Help with etx 90

[Jess]

Hi guys so i recently got the meade etx 90. Do i need to align every time i use it?? Even when i align it, face it true north i use the compass, but then when i use the hand held remote thingy i click on the moon and it doesnt face the moon haha i found it so hard to actual focus but when i focus on the stars for example i can honestly see them better just by looking up unless these stars are deep sky but yeh the manual confuses me.. it came with the 9.7mm eye piece and the 27mm i think which one is better.. any info u think will help me actually start seeing planets and so forth.. Thankyou

[Peter Drew]

Hello Jess, welcome to this forum. I think you will have to align the telescope each time you use it. What procedure are you using?, I expect you will have to enter your location, date and time before it will find anything. Even if you can't get the goto to work initially, provided that the handset allows you to move the telescope Jupiter and the Moon should be easy targets. The ETX 90 has a small field of view so make sure the finder is aligned and use the 27mm eyepiece first. The stars will not seem as plentiful in the telescope as they do to the naked eye unless you are looking at the best star clusters. 

[carastro]

Agree with Peter, yes an alignment procedure is needed every time even when you haven't moved the set up after switching it off.  It needs to know where it is pointing.  

Also agree with Peter to check you have your location date and time correct.  The location only needs to be done once unless you move to another country.  If you bought it new it might well be programmed for the USA which is why it won't GOTO the right place. 

Lastly, make sure you enter the date in American format i.e. MM:DD:YY  this trips everyone up even after doing it for many years.  Also in the Summer you need to tell it you are daylight saving or it will be an hour out. 

On an ETX there is a Home Position procedure where you turn the scope as far as you can to the left and then back again to the North Pole, and then make sure the scope is horizontal (parallel to the ground) before starting the alignment procedure with the handset, again so it knows that is where it's starting point is.

I used to own an ETX105 some years ago.  

HTH

Carole 

 

[Jess]

Im in australia and i did put in my closest city (melbourne) but it asked for an area code.. here its post code which is only 4 digits not 5?? Also the red dot finder when i point it at something perfectly then look thru the scope i cant see it??  Which eye pieces are the best to buy? And also the disc that comes with it. Whats the purpose?  So once aligned i can GOTO something like when it reccommends the best views for the night it should automatically go to that planet etc?

[carastro]

Best to start with low powered eyepieces, they give better definition and a larger field of view (FOV) so easier to find your target.  

I never used the disc myself, could not see the purpose of it and never missed it.

You need to have your red dot finder aligned with the scope, I never used a RDF so not sure if it is possible to use during the daytime, but you need to get the scope and RDF looking at the same thing, preferably in the centre of the FOV, then when you use it for GOTO it will better help you find your target.  If it won't work in the daytime (i.e. red light doesn't show), then the best thing to use is the Moon as it's bright and difficult to miss.  It's not up until the early hours at the moment.

Also are you sure you are in focus when looking through the scope but have the target in the RDF?  Again use the Moon as a guide and then try not to move the focus between viewing sessions.  You might not see anything simply because it's right out of focus, can you see anything at all, such as stars? 

HTH

 

[ronin]

You will ahve to go through the alignemnt procedure every time.

Your description does not seem to imply that you did the alignment for the goto:

Hi guys so i recently got the meade etx 90. Do i need to align every time i use it?? Even when i align it, face it true north i use the compass, but then when i use the hand held remote thingy i click on the moon and it doesnt face the moon haha i found it so hard to actual focus but when i focus on the stars for example i can honestly see them better just by looking up unless these stars are deep sky but yeh the manual confuses me.. it came with the 9.7mm eye piece and the 27mm i think which one is better.. any info u think will help me actually start seeing planets and so forth.. Thankyou 

I would guess that a compass is also not indicating true north for you either, have you a phone (app maybe) tht would indicate true north. It is essential especially on the ETX-90.

