New 6" F/8 ED Doublets from APM Telescopes

A great update! I'm looking forward to the lens upgrade kit!

Very impressive! And I'm not even talking about the scope. The way you have taken this from idea to design to pre-production in such a short time is really amazing.

and on top of all, we start nw to design a motorfocuse for handcontroller and PC and I-Phone controle :-)

if this scope find a success we are ready to do start with same speed a 140 mm and a 165 mm doublet

There seems to be a big price difference between the cell and telescope. If retrofitting the cell is an easy task it would seems to be a lot cheaper to just buy the cell. Then get a used 6" for $500 or so. Total cost would only be $2500 vs $3500-3900 for the finished scope.

There seems to be a big price difference between the cell and telescope. If retrofitting the cell is an easy task it would seems to be a lot cheaper to just buy the cell. Then get a used 6" for $500 or so. Total cost would only be $2500 vs $3500-3900 for the finished scope.

And? The APM tube is likely 1000% nicer than the Synta/Sky-Watcher/Celestron 6" f/8 OTAs. A used 6" f/8 for $500 and then the APM ED lens for another $2k may sound like a great deal, compared to the ~$3500 price tag for the APM ED OTA, but when you consider that you'll also need to upgrade the focuser on the Synta, and to a really nice one at that, to match the quality of the lens, then the difference is not so large anymore.

The real deal is for us who already own an upgraded Synta with nice focuser, finder, rings, mount, etc. We can get the lens in cell for ~$2k, put it on our already excellent scopes and suddenly have a near-apo for 1/3rd the price. If you have to go out and find a used scope first, a lot of the bargain appeal disappears.


Clear skies!
Thomas, Denmark

Of course, if you can find one with a big ol' clamshell on the lens for just north of free, it could be a really sweet deal!

a major part of the big price diffrence is not the tube right rings and case, but also much much more expensive international shipping cost, taxes , etc.

Think about the packing of a little 6" lens and of a 6"F/8 scope in alu cae, double boxed

thats why we make the lens attractive to you

Is there going to be a OK4 doublet coming soon?
I believe there is talk of it being 6" f/8.

The Massimo Riccardi Designed OK-4 Doublet , made by LZOS is in our stock in germany for daily shipping

lens in cell http://www.apm-teles...l-2-lenses.html




and complete optical tubes with 2.5" focuser http://www.apm-teles...mm-2.5-ZTA.html

or with 3" focuser http://www.apm-teles...m-2.5-ZTA1.html




so if you want one, send your order

For those looking for a high quality $10,000 APO refractor, I have no doubts that the one Markus offers in this class is in the upper tier of superb scopes available, and well worth the cost.

But that's also not the scope, nor objective, that this thread is about...

The Massimo Riccardi Designed OK-4 Doublet , made by LZOS is in our stock in germany for daily shipping

lens in cell http://www.apm-teles...l-2-lenses.html




and complete optical tubes with 2.5" focuser http://www.apm-teles...mm-2.5-ZTA.html

or with 3" focuser http://www.apm-teles...m-2.5-ZTA1.html




so if you want one, send your order

Hi,
The link for the 3-inch focuser model takes me to the same page for the 2.5-inch focuser model..,

Regards,

skybsd

ups sorry, here the correct one http://www.apm-teles....html?info=3290

picture on the side with 3 inch focuser follow this week

Nice!

Ok, I came really late to this party, but I'm really interested in a 152mm ED upgrade for my Helios 6" f8 OTA with Moonlite focuser. Would the lens in cell require new baffle placement? Would it fit my Helios 150 tube? It's virtually identical to the Celestron and Skywatcher C6 models I think.

Ant

Markus & his associates have proven pretty resourceful in dealing with this general kind of thing in the past, so I'm giving him the benefit of the doubt right now... He has excellent machining services, and telescope assembly resources at his command.

So, just try & be patient, & let this process take it's natural course... The proof (or not, but again, because of his record in the past, I'm certainly more than willing to give Markus the chance to show us what he can DO, and so far, he's been doing just fine...) is only a few more months ahead...

