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Homemade 0,65m f 1.5

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#26 Jon Isaacs

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Posted 23 September 2019 - 06:53 AM

I don't know if any of this really matters, except to give Valery Terebizh proper credit for all the telescope optical designs used for Borisov's comet discoveries.

 

 

Mike:

 

I find it interesting, I am definitely glad you made the effort to post it.  

 

Jon



#27 PrestonE

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Posted 23 September 2019 - 08:13 AM

Here is Gennady Borisov's discovery page in a Russian Forum...

 

https://astronomy.ru...c,175643.0.html

 

Very interesting Forum overall...

 

Best Regards,

 

Preston



#28 Vla

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Posted 23 September 2019 - 10:51 AM

Gennady Borisov: a homemade Hamilton telescope.

https://astronomy.ru...html#msg4827179

Not much about the instrument itself, only Borisov saying it's a "pure" Hamiltonian. He said he'll described it in more details if forum members show interest, but somehow they did not. Since "pure" Hamiltonian does not have field corrector, it is not the accurate description, since this kind of system wouldn't work without it. The simplest next configuration is with a singlet field corrector, and here's what it looks like (I rescaled it down to match the f# and forgot to scale back to 325mm, so everything is 4% smaller). This thing could actually work even as it is, but astigmatism - needed to flatten the field - can be reduced by reducing Petzval curvature, mainly inflated by the front surface of field corrector, relatively insensitive to aberrations. So it can be better than this, and that would be important for making the super-tight tolerances little more relaxed. I read in a PDF file that this kind of instrument needs to cover 0.3 micron spectral range, and produce not larger than 2-3 arc seconds spots. This system satisfies that requirement up to about 1.2 degree field radius. At 1 degree the 80%-energy (polychromatic) is 12.7 microns, 18.9 microns at 2 deg (w/o seeing of course).

 

As for to whom goes credit for the system, far as I know it is Busack from Germany (although Honders and Riccardi may have independently created similar systems later). Btw. if you ask Borisov where does he work, am sure he'll say Russia, not Ukraine.

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#29 Ed Jones

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Posted 23 September 2019 - 11:41 AM

His avatar even though it's small looks like there is a full aperture lens in front of the imager.

#30 PrestonE

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Posted 23 September 2019 - 12:18 PM

In the video, it shows a Full Aperture Lens just behind the spider assembly that is 

holding the Camera and whatever else...

 

Preston



#31 555aaa

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Posted 23 September 2019 - 02:22 PM

<snip>

 I read in a PDF file that this kind of instrument needs to cover 0.3 micron spectral range, and produce not larger than 2-3 arc seconds spots. This system satisfies that requirement up to about 1.2 degree field radius. At 1 degree the 80%-energy (polychromatic) is 12.7 microns, 18.9 microns at 2 deg (w/o seeing of course).

 

<snip>

That makes sense - the ATLAS survey telescopes on Maui (f/2 0.5m) have a 1.9 arc sec per pixel scale and a design PSF of about 3.8 arc seconds at 1.5 arc second seeing.  https://arxiv.org/pdf/1802.00879.pdf



#32 Vla

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Posted 23 September 2019 - 02:39 PM

Our friend at TEC, Yuri Petrunin, regularly reads this and other Cloudynights forums.  He knows a load of Russian optical and astronomical folks, and wrote me with some additional information on Borisov's telescope.  Here's some of what Yuri wrote, with his permission to put on CN.  The only purpose here is to give proper credit where credit is due.

 

Start this with a Google search on "valery terebizh".  You will be amazed.

 

All of Borisov's comets were discovered with telescopes designed by Dr. Valery Terebizh (VT), an excellent optical designer of a number of different wide-field, low focal ratio astrographs.  Many of Terebizh's designs have been built, including all the instruments Borisov used to discover comets listed below.  

