Alignment failure after adding DSLR

[vance1977]

Hi guys I'm having a frustrating time with alignment after adding my dslr, I have a celestron astrofi 130 wifi controlled via my phone running sky safari 5 pro.

After getting alignment I remove the eyepiece and insert my canon eos 550d using prime focus, being really careful not to move the scope, but if I goto any target my alignment is way out by quite a lot and I'll have to start the align process again.

I'm guessing it has to do with the weight of the camera but I've seen you tube videos of people using altaz mounts with no trouble, do you have any ideas on what it could be and if I can solve it.

Also if I don't add the camera the alignment is perfect.

Cheers

Vance

[StevieDvd]

Can you adjust the balance with the DSLR on and make sure the clutches are tight.  The extra weight if not balanced and loose clutches will make the motors work harder and perhaps not as accurately as you need.

 

[JOC]

I have an entirely different set-up on my Dob, but seem to have similar issues when I add something heavy to the objective end.  I think these Goto mounts, in whatever configuration, are fairly sensitive to weight change.

[ronin]

You would need to rebalance the scope with the DSLR on it and that means moving the scope and "losing" the alignment - possibly. I say possibly as the alignment is the scope determining where is is and working out the corrections that it needs to apply. So possibly the scope may have moved but the corrections could still be applicable. I would not like to say Yes however.

You are adding about 700gm to the end of the scope and that is a lot.

Best I can suggest is mark the balance position for scope+eyepiece and for scope+DSLR. So you can make the change quick.

Do the alignment with eyepiece, goto a star that is easy - bright and on its own and center it, then checking everything is tight (clutches) swop the DSLR into place, loosen the dovetail and rebalance for the DSLR - position markers as above. Then recenter the star on the DSLR and perform a Sync action to tell the scope that it is pointed at whatever star.

That could/should/might mean the balance is OK and the scope starts from the postion of the synch star. Put it like this that is how a club I know does it but they have video cameras not a DSLR.

Quote

I've seen you tube videos of people using altaz mounts with no trouble

Do you know anyone putting up a video showing you how to do or use something and actually showing they were a complete failure and couldn't do whatever. My guess is you only see the "good" ones, and I would not be too surprised if many of them were not 100% good. Video editing can take out a lot of mistakes and problems. That 5 minute video of "How to do it" may have taken 2 weeks and several peoples input before they had enough to make it look easy, or even possible.

I always remember a person showing how they caught a fish on their first cast. They announced "You are not going to believe it, this is ny first cast and I have a bite" The slightly overlook bit was they cast out on a rod with a spinning reel and wound it in on a rod with a small baitcast multiplier.

Edited May 27, 2017 by ronin

[SonnyE]

Try using live view with your camera attached for your alignment. (Think of it as an electronic eyepiece)

You can not (as you are learning) do an alignment, then add a 2 pound balance change, and expect accuracy.

You need everything you are going to use for your photography attached and balanced first.

Are you using PHD2 for guiding? I use the view of PHD2 as my 'eyepiece' for alignment.

But you can't go changing things around because (obviously) it upsets the entire alignment you've done.

Edited May 27, 2017 by SonnyE

[ronin]

One other thing is reduced the maximum slew rate of the mount, make life a little easier on the motors. If the are 10 options then try 6.

[vance1977]

Thank you guys for your help,  I will try and get alignment using live view and backyardeos, unfortunately I can't adjust balance as my scope only has a really small dovetail so I can only have it in one place for mounting also it dosent have clutches as far as I'm aware all I can see on the mount is lock nuts not the twist caps that are on the more expensive edge series.

When I get a clear night again I'll put all your advice into practice.

Thank you for your help

Vance.

 

[Star101]

If I am correct in assuming this is your scope and mount. Balance will be difficult. It could be the camera is too heavy for the motors. Maybe you could try adding a slight counterweight by taping it to the scope. 

 

 

[vance1977]

Yes that is my scope for now.

I knew I'd be asking it to do a bit to much, I will be upgrading soon to a eq5pro and 150mm refractor so I might have to keep doing visual viewing or webcam.

[SonnyE]

Good deal Vance!

If you want to pursue Astrophotography, consider the telescope carefully. Better pictures can be had with things like ED - Extra low Dispersion, Triplet over other forms of lenses, and where I wish I had done different was my choice of DSO camera.

It has taken literally years to get going for me. And I started with Astrophotography as my goal.

[alacant]

Hi. There's a thread dedicated to astro-photography with alt-az mounts. Maybe post there too?

JTOL but is it possible to piggyback the camera on the telescope without connecting it to the optics? I also tried with a telescope, but I wish someone had suggested this method to begin with. It's so much easier with just the camera and you can get some great wide shots. HTH.

[spillage]

You may find it easier to start with a larger object. Either the moon or jupiter or even a daytime object. Make sure that once you have the object central using your eyepiece then double check the red dot finder and make sure this is set up correctly and pointing at the same object.

Attach the dslr and then repeat the above.

Once you have your finder dialed into your dslr it's easy.

 

[iapa]

On 28/05/2017 at 15:43, vance1977 said:

Yes that is my scope for now.

I knew I'd be asking it to do a bit to much, I will be upgrading soon to a eq5pro and 150mm refractor so I might have to keep doing visual viewing or webcam.

I had an SLT 130 which was also ALT-AZ.

I purchased an 11" dovetail and a pair of scope rings which gave a much greater range of movement and allowed balancing with the DSLR attached.

Then I started using the DSLR live view to get my alignment stars - in winter easy. Spring/Autumn not so much

Next step was to get BackYardEOS and stellarium/astrotortilla - I'd start alignment, select the star on the Hand Control and slew the mount. Then using stellarium, select the same star and plate solve. Then back to the HC and just pressed enter twice to accept that first star. Repeat with 2nd (and 3rd if yo do 3 star) and done.