Deadlake

7 minutes ago, jetstream said:

DPAC will tell us both how good our scopes are

Also just as good as the tester... 

I wonder what it will do now scopes from premium manufactures will be DPAC tested, do you send them back?

1 hour ago, 900SL said:

It will certainly lead to higher prices, and people returning perfectly useable scopes because their test results were less than ideal.

 

Most of the premium market do not report Strehl due to cherry picking. 

A scope is rejected as Strehl is 0.96 and not 0.97 for instance.

You could have a lens with a high Strehl however the lens is not smooth, all ripe for some marketing....

54 minutes ago, nicoscy said:

I may be wrong, but I believe that most of the scopes also coming out of China and sold by various rebranders, are also tested in red. 

I think that’s another thread…

8 hours ago, John said:

What wavelength of light is hindsight best tested with ? 😁

I think it's been accepted for a while that the most exacting light to test scope optics in is green. 

The point is SV are the only manufacturer I can think of that tests in red, green is as far as I can see an industry standard. No hindsight then, a red flag. Ho ho ho.

10 hours ago, nicoscy said:

I prefer less drama and more substance. But, I am one of many and since we are not Borg, no collective consciousness and no assimilations!

In some ways the CN thread has run it’s course. I do not see any thing more to add once the scope got taken back, unless Vic decide’s to use green wavelength to null the lens too. It’s not the end of the discussion,  it they could be on other threads and maybe less pruning for you. I see you have your work cut out with the NVD forum as well. 😃

On 13/03/2023 at 16:16, John said:

DPAC can deliver some surprises. Here is one that I don't think many saw coming:

Bench Test of a StellarVue SVX180 Apochromat - Refractors - Cloudy Nights

 

Well if you knew SV was testing red you might. The colour band was not on SV’s site until this blew up and you would of only got a hint if you looked at SV’s Facebook page.

54 minutes ago, jetstream said:

Any tube can have tube currents.  It is a function of the temperature difference between the lens assy and the tube itself, including the focuser etc or anything that could be a heat or cold sink.

True, but some tube materials will give less thermal currents than others. 

Polymers of most kinds are self-insulating, as is phenolic/paper, and so is fiberglass.

Carbon fiber tubes are not self-insulating.

All metal tubes need insulation of some kind.

Hence using a phenolic tube gives less chance of tube currents running the view.
 

56 minutes ago, jetstream said:

I hope the OP can garner some useful information from this thread in his future telescope choice.

Yes, there is no free lunch in hoping once scope will behave in a particular way, all a function of environment the scope is being used in...

1 hour ago, Stu said:

It’s just basic physics, start temp and outside temp, and whether that is stable or falling. 30 mins is probably about right, a doublet is faster.

I think there are many factors making up when a scope lens reaches null.

If you are really keeping track of it you would be testing the lens against green light, but how many of us do that?

The environment is not just temperature difference, it also includes cooling factors, change in pressure, how much latent heat is stored in the tote systems (lens tube, ground etc) from the day before all play a part.

How much the lens is over corrected to start with will be a factor of height and air pressure and hence how long to get to null.

Too much over correction at the start is a way to a decrease in contrast as the lens changes shape.

I think this conversation has been done to death on CN with the simple conclusion that to many factors to give a simple answer of it's 30 mins for this scope and 60 mins for another scope, etc..
 

3 hours ago, jetstream said:

Great point and I must add a carbon fibre tube takes longer to acclimate.I chose CF for the 90mm because of all the abuse it would take on dark site trips and extreme temp differences. It has been "thrown" in the truck, no dents obviously and CF will not move around like an aluminum tube in wild temp swings.

A well designed aluminum tube and cell wont impact views in extreme temps ie the TSA120.

Its a crap shoot if the SW120ED will have a successful cooldown from 21c to -30c. The cell pinches more than 50% of the time, making it unuseable for a session then.

There is no question air spaced triplets take a fair bit of time to cooldown IMHO. Eventhough my TSA is stored in a seacan, I still give it time to settle down, maybe this is just me.

But the views speak for themselves..

So far we've had three tubes types mentioned. aluminium, phenolic and Carbon.

Gerry do you know if carbon has tube currents like aluminium? 

Also we looked at lens being pinched, the LZOS is good to -30 oC so I imagine at more normal temperature it can compensate better then other designs.

32 minutes ago, Stu said:

Ah, so not a warm garage but a cool garage, makes a big difference. The only reason I’m being specific about this is so people don’t have an expectation that a fast triplet will cool in five mins.

