When does a rotator make sense?

My refractor has a manual rotator so I’m not even really considering one for that, but my C8 doesn’t, so I might get one for that. It’s mostly for convenience, everything else is automated, why not that too. If I really wanted to, celestrons t-adapter can be rotated easily without taking things completely apart. 

I feel like they’re more important the more narrow your field of view is. In wide field set ups a lot of the time the object is smaller than the FOV anyway so it’s easy to crop and rotate in post.

Also to add to what others have said, you don't need a rotator when your camera is attached to the telescope through a normal nosepiece. Some telescopes don't have normal focusers and don't accept nosepieces and use threads on their focusers, that's when you'll possibly need a manual rotator.

Only my thoughts.
- messierman3000

I've been thinking about this for a while and I wonder about flats.  I take flats at the beginning of a session.  If there's anything that is contributed by the optical tube then rotation of the sensor separate from that optical tube will render the flats invalid.  I haven't tried this, I'm a set it and forget it kind of imager so I have rotation set before I do flats and I'm done.  That being said, I'm interested in a rotator for my Rokinon 135mm rig.  Some targets I want to shoot would require fewer panels if I could rotate the camera.  But I want to rotate the lens too, so not expecting a traditional rotator will do the job.  I've got some time off in December I was planning to tinker around with some design and prototype 3D prints.

I recently purchased a Pegasus Astro Falcon rotator and really enjoy using it.  Not much extra weight and it allows me to get the most out of my IMZX294 sensor.  Also, it's exactly repeatable so I can image multiple targets throughout the night on autopilot and go back and collect flats at a later time when seeing conditions aren't that great.  Once you have one, you'll wonder why you didn't have one before. No more fiddling with your image train or manual rotator trying to get the right framing.

Clear Skies!

HBNorm

I'm probably the fews who think that a motorized rotator is a plus in a setup. I have manuals, but recently I gave up on them because they are creating tilting in my optical train, a thing that I only figure it out with my Samyang 135mm at F2, since I never needed when using the Hyperstar.

The use of a motorized rotator is importante to me because of ajusting my composition of the images mainly, even when the sensor is square, when you also want a most autonomous and robotorized setup, and finally when you need to adjust an OAG or when you need to mount and dismount your setup in the field. Yes, you can do it in the field, there are tools less expensive to do it, but my advice is when you have everyting ready to imaging, try to spend as minimum time adjusting the telescope and more important: spend the minimum time messing up with the optical system, specially if your're using mirror telescopes.

I came from daylight photography, mainly landscape.. so planning my images as well framing them properly, compositions.. it's important to me.
My setups after adjusted, polar aligned and lefted in the terrace for imaging, I don't want to have anything with him beside controlling it remotly, this prevents me when using mirror telescopes of taking them out of collimation for example.

Since I'm always changing telescopes and the parts of the optical train between them, another thing is when I put the data into the computer to do the photos, they need to match, it's not just the plate solving, location etc. but the angle also to avoid as much as crop possible. Like I said: I came from daylight photography, when I did my academic studies, they taught us to prepare as much as we can in the field, rather than do it after in the post-processing (usually when the mistakes are already made and somehow we could avoid them).

I also use a mini remote computer, others use like raspberry pi's, asiair's, eagle's, etc. which means that I don't have a screen right to the telescope everytime I want to adjust something, like using setting up the OAG to find one good guidestar. It's better if you already have a electronic way of doing it.

Those are my thoughts.. I think is a plus having a motorized one, but I have the same opinion like the most of the world on this: they are expensive as hell, and manufactures should lower the prices on them. They are simply a motor and a treaded tube with a small electronic to adjust the photo's angle. The focusing motor and filter wheels have in some manufactures a more sophisticated design and the are cheeper than all the rotators in the market. Doesn't make sense. Let's hope that ZWO for example, when put their CAA in the market, do a fair price in order to make the rest of the manufactures lower their owns.

Clear Skies,

Cesar

I got a Nitecrawler 3.5" This summer and haven't looked back. Best purchase I've made. Nothing else matters after that.

Kevin Morefield:
Having used a square sensor in the past I can say that I specified a different rotation for every shot.  Composition is key.  If you are shooting a single target all night and using a hands-on rig you can get by without an motorized rotator.  But if you are using an all night script with multiple targets the rotator is needed. 

Of course, if you are shooting quite small objects with a generous FOV you can always crop.  I suspect guys who primarily go after planetary nebulae won't pay much attention to the rotation.

Unless theres 1 star in the fov I want to keep and spikes outside of the view. That always bothers me to no end.

I agree with Kevin that composition is key. A rotator opens up lots of possibilities. I find it to be an essential piece of gear.

I have a Pegasus Astro Falcon Rotator. I had an EdgeHD 8 SCT and grew tired of adjusting my camera to get the desired framing/composition. What I didn't realize was that because I had a focal reducer (to shorten capture times and widen my FOV) adding a rotator added to my already frustrating Back Focus woes (the EdgeHD 8 is infamous for having nearly zero space available for adding things into your optical train).  When I upgraded to an Askar 130PHQ refractor I had plenty of backfocus and go figure…it came with a manual rotator. That said it is convienient to be able to set the rotator in NINA and get exact rotation when shooting compositions over multiple nights. Some would say using the manual method would be cheaper…that is true…just like swapping filters rather than using a filter wheel is cheaper and works too. It does add a little weight to your optical train. In the end, it's a matter of convienience, money and willingness to learn something new. CS & GB!

A rotator can be of use to optimise tiles overlap of wider field mosaïcs, especially closer to the celestial poles.

Christian Großmann:
We all know that astro photography is an expensive hobby. So I guess the prize of rotators is not the main reason, why they are not used that often.

My refractors both have a manual rotator that I use for composition. My reflector allows me to compose using the rotation of my coma corrector in the focuser. But for the latter, I generally choose not to and go with a fixed corrector position. Of course this limits composition, but I am personally happy with the images I get, and that'll all that matters.  I have never felt the urge to purchase a motorized rotator. Yes, composition is important, but is it important enough to YOU to spend the money on a pursuit that is a cost center rather than a profit center in your life? Only you can answer that. So to answer your question "When does a rotator make sense?". The answer is "If it matters enough to you to spend the money on it." Never let others' opinions on what is necessary dictate how your money should be spent.

I guess you mean a motorised rotator, when you talk about 500g weight.
But as others described here you can use a manual one, too.
From my POV such one is good enough to align with your former rotation if necessary.

Just my 2cents
Mike