Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

What is a good NV eyepiece white phosphorous and inexpensive?

  • Please log in to reply
32 replies to this topic

#26 t_image

t_image

    Gemini

  • -----
  • Posts: 3214
  • Joined: 22 Jul 2015

Posted 12 May 2019 - 04:23 PM

And if one needs additional examples of how added layers of amplified noise can adversely impact clarity, they need look no further than the posts of the contrarian, above.......

I see what you you did there, very kind of you sir.

However fun you mental experiment may be,

you are starting with false premises (readily available mono camera sensors are as sensitive as NV sensors)--by NV sensor do you mean intensifier tube?

Your lack of precision is confusing.

You additionally do not recognize the ceiling of amplifier noise you talk about is far above some simplistic notion of what you imagine.

It is rather making a distinction without a practical difference. And why bring IQ into a discussion in the EAA?

Do you intend to criticism the whole of EAA because it doesn't have the IQ of long exposure photos?

 

And a pre-amplifier in a system that can image particular things is much better than a system than cannot possibly image those particular things under any other circumstance.

That's why for example meteor trackers aren't using your mythic "mono camera sensors that are as sensitive as NV....."


  • Doug Culbertson, Vondragonnoggin and cnoct like this

#27 Rickster

Rickster

    Viking 1

  • *****
  • Posts: 838
  • Joined: 09 Jun 2008
  • Loc: NC Kansas Bortle 3 SQM 21.8+

Posted 16 May 2019 - 03:52 PM

VND,

When it comes to imaging, you gain absolutely nothing by putting an intensifier in the light path.  It does not reduce exposure time.  It is simple physics.  Cnoct has said this many times.  I am sure jdbastro will also confirm it if asked.

 

 

 bigshock.gif Really! 

 

If image intensifiers didn't reduce exposure time, I certainly wouldn't be exclusively using them for all my NV astro captures, both video and stills. 

 

I and my NV astro digital footprint disagree with you!
 
 

 

 

 

OK, That isn't exactly what Cnoct said.  Here is what he actually said.  (It took me a while to find it).

 

"In contrast, low cost ccd/cmos imaging cameras will outperform the comparatively higher priced image intensifier when it comes to stills it's not even a contest, ccd/cmos is the best technology for this type of imaging. So for me, taking photos of celestial objects is still the domain of ccd/cmos cameras while real time video and viewing is the domain of image intensifiers." 

 

https://www.cloudyni...a/#entry6902162


Edited by Rickster, 16 May 2019 - 03:54 PM.


#28 Vondragonnoggin

Vondragonnoggin

    Cosmos

  • *****
  • Posts: 8619
  • Joined: 21 Feb 2010
  • Loc: Southern CA, USA

Posted 16 May 2019 - 07:52 PM

I think it’s obvious that his statement was referring to resolution quality and nothing to do with exposure time and that was the confusion - an Intensifier in the light path increases light sensitivity and therefore decreases exposure time needed.

 

This is why emICCD beats emCCD when going to single photon detection and sensitivity.

 

https://www.princeto...hnote_revA2.pdf

 

That would be an obvious benefit to some (obviously to scientific imaging by the link I gave). I definitely think the blend of camera and Intensifier has a valid place in EAA and we have members that have been doing this for years. Discriminating against the process or trying to one-up the method by statements trying to invalidate it isn’t in the best interest of the forum or users interested in the method.

 

Maybe someone with a monochrome ccd doing narrowband Ha can explain their focus process also.

 

With my unmodified Nikon D3300 entry level DSLR, my focus process with a 3nm Ha filter was to look in the viewfinder and turn the focus knob until the view of the nebula and sparse stars showing through were in focus. Very easy focus process just looking in the viewfinder. Is the focus process with a 3nm or 5nm narrowband on a monochrome ccd a live view focus of the nebula, or is it a bahtinov mask used on a bright star and some exposure time or integration time required for the nebula to actually show up?

 

I would encourage the OP to try this out if he is interested, but to get the big narrowband benefit of decreased exposure time the best, a gen 3 Intensifier should be used.

 

I think with the testimonials here in this thread, that the question of Intensifier benefit can be put to rest. Yes a benefit - of decreased exposure time at the expense of resolution.


  • cnoct and Jim4321 like this

#29 Rickster

Rickster

    Viking 1

  • *****
  • Posts: 838
  • Joined: 09 Jun 2008
  • Loc: NC Kansas Bortle 3 SQM 21.8+

Posted 17 May 2019 - 11:19 PM

There is no point in getting angry with me Eric.  Digital technology is taking over.  It won't be long before intensifier tubes are obsolete curiosities.  Neither of us will have any influence in the matter.  You may as well relax and enjoy the ride.  I know I am.