Doing a Google around this there is a huge range of cooling times for the same scopes, and even then if nighttime temperature is changing this has a large effect too. 
 

The other item to remember is the phenolic tube thermal expansion will result in better focus compensation than using an aluminium tube. Also apparently zero tube currents.

Back to the OP, I was going to suggest a 115 mm triplet is the best compromise between weight and performance, it has just that little more aperture and keeps the weight around 6-7 kg so no expensive mount.

51 minutes ago, Stu said:

Interesting. Matthew puts it at 30mins for the same scope from warm house to cool outside.

Triplets will take longer to cool than a doublet of similar aperture due to the extra glass, and while the lens in the 105 is very thick and heavily curved, cool down time is good, taking about 30 minutes to produce excellent images after moving from a warm house to cool viewing location.

http://alpha-lyrae.co.uk/2014/01/01/the-apm-tmb-105-f6-2-triplet-apochromatic-refractor/
 

I wonder what is different about yours?

It’s coming from a garage, not quite same temperature as outside. For instance metal of an AZ100 will be cold to the touch as will metal handle of scope and FT focuser. So still some acclimation but not much. 
The only time the scope spends in the house from the garage is to put on a finder scope, so not much time for it to warm up. The phenolic tube is not a great conductor of heat.

The night I took it out was also not relatively cold, i.e no frost in the tube like this

Still on that night maybe 25 minutes for it to settle down. Again a phenolic tube.

The phenolic tube is a very good insulator making it maybe harder for a thermal gradient to form. Might help???

55 minutes ago, Stu said:

Presumably your scopes are kept somewhere cool Martin? A fast triplet takes longer than five minutes to cool if taken from a warm house.

Like Gerry, I see differences in susceptibility to seeing between 100mm and 130mm.

The 105 mm takes 5 minutes from a warmish garage to freezing to acclimate the 130 mm longer maybe 30 minutes.

As far as seeing, recently moved house. It’s 75 meters higher then last house and hidden behind a large hill, one of the highest in the southern downs.
 

Maybe the lower boundary layer turbulence does not effect so much when I view from the new house as much or maybe I’ve not been out as much, I’m picky on nights to view.

Although the new house is only five minutes from the old house it’s a noticeable step up in ‘seeing’ quality…

Triplets give better colour but at the expense of weight, which is the trade off you need to make. Also they can take a little while more to accilimate, but the 105 mm I have takes around 5 minutes and then is razor sharp. 
 

Much has been made of the TSA-120, and like many Japanese scope you get a very compact scope that is lightweight which I think cannot be over looked. 
 

Same time the ‘seeing’ does not make much of a difference between a 105 and 130 I have, but for a larger scope like the 10” then for sure that’s going to be a point.

I’d work out how you are going to mount the scope, once you go above 6-7 kg the options you have are going to be a step up in cost and also will remove flexibility. You might need to move the scope around the garden to dodge trees for instance.

On 28/02/2023 at 16:18, jetstream said:

What I like to see is "secondary detail" ie not just Jupiters bands but the sharp tonal differences in them. The 15" will bring out very fine edges in the bands and in much earlier reports called them "riffles". The TSA is also excellent for its aperture.

I have no doubt that this is due in part to the 15" (and your Mewlons) higher spacial frequency and the high quality optics that allow the contrast transfer to happen.

I also find the eyepieces do matter and the interaction between them, the scope and the individual.

I notice a difference in looking thru a Vixen HR and a Takahashi TOE when looking at Jupiter. The TOE colour is more saturated then the HR that does not add any saturation.

tHard to put into words, but I think with the HR my eye can see more detail then the TOE, note its 4 mm vs 3.6 for the HR.

On the moon the HR and LZOS looks like a ultra high resolution black and weight photograph taken thru a Zeiss lens, whereas my Vixen looked like a high end Canon lens. 

Maybe the TOE would suite a slower scope…

32 minutes ago, saac said:

Isn't that the problem though, to contrive to measure a one way flight path - no reflected journey, no traveling back on itself.  Synchronised clocks - how do you tell the 2nd clock to start?  That is the problem.  Black holes , I can see a few problems there    It sure is a frustrating problem conceiving how this could be done for sure. 

Jim 

A one way journey, no mirror, no clock synchronisation. 
 

The is called a light ring around a black hole, I leave the expert to it

I’ve not read the whole post, however ways of measuring the velocity of light are 

1) Reflection, where a mirror is used to return the light.

