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New 6" F/8 ED Doublets from APM Telescopes

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#326 t.r.

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Posted 03 January 2013 - 09:48 AM

I can testify to those seeing conditions...in Seoul S. Korea during summer I was able to run my 4" Genesis routinely to 260x on Jupiter and it wanted more! Ganymede looked like a marble transiting across the face! I'll never forget it.

#327 APM M.Ludes

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Posted 03 January 2013 - 10:29 AM

I also understand what you both mean, but such powers are called empty powers and per physics, all this powers doing is making the object bigger and reducing the visible details.

450 to 600 power in a 15" confirms the rule.

we have low contrast and high contrast objects. Satrun is a high contrast object, as well as Moon, but Jupiter with its great surface details is a low contrast object and low contrast objects should be observed also below the theoretical max power

so please do us the favour and when you have your next observation try Jupiter with the real good power between 180 and max 250 times and let us know what you see then

#328 APM M.Ludes

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Posted 03 January 2013 - 10:46 AM

The designer of our Chinese 152 ED can read on CN Refractor forum but not post there due his poor english , so he asked me to post here his comment regards the CA discussion in englisch.
---------------------------

Hallo Markus,
As I read on CN's it all about the color correction blue against red
Valery compares a doublet with a correction E-D-F (FH lines d and F have a common focus) with a doublet with the correction E-C-F and means the E-D-F correction is worse.

Both fixes are not ideal for visual observation after photopic (tags marriages) viewing.
Sensitivity tags marriages photopic in our eyes
F ... 18%
C ... 8%

Hence our optimized doublet has neither a correction E-D-F nor E-C-F correction but is seen for the photopic, exactly like it did when Massimo LZOS Doublet, which should also yield the best result on Jupiter.


May you write something for me or I write there but then you would have to translate the previously because as mentioned before my Englich too rough.





Greetings Gerd

#329 Ambiorix

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Posted 03 January 2013 - 11:31 AM

Yes Richard, unfortunately I have to agree (for once ;)) with Markus about the empty magnifications you where using!

Lichtenknecker optics always told me that the optimum magn. was around the diameter of the lens, which would be around 150X for your 6" ED. Off course opticss have changed for the best, so I would say that about 200X max. for Jupiter and perhaps about 225X for Saturn and moon, should be what you should use in a 6" refractor! I am not saying that, so it seems, under your extraterestrial seeing conditions, higher mags can't be used, but as Markus is saying they are completely useless, and will only show a bigger ball in the sky, but not more details. If you like big balls in the sky, use big glass down here:)
No, really, an exit pupil of 0,8mm on Jupiter is more than enough, and one of 0,7mm on Saturn, Mars and the moon is good to, but no more. And certainly not when testing two scopes against each other!
So, I would like to hear the verdict when you do the test over again, this time with normal magnifications of around 1mm to 0,7mm exit pupils....I think the difference will be less noticable.
I cannot believe that I am defending Ludes here, usually we fight together all the time, but when he's right he's right :shocked:

#330 Alvan Clark

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Posted 03 January 2013 - 03:56 PM

Yes Richard, unfortunately I have to agree (for once ;)) with Markus about the empty magnifications you where using!


I disagree. Like enlarging an image on a computer, You don't gain any detail if you keep enlarging it. Just makes what is there easier to see. You don't lose any though if you keep making it bigger. The same amount of information is still there.

In the case of a telescope you may lose detail at some point because it's "seeing" limited. The quality of the seeing would determine that point.

#331 APM M.Ludes

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Posted 04 January 2013 - 02:07 AM

Hi Alvan

if I make a picture on the computer much bigger, it start showing less due the pixels, nothing else happens on the telescope if you make the picture to big you loose details.

The word Loose is maybe wrong you are right, because you do not really loose something , it is still there and if you make it smaller again it is there, so what you do is you wash out the picture or spell it any other way, in any case you see less if you oversize it

#332 Ambiorix

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Posted 04 January 2013 - 03:03 PM

Yep, I can't believe what is happening, but once again I must agree 100% with Markus here :confused:

If this continues we might even become good mates :foreheadslap:

And Alvan, let's be honest here, do you really like the darkness of an exit pupil of little more than 0,4mm?
I don't, that's for shure. Even 0,5mm is much too dark for my likings!

#333 Live_Steam_Mad

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Posted 04 January 2013 - 04:02 PM

Yep, I can't believe what is happening, but once again I must agree 100% with Markus here :confused:

If this continues we might even become good mates :foreheadslap:

And Alvan, let's be honest here, do you really like the darkness of an exit pupil of little more than 0,4mm?
I don't, that's for shure. Even 0,5mm is much too dark for my likings!


Interesting to hear someone mention that the very small exit pupil is darker, a thing that I had not noticed before myself.

BUT I have noticed that 0.5mm exit pupil on any 'scope that I try really is not great for me because it shows up the floaters and cells in the back of my eye quite noticeably and it interferes with the view I get of Jupiter.

So I would want a 1mm exit pupil at the smallest, preferably (personally).

As a side note, an exit pupil of 4mm shows the astigmatism that I have in my own eyes really badly (small-ish but very noticeable crosses on the brighter stars on M45 for example), even when I have my spectacles on (probably because my prescription is 3 years old and I am starting to need new glasses since my astig. has probably got worse, I already had 3.0 diopteres (severe) of astig. in my right / observing eye, which my glasses don't appear to fully compensate for). At this point I could really use an eye test and a Dioptrx lens for my 32mm TeleVue Plossl...

