB

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Posted 05 March 2018 - 11:09 PM

Practice, practice, practice.



#4 JamesMStephens

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Posted 05 March 2018 - 11:11 PM

That sounds like a funny choice for a finder and sounds more like something that would need a finder.  Take a look at more conventional finderscopes, like you see here https://www.telescop...pes/pc/3/49.uts  A 60mm finder would be very large for your telescope and you don't need that much aperture, but you might find a right angle finder more comfortable with the stubby ETX.

 

Make sure you're getting the GoTo system aligned well and are using an eyepiece with a suitably wide field in the -125.

 

You also might be better off not wearing your glasses looking through a telescope, but focusing for your eyes.  Unless you have a lot of astigmatism.

 

You'll figure something out,

Jim

 

PS: One thing about red dot finders is that they are (my opinion) always too bright.  They're useful, but even at the lowest brightness setting they overwhelm everything but bright objects.


Edited by JamesMStephens, 05 March 2018 - 11:33 PM.

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#5 NearVision

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Posted 05 March 2018 - 11:44 PM

Yes. Yes. And yes.

 

The ETX has goto and I'm learning how to get it aligned, so I am practicing. My problem is impatience. I tend to get my feet wet by jumping in headfirst.

That being said. I may just be over-reacting. We finally had 3 clear nights in a row and in spite of the moon being so bright I could read outside I got to look at some stars and nebula. But after an hour or so I noticed that the scope wasn't slewing correctly and would be near but not on target. After a few hours it seemed to think everything was in the same place and stopped moving on it's own. I could manually move it with the controls so maybe it had brain-freeze at 30F.

 

It's snowing now, so I'm thinking about accessorizing. I've looked at various finders like the page Jim linked. What was on the scope when I got it was a 8x25. My line of reasoning was that something  like the 70mm or 9x50 on that page would be a brighter image for my eye so I could see the dimmer or washed out objects easier. I just had the wild thought of the 82mm LightBridge because bigger is better/brighter. I agree it does sound like a funny choice for a finder. Another reason I looked at it was the price. I know it won't be as sharp an image as the 70mm finder but it's $60 vs. $100! Either way I'll need to tinker to mount it so it comes down to quality of optics vs. price and if the ETX can bear the load of anything worth getting. I tried a ES wide Eyepiece a while back (I think it was a 24mm by 82deg???) and was impressed with the FOV so that may be the way to go.

 

This is why I asked. Information and encouragement.

Thanks!


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#6 JamesMStephens

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Posted 05 March 2018 - 11:49 PM

I don't think your scope likes being cold!  Always make sure the batteries are fresh, and if the hand controller has a little coin battery go ahead and change it.  I think you might like a nice 30 mm finder.

 

Jim



#7 nitegeezer

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Posted 05 March 2018 - 11:52 PM

I would be concerned about adding too much weight to the 125, it was just not built to take that much.  I live at a dark site so I do not have to travel and I have internet and power handy.  If you can do the same or make up for it in other ways, this is what I am learning to do.  I have goto with my scope also, but some targets are off just enough to be a real pain.  I have my camera hooked up to a laptop and I take an exposure and then plate solve to determine how far off I am.  I will move my scope to compensate and repeat another exposure.  Even if I can't see the target in the exposure, I make it fairly short, but I can normally dial my target in with 2 or 3 passes and always by 5 should I be real picky.  Now I like the really faint fuzzy things so my short exposure is 1 to 2 minutes and my capture exposure is out about 15 minutes.  The thing that allows me to go 15 minutes is I am guiding my scope with PHD2 with a separate guide scope and camera.  Some go with an OAG rather than a separate guide scope and I am trying to learn that but for now I am better with the second scope.  That you are not going to be able to do with the 125 as we are back to the weight issue.  If you get real good with your polar alignment, I am guessing that your long exposure is going to be in the 1 to 2 minute range depending on where you are in the sky.  The plate solver I use is over internet, I would have to look for the site if you are interested, but there are also ones that you can download everything required an do it locally, and both are FREE.  I would suggest that you try this and not push the capability of your 125 too far.  Stay as light as you can for as long as you can and then you will know what you want in an imaging system.  We are both at long focal lengths which many say is the wrong way to start.  As far as I am concerned, learning on what you have lets you know how serious you want to get!

