Deadlake

3 minutes ago, John said:

It's shame if the two major forums feel that each other might "trash talk" each other. I've been a member of both SGL and CN for a similar amount of time and found them both very useful but in different ways and with different styles.

I'm sure we used to have a rule on here about not rubbishing other forums and likewise on CN. I'd like to think that mutual respect still exists.

 

 

I noted it because I was shocked to see it being noted.

 Your right nothing happens in a vacuum so to say.

There was a post on CN noting posters on SGL where complaining about the froth in the APM superzoom thread today. 😄

On 29/03/2021 at 16:11, Louis D said:

It's my understanding that they take Chinese scopes and refigure, respace, and recoat the lenses for optimal performance.  At least that's what I read somewhere once.  They don't do everything from scratch like A-P.

They now do, even up to 180 mm APO. I think they have no where else to go. Either mass production or high end.

Here you go:

https://www.stellarvue.com/optical-glass-types/

2 minutes ago, Louis D said:

Well, the 55 degree planetaries have been sold over the years under numerous other labels, their UWAs are the same as the 4mm, 7mm, and 16mm UWAs sold under other labels, and their Optimus eyepieces are the same as the APM XWA HDCs.  I'm not as familiar with other suppliers for soft cases, though.

The Stellarvue Ep's have stainless steel barrels and block stray light entering (when you look at the moon) over the APM XWA's. Closer to Televue build standard. Vic does not make rubbish. 

3 minutes ago, johninderby said:

Stellarvue does make some of their own scopes but they also do buy in a lot of scopes from the same Chinese source as Altair, Tecnosky, TS etc.

I think they have stopped this now, now they make their own scopes. However nice they are, no dealer network in the EU any more. 

16 minutes ago, Louis D said:

Doesn't Altair Astro sell very similar scopes under their own label in the UK?

They do not sell Stellarvue cases or EP's.

59 minutes ago, Louis D said:

Buy local within your home country? 😉

Stellarvue does not have any dealers in in EU for example. The list goes on and on.... 

42 minutes ago, Stu said:

You talked about corvid being a reason for the price rises, rather than covid. Just a little tease 😉

The joy of auto correct.....

On another note, any cheaper way of not paying the £8 handling charge to Royal Mail for imports? All adds up.

1 hour ago, CraigT82 said:

Don't think crows have anything to do with it despite what your dealers are saying!

(Sorry couldn't resist 🙃)

 Crows???

I think a drop of 60% in trade by value with the EU would effect prices, so a little lost in thinking dealers are making things up?

On 26/03/2021 at 20:09, Stu said:

Whilst all this is very interesting, may I just gently draw this back to the title of the thread which was ‘Shocking price rises!!?’, and also give an equally gentle reminder of the no politics rule in the CoC.

Thank you all 😀👍

One question Stu, if this thread is around prices rises and a lot of the dealers I talk to (delays and cost increases) say corvid is not the only factor in prices rises but due to changes in trading arrangements shall we say how can you keep policitics out of it?

18 minutes ago, Nikodemuzz said:

Hah, that's funny! 

Although I must say that the idea about getting the rings has crossed my mind. I'll use the scope for a while as is to see how badly I really need them. No need to fix what ain't broken, especially as the rings aren't that cheap either. The handle would be nice, though. Still, I might prefer mounting the scope to the rings that are already attached to the saddle. To me sliding the dovetail into the saddle feels more awkward, even with handle. Without one it's almost a non-starter.

When I ordered the LZOS I discussed with Rupert having a handle fitted. Not surprisingly with the phenolic tube option (which apart from stopping dewing will stop my hands getting frozen to the tube) is not a standard option. In the end he had a spare APM handle and when the starlight rings where ordered the dovetail was sized to match the length of the standard APM handle. Trying to unattach the scope at the end of the night without a handle would be an expensive accident.

3 hours ago, osbourne one-nil said:

My bottom lip has disappeared - it should be with me today!

I just had some Vixen items turn up on Monday. I suspect there was a large delivery to come in from the Far East. Hopefully other delieries from the Middle East  not going via the Suez Canal.

1 minute ago, KP82 said:

Excellent plan. But I'm pretty sure you won't sell it. 😁

Have you thought about replacing the Tak cradle with a pair of tube rings? You can then attach a handle or another dovetail bar on the top to improve handling and prevent flexure in the ota.

I wondered how long it would take for the handle police to turn up. Must be an SGL thing. 🤣

I thought @JeremySor @johninderby would be first.

1 hour ago, KP82 said:

The steel lens cell of the LZOS adds substantial amount of weight to the scope. Among the premium brands I believe APM/LZOS scopes are some of the heaviest. For example, my APM115 weighs 8kg whereas a slightly larger aperture TSA120 is only 6.7kg. I suppose the weight difference is partially downto different metals used for the lens cell. However I've never read any reports of pinched optics on the TSA120.

The TSA120 is an outlier on weight. I believe Takahashi claims -25 degrees is the limit on operating temperatue.

The APM's (mark II models) use a phenolic tube (composite) which reduces the weight to balance out the weight of the steel lens cells.

The moon is amazing, even a little high altitude cloud did little to obscure the view. Last time the moon looked so clear was last August 2020. Running with a 1.6 HR, gives x 497. Smooth silky views, with no shakes due to floating over the moon using the star book joystick. Once slewed (which is quite), the mount sounds like a quiet wrist watch, belt drives rule.

2 minutes ago, JTEC said:

Thanks, Deadlake - interesting link!

