I actually bought it thinking it may work with the binoviewers but due to a complication of the binoviewers nosepiece fitting, it will not slot into the barlow... However, I needed a barlow anyway for mono mode particularly to use with my 7mm Pentax XW - I figured this with the barlow amplication would give somewhere around 3.1 to 3.2mm eyepiece focal length which should be still very useable with the 80ED and the 102 ED.
So... Luck would have it that clouds fully cleared around 7pm, the moon naked eye looked extremely steady in the still bright sky as we approached dusk. I was keen to try out the barlow so around 8:30pm I headed out with the 4" refractor. For a change it was not overly cold outside and suspected that the refractor would not need much cooling down time so I got right down to observing...
The seeing was pretty good - Using the 5mm Pentax for 143x the contrast is stunning with this refractor across the entire lunar surface. Some of lower contrast features like Plato really come alive and the occasional pock-mark of a craterlet (mainly the central one) shows up at this level. The mares also come alive with features on their surface.
Most of the interest though is at or close to the terminator and where there is much much higher contrast I've always though that these refractors are much more capable of increased power.
Starting with the 7mm Pentax for 230x the view was astonishingly good. Going back to Plato, the contrast had obviosly suffered a bit and was a little too much shimmering at this level for the craterlets. It was good to note that absolutely zero
Herodotus was magnificent with the starting point Schroters Valley coming off this showing intense depth and the Agricola mountains just to the north of this really quite prominent. The "horse-shoe" like feature of Prinz is also worth noting and actually this entire region is fully of interesting features that pop with the additional contrast at this illumination level.
With the libration tilting the Moon away from us on the north side, the large crater Babbage was almost side on, this allowed a fantastic three dimensional view with the depth and darkness of the main crater with the central almost perfectly formed crater that rises dramatically in the centre of Babbage.
Schickard was the next stopping point and another area of great detail and large contrast of the features really made the extra magnification of using the barlow worth it... I dared to try swapping the 7mm Pentax for the 5mm Pentax at this point which yielded approx 310x with (calculated) 2.3mm eyepiece focal length and 77x power per inch. I half expected this to be completely unusable however the opposite was true. While, oddly, I didn't experience any floaters with the 7mm Pentax and barlow combination, I did with the 5mm... However it was still very sharp in the moments of clarity and I noted that focus at this level was within a very small range. The seeing level was perhaps not quite sufficient to prolongued use, but I was amazed at the amount of contrast still given. The view was definitely not too dim and a wealth of detail was popping into view on the floor of Schickard with many craterlets and features in the walls of the main crater itself. Quite something!!!
I packed the scope up after an hour for something to eat and get some work done. At about 11pm I headed out again but with the 80ED and lighter eyepieces and the barlow. The seeing incredibly had got better. There were some wisps of high cloud about and seemed to be incoming as was forecast to cloud over. The 80ED with the 10mm BCO and barlow for approx 4.5mm seemed a touch sharper when I compared this with just using the 4mm TMB on its own and so I popped the 4mm TMB in the barlow for approx 1.8mm and around 330x and a completely ridiculous 106x power / inch... Expecting mush I was astonished to find that the refractor was supporting it amazingly well at this power and still great sharpness! The seeing was such that it was actually holding very steadily at this power and the mount was becoming more of an issue (was on the AZ4) so I had to take care a bit not to touch the eyepiece much to keep it steady. I went over Schickard and Herodotus again taking in the features at this level and enjoyed another 5 minutes scanning about before the clouds came in fully.
Next, if there's an opportunity while the moon is very bright I'll have to attempt some double star splits that are a bit more challenging for the 4" refractor.
Since I started observing it properly in Feb - I found it giving me many more observing sessions - when 
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