 

If you have questions, I do not claim to be an expert, but I may be able to save you a little frustration and would enjoy helping you like others have helped me.

 

Chuck


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#8 NearVision

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Posted 06 March 2018 - 09:18 AM

Thanks for the info guys!

 

Jim, I agree about the red dot finders. I found out really quick that the brightness and blink rate controls on the Rigel are useful.

 

Chuck, I'm concerned about the weight-bearing on the 125 also after everything I've read about it so far. I think you've just confirmed my thoughts on the weight wearing it out quickly. I'll look into plate solving. That may kill 2 birds with 1 stone. The other night I tried looking at the double double and while it was interesting there were so many stars visible that I wasn't sure which were which! I've tried a few pictures but so far it looks like there are some stability issues. I'm seeing some movement and blur, even with the mirror locked up and a remote. I have noticed some shaking while viewing when the wind gusts. I haven't figured out if that's within reason or not. Am I right in thinking the guide scope/camera will only help once it sees what I'm looking for? Or, will it help with goto functionality also?

 

Looks like more learning before buying is in order.



#9 nitegeezer

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Posted 06 March 2018 - 12:14 PM

The guide scope/camera is only used once you have your target framed the way you want it.  I have not worked with the 125, but from everything I have read you have to be careful about weight and some have had trouble just with a dslr, but older ones were heavier.  I would not suggest adding a guide scope/camera until you have more experience with the mount.  I have an LX200 rather than an ETX, so while they share a lot of the same controls/features, the LX is built like a tank, so I do not worry about weight, just balance.  There are three things that you can address to try to improve your images.  You really need a great polar alignment so you don't have significant field rotation, and you need to have a good wind break, so these are the ones you will have to address every night.  I believe the ETX has periodic error correction, and if so that would be worth getting working.  This would be a good thing to play with around a full moon when imaging is not that productive.  You would probably want to update that about every 6 months if it is supported.  I have played with periodic error a little, but that is another thing that is helped with guiding.  Once you get a stable aligned system, now we can talk about your image capture.  Start with short exposures and only go longer if your stars are round.  This is one area that I really struggled in as I would think my stars were not that bad but the stacking software would not stack.  If you don't have round stars then stacking is a waste of time and that was hard for me to accept.  When the stars are round, you will want to take darks with the same exposure to compensate for hot pixels, I always take mine just at the end of imaging.  There are two stacking programs that I am aware of, the most common being DSS, Deep Sky Stacker.  That is what I started using and it does a good job, then I found another which I like better, just can't remember the name at the moment.  Now what I am only talking about is only for deep sky objects, for planetary imaging there is other code that is used but I am not familiar with it.  With planetary, the exposure time is fast but it is also very dependent on the stability of the atmosphere and is commonly known as lucky imaging as you may take hundreds of short exposures and only stack the good ones.  Not sure I can add anything else at the moment, I will be watching to see how you do and how I can help.  I would suggest staying in this forum for this discussion rather than going to one of the imaging ones.  There will be some good info to read in them, but if you start asking questions they will try to convince you to change equipment.  There are a few of us that like the forks on a wedge, and in the beginning the issues will mostly deal with the equipment so staying here is a good thing.  Once your questions are primarily image processing, then the imaging forums will be better information, just understand that you will have to wade through the responses to eliminate those pushing for different hardware and software.



#10 aeajr

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Posted 06 March 2018 - 12:40 PM

Hi all,

I have a question or 2 to pose for thoughts, consideration, recommendations. I'm somewhat new to astronomy but have used a 35mm camera since the 70's. So I know how lenses work. At least on this planet. undecided.gif

 

What I'm running up against is finding things to look at. Here's what I mean. The ETX-125 has goto functionality and I use it, but it's often 'close' to what I want to see, but not in view of the scope. The finder scope that came with was worthless, so it  quickly got replaced with a Rigel QuikFinder. I bought the ETX used, so I don't think the finder was original.

