[mental4astro (Alexander)]

Four conditions need to be met to see it:
* Excellent optics
* Outstanding seeing conditions
* Sufficient aperture
* Acute vision

And it is not so clear cut as these simple statements either. You may need to try different things such as using filters if using large aperture in order to improve the noise to signal ratio - in other words, tone down the glare from the rings. It's a question of contrast. Collimation must also be so tight that the optics are squealing. If your scope shows mirror shift, you must know how to work with it. When using a reflector (of whatever flavour, Newt, Mak, SCT, etc), use a very small doughnut for final star testing tweaks as a large one will spread out any colllimation error and not provide the final quality control. Don't rely just on your laser - verify it with star testing. Even learn how to identify different aberrations (such as astigmatism, chromatic aberration & others) to help sort out your gear.

There are also other features that are in the same realm of the Encke Division. On the Moon there are the two wee riles that run down the centre of the Vallis Alpes & Vallis Schroteri. The angular size of each wee rile is the same as that of the Encke Division. Yet seeing or photographing these two features is neither questioned or denied. To see either one of these through a large aperture, the image may needed to be attenuated or the glare of the Moon as a whole will overwhelm the faint signal that is these two riles. An 82A filter is a good start - I use one now with my 9" Mak to pull detail that is overwhelmed by the mass of light 9" of aperture pulls in. I use it along with no filter together.

To spot either one of these two lunar features, all four of the above conditions must also be met.

To argue that it took a 32" refractor to first show the Encke Division is a mute point. Refractors of that time were all achromats with questionable eyepieces (all excellent for their time though) and it wasn't until the that particular scope that an instrument of sufficient quality was available to make out the Encke. We also do not know how the scope was being used to show it - ie filter?

I have seen it on three separate occasions through four different scopes. I have not been able to see it again since with any of those scopes and I know seeing conditions have just not matched those nights. Of my 12 scopes I know only one is capable of doing so, and one other I haven't tried. The others no chance including my 17.5" (It's astigmatic and I am honest to say this).

No one quibbles when the Cassini Division is seen through a high quality 50mm scope. If one still insists on believing the Rayleigh and Dawe's limits are the smallest detail that a given apertre can show, your 8" scope shouldn't show you the Cassini Division either. So think about it.

I am not just only saying I've seen it. I am also giving tips on how to improve your chances.

The Encke Division is a very illusive feature. Not all scopes can show it. Not all eyes can see it. There are also lunar features that are the same angular size that provide a parallel test.

You can only try, and try often. If you don't, then one or more of the above four conditions are not being met. Seeing conditions for me this year have not been good enough. But I will keep trying too.