For location you can enter a custom one, best to do so anyway, you need to give it a name, (NUM I guess) then the Latitude then the Longitude and your Timezone in terms of UTC not sure what yours is but expect something like UTC +10. Once set the scope will use that until you change it. At this time you can ignore giving it the date, time and other bits, that comes later even if the scope asks.

Align the finder with the main scope and do that well. Again when you level and North the mount and the scope (BOTH) do it well. THe reason for this is that the field of view of the 90 is a bit narrow, I have the 105. The more accurate the initial setup is the greater the chance of the first alignment star being in view.

Actually a bit unsure how these scopes handle being in the southern hemisphere, cannot recall seeing a N/S selection but equally never really looked. Maybe they read the Latitude and determine it from that, should be easy to do I suppose.

Do the alignment, the easy align is likely the best as Meade select sensible stars, well they do for the Northern hemisphere. When alignment is complete and more or less working as in goto Betelguese (easy red star) then center it and perform a Sync - hold Enter down for a couple of seconds, make sure the star in in the center and confirm Sync (press Enter again) that gicve the scope a defined RA/Dec (Alt/Az) to use as a datum.

Biut to be boring the location is best as a custom and it is more exact, the mount needs to be level, and the scope needs to be level and North - all these positions as accurate as you can, spend a few extra minutes doing it well.

Will go look through the manual to see if there is mention of N/S half suspect there has to be.

[Peter Drew]

Jess is in Australia, this could further complicate matters!. The red dot on the finder turned full on should show up against a target in daylight. @jess- point the telescope at an obvious distant object and centre it in the eyepiece. Next, using the adjusters on the finder centre the dot on the same target, from then on anything in the night sky that the red dot is on will appear in your telescope with the low power eyepiece fitted.   

[michael8554]

I've read that Southern Hemisphere Alt/Az alignment is point true north too.

Michael

[Jess]

Yes i can see things now such as stars. I could actually see the moon last night but i was a bit too close i would like to see the whole roundness of the moon maybe that requires a smaller size eye piece. This one was a 27mm which was way too close the 9.7mm was supet close. My alignment seems pretty good the compass faces true north and the bubble on it shows that the scope is level.. it sounds like there is a general alignment then a goto alignment???  Someone metioned?? Whats the diff? When i do goto nothing seems to be in view yet. Scope says rises at 3 am or something, or the scope faces too close to the ground where theres a fence or a house.. im not familiar with all the terminology used haha its frustrating not knowing how to use it yet.. might have to set an alarm for when something rises then see how the scope goes??

[carastro]

If it is saying Rises at 3am this means that the target is below the horizon.   Now if this is a target you definitely know is NOT below the horizon I.e. the Moon because you can see it, then that definitely says there is something wrong with the  information you have input.  I.e location, date (American format), and time zone and your local time ignoring any daylight saving times as this will just confuse the issue.  Carole

[carastro]

Having said the above, l could be wrong about putting  in local time never having used a scope away from the UK.  Should one put in universal time at Greenwich having  previously put in their location and timezone, or should they put in local time in Australia ignoring daylight saving even though they I have already put their location and time zone.  Also am surprised ETX requires pointing at true North as equatorial mounts use the south pole, might need an antipodean to answer this. 

[ronin]

Yes there is a "alignment" that is a case of set up the mount and OTA as Level and North - I still do not trust a compass.

Then you do the alignment that enables to scope to know where it is and what compensations it has to apply, these compensations are for time and level and directin of the scope. Look upon it as you do the gbest you can then the scope does the bits that you got wrong.

You should level the mount, level and North the OTA. Then you select easy align. The scope asks for Date, Time, and DST. You enter each in turn.

The scope should display "Calculating" and then says "Slewing to ABC" and off it goes towards where the star ABC should be - all dependant of the data you have given.

When it gets to where it thinks ABC is you center it and press Enter, then is says "Calculating" again and then says "Slewing to XYZ" and off it goes to star XYZ. It gets there and says Center XYZ and Pres Enter. If both are centered in reasonable time it should say Alignment Successful. Then you select a target and press Goto and it goes to it (hopefully).

