It is a fact that daytime observations can reveal what is impossible to see at night. Today I tried. A dark, cloudy day and a tree against the sky. In other words, very demanding conditions because on the one hand there is a strong contrast of details against the sky, and on the other hand - details of the trunk and bark are poorly visible in poor lighting.
An additional drawback of Kogaku immediately came to light - an unblackened sleeve in the focuser, causing reflections visible in the eyepiece. Even on the Moon it was not visible, but during the day it was immediately obvious. Interestingly - it is noticeable only with a diagonal. Therefore, I conducted further observations without a diagonal, and I will have to repeat the night observations.
- It was confirmed that Polarex seems to find focus much easier and faster. You can do it "in one movement" while Kogaku requires experimenting "back and forth". I suspect that this feature is related to the quality of the optics - although I cannot say why. At around 100x magnification, both telescopes showed details of similar quality, but the pleasure of observing remains with Polarex.
- I expected that dark branches against the sky would be burdened with greater chromatic aberration in Polarex. CA is very clearly revealed in such conditions. To my surprise, this time I did not notice a clear difference. Perhaps Kogaku was slightly cleaner, but to a degree that made it difficult to issue a final verdict.
- I also expected that Polarex would cope better with the faintly visible details of the dark surface of tree trunks. Already in the case of my previous Polarex, I noticed that it had a strange ability to brighten dark areas and pick out details from them that are less visible in other refractors. The dark side of the Moon is a good example where this ability can be observed. It is a bit like HDR - shadows are "boosted" even though as a whole, the image does not seem brightened. And it was confirmed - dark branches against the dark gray, poorly lit trunk were perfectly visible, while in the case of Kogaku they were of course visible - but I would not use the term "perfectly"...
By the way, I had the opportunity to test the eyepieces that came with the telescope. According to the list I found in the original box, they should be HM 8, 12.5 and 20 mm eyepieces. Instead of HM8 there is H8 (at least that's what the inscription on the housing, which looks different from the other two, says), so maybe this eyepiece is not original, or maybe only the black frame was replaced. In any case, these are quite decent eyepieces, apart from the limited field of view.
If I had them, would I buy the Zeiss O-10 today, which I compared them with? I know I will upset Zeiss enthusiasts, but I will ask: Why? I did not see anything more with it... :-)