 

Comet              Instrument     Design
C/2013 N4 (Borisov)  GENON        VT78-A  (First comet of independent Ukraine)
C/2013 V2 (Borisov)  GENON        VT78-A
C/2014 R1 (Borisov)  GENON Max    same but scaled 1.5X or other VT design
C/2014 Q3 (Borisov)  GENON Max    same but scaled 1.5X or other VT design
C/2015 D4 (Borisov)  GENON Max    same but scaled 1.5X or other VT design
C/2016 R3 (Borisov)  GENON Max    same but scaled 1.5X or other VT design
C/2017 E1 (Borisov)  GENON Max    same but scaled 1.5X or other VT design
C/2019 Q4 (Borisov)  no name yet  VT-8b scaled (Hamilton)

 

This site is interesting, but fails to mention that the optics for all the GENON scopes above were designed by Terebizh:

 

https://uk.wikipedia...орисов_Геннадій

 

Yuri said that the optics for Borisov's 650mm F1.5 system were made by highly skilled professional opticians.  Borisov evidently made and assembled the telescope mechanical parts, but he did not make the optical components.

 

The telescope is installed in the dome that belongs to Roscosmos, a company that does government military orders for satellite tracking programs.

 

https://www.roscosmos.ru/26801/   

 

When translated to English the first paragraph states: "Director General of Roscosmos State Corporation Dmitry Rogozin met with an employee of the Crimean Astrophysical Observatory Gennady Borisov. Using a telescope reflector of his own manufacture, the astronomer made the discovery of the first interstellar comet."

 

Borisov really put Ukraine on the map by discovering this interstellar comet.  But to clarify, "...of his own manufacture" does not mean Borisov made the optics, rather he had them made and integrated them into his telescope structure.

 

I don't know if any of this really matters, except to give Valery Terebizh proper credit for all the telescope optical designs used for Borisov's comet discoveries.

Interestingly, some Russians on the forum at the link posted by Preston follow CN, and they posted this Petrunin's account there. Borisov says it is incorrect, in that he didn't scaled up Terebizh VT design, saying that Terebizh himself told him it can't be simply scaled up, and that the calculations for a bigger system of that kind would take to long for him to do, so Borisov did it himself (at the time the two were working close to one another, not sure was it for the same institution). Also, for scaling VT8b, Borisov says he never saw it, and that he didn't speak about optics with Terebizh since February 2013.

 

A forum member ironically asked if someone discovers a comet with self-made Newtonian, should he acknowledge credits to Isaac Newton? We don't know other than what is said, but it is just as much possible that someone is looking for a credit where there is none to give.


Edited by Vla, 23 September 2019 - 03:24 PM.

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#33 PrestonE

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Posted 24 September 2019 - 09:30 AM

"Not much about the instrument itself, only Borisov saying it's a "pure" Hamiltonian. He said he'll described it in more details if forum members show interest, but somehow they did not."

 

Would it be possible to reach out to Borisov on the Russian Thread and ask for more information???

 

I for one would be very interested!!!

 

Though I do not speak Russian confused1.gif confused1.gif confused1.gif

 

Best Regards,

 

Preston



#34 Vla

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Posted 24 September 2019 - 01:20 PM

Neither do I, which is a shame, since I had it in school altogether 10 years. If you don't speak, you lose it. But I still understand, written better than spoken. I posted question, will see if he is still around. Not sure he would give the prescription, though. And, I was curious what the configuration with a singlet field corrector looks like when astigmatism is taken out. So here it is: significantly better, although still not as good as Schmidt camera on its best (curved) field.

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#35 PrestonE

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Posted 24 September 2019 - 01:49 PM

"I posted question, will see if he is still around. Not sure he would give the prescription, though."

 

Thanks Vla...

 

I don't see why he would post the perscription...as made by professional optician and not likely

copied as Too Expensive...

 

Let's hope he replies...

 

PS...what type of glass is needed for the Margin Primary???

 

Best Regards,

 

Preston



#36 PrestonE

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Posted 24 September 2019 - 03:55 PM

Gennedy just posted that it is an All Spherical System with the below design...

 

with a 3 element corrector...

 

65cm Gennady.JPG

 


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#37 Vla

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Posted 24 September 2019 - 05:31 PM

Well, now we know it, finally. I'm a little surprised it employs 3-element field corrector, since seems that even a singlet can do admirable job. But more lenses make possible better correction of spherochromatism, and there could be some extra requirements that were addressed. Borisov says it performs well in practical use, but he is a professional using it in a professional facility, so it is a level or two above even advanced amateur telescope maker's.


