I feel like I need to elaborate on my post a little bit..
I continued testing my telescope.
The farthest thing I can see from my balcony are the fir trees 2.6 km away, both live and standing dead.
I can easily focus on them with 40x magnification, after rain at a temperature of +19 celsius, when the thermal fluctuation of the air is at a minimum. It is pleasant to look at that sharp image.
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One more thing:
I can imagine, even though I can't find it by searching this forum, that the forum has previously brought to light things that affect the kind of image you see when looking through a telescope.
So one more time,
you really should know and take these all into account when you go telescope shopping.
I wish I had known these things when the telescope fever hit me!…
Your list is why some folks have several scopes of different sizes and brands.
I gave up on star testing. Trying to do it didn’t work for me. Where we live convection based thermal heat waves of some sort always seem to be present and they are very strong. Inside the house we don’t have enough distance to make testing meaningful. Add to that not having a good setup to photograph the images, and the result was endless frustration.
Did the comparing of currency bill micro print test, plants, etc. Yup, there’s the micro printing on the currency.
In the end we simply compared scopes side by side, outdoors, under identical conditions. For how we would use them that was enough for us to sort out ones that worked from ones that didn’t.
When looking through the scopes found in our birding group, in general, I haven’t found scope sample variation to be the limiting factor for ID’ing birds in the field (Yes, there are always exceptions). It appears that birders have more difficulty getting IDs in the field because their scopes shake and are not stable, and not because of scope sample variation.
For example in our birding group there are four Kowa TSN-883 scopes manufactured in different years. The tripods they are mounted on are all different, and the tripod heads used are all different. The setups are not of equal stability. But there is one setup that is the most stable.
When birders are having difficulty with IDs with their scope, and move to the most stable setup, they usually see the markings very quickly and clearly. And they usually also comment on how clear the image is.
In the group we also have scopes by Swarovski, Zeiss, Meopta, Nikon, Pentax, and Vortex. All mounted on different levels of tripods with different tripod heads. When all these different brands of scopes are setup side by side looking at the same objects, with the same atmospheric seeing conditions, usually the folks who get the IDs the easiest are the folks with the most stable platform.