And I can't use my left eye, since that's even worse at 3.5 diopteres of astig... :tonofbricks:

Cheers,

Alistair G.

#334 faackanders2

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Posted 05 January 2013 - 09:23 PM

Markus, you are the best for getting this going! Can't wait to see the offerings!

(on a side note - any newer news on that apo BT with 90 degree oculars?)

No pressure. Still patiently waiting.


Would these be similar to the big binos, or an all new binocular telescope?

#335 APM M.Ludes

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Posted 06 January 2013 - 08:47 AM

the Apo Binos will be real binoculars , they still working on them, going slowly, but they will come for shure, no vapour, maybe a few more monthes

#336 Live_Steam_Mad

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Posted 06 January 2013 - 01:56 PM

the Apo Binos will be real binoculars , they still working on them, going slowly, but they will come for shure, no vapour, maybe a few more monthes


Any chance of creating binoculars which are Dioptrx compatible? and / or where you can change eyepieces? With 50mm aperture? I wish TeleVue would do some. But I can't contact them, they have no e-mail.

Cheers,

Alistair G.

#337 APM M.Ludes

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Posted 06 January 2013 - 02:14 PM

50 mm ? , what sense does it make ?

#338 Live_Steam_Mad

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Posted 06 January 2013 - 06:11 PM

50 mm ? , what sense does it make ?


OK, first I started off by using my late father's 10x50 Pentax bino's and the views were awesome - before my Brother used bog roll (toilet paper) to clean the lenses (doah!) and scratched the coatings to hell :shocked:

Then it didn't help that as a teenager I dropped the bino's onto solid concrete several times by accident... and it ruined the view :o

...however later on in life I bought a pair of Nikon 8-24x25 Travelite V binos for use with Astronomy (don't be too quick to judge) (because they were lightweight, the Pentax bino's were 1,200 grams!), and although the performance at 8x was not incredible, it was still very high contrast and sharp on axis, and at the high end of the magnification range the correction at the edges improved dramatically and the field expanded hugely and it hugely REDUCED that horrible orange glow as I zoomed in (as it darkened the background sky) so that on one night whilst looking at the Double Cluster being just about overhead and filling the view, and seeing diamonds against dark velvet, and being mesmerised, I realised I was getting hooked on zoom binoculars :jump:

And then I started to want more aperture... but they get heavy really quickly, and 40mm Nikon bino's are heavy (as heavy as the Pentax 10x50).

So I was looking for a pair with say 8-20 (zoom) x 50mm aperture, carbon fibre body like the Nikon's I have for lightweight, and then I WANT TO BE ABLE TO TAKE OFF MY GLASSES when using the bino's as I have severe astigmatism and using my glasses all the time with 'scopes / bino's sucks :(

So I thought, what if you could have Dioptrx compatible bino's (surely I can't be the only person that has thought of this - how many people are there with significant astigmatism...) and get a sharp view and be able to zoom in and darken the sky (the Ethos versus Plossl argument, the "majesty factor" as Uncle Al puts it), and with a pair of bino's that are say 1Kg max. Hell I'd buy them.

Cheers,

Alistair G.

#339 APM M.Ludes

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Posted 07 January 2013 - 06:40 AM

for such a special binocular you need to order minimum 500 pc or 1000 pc and prepay , otherwise nobody would it and who will buy so many ? Therefore I am not going such way, sorry

#340 Live_Steam_Mad

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Posted 07 January 2013 - 12:29 PM

for such a special binocular you need to order minimum 500 pc or 1000 pc and prepay , otherwise nobody would it and who will buy so many ? Therefore I am not going such way, sorry


Couldn't some company just make a binocular to be Dioptrx compatible (i.e. with that ring around the eyepiece tops like the Televue eyepieces have), I mean, how hard can it be?!

Cheers,

Alistair G.

#341 APM M.Ludes

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Posted 07 January 2013 - 03:33 PM

its not hard, its only a question of quantity

#342 Alvan Clark

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Posted 07 January 2013 - 03:37 PM

And Alvan, let's be honest here, do you really like the darkness of an exit pupil of little more than 0,4mm?
I don't, that's for shure. Even 0,5mm is much too dark for my likings!


I wasn't recommending any particular power. People have their own preferences. The objective lens provides all the information/detail/resolution. Once you have magnified the image enough to see all that detail, there is no need for further power. This has been referred to as 'empty' magnification. However I don't think more power hurts or causes loss of detail as long as the "seeing" conditions allows it.

#343 Alvan Clark

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Posted 17 April 2013 - 12:04 PM

Have you been satisfied with the project so far?

#344 APM M.Ludes

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Posted 21 April 2013 - 03:10 PM

absolutly yes

#345 mblack

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Posted 26 April 2013 - 06:24 PM

Hello Markus,

Which shipping method did you settle on (sea / air)?

Delivery month?

Thanks.

#346 APM M.Ludes

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Posted 27 April 2013 - 01:28 AM

airfreight cost 5 times as much as sea freight, so we go by seafreight, otherwise we have to ask higher price

when shipment goes out I know when I get it, should be soon

#347 mblack

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Posted 27 April 2013 - 09:57 AM

Thanks :grin:

#348 Traveler

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Posted 03 May 2013 - 10:05 AM

Hi markus,
Do you have plans for bringing this telescope to the next att?

#349 APM M.Ludes

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Posted 03 May 2013 - 01:10 PM

yes we do

#350 Traveler

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Posted 03 May 2013 - 02:43 PM

Great! See you then.






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