Hi Ant

if you replace your achromat with this new ED Apo , no baffle replacement needet. What you need is a new tube adapter to connec tour lens cell to your tube, that what we will be offering to anybody

Found this on the APM website.

Also this for the OTA.

Those items seem to be exactly what Markus is talking about in this thread. Not sure about Australia, but he indicated he's looking for a distributor here in the US before offering the scope/lens assembly here.

Hi Warren

we started already to accept pre-orders with european dealers. As soon I have tested the first 3 samples , I will contact US dealers.
I will have one for demo and sale at the First Annual Arizona Science & Astronomy Expo November 10 & 11, 2012! in Tucson.
This will be Nr.1 sold in USA.

As soon as my test of first samples is done, we will move fast and delivery up to 250 pc before christmas, if we get so many orders :-)

Hi Markus, do you guarantee that this 6" F8 OTA from you will have a certain maximum level of spherical correction? If so, what will it be? As I am wanting to upgrade to a very good planetary 'scope.

I have a Meade StarNavigator 102 (don't laugh!) and it splits the Double-Double (Epsilon Lyrae) easily, for example (2.3") but the 1st diffraction rings on those stars (E2) were quite easily visible at 200x, and I see that in the excellent Aberrator 3.0 Beta (did that guy ever update it?) that I seem to have about 1/4 wave optics (maybe 1/4 wave SA, maybe a little HSA, and a "small" amount of astigmatism maybe 1/5 wave, some of which seems to be coming from the diagonal).

I also see from Aberrator, and that if I had e.g. a 6" refractor with say 1/6 wave or better optics, I could see a LOT more detail on Jupiter with "decent" seeing conditions, compared with my 4" F8 Meade Achromatic refractor.

Is it possible that you could offer this 6" OTA with say 1/6 wave SA maximum guaranteed (and only say 1/8 wave of astigmatism at most), so that I could get excellent planetary performance, in which case how much would such an OTA cost from you?

As I get annoyed at manufacturers who cannot do excellent optics LOL (I wasn't referring to you!) as it makes all the difference with details on Jupiter (mushy view versus awesome view), and in my mind reputation should be more important than profits... Meade are you listening?!...

I am no longer willing to accept merely 1/4 wave ("Diffraction limited") optics as I need about 1/6 wave minimum. And I saw in a review once that a TeleVue 'scope had only 1/4 wave optics, which annoyed me, whereas I have never read of a TMB, Astro-Physics or Takahashi OTA which had worse than about 1/6 wave optics? Pity about the "enormous" price tags.

I also see that e.g. a 6" OTA with 1/6 wave optics or better just about completely removes that annoying 1st diffraction ring that I am seeing. At least Aberrator seems to think so?!

Also, is there an Alt-Az mount that I could mount this OTA on which has GOTO and tracking motors which have no vibrations at high powers (350x or so)? Since my mount's drive motors vibrate the objects at 200x !! Yeah I know, I bought an entry level 'scope LOL.

I am glad that you are going for a lightweight instrument, and that you are using a doublet for faster cool down times compared with a triplet.

Cheers,

Alistair G.

Hi Alistair

depends what you mean on 1/6 wave, do you mean overal correction, which is what you see at the startest, or do you mean critical carefull measured by interferometer ?

we sold many LZOS which show a 1/8 wave startest but measured due small areas on paper by interferometer 1/4 or to 1/5 wave.

we do on each scope a startest and we will accept only good scopes by my human eye startest.
Lemons we will return in case we get such.
If you want super high end, get a LZOS 152/1200 doublet, we have them now in stock.
On a mass production of 250 pc as we do with the chinese we have to accept a kind of varation in terms of quality, but we will test them and sell no Lemons

Hello Markus,

depends what you mean on 1/6 wave, do you mean overal correction, which is what you see at the startest, or do you mean critical carefull measured by interferometer ?