But, what I'm finding now is that will the QuikFinder is great and really helps me zero in, I still have to be able to see at least a dim spot of light in the sky to use it.

 

I'm thinking that a 'larger' finder scope would help. By larger I mean something that would gather more light over a wider field of view. Just like a camera lens that is wider aperture and lower f-stop shows a brighter image in the view-finder.

 

What I looked at was the Meade LightBridge mini 82. It's an 82x300 reflector. What I planned on was to mount it on top or to the side of the ETX body and use it as a finder. I've looked at smaller finders 24 - 60mm, but I'm a little concerned that they mat not be bright enough for me to see.

 

I know that 82mm is huge for a finder and would probably end looking like the space shuttle on it's carrier 747 on a trip back to the cape. smile.gif

My other concern is the weight and how that would affect the drive mechanism in the ETX.

 

What do you think. Am I barking up the wrong tree with a larger finder and just need to get familiar with where things are?

Will I really see the things that are too faint for my eyes to currently see?

Will the weight be a problem seeing as I plan to keep the QuikFinder mounted?

At this point I'm not real concerned with the quality of the viewing with whatever I end up with. If the edges are somewhat blurry or the color is shifted, it won't matter. it's primary use is to get the large scope centered.

 

Keep in mind that I need glasses to see anything more than a few feet away and have for over 50 years now so my eyesight never was the greatest.

And don't suggest a huge 'light bucket' with all the bells and whistles. While I don't mind spending money on quality, there are budgets and a wife to contend with.

 

So!

Thoughts. Comments. Suggestions. General laughterlol.gif confused1.gif confused1.gif confused1.gif

I think we need more information.    

 

Which ETX 125 do you have? Since you got it used, is it an ETX 125 Observer, the current model?   Or an ETX 125 EC that has been upgraded with the GoTo 494 hand control?    I have attached the 494 manual, in case you don't have it.

 

  • What eyepiece are you using to do your alignment?
  • What eyepiece are you using when you move from target to target?
  • What hand control are you using?
 

 

I have ETX 60, 80 observer (current model) and ETX 125 EC (old model) with an upgrade 494 controller for GoTo.  I think I can help.

 

I use the stock 6X30 finder on the ETX 125.  Good enough to get the alignment done and I use it when I go hunting manually with the clutches released.

 

 

See page 13 - Training the drive - improves accuracy

 

 

See page 15 - Spiral Search -

 

TIP: Another method to find the alignment star if

it does not appear in the eyepiece is to perform
a "spiral search." If the alignment star is not
visible in the eyepiece when the telescope finishes
its search, press GO TO and the telescope
starts slewing in a spiral pattern at a very slow
speed around the search area. Look through the
eyepiece and when the object becomes visible,
press MODE to stop the spiral search. Use the
Arrow keys to center the object.

 

 

If I don't see the target in my higher power eyepiece I switch to a lower power wider FOV eyepiece.   However this spiral search  works during normal GoTo also. So if you don't see the target, use a lower power eyepiece or use this spiral search.  Sometimes it is just outside the FOV.  

 

Never release the clutches once you turn the hand set on.  If you do, the system has no idea where it is.

 

 

To get the widest field of view in the ETX 125 use a 40 or 32 mm Plossl eyepiece.  This provides the lowest power and widest view you can get in the ETX 125.  I use a 32 mm plossl for 59.3X and .84 degrees FOV.   If you are not hitting targets within this FOV then your alignment is off.  But if you are just missing, try the spiral search, above. 

Attached Files


Edited by aeajr, 06 March 2018 - 03:46 PM.

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#11 aeajr

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Posted 06 March 2018 - 12:53 PM

I have owned the ETX 60, 80AT, 80 observer, 125 EC which has been converted to GoTo.   I have used the ETX 90 observer.    They all work the same as the brains are in the hand set.    So I will walk the process I follow and you let me know where you are having a problem.

 

  • Power off
  • Be sure you have fresh batteries - low batteries will cause alignment and motor errors
  • Set up tripod and scope - alt and az clutches are released.
  • ​Tilt table is down, not raised
  • Adjust the tripod legs if necessary to get level in all directions.
  • Confirm level with the eyepiece level.   Just get it very close
  • Set the scope (OTA)  approximately level and pointing either magnetic north or in the direction of Polaris but the OTA is level, not pointing at Polaris.

