Where are Baader Morpheus Made?

[Don Pensack]

Gerry,

To test the limit of an eyepiece, it would first have to be used on an appropriate target, such as stars in NGC206 in M31.

Or whether thousands of stars can be resolve in, say, M14.

Then, the focal length should yield a 1mm exit pupil or smaller, since high powers always yield the faintest stars.

So people who test such things would need to specify scope size and f/ratio as well as exit pupil.

And, for such a test to have value, it would have to be compared to another eyepiece of equal focal length.

And, the observer would have to specify whether the limit observation was truly a limit observation (i.e. visible with averted vision only, and only 10% of the time).

 

[jetstream]

1 minute ago, Don Pensack said:

the focal length should yield a 1mm exit pupil or smaller, since high powers always yield the faintest stars.

In theory this is correct but I notice that there is a sweet spot as far as mag goes and higher is not necessarily better. In my own un scientific, hillbilly testing I use the central star in M57 with my 15" for example.

Yes, my scope is equalized and very well collimated. Not picking on TV here but an example of transmission for me is the 3-6 NZ- no central star compared to a "good" 5mm ortho.

I agree that to truly evaluate transmission exacting methods should be used but I also believe that less than perfect methods reveal much as well. I also know that differences in transmission can be small and on paper might not be able to account for the observations...but...

[Don Pensack]

And seeing, which seems to bother the big scope owner more than the small scope owner.  I just about ALWAYS see the central star in M57 and, often, the star superimposed on the ring,

with my 12.5" at around 300x (about a 1mm exit pupil in that scope), using a 6mm Ethos.

And, while it is very true that seeing is a strong determinant of the limit magnification, where stars are concerned, if the seeing is up to it, it is a rare circumstance where the limit stars are seen below the magnification yielding a 1mm exit pupil, and exceedingly rare to see even fainter ones as magnification is raised to 30x/inch or 35x/inch or even higher.  I don't really count things like the faint moons of Uranus, where separating the moons from the planet is key in seeing them.  I've never seen Miranda at magnifications below 400x, but I do occasionally see it above that magnification if seeing allows.  That magnitude is not hard for a 12.5"--I regularly see much fainter stars near M57--but the planet's proximity just makes that one a really difficult target.  You just need separation.

So I agree about the "sweet spot" in magnification, but exactly where it is, I can't say.  For me, it is at least at the 1mm exit pupil, but my next jump in magnification from there is 90x, and it's possible something in between might prove better.

In my 4" apo, it is similarly hard to determine, as the 1mm exit pupil is 102x, and my next magnification is 143x, and that jump may be too large to tell.  I think it is at least that 1mm exit pupil or even smaller, though.

So I may agree with theory, here, but I think it is more of a rule of thumb than a fixed optical principle.

Edited July 12, 2020 by Don Pensack

[jetstream]

I find that the bright nebulosity in M57 makes the central star harder than the listed magnitude of 14.8. If aperture is a detriment due to seeing sensitivity, it I'm not sure why my 24" has such an easy time with it at higher mags than the 15".

So-does the Morpheus show the central star in M57 using the 12.5"?- where from LA?

[John]

I thought the central star was mag 15.3 ?

 

[jetstream]

2 hours ago, John said:

I thought the central star was mag 15.3 ?

I think the star is listed at 14.7-14.8 and might be variable a bit. When the effects of the bright nebulosity are taken into account I've seen "visual" magnitudes almost at 16 mag.

from @SimonfromSussex 2016 thread and quoting Omeara"

"Stephen O’Meara in his deep-sky companions “The Messier Objects” says: “many veteran skywatchers have estimated it be as bright as 14^th magnitude (putting it within the range of a good 4-inch telescope under a dark sky). Yet Burnham notes that the star was fainter than a 16^th magnitude when he looked at it in 1959 through the 40-inch reflector at Lowell Observatory"

I feel that this star is much fainter than 14 mag and fainter visually than 14.8 mag. I have to wait for it to appear in the 15", in the 24" its there all the time. I also feel that seeing it with a 15" scope is an accomplishment- not to say that a bit smaller aperture won't work, but my 10" does not show it.

I hope to hear about the Morpheus performance on this and if it shows it in a 16" scope or so then its right up there with Delos IMHO.

https://observing.skyhound.com/archives/jul/M_57.html

[Don Pensack]

There isn't a lot of photometry of this star for a reason, but most on-line references are 15.1-15.2 for the central star, with a range of 14.7-15.7.

I strongly suspect the magnitudes brighter than 15 are B magnitudes, given the spectrum of the star, and the 15.1-15.2 estimates are V magnitude.

It is not known to be variable.

That's a pretty good limit for an 8" scope under normal dark sky conditions, so the fact it takes larger scopes to see it is indicative of low contrast.

I've found that by viewing at high altitude (2550m), I get better seeing much of the time, allowing 300x on the 12.5" with steady star images.

Some nights, I can hold the center star with direct vision, other nights only occasionally with averted vision, and other nights not at all.

Seeing is the reason--when there is no atmospheric movement, the star becomes fairly easy to see.

Outside the ring, I often get to well past magnitude 17 with averted vision, so it should be easy, but it's not.  However, it is visible about 80% of the time at that site.

At any rate, I have not really attempted to see this with less than 300x, which is a 6mm eyepiece in the 12.5".

[John]

There's our problem in the UK then - our highest point is just 1345m and that is Ben Nevis in the Scottish Highlands !

Most of my observing is done from 2500m lower than your high spot Don

 

I feel that I've glimpsed the central star in M57 once or twice with my 12 inch dob but I

[Louis D]

54 minutes ago, John said:

There's our problem in the UK then - our highest point is just 1345m and that is Ben Nevis in the Scottish Highlands !

From what I know of Ben Nevis, you probably wouldn't want to be observing from its summit, either.  You were higher than that when you were visiting the plains of northern Arizona!

[Alan White]

Ben Nevis, when is it out of cloud?

[Louis D]

18 hours ago, Alan White said:

Ben Nevis, when is it out of cloud?

It probably has weather very similar to our Mount Washington in New Hampshire.  Most of the times I've been to the top, it's been socked in with clouds.