Camera Rotator - why would I want one?

[Jannerland]

Curious if folks who image would feel the need to add a camera rotator to their image train if one isn't already part of their setup?

If so why and what would you choose as an aftermarket solution?

[Realtimedoctor]

Hi,

In my opinion this is a primary driven by the setup, and what the person is trying to achieve. 

Adding a electronic rotator helps in framing especially large targets on smaller sensor, as this can be done remotely via your choice of software (I'm assuming people buying electronic rotators are almost always into automation). Greatly optimises doing mosaics etc. 

Getting a manual rotator on the other hand is slightly different. Reasons are pretty much the same as above i.e. Framing and automation

There is a nothing a manual rotator does, that you cannot do yourself by just turning the camera in the draw tube. If you have flex or tilt in the draw tube, a manual rotator maybe be beneficial as then you'll not be moving anything around the focuser once mounted. 

Instead of buying a manual rotator, you could just stick a small circle of white paper with rough 90deg markings on the focuser draw tube to align the camera ( that's what I've done, and works like a charm every time I need to rotate my imaging train for framing.) 

I hope that helps. 

 

Cheers, 

Nish 

[Padraic M]

I think most people would view a rotator as a nice-to-have. As @Realtimedoctor says, you can adjust the camera angle in the drawtube. NINA provides a great manual rotator control that prompts you until the angle is within an acceptable range.

Having said all of that, I'm waiting for a manual rotator aka 'Camera Angle Adjuster' to arrive in the post. My rationale is that my camera is connected by screwed connectors only so there is no way to rotate the image, and I now have a second imaging rig and if I'm going to combine data from both, the camera angles will need to be aligned.

One big downside is that if you rotate more than a small amount, you will need to shoot new flats. For example, dust bunnies on the camera-side of the rotator will no longer line up with dust marks on the scope side of the rotator.

If you have a fully automated remote setup, then an automated rotator is a higher priority, although still not essential.

[AndrewRrrrrr]

thinking of doing this myself. reason being is that I have recently added a pegasus focuscube and i'm no longer able to use the rotator on the focuser for more than ~45 degrees as it fouls the guidescope one way and the dovetail the other way.  i'm 99% decided to get a Baader T2 heavy duty quick change unit and place that in front of the FW. 

picture should explain it........

(budget won't stretch to an electronic rotator! )

[Jannerland]

Thanks all, that makes  a lot of sense.

I am definitely interested in automation so just from a framing perspective I like the idea of an electronic rotator.

Once set up and soon to be permanently there my  rig is sat out some distance from the house and I'd like to be able to  as much as feasible from inside.

The current setup with Esatto focuser (which I like very much) actually makes manually rotating the image train downstream unrealistic for the reason both Padraic and Andrew mention

1) as its all screwed into the focuser drawtube 

2) the focuser design means blocks on the losmandy plate for a fair proportion of rotation

A manual rotator like the Baader in the downstream elements would work for sure but then with an electronic one would keep me in the warm (yes I'm trying to decide if the spend is worthwhile / can be justified to director of accounts).

The other thing that makes me consider the very spendy PL Arco is that I can put that upstream of the reducer / flattener and not upset the tilt adjustments when I rotate - that's assumption of course and I know it will add some complication wrt OTA length.

Cheers

Rob

[Adreneline]

1 hour ago, Jannerland said:

Curious if folks who image would feel the need to add a camera rotator to their image train

Just to offer a counter-view. I've been imaging for just six years now (not long really) and have never felt the need for a rotator. I have one built into the RedCat 51 and have never used it other than to help align the camera sensor orthogonal to the mounting bar when I don't want to use spacers to achieve the same end. Anything that just might introduce 'droop' into the image train is a complication I can do without; any droop or misalignment will seriously compromise the image quality, especially star shapes. This is especially the case with my Samyang 135mm setup where I have done everything I can to minimise alignment issues and keep everything rigid between the camera (ASI183MM) and the lens, even to the point of replacing the EoS fitting with an M42 precision thread.

If the target I want to image won't fit in the field of view then I would rather do a mosaic to make it fit than rotate the camera, e.g. Sh2-240 in the RedCat + ASI1600 setup. If ever you go back to a target in the future to add more data it is just one more thing to setup and adjust.

I also ensure both my cameras are aligned in the same orientation - in my case 'portrait' with respect to the mounting bar. That way I can easily combine data from the SY183 or the rc1600.

My advice is keep it simple.

Sorry - probably not what you want to hear.

[Jannerland]

No - I do want to hear the counterpoint!! That's a very fair point - the additional point(s) of failure & complexity not to mention the expenditure. 🙂

I feel like will have to do "something" because at the moment I have no means to control the camera orientation at all. Equally the alignment issues I've been working through are definitely in the back of my mind ....

[Adreneline]

3 minutes ago, Jannerland said:

I feel like will have to do "something" because at the moment I have no means to control the camera orientation at all.

To get my ASI1600 in 'portrait' with respect to the mounting bar I ended up introducing a single 0.2mm spacer between the camera and the EFW; my EFW is offset to one side of the RedCat to counter the weight offset due to the EAF in the BlackCat mount. The RedCat rotator is a manual rotator and very, very stiff to move even with the locking screw fully withdrawn.

The Samyang was much more problematic as 0.2mm spacer (even a 0.1mm spacer!) would have thrown out the focus position completely. In the end I was lucky and was able to orientate the lens+EAF+camera assembly in such a way that I could still slide filters in and out of the manual filter drawer. Phew!

Good luck - I hope you get something sorted that meets your needs.