I mean by the Star Test done by an experienced human eye, I do not much trust interferometer testing just yet.

we sold many LZOS which show a 1/8 wave startest but measured due small areas on paper by interferometer 1/4 or to 1/5 wave.

Understood. I would accept the LZOS as a high quality planetary instrument if I saw a 1/8 wave Star Test. I don't really care what the interferometer says.

we do on each scope a startest and we will accept only good scopes by my human eye startest.

Now you see there's what I mean. You Star Test each of your new 6" F8 OTA (the subject of this forum topic) but WHAT level of correction are you going to be rejecting as being not good enough?

I need 1/6 wave minimum of SA (Spherical Aberration) (and no astigmatism) on the Star Test to give me the correction that I need to give me good detail on Jupiter, from what I see on Aberrator.

Wish I could test my Meade SN102 on Jupiter but it's too low down at the moment to get a good view.

BTW When I say Star Test, I mean using the methods in H R Suiter's book (on my Meade SN102, I tested on Alkaid, the left most star in Ursa Major, a 2nd mag. star, at 100x and defocussed by the amount recommended in his book either side of focus, and saw about 1/4 wave of undercorrection in SA. For a 6" I would want to still see a good star test at say 350x, but you do the main test at 10x per 10mm of aperture, so at 150x for the 6", as I understand it?).

BTW How do you conduct your star test on a 6" F8, I am curious to know if I am doing anything "wrong"?

If I see great detail on Jupiter with your 6" F8 that I might buy, and a very faint 1st diffraction ring on mag. 2 stars, then I will be very grateful, and will realise that the instrument is excellent.

For me, 1/4 wave is merely "good". 1/6 to 1/8 wave SA and no Astigmatism or other faults I consider to be excellent, and it's an excellent 'scope that I need to upgrade to. "Good" just isn't good enough. "Diffraction Limited" isn't good enough. Aberrator shows me that.

>Lemons we will return in case we get such.

Good, since I have a 19.5" F4.1 that has about 1.5 waves SA (!), and I grew up with a 60mm refractor that never even showed ANY diffraction pattern at either 37x or 125x (!) so I have had my fill of *BLEEP* optics for one life time. But then I got more lucky and got a just about perfect C11, and a Meade 7" Maksutov LX50 OTA for 100 GBP that is pretty good on the Star Test.

I bought the SN102 as a grab and go 'scope, it cools in 25 mins and has good optics. Unlike my friend Jon whose SN102 is moderately astigmatic, and has 1/2 wave undercorrected SA...

>If you want super high end, get a LZOS 152/1200 doublet, we have them now in stock.

If only... funds are limited to say the least. I still haven't even got a mount yet for the two OTA's I have. Would the HEQ5 or EQ6 be fairly stable (damping times 2 to 3 seconds at 250x) with your 6" F8?

>On a mass production of 250 pc as we do with the chinese we have to accept a kind of varation in terms of quality

Now you see that is what makes me nervous to order one. Of course what matters is the amount of variation - it is the minimum level of correction that I have to worry about as a potential customer. However if you can guarantee at least 1/6 wave at the star test with human eye then I would order one as soon as I have seen impartial reviews (Ed Ting, Todd Gross, etc).

Cheers,

Alistair G.

Hi Alistair

if youz are really such a critical startest, sometimes you would reject even some worldfamous apo's which show sometimes a startest you would never believe to see by the high claims.

so I bring you some samples to get us at the same startest level



above is a startest of a excellent optics, guess around 1/8 P.t.v. with a very mild little center zonal defect , very smooth, but if the effect I see on the smaller defocused images is not from camera, then this optics would have a cell pinching, seen by the non round 6 corner circle

-----------


above is not a bad scope either, it has more color and a small undercorrection and is not as much smooth as first picture, but a general nice polished surface. Again I can notice a zonal deffect, but this time a very low wider diameter, almost invisible, such once you find in very many apos of very many manufacturers even famous once.