All confirmed?

  • Lock the AZ clutch ( slide the lever right)
  • Lock the Alt clutch ( firm not crazy tight)
  • Power on
  • Do not release the clutches at ANY time once you have powered up.
  • replace the eyepiece level with an eyepiece - I usually use the 26 mm.

Next steps are all in the hand set.  I don't do this every time but you have to do these at least once, then the information is saved.  Let's just make sure

  • Correct telescope is selected
  • Correct time zone 
  • Make sure date and time are correct, to the minute.  Every minute error is a .25 degree/half the moon, targeting error
  • my ETX 125 does not save the time
  • Make sure you have the correct location – I think it accepts Zip codes in the USA. 
  • DST, daylight savings time is on or off depending on time of year.  It should be off now.

Once all of this is confirmed, select EASY alignment - this is the two star alignment and the telescope chooses the stars

  • I think it asks if you use magnetic ( using compass)  or true north, in the direction of Polaris
  • Scope should select the first star and slew to it smoothly without slippage or jerking.
  • Likely it will not hit it perfectly so you will have to adjust it with the hand set after it beeps.
  • Once it beeps, use the arrows on the hand control to get the obvious bright star in the center of the eyepiece, hit enter. While it should be close, if your initial set-up is off the first star will be off.  Not an issue, just adjust it to center the star in the eyepiece.

If it seems that the scope is not moving when you hit the arrows it is on a very slow slew speed.  Hit number 5,6,7 or 8 to increase the slew speed and try again.

  • Do not release the clutches or you will mess up everything.
  • Scope will select the second star and slew to it smoothly and without slippage or jerking
  • Using the hand control get the bright star centered in the eyepiece​, hit enter.
  • You should get "alignment successful".

 

Areas where I have seen people have problems:

 

  • Forgot to lock the clutches
  • Released the clutches and moved the scope to align with the star - very bad
  • Tripod is no where near level
  • Mount table is raised - only for EQ alignment do you raise this.
  • Forgot to hit enter after getting the star centered in the eyepiece
  • Can't align to the star because the slew speed is too slow and they think nothing is moving when they hit the arrow keys.
  • Centered in the finder scope, not in the eyepiece
  • Batteries low
  • Date and time off - every minute is a 1/4 degree error
  • Location incorrect
  • DST, daylight savings time, is incorrect - Introduces a 15 degree error if it is wrong.

 

So, where are you having problems?


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#12 NearVision

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Posted 06 March 2018 - 03:26 PM

Thanks for the tips Ed!

 

Most of those I'm already doing.

I bought the scope used from someone that bought it from a professor at the local college, so it's several years old. I'm pretty sure it's a ETC-125EC. This is similar to what I have the only difference between mine and the picture is on mine the logo on the clutch is grey not blue. And, I found a manual online that has the most accurate pictures and descriptions that dates from 2001.

51QKT9PT57L.jpg

 

The finder on this looks to be the same. Mine came loose, the alignment screws are plastic and were bent and the prism on the finder scope (8x25 right angle) comes off if you look at it sideways. It has a tripod similar to the current model but the spreader is plastic 3 arms that meet in the middle and has a hole in each leg for EPs. It came with the 497 controller instead of the 1 shown here and a set of EPs that look like these. https://www.amazon.c...E1EEEJKSD1584B9

I also got a Meade 8-24 zoom for christmas so 62 deg is about the widest FOV I currently have. I'm running it from 1 of these battery packs (https://www.amazon.c...KNFD0ZFC97&th=1) and even after 5 hours it shows all lights for a full charge. So batteries shouldn't be a problem. I've been thinking about putting the meter on it to check the actual voltage to confirm.