2) Synchronised clocks reporting the velocity of light between two points?

And the aim is to measure the velocity of light one way?

Well one way (no pun) of measuring the one way velocity is to have light bend back on itself, just need a black hole to bend time/space and light will loop around and come back. The astrophysics are using this technique to find out new physics around the photon rings around back holes….

What do you do when kit is not replaceable. I have some LZOS scopes and the supply of those lens cells (even without the war) is no longer financially viable. The only scope I’d change is the 130/f6 for a AP130GTX and that’s because it’s a little more svelte and compact.

However I do have gaps, a scope with more focal length. Do I go with a C11 or a 12” Dob? 

The main reason for holding off is just moved house and I’m getting to use to observing from a different garden.

I need to move the scope to avoid the hedge/tree line. 

I suspect the dob is better however not as moveable as the C11. Wheels on the dob would help however the C11 keeps it collimation quite well.

A harmonic mount would also lighten the load when moving.

Trying to avoid kit churn which the ultimate money vampire….

16 hours ago, Space Hopper said:

I'll be putting my name down for the upcoming AP 110 F6 when it is ready, so you never know, my name could be pulled out of the hat.

I’m tempted by the AP110GTX, the light weight of it and portability is attractive

https://www.astro-physics.com/110gtx

Thanks for the scope, I’ve added some lightweight printed rings so it fits in a Stellarvue case.

the small size of the scope grows on me, handy for moving around the garden.

As far as dream scopes, tempted by a Doc Telecope 12.5” dob running at F3, would show some deep rich field views.

http://www.doctelescope.com
 

14 hours ago, jetstream said:

I have 2 telescopes that are at the top of my heap- the 15"/Ostahowki/Astrosystems and the TSA120. These 2 scopes sure provide views that the others do not. Not that the others are bad its just these 2 sit on the top shelf, and no doubt any experienced observer with good visual acuity would see it.

Your 24” is not in the list, the 15” is easier to get out while the larger scope stays in the seacan?

With the dark skies you observer under you do it need more then the TSAto see some DSO’s.

1 hour ago, jetstream said:

In the case of the TSA120 I find the diagonal doesnt affect things as compared to straight through, it sure does with respect to my SW120ED however.

prism or mirror?

On 10/02/2023 at 15:13, jetstream said:

Thanks Neil, I find it strange (but true) how some scopes can give these exciting effects. When I hear comments like the one about the A-P I pay attention.

Forgot to add- in your pursuit of the 4incher it might be of interest to note the differences in the presentation of the planets. Many owners of high end scopes will say this brand shows Jupiter better than that brand or Saturn is better in this one than that one etc. I think it boils down to colour rendition but could be wrong.

I think the Tak doublets are known for their rich colours on the planets, whereas my TSA120 is a more neutral scope, wicked on Saturn, Vg on Jupiter. Mind you were splitting hairs here... but the effect is real. The TSA120 is also wicked in WL solar.

Also Jerry the diagonal used, I find the red colours of Jupiter and Saturn come out more using a BBHS coated diagonal over say a max bright. Makes a real difference IMHO.

From what @Dek Rowan Astro has said  the joystick connects to the AZ100.
This means when using sky safari and the mount is moved using the joystick sky safari will follow. 
I quite like this approach, however does mean coupled to joysticks Rowan supports.

4 hours ago, Captain Scarlet said:

As it is at the moment, with a reduced rail, it fits in the bag quite comfortably. With that handle definitely not, but that handle is designed to be taken on and off in a moment. It’ll be great for transporting my 12” tube outside for instance.

I’ve just set it up inside (it’s raining again 🙄) and have been looking out across the countryside through some double-glazing. The focuser is very good. I’d say slightly better feel for the fine knob than BD Steeltrack (which adorns my 2 newts and a Mak). So I’m very happy with it.

I have a 105 mm and to fit the scope inside a smaller StellarVue case  I use a TS handle (£35). This way no need to take the handle off or on. Just a thought.




 

1 hour ago, dweller25 said:

I would 😈

Apart from the 12 month wait for the part it add quite a lot of wait to the EP end of the scope.

I've thought of going with the manufactures focuser for that reason...

But yes FT's are very smooth...

Has anyone got the latest software version that supports joy sticks/pads at all?

@Dek Rowan AstroHave you got a list of what joy sticks/pads you've tested with the motor kit?