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#38 PrestonE

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Posted 24 September 2019 - 05:52 PM

Vla, But would not the all spherical surfaces be Much Easier for an Amateur to do???

 

Keep the wedge under control, and then hit the radi to the specs...maybe a few test plates to make

for those surfaces that cannot be tested otherwise.

 

The ASC 330 that Jones designed for me is also All Spherical, but less lenses I think

and no Margin Primary...

 

What type of glass would one be needing for the Margin Primary, BK7 ok?

 

Best Regards,

 

Preston



#39 Steve Dodds

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Posted 24 September 2019 - 06:46 PM

Vla, But would not the all spherical surfaces be Much Easier for an Amateur to do???

 

Keep the wedge under control, and then hit the radi to the specs...maybe a few test plates to make

for those surfaces that cannot be tested otherwise.

 

The ASC 330 that Jones designed for me is also All Spherical, but less lenses I think

and no Margin Primary...

 

What type of glass would one be needing for the Margin Primary, BK7 ok?

 

Best Regards,

 

Preston

It's almost certainly BK7 it's cheap and available in  large sizes.  You really need a good reason to use something else.


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#40 Vla

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Posted 24 September 2019 - 07:05 PM

BK is a top quality glass, and it's cheap. One possible factor is sensitivity to thermal changes, but it can be controlled with fans. Some years ago I remember Roland Christen, who was about to produce Riccardi's version of this kind of astrograph, was concerned how it will perform in practice, because of tight tolerances. When someone with so many triplets behind him has those worries, there's probably some substance to it (and it was, as I remember, f/3.x system about half as large).


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#41 An18

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Posted 27 September 2019 - 04:23 AM

Well, now we know it, finally. I'm a little surprised it employs 3-element field corrector, since seems that even a singlet can do admirable job. But more lenses make possible better correction of spherochromatism, and there could be some extra requirements that were addressed. Borisov says it performs well in practical use, but he is a professional using it in a professional facility, so it is a level or two above even advanced amateur telescope maker's.

It's a bit of overdesigning, but systems targeted for professional use often do require beautiful tight spots at advertizing stage. In real life these astrographs usually perform near 1.5-2 pixels FWHM average frame quality, even if their design performance is about 80% energy in pixel or even diffraction-limited performance for slower systems. Below is a comparative RMS spot plot for both versions - 3-lens design looks really attractive on paper, but it's often more practical to built relaxed system with less elements. BTW, Santel is now building 0,5m f 1.5 for Chile, singlet design targeted for CMOS Gpixel 6060 and 4040 for initial operation. For 0.5m difference between these designs is conciderably smaller for the same linear field, 61x61 mm chip (second plot). Both plots are for weighted wavelegth set for typical BI-CMOS.

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  • 650-1.5-1lensvs3rmsspt.JPG
  • 500-750 1lensvs3rmsspt.JPG


#42 Mike I. Jones

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Posted 27 September 2019 - 03:58 PM

I designed this 650mm f/1.5 3-element astrograph to overlay the graphic Preston posted almost exactly.  Zemax file attached.  Note the RMS vs. field curves I was able to achieve compared to the plots above.

 

Attached File  650mm f1_5 Hamiltonian guess 6 based on Prestons plot from Borisov NO MF.zmx   11.95KB   12 downloads

 

650mm f1_5 3LFC Hamiltonian astrograph prescription.jpg

 

650mm f1_5 3LFC Hamiltonian astrograph layout.jpg

 

650mm f1_5 3LFC Hamiltonian astrograph RMS.jpg


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#43 Mike I. Jones

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Posted 27 September 2019 - 04:03 PM

This is the MTF I achieved for a 650mm f/1.5 Hamiltonian astrograph with the 3-element corrector as shown in Preston's plot above.  Plenty of modulation out to 100 cy/mm (equal to 5µm pixels).  These Hamiltonians are the way to go for very fast astrographs with moderate field coverage.