The "problem" is angles. Assume that you have a 1 degree field of view, that is really +/- 0.5 degrees. You set it up 1 degree off of true north, when it slews to ABC then ABC will by definition be 1 degree off. This means it is 1 degree away from the centre, which means it is not in view of the main scope. If you cannot see it then it is really difficult to locate and center in a reasonable time.

So align the finder accurately, make sure that the level and North is accurate and I went and bought a 40mm focal length plosl eyepiece for the widest field I could get. On these Maks this initial setup is simply very, very relevant and accuracy is essential. It really is a case that 2 minutes extra can easily mean you a successful alignment, otherwise you have to spend the time all over again doing it, which is going to be 5 to 10 minutes. So 2 minutes taking a bit of care or 10 minutes doing it all over again.

Just looked up Numurkah, you must have dark, really dark skies. Guessing you can see more by eye then we will in the UK with a 200P newtonian.

According to a Magnetic Declination site the difference at Numurkah between magnetic North (compass) and True North is 11 degrees. Assuming this is correct, it has been on things in the past when you use a compass you are setting the scope up 11 degrees incorrectly. As said find something that give North by GPS not a compass. With an 11 degree offset from True you will likely never get the scope to complete alignment successfully.

[Jess]

Wow thanks ronin i actually understand what ur staying i appreciate all the responses im getting but i didnt really understand what the other people are saying haha. i will try and align with a GPS not a compass, ill use the compass for leveling but a GPS for true north ergh frustrating.. im pretty sure when i press easy align it doesnt ask for date and time.. maybe ill check again. when it does say calculating, what do u mean by "centre" then press enter? Ive just been pressing enter straight after it beeps and it always says successful but im assuming the alignment is wrong cos then when i goto it doesnt show me anything theres nothing to see.. also when i finally found jupiter i added the coordinates into like a save option but then when i went to use that option it didn't take me back to jupiter.. alignment issues maybe?? And yes the skies are very dark in numurkah and im a little on the outskirts so its even better.. whats a focus length plossyl eye piece im assuming a stronger eye piece haha thanks for ur help.

[Davey-T]

A longer focal length eyepiece gives a wider view of the the sky, this rather counter intuitive as you may think X25 would magnify more than X5 but in fact the opposite is true.

Dave

[Davey-T]

If you download Stellarium http://stellarium.org/ and fill in your equipment details it will show you the view to expect through your scope.

Just done a rough calculation, here's what your view of Arcturus should be like using the 25mm eyepiece in the ETX90.

The ETX90 is what is called a long focal length telescope, 1250mm I believe, so you end up with a pretty small field of view.

Dave

 

[ronin]

Cannot remember exactly but the beep may be to tell you that it has completed the slew, and that the star may (should)  be in view, you then are supposed to put the star in the center then Press Enter to tell the scope that Star A is centered. It basically amounts to the scope saying it has done it's bit, now you get off your backside and do your bit, and tell me when you have finished. Did this 10 days ago and have forgotten exactly the steps, just fairly used to them so I don't bother to recall them much.

The whole process follows along the lines of

You set the mount up, you tell scope to align, scope ask what times, date and DST are, scope ASSUMES all is perfect (it is this assumption of perfection that is he problem) and slews to first star, scope then tells you it has done it's frist bit by squeeking and you do the "fine" tuning bit of putting first star in the center. This means the scope now has an idea of how bad the Level and North were and how badly you read a watch.

To get a better idea it picks a second option and off it goes to that, then tells you it has completed it's slew and you have again to center the second star and again press Enter. This second one is to reduce errors again.

Usually when you move the scope by the handset the scope calculates the new position it is pointed at, during the alignment this is not done in a way. The scope points at where it thinks star A should be and any fine movement made by you to center it is ignored. The pressing Enter means you have done your bit.