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08-07-2019, 10:55 AM   #16
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QuoteOriginally posted by dsmithhfx Quote
Not crazy enuf for some folks.
Crazy enough for lomography fans lol

08-07-2019, 11:05 AM - 1 Like   #17
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I still prefer a zoom over a prime distance lens. But I can see catch in focus working great with this feature. Say it's a 2meter focus lens. Get about where you need to be and walk toward your subject and shutter clicks while you maintain composition.
08-07-2019, 12:50 PM - 1 Like   #18
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This item has been discussed previously. I will merge the two threads.
08-08-2019, 02:26 AM   #19
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Comments are hilarious !

08-08-2019, 03:37 AM   #20
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QuoteOriginally posted by Paul the Sunman Quote
Unfortunately, the lens has to be defined for a particular distance to the subject. It could be infinity.
But I terms of solving the issue for telescopes, it will work just fine. Everything is at an infinite distance.
08-08-2019, 11:53 AM - 1 Like   #21
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Photoptimist and others citing reality,

I am a Chemist and my daughter is a Physicist. When we are joking about research, one of the standard pun lines is..."it was modeled as a spherical object in a vacuum at one wavelength and temperature". Reality versus hope. Hope is not a method. Simplified models do not translate well into over-arching multivariate problems. More work is needed and more Nutella!

JB
08-08-2019, 02:12 PM   #22
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QuoteOriginally posted by Lowell Goudge Quote
But I terms of solving the issue for telescopes, it will work just fine. Everything is at an infinite distance.
Astronomical telescopes generally use mirrors instead of lenses.

---------- Post added 09-08-19 at 07:13 AM ----------

QuoteOriginally posted by Take-5-JB Quote
I am a Chemist and my daughter is a Physicist. When we are joking about research, one of the standard pun lines is..."it was modeled as a spherical object in a vacuum at one wavelength and temperature". Reality versus hope. Hope is not a method. Simplified models do not translate well into over-arching multivariate problems. More work is needed and more Nutella!
JB
I'm a mathematician, and I think it's just fine.

08-08-2019, 02:30 PM   #23
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QuoteOriginally posted by Take-5-JB Quote
Photoptimist and others citing reality,

I am a Chemist and my daughter is a Physicist. When we are joking about research, one of the standard pun lines is..."it was modeled as a spherical object in a vacuum at one wavelength and temperature". Reality versus hope. Hope is not a method. Simplified models do not translate well into over-arching multivariate problems. More work is needed and more Nutella!

JB
I think the problem is that articles are written by reporters while scientists are doing the research. And I am not sure who is writing the headlines.

So a scientist says that he has found 'x' gene in mice that is linked to a certain type of dementia and suddenly reporters are spinning it into stories about the possibility of medications to treat Alzheimer's Disease. Here, the story is talking about smaller and sharper lenses, which is definitely not what this researcher was studying and for all we know, the lenses that fix aberrations may be larger than those with aberrations (probably will be)....
08-08-2019, 05:32 PM   #24
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QuoteOriginally posted by Paul the Sunman Quote
Astronomical telescopes generally use mirrors instead of lenses.
Not for the eyepiece, and the mirrors are not spherical elements, they are parabolic. (Except for the Hubble, which was made wrong because of the new computerized measurement system they used, to replace the method for testing the parabolic grind of a main mirror.
08-08-2019, 08:45 PM   #25
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QuoteOriginally posted by Lowell Goudge Quote
Not for the eyepiece, and the mirrors are not spherical elements, they are parabolic. (Except for the Hubble, which was made wrong because of the new computerized measurement system they used, to replace the method for testing the parabolic grind of a main mirror.
Schmidt-Cassegrain telescopes use Spherical primary mirrors with aspherical correction lens elements. So, the generalization about parabolic mirrors is not true in all cases.

See Maksutov, Schmidt-Cassegrain and Ritchey–Chrétien (aka Hubble) for other non-parabolic mirror telescopes. It is just to easy to over generalize.

Take a look at the list of large Ritchey–Chrétien telescopes - primary mirror is hyperbolic - very few parabolas there. https://en.wikipedia.org/wiki/Ritchey–Chrétien_telescope

Last edited by PDL; 08-08-2019 at 08:51 PM.
08-09-2019, 03:18 PM   #26
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Paul the Sunman and Rondec,

That maybe the difference in reading Popular Mechanics versus a reviewed journal article written by the authoring researcher. In industrial work we had to include an Executive Summary cover page with general purpose and conclusions summary, but no methods, data, or statistical data evaluation.

I appreciate the comments by the folks on this website that have knowledge of Optical Physics and Engineering. Keep informing the rest of us.

JB
08-28-2019, 07:45 AM   #27
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QuoteQuote:
It is unclear whether he finished eating the bread with Nutella.
That's the part I wanted to know the most though.
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