Focal Reducer Issues

[PunkJay]

Howdy all,

I use a Meade f3/3 reducer on my 8SE/SCB 2000 setup, and am experiencing difficulties when switching back to prime focus as the target is no longer in the centre on the FOV.

As the target was in the dead centre before removing the reducer, I am assuming that I've wobbled the scope out of alignment.

Does anyone have any tips on how to remove the reducer without affecting the alignment as much without investing in a sturdier mount? It is not an issue for bright planets obviously, however those dim nebulas are another story!

cs,

- Jason

[2STAR]

hi, when I use my reducer I dont tighten it, I just screw it on lightly until the thread ends. I found this helps

eric 

[Dom543]

Jason,

I don't have a remedy but have a diagnosis. The issue is that when you remove the reducer, you increase the focal length of the system three-fold. Which also means that you reduce your field of view accordingly. A reduction to one third linearly means that the area of your field is reduced to 1/9th. Not only that but your object will also become dimmer by a factor of about 1/8. If it was a diffuse nebula, it may still be in your field but too dim to see. If it was a small planetary, then even the fact that the threads fit differently without the reducer may be enough to move it outside of your field. I am not sure that a more expensive mount would solve this double issue.

As I know of no easy remedy, I try to avoid of getting into this situation. My way of doing this is not even to try to do real-time camera assisted astronomy at f/10. I am not saying that it is not possible, others may be able of doing it. Just not me. 

Clear Skies!  --Dom

[aparker]

Out of curiosity, what's the motivation behind removing the FR while the scope is pointing at an object?  Are you using it with the reducer as a "finderscope" and then switching to f/10 for a magnified view?  If so, your solution is to get an inexpensive guide cam and 50mm frac (a la the ubiquitous Orion models) and run them in parallel as your finder.  I use PHD2 to monitor the finder and StarlightLive for the main camera on my C8.  Works great.

[RobertI]

One option to consider is attach an SCT to 2" adaptor to the back of the scope and attach a smooth bore 2" to SCT adaptor to the reducer. You can then attach or remove the reducer to the scope by sliding rather than screwing (in the same way you would an eyepiece). You can also unscrew the camera from the reducer when it is off the scope. I use this config on my RC6 and it works well, although now I do not try and attempt to switch between reducer on and off during an imaging session, it just causes too much grief in so many other ways!!