A few bad attempts lol

[Milliways]

My terrible attempts tonight

1st is the M42 ISO HI1

2nd M42 ISO 1600

3rd M15 B/w ISO 1600 (Wont let me upload the others at the mo hmm.)

[Psychobilly]

Millways,

You might says its bad but actually its getting better... basically all thats wrong with that one now is an tracking error caused probably by the alignment being a little bit off...causing startrails...if you polar aligned on polarsis thats whats likely to happen...

Your getting there....

Billy...

[Milliways]

Hehe thanks mate.. There is something wrong with Ukastronomers, it wont let me upload the other 2 images

Any tips on the polar alignment?

Cheers.

Dave.

[Psychobilly]

I'm havign to dragg stuff out of the back of my heads as its a year since i used the ETX...

im pretty certain that the controller can give you an alignment error display so you can use that to make what will be small adjustments...

If you havent already (not trying to pass the buck here) acquaint yourself with Mike Weasners excellent ETX site http://www.weasner.com/etx/menu.html and work through the help and info on there... Mikes a really nice bloke ....its not run as a forum and Mike has some guidelines on how to contact him...

Billy...

Ignore any "posts" by a certain Peter Smith UK...

Just ignore any posts

[Milliways]

I polar align my scope to polaris with the 2 star alignment (Vega then Capella) Is this wrong?

Cheers for the info mate.

[Psychobilly]

no its not "wrong" its just needs to be doen precissely when you want to start imagign through wahts is a fairly long focal lenght scope... the longer the focal lenght the more accurate the polar alignment needs to be as trailign shows up much more quickly...

How are you alignign the stars... I used to use a 12mm illuminated reticule EP and sometiem would barlow it up usign a x2 or x3 barlow...

Is your using a standard EP once you get closs to the center with he 26mm change to the 6.5.. anothe rtip is instead of focusing on a pinpoitn star defocus to form a "donut" and adjust so it almost fills the FOV of the EP as its then much easier to judge when your centered...compared to a tiny dot inthe middle of the EP FOV...

Billy...

[Milliways]

Thats really good advice mate thankyou

I'll use my 6.5mm and my 2x barlow and see how i get on with that

Your a superstar mate

Thanks.

Dave.

[Psychobilly]

the 6.5 an x2 will be way to short and unless your pretty closee before you start the alignment stars will drift outr of the FOV very quickly..tyr it and you'll soon see..

I also used to use a cheap zoom EP for alignment ... quicker than changing EP's

Billy..

[Milliways]

These are the other 2 images.

http://ukastronomers.com/milliways/image/11302_normal.jpeg M42

http://ukastronomers.com/milliways/image/11301_normal.jpeg M15

[RichieJarvis]

Good attempt!

It also looks like the tracking is having trouble on the ETX - looking at the second image you posted, you can see the stars moving in right-angles. The problem with the good old ETX is that when you put a camera on the back, you unbalance it big time - especially as I am guessing from the ISO speeds that you are using a DSLR? You might get away with putting some additional weight on the front of the OTA to try and balance the system.

I must admit, I gave up with my ETX for Astrophotography, as the tracking of the mount is just not accurate enough for anything other than very short exposures in my opinion.

Cheers,

Richie

[Psychobilly]

To be honest RJ so did I...

I speant a lot of time working on and fettling the ETX scopes drives... making counter weight systems etc.. but was never really happy with the results...

I tried LPi, DSI's etc both of which are signifficantly smaller and lighter then the dslr and dont have mechanical shutters to upset the scope and had some joy not a lot though...

If you were to use a webcam on it it makes a very good planetry and lunar imaging setup...

Billy...

[MartinB]

Keep working at it Dave.

I'm confused though. Isn't the ETX fork mounted? Are you using it in Alt az or does the ETX have a wedge to make it equatorial. The alignment routine is only to make the goto accurate. If you are in alt az you don't need to polar align but your exposures will be limited by field rotation. If you are in equatorial mode then you need be more precise than lining up on Polaris - you can drift align or use a goto method.

[Milliways]

Keep working at it Dave.

I'm confused though. Isn't the ETX fork mounted? Are you using it in Alt az or does the ETX have a wedge to make it equatorial. The alignment routine is only to make the goto accurate. If you are in alt az you don't need to polar align but your exposures will be limited by field rotation. If you are in equatorial mode then you need be more precise than lining up on Polaris - you can drift align or use a goto method.

Yeah it is folk mounted and i am using the tilt wedge to polar align it. I try to align polaris the best i can but still get a little streak

God knows what i am doin wrong... I think i'll take note of exactly what i am doin and let you guys work out what i could do to help... never done astrophotography before so i am bound to make mistakes :mrgreen:

I really wanna get to grips with registax (taking the online tutorial lol) And dont have photoshop to soften the images

Anyhoo i did the best i could with what i got and this is the result hehe.

M42..bmp

[Psychobilly]

Definitely getting there

Martin the Meade #884 tripod has a tilting top plate so you can effectively use it as a field wedge as well as in Alt/Az mode.....

I would possibly try DeepSkyStacker instead of Registrax... and GIMP is a great free image manipulation program

[MartinB]

Definitely getting there

Martin the Meade #884 tripod has a tilting top plate so you can effectively use it as a field wedge as well as in Alt/Az mode.....