This ia good scope and would pass my test for shipping, of course if there is not coma and not astigmatism on the axis
--------


aboe not a to bad either, it has a small turned edge ( undercorrection) and a visible center zon, so this one would be around my lower border for passing

finaly, the guys you mention I know personaly very well from old days and I repesct here work very much, but they are in no way reference people for me for doing startests, not at all.

Since you seems to see a person who wait till others jumped in and reviewed stuff, you will be one who has to wait a lot longer before you may buy and get one

on Top here http://www.teleskop-...apochromats.jpg

a web link which show many diffrent startest images , not talking about the color, only about how they look like, all of them would be allowed to go into the market

Th SKW 120/900BD and SW66/400 would be my lowest limit of allowed undercorrection

have a great weekend

Hi Markus,

so I bring you some samples to get us at the same startest level



above is a startest of a excellent optics,

Concerning these first group of images of the 100/550... I don't understand how this is a Star Test in the normal way. Since the DSLR in question has a sensor width of 22.5mm and sensor height of 15mm, then magnification here at Prime Focus with this 550mm FL 'scope would be 20x

http://www.astro.sho....htm#calculator

http://www.canon.co....MOS_Sensor.aspx

...whereas according to Mr.Suiter's book you should instead be Star Testing at 100x with a 4" refractor (1x per mm). Presumably you should also be using the Eyepiece Projection method, and an integration of say 2000 frames of short exposure, aligned with e.g. Registax).

I don't see how you can call this excellent optics without seeing a test at 100x .

Now, if you see these same patterns at 100x then I can see that the two large images are defocussed way too much (maybe around 18 waves or so?) whereas they should be defocussed to 12 or 10 waves at most (count the rings).

With the two medium sized patterns, they seem to be defocussed to the correct number of waves (but contrast /resolution is problematic so I can't see the ring stucture properly). The outer ring is noticeably brighter for the intra-focal pattern, so it's Undercorrected for Spherical Aberration, in this case by about 1/5 wave, simulating it with Aberrator. Yes I agree with there being a central zone (darker in centre on one pattern and brighter by same amount on the corresponding pattern).

The two small images are puzzling. They look to be defocussed by 5 or 6 waves, but the SA looks to if anything be showing overcorrection! But then again the extra-focal pattern is smaller than the intra-focal pattern, so they can't be directly compared properly I suppose.

On a side note - Suiter's book says that when there is a turned edge in a refractor, the inside focus pattern has contrasty rings, whereas the outside focus pattern has low contrast (poorly defined) rings. Oddly enough in my SN102 the situation is reversed. I have high contrast rings on the outside, lower contrast rings inside. But the outer ring is quite similar brightness on both patterns on my 102, only a bit brighter inside focus (showing maybe 1/4 wave SA undercorrection).

>guess around 1/8 P.t.v. with a very mild little center zonal defect , very smooth, but if the effect I see on the smaller defocused images is not from camera, then this optics would have a cell pinching, seen by the non round 6 corner circle

If you have two images that are oval, I always check for one pattern being at 90 degrees rotation from the other, and being oval by the same amount, which is a sure sign of Astigmatism.

I have 3.0 Diopteres (!) of astigmatism (severe) in my best eye, which means that with my SN102 I can remove my glasses at 180x and 200x (9mm Meade MA + Barlow, 8mm TV Radian + Barlow, 0.5mm exit pupil) and see a sharp round Airy disc with one rather fainter diffraction ring, but at 90x or 100x (without Barlow) (1mm exit pupil) my own astigmatism makes me see definite crosses even with my glasses on, which annoys me. My spectacles are 3 years old so maybe I need a eye test.

With low power (32x, 64x) I see very noticeable crosses on stars, I can tell it's from my own eyes because when I defocus the pattern is rather oval (unlike at high power) and the pattern's ovality rotates WHEN I ROTATE MY HEAD, and at high power there is just a little astigmatism and the oval pattern stays fixed in orientation. When stars go towards the edges of the field the eyepiece off-axis astigmatism dominates the view. With my glasses off, my eye's astigmatism dominates everything and stars are horrendous crosses.