 

The steps I go thru are:

 

  1. Setup the tripod with about 2-3 inches of the legs not fully extended. (right height)
  2. Level it with the bubble level in my phone. I periodically recalibrate that.
  3. mount the scope and aim it north with the compass in my phone. (again, periodic calibration) I use true north that the phone calculates from GPS. It's less than 3 deg different here if that matters.
  4. I then level the scope with the ring on the left side. (that gets checked also smile.gif ) It didn't have an eyepiece level so I use my phone.
  5. Then  the 2 star alignment process.

 

I have noticed with the zoom that if I center the 2 stars and then zoom in and keep centering that I get much closer when it goes hunting for stars. So it seems like close enough isn't. I need to find out more about the spiral search and probably look into a wider EP. 32 or 40

 

The reason I started this was when it doesn't get the star in view it's usually anywhere from just outside to double the distance of the outer circle on the Rigel QuikFinder. I can use the arrow keys to move the scope and see it then. My problem is when something is too faint or washed out for me to see 'naked eye' I can't align with the QuikFinder. So I had the brainstorm to mount a 'small' finder scope (read that as light amplifier) to help. As is usual I went big with the 82mm and have decided against it because of the weight stress.

 

Was I on the right track in thinking that a good finder scope would help me see things that are too dim for my eyes? I don't need it crystal clear, just enough to see the brighter spot for aiming within the FOV of the 125.

 

Again, thanks everyone for the input.

I really appreciate it!

Tom


Edited by NearVision, 06 March 2018 - 03:27 PM.


#13 nitegeezer

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Posted 06 March 2018 - 03:47 PM

It looks like I might have given you a lot of useless information for what you are doing, sorry about that.  For some reason I saw your mention of a camera in your first post so my mind went straight to imaging but reading other posts it sounds like you are visual only for the moment.  If you have gone through all the calibration steps to get the drives working correctly, then it comes down to how accurate you center the alignment stars.  It may help to defocus the star and use the donut to center the star, that makes it easier for me, I will defocus until the donut is almost as large as my fov, and that way when the donut goes off the edge I can bring it back to center.  In my LX200 there is a High Precision option that will really help on the faint fuzzies.  If you have it in your ETX, all you need to do is enable it.  Now with a goto, the mount will first want to center a bright star near your target to get a local calibration, and from there it can center the target very well.


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#14 aeajr

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Posted 06 March 2018 - 03:57 PM

NearVision,

 

Thanks for the added info.  It helps.

 

The finder in the photo is the one I have.

 

That power supply should be fine.  The system does not take a lot of power.  When tracking it uses very little.  Slewing is where it uses the most but I think even during high speed slew it uses less than 2 amps and then for a short time only.   I think you are fine. 

 

I mistakenly posted the manual for the 494 controller.  I deleted that one and uploaded the 497 manual which is the correct one for that scope.  I will reference it below.

 

Getting the mount level is important. 

 

The starting point for the scope itself is just to give the scope a chance to find the first and second alignment stars.  Don't worry if they are off an you have to use the hand set to move it to get them into view.   Once alignment is done, it is the accuracy of your centering of those two stars that will drive the accuracy of the GoTo.   You can use a low power eyepiece to get them into the field but use a high power or an eyepiece with a cross hair to center the star. The more accurate the better.

 

 

I don't see a reference to the spiral search in the 497 manual so it  may not have it but try the procedure anyway.  It may work.  I posted it earlier. 

 

 

Since it is an old scope there may be slippage in the clutches and slop in the drives.

 

If you want to test the scope, after you do the alignment and confirm the second star, tell it to GoTo the first star by selecting it from a menu.  It should hit it close to dead center.  If it does not, that is your slippage and  your gear slope.

 

 

Page 3 references self calibration:  Likely you need to calibrate the scope motors. Since that scope did not come with that control it may have been moved from another scope. 

 

Self Calibration: “Testing Motors” is displayed and the telescope
moves a short distance in both axes. Automatic calibration of the
motors happens only once, the first time Autostar is used.
NOTE: If Autostar is moved to another telescope, it needs to be
recalibrated (see the Setup:Telescope:Calibrate Motor menu).

 

 

Page 10

 

Calibrate Motor: If the telescope motors appear to have any

sort of problem, use this option to retest the motors before
doing a “Reset.” This option is also used if Autostar is moved
between telescopes to match Autostar to the telescope.

