DSLR - Red dot finder shoe & Alignment Process

[Droogie 2001]

I have an Celestron AVX mount which I have been using for over a year. Recently I decided that I would like to attach my DSLR to the mount so that I can get longer wide field exposures. This is because currently I am using a static tripod so limited to about 30 seconds.

I want to get a better understanding on how much alignment will be required with my mount. Initially I thought I would attach my scope and run through an alignment and then a Polar alignment next swap the scope OTA with the DSLR. Please note I do not want to attach the DSLR to an OTA as I am trying to be more portable.

This switching OTA to DSLR seems counter productive to me, not mention having additional equipment as well as hassle over what should be a simpler solution?

If I get a red dot finder shoe and add this to my DSLR (with my spare red dot finder) will I be able to align the mount with it usual 2 Star Alignment +  Calibration stars.

Obviously going further will Polar Aligning be possible as not having an eye piece to look through may mean the PA is not very good. I suppose I could use Live View if the star is bright enough?

Do I even need to Polar Align if I am aiming for say maximum 2-3 mins exposure as guiding is out of the question.
I am using quite a Wide field lens (16mm) so this maybe more forgiving than a longer lens?

So is anyone running a similar setup and can tell me how long exposures can be achieved then this would be very helpful

Thanks.

[JamesF]

I think I'd be tempted to roughly align using the polar scope and then use the camera to drift align if possible.

James

[Droogie 2001]

Thanks James.

I do not have a Polar Scope as I use the ASPA built into the mount.

[fwm891]

Align as best you can otherwise even with wide lenses you will see field rotation - especially at the extremes of the frame even at 2-3 mins.

If you have a longer fl lens use that with live view on brighter stars to align the PA then swap lenses

[Droogie 2001]

Thanks for the advice so far. So I am on the right track it will just depend on whether the alignment will be sufficient for longer exposures.
I mentioned 2-3 mins I may well find shorter is sufficient for my requirements.
 

[Psychobilly]

I used to use the centre AF point marker in the camera viewfinder to align stars during the alignment procedure...  Depending on the reticule you would either look for it disappearing behind the point (older cameras) or appearing inside the clear square - my newer ones...

Peter...

[Droogie 2001]

Good tip. I have not really used the AF point maker before so will I check this out.

[Alien 13]

A very basic polar align will often be enough for 2-3min subs with a 50mm lens in fact I have used marks on some slabs from a previous alignment without even adjusting with no problems.

You can also use your camera live view if you want to realign (zoom in for more accuracy) it will easily see any of the brighter stars.

Alan