I would possibly try DeepSkyStacker instead of Registrax... and GIMP is a great free image manipulation program

So does the ETX handset include a polar alignment routine? One simple way it to line up as close as possible then do the alignment. Then do a goto on polaris. Bring polaris into the centre of the screen using the alt az adjusters then rpt the alignment. Keep doing this until the goto brings polaris to the middle of the FOV

[Psychobilly]

IIRC it tells you how far out you are so that you can make the adjustments and repeat....

Its a long time since i fired up the ETX....

Billy...

[MartinB]

The key message for newcomers is that it is the alz and az adjusters on the mount which have to be used when polar aligning, not the handset.

[Psychobilly]

indeed...

The other crucial thing is leveling the tipod peoperly before you start I bought a digital angle gauge which I used to "calibrate" to a fast level I would then use this to cross level the tripod before mounting the scope and would then adjust the angle of the mounting plate using the guage to set the correct angle for the latitude of the observing site.

I also bought an illuminated reticule EP to help with accurately centering the alignment stars in the FOV. Although a cheaper method (if the collimation is ok) is to just mis-focus the star to a donut mode which largely fills the view through the EP - its much easier to center this than a tiny dot in the middle of the FOV...

Billy...

[Milliways]

Thats really good advice thanks Is there any other way of gettin polaris dead center other than moving the mount around? In the manual it says that i have to keep the scope at 90' and center without using the arrow keys?? this takes me about 30 mins to sort out

Thanks for the info on the other programs They are quality! had a muck about with one of my images but not sure if i made it worse or not lol.

Here it is.

[Psychobilly]

Unfortunately you have to move the mount... what surface are you setting up on... when i was on grass i used to have three 5 inch stainless steel disks which I could put under the tripod legs I would hammer these level and peg them down before mounting the tripod in AV mounts... that way I was able keep the tripod reasonably level when i moved the tripod to refine the alignment.

After a whiel i gave up tryignto do Prime Focus Astrophotography ont he ETX and instead did Piggyback work with shorter focal lenght lenses which are more forgiving to mount misalignment. I also made an adaptor to use old M42 lenses with Meade DSI CCD's and another adaptor which allowed me to mount this via the EP port. I used this setup to image Comet Holmes and a few other targets...

Billy...

[Milliways]

Yeah i set up on grass, thats prob where i am goin wrong, I didn't level the mount.. and i am pretty sure the legs arn't the same length (DOH!)

That might explane why my images have right angle streaks hehe :mrgreen:

Just waiting for some clear skies to have another go.. I have some dumbell waights that i'll put down and get level

Thanks for the advice again mate

Best regards,

Dave.

P.s, Did you have a good new year?

[661-pete]

I set up on grass too, merely pushing the tripod legs well into the turf. In summer the lawn gets quite hard (this is in France) and I never seem to have any problems with tripod stability. But in the quagmire that passes for my back lawn in England, in the autumn and winter, it would be a different tale...

I get curved trailing too, like on Dave's #2, sometimes. In my case, on a German equatorial, it could be a combination of drive PE which would add trails in RA, and incorrect alignment which would cause trails in declination. I suppose this could happen on a fork mount too. But in my case, I think the declination errors may be down to the RA bearings in my somewhat overloaded mount, rather than polar alignment which I've got quite adept at!

[Psychobilly]

The Problem isnt settugn up on Grass which is a very good surface to observe over... its beign able to keep the tripod accurately levelled when you need to make adjustments to the polar alignment by moving the tripod... the chances are that you will end up being out of level , so you end up chasing your tail...

Fro PF astrophotography you need Everythign spot on... the tripod mus be cross levelled - levelled East West and North South at the same time and accurately aligned to the North Celestial Pole (NCP) in both Alt and AZm (the ALt and Azm) are still used to desrcibe the aligment even though your EQ aligned... ALt is the angle between the Angled face of the "wedge" and Azm its rotation with respect to North...

Billy...

[RichieJarvis]

Also - when polar aligning in a fork mount, the OTA should be in line with the forks, not at right-angles.

The way I used to do this was to get the OTA near enough lined up by eye, and then rotate the base left and right whilst looking through the eyepiece so the stars spin. Once they are spinning in a circle, its inline. You can then lock off, and align to Polaris, which is pretty easy to spot, as its the brightest double (well, its actually a triple, but I doubt an ETX will show all three!)

The trick is then going to be doing drift alignment to compensate for the lack of accuracy of Polaris' position.

And make sure you select Polar Aligned in the Telescope -> Mount options before you do your scope alignment, otherwise its going to get confused!

[Milliways]

Also - when polar aligning in a fork mount, the OTA should be in line with the forks, not at right-angles.

The way I used to do this was to get the OTA near enough lined up by eye, and then rotate the base left and right whilst looking through the eyepiece so the stars spin. Once they are spinning in a circle, its inline. You can then lock off, and align to Polaris, which is pretty easy to spot, as its the brightest double (well, its actually a triple, but I doubt an ETX will show all three!)

The trick is then going to be doing drift alignment to compensate for the lack of accuracy of Polaris' position.

And make sure you select Polar Aligned in the Telescope -> Mount options before you do your scope alignment, otherwise its going to get confused!

The way i do it.. step by step, is...

I put the scope at 90' Then eye up polaris in the EP, move the mound around till i get it in the middle of the ep, then still looking through the ep i adjust the tilt plate so that polaris is as center as i can get it.. Then i align to polaris.

Anythin else i could do apart from gettin a spirit level to the mount? am gettin my remote for my camera soon and wanna start takin some longer exposures but dont wanna capture a large bundle of worms lol.

Cheers guys.

Dave.