 

 

Telescope Training - Page 6

 

Autostar is not able to accurately point at objects unless it is aligned
and trained. Training Autostar allows it to collect data about the
gears in the telescope motor system. Once training is complete,
Autostar saves the data for later operations. Use great care in
training the Autostar system to achieve maximum accuracy.

To train Autostar, prepare the telescope for optical viewing by
removing dust covers and inserting an eyepiece. The viewfinder
should also be aligned and ready for use. Select a fixed land object
as a reference for the training process. Point the telescope at the
selected object and center it in the eyepiece. Press MODE until the
main menu is displayed (“Select Item:”). Press a SCROLL key until
“Setup” is on the bottom line, then press ENTER. With “Setup:” now
on the top line, press a SCROLL key until the bottom line reads
“Telescope,” then press ENTER. In the “Telescope” menu, press a
SCROLL key until “Train Drive” appears on the bottom line, then
press ENTER. The top line of the screen should read, “Train Drive:”
and the bottom line should read “Az. Train.”
Both telescope motors need to be trained separately. Start with “Az.
Train” by pressing ENTER and following the instructions given.
Autostar moves the telescope away from the centered object and
asks that it be centered using only one ARROW key (all other
ARROW keys are disabled). After the object is centered, press
ENTER. Autostar now moves the telescope in the other direction
and ask for the object to be centered again. Center the object and
press ENTER. The training for the Azimuth axis is complete.
Autostar has returned to the “Train Drive:” menu. Select the second
motor using a SCROLL key until the bottom line reads, “Alt. Train.”
Press ENTER and follow instructions as before. This time, the
telescope moves up and down otherwise the training sequence is
the same as “Az. Train.” After completing “Alt. Train,” Autostar is
ready for alignment and operation. Remember the accuracy of this
training determines how well Autostar finds objects.

 

 

Bottom of Page 7  - Synchronize Function:   I have never tried this

To improve the ability of Autostar to find

objects, a “sync” function is included to make minor alignment
corrections. If an object is not centered in the eyepiece, press and
hold ENTER for two seconds. Autostar requests that the selected
object be centered, then press ENTER again. This improves the
accuracy of alignment, particularly in the region of sky immediately
around the “sync” object.

 

 

If you have not done these then you should.  They may greatly improve the accuracy of the Goto.  I do this about once a year just as a tune-up.  I do it during the day.  Only takes a few minutes. 


Edited by aeajr, 06 March 2018 - 04:15 PM.


#15 NearVision

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Posted 06 March 2018 - 04:15 PM

Chuck,

The information you gave was helpful. It is something I want to do and 1 of the primary reasons for getting a scope. I'm just not quite there yet. frown.gif What I currently get looks more like an instamatic from the 60's than a current DLSR. So right now I'm concentrating on viewing and occasionally snap a picture. I found an old topic on the AWB one-scope here that has the topic starter's diary almost. I can really appreciate what he went thru. I'll work on the calibration and setup. Accuracy counts!

 

Ed,

I did the motor training and calibration but will probably do it again soon. I understand that it helps with accurate tracking. There may be some slop in the drive train. It came with an extension on the focuser knob that looks like a flexible steel cable. The guy I got it from said it helps reduce shake when focusing. I have noticed that even just touching it little can jar the image in the viewer and make it jiggle for a second or so. Is it really that sensitive? Or am I that gorilla fisted? I am a little concerned about old age and wear. The scope not me... Any signs I should be aware of that the drive train needs an overhaul?

 

If I understand the setup process. Getting it level is critical so it has a good horizon reference when it moves. I try to get it within +/-0.2 with the level. Then the north alignment is to get it close for the 2 star alignment. If I understand this correctly, if north is off a little it will only affect the alignment process and get canceled out by the 2 star alignment. Finally, the 2 star alignment is where it's critical to center the stars for accuracy when using the goto. And once it's aligned don't add a camera or extra heavy EP! At least not without realigning. I once did an alignment, then mounted the camera and watched the scope sag because the clutch wasn't tight enough for the extra weight on the backend.


Edited by NearVision, 06 March 2018 - 04:17 PM.