 

650mm f1_5 3LFC Hamiltonian astrograph MTF.jpg

 


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#44 PrestonE

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Posted 27 September 2019 - 04:48 PM

Hola Mike...I'm going to regret knowing you someday bow.gif bow.gif bow.gif

 

"This is the MTF I achieved for a 650mm f/1.5 Hamiltonian astrograph with the 3-element

corrector as shown in Preston's plot above.  Plenty of modulation out to 100 cy/mm (equal to 5µm pixels). 

These Hamiltonians are the way to go for very fast astrographs with moderate field coverage."

 

I am guessing that the Corrector glass is really going to cost in those sizes, approaching 8 inches diameter???

 

What about the Correctors for something like my 330mm BK7 blanks that I was thinking into making Jones 330ASC

 

Looks like if it scales down Ok...then the Primary Margin mirror in BK7 would be around 250mm...doable in cost.

 

Is this an "All Spherical System" also?

 

At F1.5 if the corrector blanks do not kill the bank, I would really be interested in this design.

 

Nothing wrong with Ed's , but the speed is really interesting and wide field to boot...

 

Your one of the Kindest most giving people on this board and it is Very Much Appreciated. bow.gif bow.gif bow.gif

 

You stimulate the old Knogen or the gray matter between the ears.

 

Best Regards,

 

Preston


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#45 Mike I. Jones

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Posted 27 September 2019 - 11:54 PM

funnypost.gif funnypost.gif

 

Yes, all spherical.  Scaling down to perhaps 300mm or 330mm could make the corrector lens glasses more likely to be available. 

 

What is the ASC 330?  Is it something Cuzzin Ed did, or me?  Can't recall.

 


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#46 PrestonE

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Posted 28 September 2019 - 07:43 AM

Cuzzin Ed's 

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#47 gregj888

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Posted 28 September 2019 - 05:45 PM

Hola Mike...I'm going to regret knowing you someday bow.gif bow.gif bow.gif

 

"This is the MTF I achieved for a 650mm f/1.5 Hamiltonian astrograph with the 3-element

corrector as shown in Preston's plot above.  Plenty of modulation out to 100 cy/mm (equal to 5µm pixels). 

These Hamiltonians are the way to go for very fast astrographs with moderate field coverage."

 

Best Regards,

 

Preston

Preston, I agree with you.  I'm barely making progress on my Harmer Wynn and Mike posts this....  What's a guy to do? 

 

bow.gif bow.gif bow.gif bow.gif bow.gif waytogo.gif waytogo.gif waytogo.gif 


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#48 Vla

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Posted 30 September 2019 - 03:59 PM

It's a bit of overdesigning, but systems targeted for professional use often do require beautiful tight spots at advertizing stage. In real life these astrographs usually perform near 1.5-2 pixels FWHM average frame quality, even if their design performance is about 80% energy in pixel or even diffraction-limited performance for slower systems. Below is a comparative RMS spot plot for both versions - 3-lens design looks really attractive on paper, but it's often more practical to built relaxed system with less elements. BTW, Santel is now building 0,5m f 1.5 for Chile, singlet design targeted for CMOS Gpixel 6060 and 4040 for initial operation. For 0.5m difference between these designs is conciderably smaller for the same linear field, 61x61 mm chip (second plot). Both plots are for weighted wavelegth set for typical BI-CMOS.

I thought it may be overkill just looking at the performance of a 3-singlet system. Plots that you posted show significant difference in the RMS blur size, but what really matters is energy distribution. So the key indicator is FWHM which, according to what you say, and taking pixel ~10 microns in size, comes to 15-20 microns in diameter. The simplest system of this kind shown below falls close enough to your plot RMS-spot wise, but I think we should do more detailed comparison. Mike's 3-element corrector system is better than what the plot shows, so I'll go with it as the probable near-limit scenario for the system of that type.

