vlaiv

I'm not entirely sure if angled focuser will present itself like above - one side of focus ok and other not concentric. What could happen is focuser tube sag. Good image is with focuser tube moved inside focuser - and bad image is with focuser tube drawn outside, right? Maybe it is focuser tube that is tilting with respect to focuser when you rack it too far out. Do you have any sort of 2" extension like this one: https://www.firstlightoptics.com/adapters/astro-essentials-2-35mm-focus-extension-tube.html that you can use to get out focus image - without racking focuser that much out?

First step would be to loose focal reducer. It could be some silly misalignment in reducer lens or reducer not being square with focuser or whatever. You want to take that variable out of the equation.

Alternative is to smash the pier itself - making sure at least some rebar is left sticking out of the base. Then another set of rebar is welded to those bits and another pouring is done - this time with preparation and adhesive. Maybe even special concrete mix should be used to avoid shrinkage.

Why do you think that? Here is what I'm contemplating at the moment. Not sure if it is good solution - but it is an idea. I'm sure we can work out pros and cons of it. Idea would be to add x4 L brackets with anchors to fixate pier to base and then pour one "step" of pyramid around it? Something like this: I know that you think pouring it in one go is best way to do it - but I don't really see how that can be done at this stage unless I bring down whole structure and redo it again?

Ok, so I'm learning something new here. What we have here is failed cold joint. I'm pretty sure they did not use any sort of adhesive in this case - but I guess they should have done so.

That one is made out of wood (notice brown color)

As I said - I'm not very versed in building materials or structural stuff - but we have here 5-6 meter high 250mm concrete posts for electricity. Those things weigh half a ton and manage to stand still in high winds and all kind of weather.

To be honest, I find that hard to believe, but I'm not going to argue since I know nothing about construction.

I know you do. There is no need to mention it. I'm not sure I understand what you said there though. Do you think pier design is poor? Maybe too thin or something?

I'll consult with builders tomorrow. Whole deal is rather upsetting. Same people built my house. If this can happen, I wonder if they managed to mess up anything else. So far everything is standing upright, but one never knows ...

Not sure but I aimed approximately for 1m x 1m x 1m

Yep. I just went out to examine it again (armed with torch and all ) - it is really easy to move it as it is completely detached from base. It simply did not bond for some reason with the base. It is holding only by rebar which is flexible so whole thing can bend. You can't see crack - but I was on platform moving it and my wife says that it can be seen that it is detached at the bottom (she came along for inspection).

I think it was at least a week if not two before they started removing planks few days ago. I did not go near it up until tonight.

Mounting plate was welded for some steel rebar (same diameter as used for pier itself) and sunken into freshly poured concrete. Whole thing did not twist - but rather bend. Force needed to bend it was not very big - I sort of just grabbed it with one hand and managed to get it swaying left / right with tug or two - it was easy to get its resonant frequency. Top moved an inch left / right when I was doing that.

I wonder how one breaks 8" x 8" concrete reinforced pier

At this point, I'm not even sure what you are asking. Sorry - too much building technical terms that I need to look up. We did not use any sort of fitting - rebar was left sticking out of foundation and wooden casing was built to measure around it and concrete poured inside. One possibility is that concrete did not bond well with foundation for some reason - or as mentioned above - that something happened during curing time that caused it to crack at the base.

Observation deck was poured first but there were wooden planks already placed for encasing the pier (and some very thin polystyrene sheets as spacers to the deck). Concrete pier seemed as simpler solution that just works, but apparently it is not the case. I did not even look for steel piers to be honest.

That is interesting option provided that problem is near base.

I think that total height of pier is about 6ft and it is 8" x 8" square. Observation deck was poured first but there were wooden planks already placed for encasing the pier (and some very thin polystyrene sheets as spacers to the deck).

Yes - it was fully laid with wooden planks - supported by multiple beams and also couple of cross beams (you can see one still sticking out in that picture):

This is from the phase when only foundations were done: as you can see - there is section of foundations that is only meant for pier and it has rebar for pier put in place In the mean time - some of it was built - this is image from a week or two ago: I outlined observation deck that was poured. In this image pier can't be seen - but it rises in the middle of observation deck to the height of about 90cm or so. Walls are at 130cm I think - but slightly higher than pier. I'll have better images tomorrow to show the extent of problem.

How about using IR pass instead? IR part of spectrum is the least susceptible to seeing. 800nm + range won't be as "spread" over focal range to result in bloated stars (it will be focus shifted - but you can refocus to it). Some cameras - especially some OSC models - have good / uniform QE over 800nm.

If I go with such option - how confident can I be that it will be solid and stiff? Just recently I was looking up building material and I found "repair mortar" - it is fast curing mortar used to repair concrete elements - contains synthetic reinforcement micro fibers. Will that do the trick?

I guess it should be possible. I'll have a look at it first thing tomorrow morning when there is enough light to thoroughly inspect it. Builders will also be here so I'll file an official complaint and we'll see why it's happening.

It was cold - but not freezing, I guess around 5-10C at night, 10-15 during day.