#16 nitegeezer

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Posted 06 March 2018 - 04:56 PM

 

I have noticed that even just touching it little can jar the image in the viewer and make it jiggle for a second or so. Is it really that sensitive? Or am I that gorilla fisted?

It is that sensitive, you have a long focal length which amplifies any contact whether it be you or the wind.  I have been comparing to my system and will do it again.  As far as I am concerned, mine is built like a tank, and is very accurate but still not perfect.  It came with electronic focus for a reason!  Since you only have a mechanical focus, you will want to turn through focus and then come back, and I believe it is CW and then CCW so the focus has the best load on it.  If I use my manual focus, my scope shakes just like yours, not that much but when amplified by the focal length it is huge!  Focus, settle, and repeat as needed.  

 

The above is all dependent on how stable the atmosphere is.  If you look at some dark object during a bright sunny day you can see the heat waves going up with just your naked eye.  Now imagine that through your scope.  Right after sundown, that is what you will be looking through and if there are no other weathers issues it will slowly get better during the night.  This can be seen by looking at one of the planets, you will think it in focus and then it is not.  Leave the focus alone and watch, it will come in and out of focus and is the source that causes lucky imaging which I mentioned above.  In this situation chasing focus is a lost cause.



#17 aeajr

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Posted 06 March 2018 - 05:10 PM

 

If I understand the setup process. Getting it level is critical so it has a good horizon reference when it moves. I try to get it within +/-0.2 with the level. Then the north alignment is to get it close for the 2 star alignment. If I understand this correctly, if north is off a little it will only affect the alignment process and get canceled out by the 2 star alignment. Finally, the 2 star alignment is where it's critical to center the stars for accuracy when using the goto. And once it's aligned don't add a camera or extra heavy EP! At least not without realigning. I once did an alignment, then mounted the camera and watched the scope sag because the clutch wasn't tight enough for the extra weight on the backend.

Motor training and calibration once a year is enough.  

 

Mine has the steel cable focuser too.   Yes it jiggles a little, but so do most scopes.  Both of my ETX scopes do that. My friend's NexStar 6SE shakes.  My 8" Dob has almost no shake at all but that is not on a tripod it is on a ground sitting Dobsonian base. 

 

Drive train overhaul?  Not sure if that is possible.  At least I don't know anyone who does it.  I would not worry about that.

 

I would not worry about heavy eyepieces.  That is a 1.25" focuser so eyepieces just don't get all that heavy.  And the ETX 125 is very front heavy by design so that isn't an issue.

 

Frankly I have never put a camera on mine.  I presume you mean onto the rear port.  I can't comment on that but I would not put the camera on it before alignment as it might prevent the scope from scanning up to hit the alignment stars, jamming the drive system with the camera.

 

Hopefully you have picked up some good tips here and come to enjoy your ETX as much as I enjoy mine.



#18 NearVision

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Posted 06 March 2018 - 05:41 PM

Thank you!

I have gotten some great tips and ideas here.

And reassurance that I'm on the right track.

 

BTW Great observatory Chuck!


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#19 nitegeezer

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Posted 06 March 2018 - 06:14 PM

Thank you, I really enjoy it!

 

I have just checked the manual for what I think you have, and it does have High Precision mode.  This will make finding the faint objects much easier.  I do not know the night sky that well, thus a goto scope for me, and this feature has helped me a number of times.  Get those two alignment stars as good as you can and the rest is easy.  

 

Hope you have some clear skies to have many nights of enjoyment with this scope!



#20 aeajr

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Posted 06 March 2018 - 06:32 PM

Here are some other resources that you might find helpful.