 

[Adreneline]

P.S. On my 6" RC I use a Baader Click-Lock - provides total flexibility of camera angle but I still position mine in 'portrait'.

C.S.

[teoria_del_big_bang]

Is a rotator  necessary for imaging ? As already discussed No.
Is it useful to have one ? Well I had a bit of cash built up due to birthdays and so on and bought one and I love it, so my experience is yes they can be useful.
When imaging targets that only just fit in the FOV (Heart Nebula springs to mind) then it really comes into its own, and although I have not ventured into mosaics yet from what I have seen in NINA especially it makes taking a mosaic so simple even in one sequence.
But then again as

 

@Adreneline says then this ease in NNA of doing mosaics could be used for any image and then crop.
Smaller targets then it makes no difference as quite often a fairly hefty crop takes place anyway so not to drown the target with background.
Also not everyone has the advantage of manual rotation by rotating camera, I didn't as everything was fixed from focusser down to camera. There is supposedly a manual rotator on the Esprit 100 but I could never get the thing to work as it took so much effort to loosen the thing on the first place and then if you did not tighten it enough it moved so easily so I never even tried to use the scopes rotator.
So I guess for me the question would be is it worth £500+ for the ease of rotating the framing from your laptop.
And, secondary is if doing mono and already have a filter wheel in the train how easy can you fit one in the BF ?
I had a pretty thin FW (18 mm I think) but only had a small distance to fit a rotator and originally bought the Falcon which according to the spec should have just fitted with 1 to 2 mm to mess with small spacers to get the BF spot on but when it arrived it was thicker than the specification and with an adaptor was too thick to fit in the train without violating the ideal BF in the end I got the DeepSkyDad rotator, probably the cheapest automatic rotator on the market and it fitted just fine and so far not seen any issues with added tilt and works flawlessly with many sequence software (I have used with NINA and EKOS).

Steve

Edited April 7, 2022 by teoria_del_big_bang

[teoria_del_big_bang]

16 minutes ago, Adreneline said:

P.S. On my 6" RC I use a Baader Click-Lock - provides total flexibility of camera angle but I still position mine in 'portrait'.

C.S.

I too have this setup on my RC and would agree it makes manual rotation pretty easy.

Steve

[teoria_del_big_bang]

Also where an automatic rotator becomes very useful is when adding two targets to the nights sequence (maybe 1st target foes out of view at some point in the evening) that really do need a very different rotation to get them in the correct framing as you can use two previous images, or even use two images found on line with correct framing if you do not have previous images) and the software (certainly EKOS and NINA will) will platesolve and rotate to correct framing whilst the rig was left unattended and you are getting some zzzzzz's in.

As already mentioned though ideally you should use separate flats for each of the rotations. In practice when I check I see very little difference between flats at different rotations as I think most of the visible dust bunnies and vignetting seems to be cause by things after the rotator (filters, CCD) but still when I can I do take separate flats and so it is a good idea to add the rotation angle to the image filename (easy in NINA) so you can replicate the same angle for the flats.

Steve

Edited April 7, 2022 by teoria_del_big_bang

[Padraic M]

4 minutes ago, teoria_del_big_bang said:

Also where an automatic rotator becomes very useful is when adding two targets to the nights sequence (maybe 1st target foes out of view at some point in the evening) that really do need a very different rotation to get them in the correct framing as you can use two previous images, or even use two images found on line with correct framing if you do not have previous images) and the software (certainly EKOS and NINA will) will platesolve and rotate to correct framing whilst the rig was left unattended and you are getting some zzzzzz's in.

Steve

Do you bother with separate flats for the two rotations? Does it make a difference?

[teoria_del_big_bang]

1 minute ago, Padraic M said:

Do you bother with separate flats for the two rotations? Does it make a difference?

Sorry I edited the post to add the following which you must not have seen 🙂 
As already mentioned though ideally you should use separate flats for each of the rotations. In practice when I check I see very little difference between flats at different rotations as I think most of the visible dust bunnies and vignetting seems to be cause by things after the rotator (filters, CCD) but still when I can I do take separate flats and so it is a good idea to add the rotation angle to the image filename (easy in NINA) so you can replicate the same angle for the flats.

Steve

[teoria_del_big_bang]

3 minutes ago, Padraic M said:

Do you bother with separate flats for the two rotations? Does it make a difference?

So I would say it is not a must do and would be quite happy to use one set of flats, if I have time then I do take them.

Steve

[Padraic M]

I replied too soon! 🙂

Good to know that. I had assumed that if you want automation including an electronic rotator, you would also have to add a flip-flat-type flat panel so that flats could be taken automatically as part of the sequence. And those flip-flats ain't cheap!

[teoria_del_big_bang]

46 minutes ago, Padraic M said:

I replied too soon! 🙂

Good to know that. I had assumed that if you want automation including an electronic rotator, you would also have to add a flip-flat-type flat panel so that flats could be taken automatically as part of the sequence. And those flip-flats ain't cheap!

No, but I did add one, also DSD and very happy with it, no affiliation to DSD so sorry to go on how good I have found them (for the price) but for the price it is a great panel, by altering the light intensity instead of exposure length, which NINA can do automatically, I can get all flats 3 seconds exposure length and therefore use the same 3 second master dark from a dark library.
However (don't want to go off topic too much)  I have seen one issue where by it can collect a lot of dew through the night and then when it closes it dumps it all on the lens and you get very strange flats.
Not tried it since but I am hoping a combination of change of angle of the flip flat and also making sure the scope is flat before closing the panel will sort that out.

Steve