Do I need an illuminated reticle eyepiece?

[Malcolm]

I have a 10" Skywatcher dob on a Synscan GOTO mount. I usually do a two star alignment, using a 2" 32mm GSO Wide Field eyepiece on a 2" Barlow., this helps to locate the first star. The mount then slews to the second star of choice, usually a bit out of alignment but no biggie to line it up. I get the Alignment Successful from the handset as usual.
Then, for example, if I decide to take a peek at Saturn, slew to the object, I always find it is not centered. Now if I was using a 10mm eyepiece, it wouldn't even be in the field of view.
The base has been modded with three adjustable screw legs, so I can get the base perfectly level, the location and the height is accurate, as is the time.
I have tried using the PAE function in the Utility Menu, on selection it knows what I'm looking at, as it asks to centre Saturn, which I do using the direction keys and then entering that data into the handset.
So, moving right along and selecting a new object, such as Centaurus A, I find it is not in the field of view. This is frustrating and I'm really not sure what, if anything I am actually doing wrong.
So, my question is, would a reticle eyepiece be useful for centering on alignment, what focal length is recommended as there are many to choose from, and or, is there a fault in how I am performing the alignment in the first instance?
I have a good quality power pack so a faulty power supply is not the issue here.
Any thought and advice is appreciated, Thanks. M.

[glend (Glen)]

Do not expect your dob to be dead centre on target in a relatively narrow field of view ep. After alignment i would use a 20mm ep as a minimum until you get it spot on. There are ways to avoid the issues with syncscan, if you connect an Astro Devices Nexus wifi module to the hand controller port you can drive the scope using Sky Safari Pro via tablet, which allows aligning on a nearby bright star in the area of interest.

[dimithri86 (Dimithri)]

I think you would only need the illuminated eyepiece to do polar alignment for imaging.

I don't see how it would help much for a dob. I generally use a low powered piece to find the object before switching to the more powerful piece.

[Malcolm]

I am using a low power ep. The point is after doing a successful alignment, the new object is either not there or not centered. This happens every time. After finding the new object and using PAE which I thought was supposed to correct any mis-alignment, I get the same thing again when slewing to a new object. If I'm looking for a faint DSO with a low power ep, the object just isn't there.
When I do the alignment, I usually choose Hadar as the first star, then Fomalhaut as the second. Surely far enough apart to provide a reasonably accurate alignment. I spend a good bit of time to make sure the base is perfectly level as well.

[The_bluester (Paul)]

I am not sure how touchy the dob mount is, but I would try doing the alignment differently.

First get the base as level as you can (Do it with a small spirit level, just a plastic Bunnings job would do fine) then I would first find your first star with the 32mm EP but then change to the 10mm and then the 10mmin the barlow to refine the centring of the star. Do the same with the second alignment star, use the low power EP to rough centre it if it is not in view at the higher power, but use the high power EP and barlow to centre it as closely as you can.

I have found with both the goto mounts I have had (A Celestron CPC and now an Orion Atlas pro AZ-EQ mount) the care taken with the alignment, starting with making sure it is level really does pay you back in goto and tracking accuracy all night.

[Tinderboxsky (Steve)]

I agree.
There is another little trick that may work for you if you are finding it tricky to judge if the star is in the centre of the field of view. Simply refocus the star into a large diffuse disk. For some it is easier to judge centring this rather than an in focus point of light.

Cheers

Steve

Originally Posted by The_bluester

I am not sure how touchy the dob mount is, but I would try doing the alignment differently.

First get the base as level as you can (Do it with a small spirit level, just a plastic Bunnings job would do fine) then I would first find your first star with the 32mm EP but then change to the 10mm and then the 10mmin the barlow to refine the centring of the star. Do the same with the second alignment star, use the low power EP to rough centre it if it is not in view at the higher power, but use the high power EP and barlow to centre it as closely as you can.

I have found with both the goto mounts I have had (A Celestron CPC and now an Orion Atlas pro AZ-EQ mount) the care taken with the alignment, starting with making sure it is level really does pay you back in goto and tracking accuracy all night.

[wskiscope (Frank)]

You get a lot more accuracy using a illuminated reticle. I ave the same scope but i use altair and hadar, i think fomalhaut and hadar are to close to each other for good alignment.
Also i found if using a heavy eyepiece when slewing accuracy is not so good. As i have a GSO 30mm and 2" barlow and when using them when slewing to a new object sometimes the object is nowhere in the eyepiece (i think the clutch for the altitude slips), so i use the 25mm eyepiece when slewing and have no problems finding objects.

[AstralTraveller (David)]

Originally Posted by Tinderboxsky

I agree.
There is another little trick that may work for you if you are finding it tricky to judge if the star is in the centre of the field of view. Simply refocus the star into a large diffuse disk. For some it is easier to judge centring this rather than an in focus point of light.

Cheers

Steve

+1 I start using a low power ep and then use a 10mm ortho with the star image defocussed until it fills about 3/4 of the fov. Judging when that is centered is far easier than with a point of light. My guess is that that will improve your alignment significantly. I also always do a few extra alignment stars - probably 4-5 stars in total - and this also seems to help a bit.

[gaseous (Patrick)]

Perhaps a silly question, but are you using true north or magnetic north when you first set up your dob?

[Malcolm]

Originally Posted by gaseous

Perhaps a silly question, but are you using true north or magnetic north when you first set up your dob?

Not a silly question, it is an alt az handset, no need to find north for setup.

[gaseous (Patrick)]

Thanks Malcolm. Don't you need to have the OTA level and pointing north before switching on the handset power? That's how my skywatcher dob + synscan goto recommends getting started. Happy to have you say otherwise though, as it'll save a bit of stuffing about for me next time! True north gives much more accurate alignment, but as has been mentioned, most compass apps are set to magnetic north, which I recently discovered after having similar misalignment issues.

[Malcolm]

Originally Posted by gaseous

Thanks Malcolm. Don't you need to have the OTA level and pointing north before switching on the handset power? That's how my skywatcher dob + synscan goto recommends getting started. Happy to have you say otherwise though, as it'll save a bit of stuffing about for me next time! True north gives much more accurate alignment, but as has been mentioned, most compass apps are set to magnetic north, which I recently discovered after having similar misalignment issues.

All I do is plonk the base outside, I use a small spirit level to set the adjustable feet I have fitted to get the base perfectly level. Then I just start the alignment after fitting the OTA. One thing I have noticed after doing the alignment I get a message on the handset saying that the previous PAE has been applied. I'm yet to work out how to delete any PAE before I start an alignment so maybe that has something to with my problem.