 

 

Stellarum -  FREE - If you don't have this loaded on your home computer you MUST get it now

http://stellarium.org

 

 

Getting Started with Stellarium

https://www.youtube....h?v=bYF7SR99ZOw

 

I also have the mobile version on my phone - $2.50

 

 

Turn Left at Orion - probably the best first book for someone getting
involved.   It will help you understand the terms and the types.  The
biggest benefit is that it is NOT full of pretty color photos that don't
look anything like what you will see in the eyepiece.  It  has realistic
sketches that show you what you will see.
http://www.amazon.co...n left at orion

 

 

What is SEEING and why it can be bad.  This is not a problem with your telescope
http://www.skyandtel...ing-the-seeing/

 

 

What’s Out Tonight
http://whatsouttonight.com/
http://skymaps.com/downloads.html

 

 

Come hang out with others who are new to astronomy.  You might enjoy this discussion.
A Newbies Observation log – come join me – Cloudy Nights
http://www.cloudynig...on-log-join-me/

 

 

Telescope Terms Dictionary
http://www.hioptic.c...copes/index.htm

 

 

Observation Chair- Denver Chair – Works Great!
I built this one .  It took about 2 hours.  Can be built from scrap but if
you went all new, about $30.
http://valleystargazers.com/Chair.pdf

 

 

Create a list of targets sorted by constellation using Tonight's Sky -
http://www.cloudynig...ights-sky-free/

 

 

 

Observing the moon – charts, maps and tools
http://www.oarval.org/MoonMapen.htm

I have this chart.  Like it very much
https://www.telescop...ord=moonmap 260

 

 

Selecting an eyepiece - Orion telescope
This is a very general discussion of eyepieces and why there are a variety
of designs
https://www.youtube....h?v=m7u9Q5hV7yc

 

 

Eyepiece Designs -  This is the one I turn to when I am trying to understand or explain the differences between the various designs.  There are so many different designs.  Many are named for their original designer, such as Huygens, Ramsden, Kellner, Plossl, Konig, Erfle, Branden and Nagler.
http://www.chuckhawk...ece_designs.htm

 

 

Filters - Planets - The use of filters – by color
http://sas-sky.org/w...al-Filters1.pdf

 

 

Filter review – From 2005 so may be out of date but reading how the eval was done may be useful
How various filters work on various nebula
http://www.astronomy...ula_filters.pdf


Edited by aeajr, 06 March 2018 - 06:33 PM.

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#21 M57Guy

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Posted 07 March 2018 - 11:31 PM

As much as I would love to see a photo of a 82x300 reflector piggybacked onto your ETX-125, I can't in good conscious recommend that. lol.gif

 

For myself, I replaced the stock 8x25 finder with a simple RDF and have been satisfied with that decision for a number of reasons.

 

While keeping your existing Rigel QuickFinder, try a low power wide field EP and see how that works for your initial goto slew, and then dial up the magnification from there.


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#22 NearVision

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Posted 08 March 2018 - 11:13 AM

M57Guy, I think you've summed it up pretty well. Although it would be quite entertaining to see! Photoshop anyone???smirk.gif borg.gif

I'm planning on getting out to catch the moon and planets tomorrow morning so I'll work on the alignment tips listed here.

I was going to keep the QuikFinder and I'll probably get a wide field EP for setup and general viewing. Even with the 24mm there are a lot of things that this scope is too narrow to see. The moon barely fits with the EPs I have now.

 

If anyone has experience with a smaller finder scope that would give a noticeably brighter wide view for when it's just too dim for my eyes to see where it is with the QuikFinder, I'd appreciate a heads-up.

 

Thanks again everyone!



#23 M57Guy

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Posted 09 March 2018 - 08:46 PM

Here's a link to a field of view calculator you can use to compare EP options with the ETX-125.

 

http://astronomy.too.../field_of_view/

 

Take time to level and aim the scope in home position.Once you get the hang of things, your alignment and subsequent goto slews should go rather smooth.  In the meantime, a wider field of view may help with getting started.

 

Good luck!  waytogo.gif



#24 CHASLX200

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Posted 18 March 2018 - 06:56 AM

I want to rig up a way to use a 50mm RA finder on my 125 ETX OTA.  .  Maybe make something with the ring mounts i have coming like a bar that mounts of top of the rings and installing a shoe is one way it could be done.


Edited by CHASLX200, 18 March 2018 - 06:56 AM.


#25 CHASLX200

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Posted 22 March 2018 - 05:54 PM

Well this is a mock up so a big finder can work.  I will fine tune and all should be well.

 

e8q3hc.jpg




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