I'm beginning to think BBHS mirror is the way forward, apart from any scope > F7. I'm going to wait and use a known performer.
It is hard to sort one dielectric coating from another as the silver Baader BBHS also have a dielectric coating applied as well.  

6 minutes ago, Don Pensack said:

One thing to note about silver--it's response rolls off below 500nm, and transmission is poor at 400nm.

Aluminum doesn't roll off significantly in the 400-500nm range.

The way to bring silver up to the aluminum level at the 400-500nm range is with special UV-enhancing coatings added.

It think it possible those are applied in some cases, but you would want to find out if they are.

Dielectric coatings can be optimized for any wavelength bandwidth and reflective angle desired, but might require custom coatings if going deep into the infrared is desired.

https://www.photonics.com/Articles/Mirrors_Coating_Choice_Makes_a_Difference/a25501

For pure infrared use, gold is great--high reflectivity and it doesn't corrode at all.  Not good for all visual, though perhaps OK for planets?

https://www.cloudynights.com/topic/346824-gold-diagonal-better-contrast-on-planets/

Someone out there offers a gold-coated star diagonal--Vernonscope?

Gold is soft, though, and should be overcoated for protection from scratches, just like silver and aluminum.

 

This is the CN thread: https://www.cloudynights.com/topic/593410-nv-tips-for-viewing-globular-clusters/?hl=+dielectric++infra#entry8373739 on the article.

14 hours ago, Don Pensack said:

I don't think the type of diagonal relates to whether or not field curvature is present or visible.

But the prismatic smear that occurs with prisms gradually gets worse below f/8.  I wouldn't use a prism diagonal at f/6.

Baader BBHS mirror diagonals are not the only good star diagonals out there, by the way.

Unfortunately the 2" dielectric coated diagonals absorb the infra-red spectrum and so are not suitable for NV usage. I cannot think of another 2" non-dielectric mirrored diagonal that does not absorb in the infra-red spectrum apart from the BBHS. Thanks for your help Don. BBHS back in stock mid too late April apparently.

On 18/03/2021 at 16:54, Don Pensack said:

Geometry.

The curvature of the field is indirectly related to the focal length of the scope, and can be calculated at different distance from the center axis.

The difficulty with refractors is the Radius Of Curvature, ROC, is about 1/3 of the focal length, whereas with a newtonian, the ROC is equal to the focal length.

That means field curvature issues are more present in refractors, and definitely explains the use of field flatteners for imaging, and even for visual use if the refractor is short.

That applies to doublet lenses.  Quite often, in some triplet designs, some field flattening is part of the formula, so you cannot necessarily assume a triplet will have the same FC as a doublet of the same focal length.

Some 4-lens refractors start with a long focal length objective, then add a focal reducer/field flattener later in the optical path to produce a flat field short focal length refractor.  That's a superb idea.

But, if the refractor is not inherently flat, adding a field flattener is a good thing to do for imaging.  Surprisingly few visual observers use field flatteners, but they work well, and allow the use

 of a lot more different eyepieces without seeing a lot of field curvature.

Field flatteners have a "working distance", so it's important to try to get the distance from the FF to the eyepiece focal plane at least approximately right.  To that end, it is useful to know the light path length through the diagonal

and where the focal plane is in the eyepiece.

If you are using the flattener on a fast scope F6 will there still be an advantage of using a mirror diagonal over a prism at all? I ask this as BBHS mirror diagonals are hard to come by at present. I want the stars at the edge to be sharp.

The other option is a Q extender,

https://www.cloudynights.com/topic/751644-apm-xwa-100°-eyepieces/?p=10889469

this gets rid of abberations around the edge by increasing the field curvature (focal length increased), but I suspect the flatterer works with more EPs.

On 17/03/2021 at 17:03, Don Pensack said:

The radius of curvature in your refractor is about 270mm.  That means a flat field eyepiece will show you field curvature.

| + ( = (

It's only if the curves match that you get a flat field:

( + ( = |

So, just about any flat field eyepiece will show you curvature.

How do you determine the curvature of a scope?

Edit:

I’ll get number crunching

https://www.telescope-optics.net/curvature.htm#For_a_doublet

Telescope in question would be a 130mm/F6.

The field flattener reduces the focus length, presume you need a flatterner that can screw directly to a prism with a short light path?

If you add VAT to these prices its quite a shocker what the UK price is:

https://www.kyoei-osaka.jp/SHOP/takahashi-tsa120-125s.html

I don't know how much shipping would be, UK has a trade deal with Japan, same terms as before with EU so that should not be a shocker.

Tak is a lot cheaper than say Vixen for UK prices, also a little funny that Vixen mounts are bundled with Tak scopes. 

24 minutes ago, Shimrod said:

The Edge 8" on an AVX is £2249 (but comes with a ZWO 120 camera) - that's only £200 more than I paid in 2019, and only £50 if you count the cost of the camera.

Edge 11 I believe was £3750 now £4249 for instance, the C11 has gone up £300.

2 hours ago, mikeDnight said:

I just stumbled across the current price of an NP101 IS (£4,449), which means TV have hiked their price for this scope by more than £1,300 in 12 years. As a visual scope, Televue will have you believe that the NP101 IS is good at everything, including lunar and planetary performer, but mine had the stuffing knocked out of it by the same aperture, much cheaper Vixen's, Tak's and SW ED's, and so I sold it after owning it for less than a year. So has this just happened or has it been a gradual stealth attack?  

Seen how much Celestron SCT (£300-400) have gone up?

By the way your are not the only one that has said the NP101 is not a keeper, I've heard that before.

I’ve just have small items dispatched from Bressner. They have been out of stock for last four momths. Ordered at the weekend.