two star alignment

[oldannie]

Not sure this is the right forum to post this question - apologies if not!  Have had my HEQ5 pro synscan for some time but lack of clear skies has meant that I haven't got further than polar aligning and setting up the synscan.  The next clear sky am intending to do a two star alignment. However the manual assumes the use of a telescope and talks about using a finderscope and then aligning in the eyepiece.  I don't have a scope as am intending to use my DSLR and lens so what do I align the two stars with?  Hope this makes sense!

Thanks

Annie

[Peter Drew]

I would have thought that using the camera with its lens as a telescope, provided that you can see the alignment stars in the viewfinder/ liveview screen, this would do the job. Alignment for just a camera shouldn't be so critical as that with a telescope.  

[ronin]

Makes sense and other then buy an inexpensive scope I cannot think of anything. You probably cannot use the DSLR on it's own as you have to centre the alignmant stars and the DSLR will be very wide and no real defined centre (could put a small  dot on the screen I suppose) and also the display may be too dim to get get a good image for alignmnet.

Will depend on future progression of the imaging set up as well, picking up a 70mm achro from TS or an 80mm from Rother Valley could be used as a guide scope if you went to an imaging setup with scope camera and guide scope.

[JG777]

The manual is referring to a main telescope, and a telescope has a small finder scope attached. They then have to be aligned with each other as near as possible before starting a two/three star alignment. Your not going to be using those 2 items so just after polar aligning the mount attach your DSLR with lens then use live view to zoom in out on your chosen stars. I guess it depends on how big the lens you use that will determine how much you see in the live view, you didn't mention what lens you were attaching.

HTH

[oldannie]

Thanks for the responses.  I guessed that's what I should do John - I'm intending to use my 300mm prime lens.  If all else fails guess I'll be looking to buy a telescope!

Annie

[D4N]

At 300mm the alignment star could well be outside of the FOV.

You could use Astrotortilla to plate solve for you then you wouldn't have to do the star alignment it will sort it out and sync for you.

You would still need to polar align though.

There are other plate solving programs, that's just the one I use.

TSED70Q, iOptron Smart EQ pro, ASI-120MM, Finepix S5 pro.

[oldannie]

Would it be worth thinking about a wider angle lens (ie. 24-120mm/17-35mm) or would they have insufficient focal length to make it a worthwhile exercise?  In the meantime will have a look at Astrotortilla.

Annie

[Viewmaster]

I use a 200mm lens on a DSLR with live view. Use the x10 to centre the chosen star each time.

Seems to wok OK for me,   no telescope or finder being used.

The FOV is about 6 degrees for imaging so any small errors are not a problem.

[oldannie]

Right - that sounds promising.

Cheers

Annie

[JG777]

And don't forget you can usually superimpose a grid in live view to help get you centred , or have it show the centre focus point?

[oldannie]

Polar aligned last night, set up the synscan and chose two star alignment, Vega as the first star.  Mount slewed to the right star which I could see in the red dot finder attached to hot shoe of camera but not in  the fov.  I assumed I would just tinker with the directional keys but met an unexpected problem!  Couldn't get the directional keys to have any effect - not expecting that!  The manual says the keys are locked out whilst the mount is slewing but I'm certain slewing had stopped by the time I tried to use them and assume the beep made by the mount told me that.  Tried the same process with the second alignment star, Alderbaran and again the mount slewed to the correct star, saw it with the red dot finder but couldn't get the directional keys  to maneuver  it into my fov though the handset told me alignment was successful.  Am I missing something obvious (again!)

Annie

[D4N]

Depends, were you aligning the Goto or doing the two star polar alignment routine?

If you are aligning the Goto then you should be able to use the keypad to slew the mount.

If you are using the two star polar alignment routine then you are supposed to adjust the lat and az to bring the stars central and complete a few iterations of this to fine tune your alignment.

TSED70Q, iOptron Smart EQ pro, ASI-120MM, Finepix S5 pro.

[oldannie]

Hello D4N - at the risk of sounding incredibly dim I don't know! I set the date and time on the date circles and then polar aligned manually, then switched on the power and set up the synscan, home lat/long, date, time etc. and at the end of that process it asked if I wanted to carry out star alignment - I chose two star alignment etc.  It would explain why I couldn't get the directional keys to work if that process was the two star alignment process I was doing rather than aligning the Goto.  Does that make sense?  

Thanks very much for your response - I guess eventually it will all start to make sense to me!

Annie

[JG777]

You only use the alt az alignment bolts for polar align. For your 2 star align IIRC the default speed on the keypad is number 1 so very very slow, are you sure there was no movement? Could you try selecting higher movement rate from the keypad ?

[oldannie]

Hi John - at the time I thought I was aligning the Goto.  Hubbie came out to check and niether of us could detect any movement.  Am going to play around with the mount indoors today so will try and change the speed. 

Thanks for you help.

Annie

[Tinker1947]

You may need to increase the slewing speed, press 2 then (i use 5 then 3) 9 is the fasters and you will hear the motors plus see the movement...

[D4N]

It would be a good idea to go through all the menus on the mount controller in the day while you have the manual in front of you.

That will make it much easier to do in the dark.

I don't have a HEQ5 so I'm not familiar with the exact process for that mount in afraid but on my mount the two star alignment is a polar alignment routine, the Goto alignment is done with a single star alignment or multi star alignment. Although I normally just tell it to slew to my focus star, correct any error then send a sync command.

TSED70Q, iOptron Smart EQ pro, ASI-120MM, Finepix S5 pro.

[oldannie]

Thanks guys - hopefully by the end of today I will have found my way round the menus!

Annie

[JG777]

Hi John - at the time I thought I was aligning the Goto.  Hubbie came out to check and niether of us could detect any movement.  Am going to play around with the mount indoors today so will try and change the speed. 

Thanks for you help.

Annie

It is unbelievably slow after the initial slew, it sounds like you are doing the correct process. You must have selected the correct button to get a selection for the second star as well then found little movement on this as well. When I had my HEQ5 I used to up the speed to 5 for the alignment stars.