jetstream

You can have a "high" PV and also a high Strehl if there only one or two little hills or valleys (you know what I mean). We should prioritize smoothness and Strehl IMHO. Btw a true 1/4 wave, .8 Strehl scope will show extremely good detail- I believe there are small but noticeable improvements up to .9 Strehl but not much after that. In the real world the best test of optics (to me) is the ability of a scope to take high mag on lunar/planetary before breaking down and the best scopes are almost impossible to break down, of course this take super seeing. Also of course this is just my opinion.

No it wont be 10x better IMHO. A big factor is the cost of the top notch glass ie vg glass these days is reasonable- to get to the levels above this gets costly and I think a lot of lenses get tossed by QA. After counting bubbles and inclusions, testing for polish, figure etc makes might have to go through a few sets of lenses produced to get the best ones for the specs required by some scope makers. LZOS probably just tosses the sub spec lenses back in the pot to be remelted. My 90mm SV Raptor has vg glass, Chinese of course. It is an excellent scope and I dont think a Baader 90mm would be so much better that I woudnt use it.

Hi Piero, does f4 level coma make threshold objects invisible outside the coma free area? Will it render detail in small PN invisible in large fast dobs? The Nagler zoom 3-6mm is a "low" transmission eyepiece ie lower than the Delos, orthos etc. My 10mm BCO delivers more transmission than my 10mm Delos with and without a coma corrector.

👍 Docter level sharpness and contrast with better transmission...IMHO

One look through a large nicely spec'd set of mirrors in a dob will convince many of the merits of good glass. Good glass is consistently found in expensive scopes and more hit and miss with less expensive ones IMHO. Many high end refractor owners, who also own good spec large dobs prefer the latter on DSO but notably on the moon and planets. In general, expensive scopes offer consistently good glass and a vg build quality.

The APM 20mm 100deg is vg.

Excellent reply Stu, this ^^ is the critical concept to understand. Upping the mag too much and reducing needed eye illumination will kill a filtered view in any scope. Hopefully more members will use the concept of exit pupil vs mag... and then good filters will work in any scope.

Filters work well for nebula and an OIII will provide more contrast IMHO. Exit pupil selection is critical. Btw, OIII,UHC and Hb work well in my scopes from 90mm to 609mm, with exit pupil being the critical factor. Filters dont work for galaxies, IMHO. Get the OIII...

Thanks vlaiv, so no gussets are needed with the 8". I'm going to build one or two and may as well make them with DSO imaging in mind eventhough for now lunar/planetary is on the agenda.I'll put one down at the lake concrete pad I poured years ago and one on the hill.

@vlaivOk I have 8" x .125" x 4ft and 6" x .250 X 4' pipe in the scrap pile. My mount is an AZEq6 used with TSA120 or 90mm Raptor. Gussets needed? It will be welded to a 2x2' base 1/2" or thicker ( I have 1" plate I can use too).

I wonder what force is required to cause the deflection listed for the sched 5 pipe? does a mounted telescope tracking cause similar deflection?

👎

👍 Weld a 1/2" thick maybe 14"x14" to the steel tube and then anchor bolt the plate to the concrete floor where the old pier used to be. Welding the plate on the tube under the floor no big deal. I use a Fronius Transpocket 180 for such things.

Doing this will be the best solution of repair IMHO. Use "anchor bolts, (actually studs) in drilled holes and epoxied. I would then drill the pier and epoxy rebar in there or maybe better bolt some angle iron to it extending past a foot or so. Yes the angle would be better. How thick is the existing slab? it has footings?

I'm not so sure that a another slab, pored around the pier (with rebar drilled and epoxied into it) on top of the other would provide what he needs. Even using bonding compound on the pier (or roughed up and "buttered") would most likely not give the wanted stability.

I would step back, and take time to think about things before pouring more concrete IMHO.

The concrete pier should have been poured "as one" with the bottom slab. Then rebar should have been in place in pier, wired in to the rebar in the top slab. Even still, the disconnect (shrinkage etc) still may allow for small movement and vibration. I would consider Per Frejvals design .

Its all good vlaiv, the house is fine. Some steps taken, not taken with this pier design could be at fault. I mean this respectfully.

Do you have pictures of the pier before they poured the concrete? Was there anything on the pier that the concrete could stick too? Numerous options here, frustrating yes but no big deal. I dont mean to minimize this but its fixable.

Excellent M1! My 24" does very well on it too. I can confirm the detail in your sketch from my observations.

In the mean time grab a 10BCO/barlow and enjoy observing

Ive heard its a good eyepiece. Many zooms change the fov when zooming, including my Zeiss zoom and Leica. After blowing wads of cash trying things out I'm in the camp of "buy once, cry once". That TV zoom also occupies a place that will never be disturbed. BTW, it was Johns excellent review of the BCO series to try them- and the 10mm is a gem IMHO.

Forgot to add- if you want one planetary/lunar eyepiece, find a Televue Nagler zoom 3-6mm.

The 10mm BCO can give views that rival much more expensive eyepieces- such as my Delos to name a few.Actually it has higher transmission than the super high transmission Delos... and is used when I'm trying to nail down true threshold objects in my scopes. The 10BCO also has a unique characteristic- its sharpness. It rivals and beats many many vg eyepieces in the sharpness dept. I say this is unique because its the combination of sharpness, transmission and contrast that sets it on the top shelf along with a very few others. Downside- its not a "true" orthos in the sense that Zeiss opened up the deisign to provide a 50 deg TFOV, yes this is a Zeiss design. It also has shortish eye relief -8mm- but more than true or symmetric "plossls". There may be sample to sample variation but Ive only heard of one here from a reputed member out of many. The 10 BCO will always sit on my top shelf, along with the Docter 12.5mm UWA. Of course this is just my opinion.

Excellent scope. And while your wading through the murky world of eyepiece selection maybe a 10mm BCO and Q barlow might suffice for a bit? This eyepiece will be great down the road as well.