Motorised Camera Rotators

[Saturn488]

I have been looking around at different camera rotators available on the market. Seems like an item not everyone has in their astrophotography kits so I wanted to ask two simple questions.

1) Are motorised ones worth it and why?
2) Why are they so damn expensive!?

[joshman (Josh)]

1.) IMHO. yes. very worth it. For several reasons:

• You can simply choose and frame your target, then tell you system to do the rest.
• I can setup multiple targets in a night, all with a different framing, and not have to attend to the system at all.
• Speed, Efficiency and most importantly, Repeatability.
• Especially useful if you pair it with a Motorized Flat Panel.

2.) The same reason everything else is expensive, they are priced according to what the market will allow. also like everything else in this hobby, they're a precision piece of equipment.

[Nikolas (Nik)]

" they are priced according to what the market will allow."
This really grinds my gear as prices are manipulated by the manufacturers and market will allow or market is dictated to by the manufacturers then thrown at the consumer to create a so called need. I honestly believe astronomy prices, considering the cost of some manufacturing processes can be cheaper, Askar have the right idea of what a true market price is.

[PRejto (Peter)]

Let me add some perspective....

Rotators are nice in theory and useful if remote but can lead to a number of difficult to solve issues.

1. If using a rotator + focuser (such as a Gemini or NightCrawler, etc), the focus range is quite narrow. So, your focus point must be known with some assurance so that proper length adapters can be sourced.

2. Rotators can sag under weight. On a refractor the length of equpiment/weight on a long arm can cause significant issues, especially with a heavy camera and FW hanging on the end of the arm.

3. If your camera chip is not centered the rotator will mess up accurate pointing depending on what the rotation position was when the pointing model was created. This can be overcome with a closed loop slew (in TheSkyX for example, but takes extra effort). Tilt adapters that allow for lateral adjustments can overcome this issue.

4. Rotators can have their own tilt issues under rotation. (tilt and sag being two distinct issues).

My advice, don't hang 11 inches of heavy weight off the back of a rotator and expect perfect results.

Peter

[TrevorW]

They are expensive because Asto imagers buy them at that price, if they didn't the price would drop, same reason cyclists are stupid enough to pay over $10000 for a bicycle. Someone out there is making a big profit at your expense

[bojan]

Rotator is needed in case ALTAZ (dob) mount is used, for obvious reasons.
Also, perhaps in slitless spectrometry, it is useful. to avoid overlap of spectra with nearby stars.

Otherwise, I can't see the reason for it..

NB:
Now I know I may have just created a lots of anger in art-oriented individuals.. but IMHO, astrophotography is tech-scientific photography. So the orientation has strict limits/requirements: North direction should be UP, West direction should be to RIGHT, always.

[joshman (Josh)]

Originally Posted by bojan

Rotator is needed in case ALTAZ (dob) mount is used, for obvious reasons.
Also, perhaps in slitless spectrometry, it is useful. to avoid overlap of spectra with nearby stars.

Otherwise, I can't see the reason for it..

NB:
Now I know I may have just created a lots of anger in art-oriented individuals.. but IMHO, astrophotography is tech-scientific photography. So the orientation has strict limits/requirements: North direction should be UP, West direction should be to RIGHT, always.

Counterpoints.

1. The majority of Astrophotography is not being taken, nor viewed, nor judged for it's scientific content or merit. And to shoehorn the 99.9% of people into the needs of the 0.1% is an incredibly narrow point of view.
2. If the goal is scientific imagery, then yes, I can see a possible need to standardize orientation, and a rotator is of no use to you.
3. North-up/West-right orientation is really only valid for imagery taken from earth's surface. I'd be very surprised if the JWST, or EUCLID or Hubble used this convention for their actual scientific observations.
4. There is no UP in space.

[bojan]

Originally Posted by joshman

Counterpoints.

1. The majority of Astrophotography is not being taken, nor viewed, nor judged for it's scientific content or merit. And to shoehorn the 99.9% of people into the needs of the 0.1% is an incredibly narrow point of view.
2. If the goal is scientific imagery, then yes, I can see a possible need to standardize orientation, and a rotator is of no use to you.
3. North-up/West-right orientation is really only valid for imagery taken from earth's surface. I'd be very surprised if the JWST, or EUCLID or Hubble used this convention for their actual scientific observations.
4. There is no UP in space.

Yes, I appreciate your views.. They are valid for you, and for lots of others (that is why I wrote "IMHO" when trying to present my view in the subject.)



However:

1. In amateur world, yes.. but not in scientific community.
2.

3. Standard coordinate grid (RA, DEC) uses North direction UP on the map, and West to the Right.
4. As in point 3. , that is valid for the photos taken from space as well.

[joshman (Josh)]

Originally Posted by bojan

Yes, I appreciate your views.. They are valid for you, and for lots of others (that is why I wrote "IMHO" when trying to present my view in the subject.)



However:

1. In amateur world, yes.. but not in scientific community.
2.

3. Standard coordinate grid (RA, DEC) uses North direction UP on the map, and West to the Right.
4. As in point 3. , that is valid for the photos taken from space as well.

I'm not necessarily disagreeing with what you say, but it feels like its a fairly narrow view on the subject.


1. This is not the scientific community. And i would posit that even the scientific community doesn't always follow NU/WR for camera orientation.

2.

3. This is an arbitrary designation based on our earthbound POV. It's neither right, nor wrong, but it is inherently an earth based POV. Which isn't likely to change until we're a space-faring species.

4. Yes, photos taken in space would still use the RA/DEC coordinate system to locate an object, and use a convention of NU/WR to orient and standardise the language around such. but the orientation of the camera itself with respect to North-up/West Right...EUCLID might observe that because its a survey platform, but the Hubble and JWST certainly don't. a cursory search through the Hubble archives shows that it didn't exclusively orient its camera to the NUWR orientation. and that might just be a product of it imaging at whatever orientation it ended up in once on target.



I do not doubt there is a scientific standard to what is considered up/down/north/west/etc in space, and i'm sure that it's good scientific practise to make sure your images are labelled and presented in that orientation. What I doubt is that the camera orientation must align to that.



If its good enough for Hubble to image at a rotation other than North-up/West-right, then its good enough for me.




But i think this is getting a bit off topic; which is motorized camera rotators. Personally i think they're very useful. They better allows me to artistically capture scientific information and try to present it in a manner that has mass appeal to get people interested in space.

[AdamJL]

Originally Posted by PRejto

Let me add some perspective....

Rotators are nice in theory and useful if remote but can lead to a number of difficult to solve issues.

1. If using a rotator + focuser (such as a Gemini or NightCrawler, etc), the focus range is quite narrow. So, your focus point must be known with some assurance so that proper length adapters can be sourced.

2. Rotators can sag under weight. On a refractor the length of equpiment/weight on a long arm can cause significant issues, especially with a heavy camera and FW hanging on the end of the arm.

3. If your camera chip is not centered the rotator will mess up accurate pointing depending on what the rotation position was when the pointing model was created. This can be overcome with a closed loop slew (in TheSkyX for example, but takes extra effort). Tilt adapters that allow for lateral adjustments can overcome this issue.

4. Rotators can have their own tilt issues under rotation. (tilt and sag being two distinct issues).

My advice, don't hang 11 inches of heavy weight off the back of a rotator and expect perfect results.

Peter

Great post.. And I own a rotator!

OP, I bought one simply because I'm lazy and I hate being out in the cold. I started this hobby with everything manual. It's much easier in that there are less headaches and things to go wrong (and software to keep updated!) but I want to automate everything, not be doing things during the night instead of sleeping or keeping warm.