 

The RMS spot size for a single-element corrector, roughly averaged for the spectral range, is about 5 microns on axis and about 8 at 26mm off, which compares to nearly 3 and 4 microns, respectively, for the 3-element corrector. That looks significantly better, but we don't really know, because the RMS spot size for given magnitude of aberration can vary significantly from one aberration type to another (for instance, if we'd  replace spherical aberration, which is dominant for non-optimized lines in a single element system, with the same magnitude of astigmatism, the nominal RMS spot size will be some three times smaller). So ensquared energy is more reliable, and it shows the 80% energy square to be less than 10 microns for the optimized wavelength, and little over 13 microns for all wavelengths. That's sufficient for the ususl 15-20 micron FWHM, counting in seeing error. And the look at the MTF shows that the difference in contrast transfer between the two is significantly less than what the blur size indicates, bordering insignificant.

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  • 650.png

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#49 An18

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Posted 01 October 2019 - 01:10 PM

Cuzzin Ed's 

This design was quite popular in Russia for previous decade, thanks to V.Yu. Terebizh and Gennady Borisov. Gennady built several 220/500 versions of these systems, usually referred as Richter-Slevogt(-Terebizh), the latter was usually required by V.Yu. in papers and working documentation. Also two 350 f2.5 optical sets was made, one for MASTER network, it's now installed in Argentina and detected optical counterpart of the first LIGO event, the other was purchased by large defence contractor for military installation at Altay http://www.terebizh....t-07b/index.htm This telescope was pathfinder for current Russian medium-class military surveillance facilities "Pritsel/Sova/OEK-OKM" with 750 mm F1.9 main survey scope with 120x120 mm mosaic CCD array, with optical design also by V.Yu. Terebizh.

 

Later production of these telescopes was ceased because of swithing to Hamiltonian designs.

 

As with Hamilton-Flugge(-Canzek, and probably more from 50-70s), this was also an easy late reinvention with powerful PC and modern software, as with Busack-Honders et al., including Riccardi and again Terebizh. We can refer here for R.Casas US patent 3489487 as an example for mature design of this family. For Hamiltonians good example is L.Canzek US Patent 4487483, an the earliest example is probably Flugge (1941). So IMHO we should refer Hamiltonian optimized with singlet field corrector as Flugge, because we clearly see this design form in the book "Das Photographische Objektiv", 1955 with reference to Zeitschr. f. Instrkde. 61 (1941), S. 175.

 

I don't think that it's correct to speak about "recent invention of modern simple form", only about reinvention without reasons for giving credits. There are two reasons - the practical one, that patent or journal publication is usually the release of final results of invention process, with many intermediate simpler/poorer performance/less practical design variations behind. The second reason is fundamental - if systems are lying in same pit of MF surface in design space, they are only variations of same inventions. Slight tailoring of systems within one local optimum clearly isn't an inventive step, but is just PHOSITA's routine activity.

Attached Thumbnails

  • 3489487B.png
  • 4487483.png
  • flugge.jpg

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#50 An18

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Posted 01 October 2019 - 01:14 PM

There are several reasons to compare primarily in RMS spot sizes:

1. It's correlation with encircled or ensquared energy is pretty good for geometrically-limited systems, like discussed ones on wide field.

2. It's usually the primary design criterion for entire development cycle from global search and glass selection to tolerancing and it's very quick and useful for estimation of performance gains and harms at every design step, just by current MF value.

3. FWHM is really useful only for nearly pure gaussian PSF, like seeing-dominated or perfectly Gauss-apodized extreme cases. In the case of non-gaussian shape like non-apodized diffraction PSF, especially aberrated, or complex geometrically-limited spot it's an approximation on the brink of vulgarization.

 

I personally like Zemax universal plots like DENC vs. field, that strictly meet design targets like "80% energy in 2x2px square", but more and more often use rough estimates at design search state, like "system with less than 1px RMS spot radius over the field is good for surveillance work", especially with clear trend to extreme speeds and great practical error margins.

 

Usually it's quite difficult to make frank assessment of real quality of fast astrograph just because of coarse sampling with operational sensor, and in most cases there is no collimation/attestation fine sensor/scanner in the observatory. So overall design cycle and particulary speed/FOV improvements are made in careful steps based on prototypes with conservative parameters, because collimation tolerances dominate over nominal residual aberrations.




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