-----------


For this second scope you do not supply any details of what the magnification is that I am seeing the diffraction pattern at, so with respect, any opinions would be meaningless unless you can tell us what the magnification is. Also the amount of defocus is far too high and the rings are very low contrast. Not a useful star test IMHO.

--------


>aboe not a to bad either, it has a small turned edge ( undercorrection) and a visible center zon, so this one would be around my lower border for passing

Again you do not give the magnification that the diffraction pattern is being viewed at (which again is of course critical) but OK let's assume that it is at an appropriate magnification, in which case WOW yes it has a very obvious turned down edge.

Using Aberrator 2, since Aberrator 3 doesn't seem to be able to simulate TDE (?) then I see about 1/4 wave of TDE, which is not "small", considering that this looks to be an expensive APO.

>finaly, the guys you mention I know personaly very well from old days and I repesct here work very much, but they are in no way reference people for me for doing startests, not at all.

Sorry I don't agree at all. I have read many of Ed Ting's reviews and he is a very experienced Star Tester and I would trust what he says (since he is not a seller or manufacturer LOL). With respect, you are not going to be an independent tester of these intruments that you are going to be selling. Hence my wanting to see some indepedent reviews (of RANDOM samples), plus at least a number of people who are also happy with the star test, before I order. Otherwise, I have seen too many optics which do not satisfy me.

I read somewhere that there are machines that can lay down 1/10 wave onto glass repeatably. Yet I see a lot of telescopes with 1/2 wave SA etc. That's the part I don't understand.

At this time I only trust TMB, Takahashi, or AstroPhysics. If someone else can keep the quality control consistently high then I would trust them too. Otherwise I have read too many reviews from experienced figures in the hobby which say things like "noticeable astigmatism on this C9.25" etc...

Quality control is EVERYTHING. LOL.


>on Top here http://www.teleskop-...apochromats.jpg

With respect, the person who has created these has not supplied details of what the magnification is of the diffraction pattern, thereby making these star test or comparisons useless. Also these are star tests on Vega, when instead Suiter states in his book that one should be using a mag. 2 star for 4" and maybe mag. 3 for 6" and larger. Not Vega, which will overestimate the aberrations.

Just my personal opinions based on what I read in Suiter's book and what Aberrator 2/3 shows me.

Regards,

Alistair G.

Hi Allister

1, everybody who does a startest or imaging a startest understand that the first image is not a prime focuse image, but a projection image, otherwise you would not get such big scale

the brightness of the images depends on exporshure times. The brightness is not important at all and not what you looking for, you look for the symmetry and if they the fressnell rings are nice and smooth and if the outer bright ring is very similar

Please use aberrator and show me your estimation of 1/5 wave side by side with this given images

regards contrast of the fressnell rings you suiter is right what he say, if you do the test right. Any apo has spherochromatism and thats why you use filters .
Apos have if perfect made a perfect spherical correction at one wavelength, normaly at green, so if you use a green filter you see perfect image on both sides, but if you use in same scope a blue or red filter you see diffrences due the spherochromatism


Second image: you are partly right, but a scilled startester or optician still can read a lot out of the second image and it shows no big errors

third image : 1/4 wave turned edge is formyself to much too, but you would not believe how many apos have such level of correction, even some famous once

You trust whom you want, your deal, I trust with whom I did togher a startest and I did startesting with ED and I have my own opinion

You trust companys due here long time earned reputation, I dont , I have seen from any company in the world , from any apo maker in the world, good and bad optics

The person who created that startests also tests by interferometer, yes he could or should supply more info, but people who know startesting very well, still can read a lot out of those pictures

the first scope was interferometrical tested with 1/6.5 wavefront p.t.v. and 96.5% strehl and thats a superb optics, espcialy when you consider its a F/5.5 triplet