globular

3 minutes ago, faulksy said:

that is about the same for me 😃

Yeah but I suspect you will get much darker skies... bet you can't wait for the move?

Not far off

9 minutes ago, markse68 said:

if these early galaxies really are measured as predicted to be much smaller than the galaxies we see in our time frame, would there not be many more of them given the universe was much smaller and denser back then? Why do we only see the odd one or two of them? Are the others just way too small and dim to see? Or are the distances between them so stretched in the intervening expansion that they look very far apart?

Lots of guesswork and approximations in this early, yet to be peer reviewed, paper.  But they seem to take an opposite view to you....
"we wouldn't expect these early galaxies to be as common as they appear to be. We estimate that if galaxies were visible at the rates we'd expect, we'd have had to search through an area 10 times larger to come up with them"

Isn't the relatively limited time frame in which the universe was in the state necessary to form these "small" galaxies (a few hundred million years) part of the answer as to why there are a lot less of them compared to the billions of years in which the more familiar ones were forming?

This eyepiece has enough eye relief for most glasses wearers to see the field stop. Have you adjusted the eyecups correctly?  Folded down for glasses use may work best. 

I'd also try (in the day) with a shroud (if you have one or just a towel or pillowcase if not) to rule out any stray light or glares.
(or wait for night time if you have more patience than me)

39 minutes ago, andrew s said:

I think you'll find it is calculated based on the measured angular dimensions and red shift  using models of the gravitational lensing and the LCMD cosmology .

Regards Andrew 

Each measurement and model will have error bounds. I assume 1,600 will be the 50th percentile result when bringing it all together.  I wonder what the 10th and 90th percentile results are? Feels to me that the error bounds must me quite large given all the unknowns. They should be published too really (maybe they are somewhere?)

1 hour ago, Ags said:

the TS write-up suggests these are an update of the original design, so maybe older reviews might not apply?

The TS website has had the same write-up since 2017... as per the (wonderful) wayback machine archive:

https://web.archive.org/web/20170909195710/https://www.teleskop-express.de/shop/product_info.php/info/p7919_TS-Optics-SWA-100--Ultra-Series-10-mm-1-25--Xtreme-Wide-Angle-Eyepiece.html 

You seem to have a screw loose Mark 

Eye relief is the biggest difference.  12mm for the Nagler T6's and 20mm for the XW's.

If you wear glasses to view, or have very recessed eye sockets, then you'd probably struggle to use the Naglers comfortably and  would probably choose the XW's (or Delos or Morpheus).

If not then the extra FOV and more compact design of the Nagler might win you over.  (Or add heft again and go Ethos for even more FOV?)

Original XWs

Current XWs

All the designs remain unchanged. 

The 30 and 40 have new product numbers because they were withdrawn by Pentax and then rereleased by Ricoh. The others have the same numbers because they have been continuously available both pre and post Ricoh ownership (although they too went through the same packaging change when Ricoh took over).

There is as much difference between an old XW5 and a new XW5 as there is between an old XW40 and a new XW40-R - just age and package branding.

13 minutes ago, Craig a said:

wonder how much it would cost to coat my 10 inch mirror in 24ct gold

4 minutes ago, faulksy said:

going to need a bigger dob

Your existing scopes are fine.  You just need a new mount that can position them near the Sun-Earth Lagrange point (2).

Simples.

1 minute ago, Richard_ said:

If it was an ad on Astro buy-sell it would say "collection only, too precious to ship" 😁

FLO have the shipping game licked 😉

6 minutes ago, Zermelo said:

I'm hoping to pick up a used HST at a healthy discount.

One HST

Customer Return

No longer required. Well used, open box.

No manufacturers warranty.

$1,500,000,000.00 $1,499,999,850.00  (saving $150.00)

7 minutes ago, Laurieast said:

HST Same target. 

http://hstrelics.weebly.com/uploads/5/5/4/4/55441139/_7111921_orig.jpg

Was that 12.5 hours too? Or more like 2 weeks?

Quote from Mrs Globular was better than their commentary.... "Wow. Lots of shiny things!"

1 hour ago, markse68 said:

Does it filter out lp? 😁

You should be roasted for that joke. 😁

On 24/06/2022 at 11:54, Ags said:

only real gripe is the thumb screws should be 2mm lower to avoid colliding with the bottom of wider eyepieces

Perhaps you could replace it with a narrow head thumb screw?

Although actually the housing is not scaled up like that, rather the shape of it is changed.

As you see below, the RA Prism has a square face holding the round clear aperture; whereas the roof prism housing is a rectangle of the same width but 71% longer.

I think the diameter would be 35% larger.

I think my attempt to help probably hindered, so sorry about that.  At least it was in tune with Edmund not in opposition.

Good luck with your finder project... look forward to seeing it.

I equated the two to try and make understanding it easier, not because it is the "right" way of thinking about it. 
The length A is really the clear aperture... slightly larger typically to give a crisper margin.  If you trimmed arbitrarily then, yes, you are changing A but you are not changing the clear aperture (unless you trim too much).  The 1.7071 only holds if your A is "optimally" trimmed.  If you trim differently then you might get 1.6, say. But 1.6A(arbitrary)=1.7071A(optimal)=A'

29 minutes ago, markse68 said:

Away from the roof apex plane the light path gets shorter compensating for the folding double internal reflection

Absolutely.  If it didn't then you would get some rather distorted images!
The reason you get an extra 0.7071A is not because of the roof, but because of the extra glass needed to achieve a roof over the whole clear aperture.

Maybe this way of thinking about it is easier....

The light path through the red bit of glass is A and the light though the two bits of blue glass is 0.7071A,  giving 1.7071A in total.

I think A in the roof prism is...

And if you equate this prism to a "normal" one then it's A' would be...

Their answer is consistent with my response above and does seems to work with their quoted figures for my non amici version - but I agree the figures don't add up for the amici.

Surely for an amici prism the glass path has to be approximately twice the clear aperture - as the light starting on the far left has to travel to the far right (= clear aperture distance) as well as through the prism (another clear aperture distance (ish)).  So if the 31mm clear aperture is right the glass path should be around 60.... or if the glass path is 50 then the clear aperture must surely be less than 31.

The figures they quote for the 2" version of the amici are; glass path 80, clear aperture 44..... this seems just about ok.

I suspect one or more of the quoted figures for the T-2 Amici Prism diagonal is wrong.  My guess is the clear aperture more like 27.

Puzzling.  Please post back when you get an answer.

My understanding is that glass path of 50 means there is 50mm/1.56=32.1mm of glass - with the light travelling 50mm due to refraction. 

And optical length of 47.5mm means there is 47.5mm-32.1mm=15.4mm of additional light travel from the glass surface(s) to the connection flange surface(s).  (Probably 7.7mm each side).

Hence the movement in focal plane of using the prism (compared with straight through) is 50mm+15.4mm = 65.4mm.

I don't have this particular prism to measure it for you - but I do have a baader prism with reported glass path of 50 and reported optical length of 100 and I can confirm my measured optical path in use (~117mm) agrees with this same formulaic approach, i.e. 50 + (100-50/1.56) =117.9mm

(I'm also happy that the reported clear aperture of my prism (47.5mm) is pretty accurate.  But again can't comment on the one you're interested in.)

Hope that helps.

9 hours ago, markse68 said:

certainly looks like you could drive a tank over it and it would still work ok

Someone drove a land rover over one.... not sure about a tank though...