#30 Vondragonnoggin

Vondragonnoggin

    Cosmos

  • *****
  • Posts: 8619
  • Joined: 21 Feb 2010
  • Loc: Southern CA, USA

Posted 17 May 2019 - 11:27 PM

There is no point in getting angry with me Eric.  Digital technology is taking over.  It won't be long before intensifier tubes are obsolete curiosities.  Neither of us will have any influence in the matter.  You may as well relax and enjoy the ride.  I know I am.

I’m not angry Rick. Just frustrated by some attitudes toward NV in a forum it is supposed to be accepted in. It was clear that when experienced users who have combined intensifiers with imaging spoke out to correct your misinformation that you posted angrily to try to paint it in a negative light (which you are still doing).

 

I find it runs opposite of the inclusivity that this forum is supposed to convey.


  • cnoct, Gavster and Jim4321 like this

#31 11769

11769

    Vostok 1

  • -----
  • Posts: 129
  • Joined: 04 Jul 2017
  • Loc: TX

Posted 18 May 2019 - 12:47 PM

There is no point in getting angry with me Eric.  Digital technology is taking over.  It won't be long before intensifier tubes are obsolete curiosities.  Neither of us will have any influence in the matter.  You may as well relax and enjoy the ride.  I know I am.

 

Expect image intensifiers to remain dominant for ~20 more years at a minimum. They will be displaced but not because of digital imaging sensors being overwhelmingly superior but because digital will offer additional capabilities that will be beneficial to the mission. Right now, intensifiers beat digital on a per power, per weight, and per volume basis and beat digital hard. That advantage will diminish somewhat with time but will always remain. It'll just matter less and less for the primary end users of intensifiers and high end digital imaging sensors. Things like requiring supplemental data overlay for almost all users will drive the technology towards digital, not raw performance. There's also a big push towards using other portions of the spectrum often in conjunction with active illumination where digital sensors operate very well but image intensifier performance falls off or has always been dominated by digital sensors. 


  • Vondragonnoggin likes this

#32 cnoct

cnoct

    Viking 1

  • *****
  • Posts: 752
  • Joined: 02 Sep 2010
  • Loc: Hawai'i

Posted 15 June 2019 - 02:42 AM

Hubble's Faint Object Camera (FOC) used two identical image intensifiers, EMI 9614 40mm Gen 1 cascade tubes, UV-Blue tubes no less.
 
gallery_139776_8407_17828.png
 

Those twin image intensifiers are credited with some pretty significant discoveries and records - Successes of ESA's sharp-sighted camera, the Faint Object Camera and Hubble's Faint Object Camera/ESA's Sharp-Sighted Camera Sets World Record

 

If intensifiers were good for imaging, Hubble would have one, the pro astronomers would use them, the guys on the AP forum would be using them, etc.


Some interesting technical details about Hubble's image intensified system:

Image Intensifier and Coupling Lens

The intensifier is an EMI 9614 three stage tube magnetically focused by means of a permanent magnet. The first-stage photocathode (like the following two) is a hot bialkali for the highest quantum efficiency in the UV-blue region and the lowest dark-count rate at 17 ̊C. It has a useful diameter of 40mm and is deposited on a MgF2 input window.

The photoelectrons generated at the first stage are accelerated by a 12 kilovolt potential and impinge on a P11 phosphor layer coupled by a 4 micron thick mica membrane to the second pho- tocathode. This amplification process is repeated in the second and third stages to achieve an overall photon gain of 1.3 × 105. Focusing of the intensifier electrons is accomplished with a care- fully shaped permanent magnet assembly and a trimcoil is added around the third stage for fine adjustments.
The limiting spatial resolution of the intensifier is 35 line-pairs per millimeter. The dark cur- rent at an ambient temperature of 17 ̊ C is less than 10 counts cm-2 s-1 (10-4 counts pixel-1 s-1 in the normal mode). Both of these characteristics are essentially limited by the first stage of the intensifier tube.

A lens assembly consisting of 9 components in a double Gaussian design is used to transfer the image from the output phosphor of the intensifier to the fiber-optic faceplate of the TV cam- era. It is designed to operate at f/2.7 with a slight magnification (1.15) to compensate for the demagnification of the image intensifier. The 80% energy width for point object images varies between 22 and 35 microns over the whole of the useful area and the light transmission is more than 60%.


  • Jeff Morgan, moshen, jdbastro and 4 others like this

#33 Rickster

Rickster

    Viking 1

  • *****
  • Posts: 838
  • Joined: 09 Jun 2008
  • Loc: NC Kansas Bortle 3 SQM 21.8+

Posted 16 June 2019 - 02:34 AM

The Faint Object Camera (FOC), removed from Hubble in early 2002, functioned during its time aboard as Hubble's "telephoto lens." The FOC recorded high-resolution images of faint celestial objects in deep space, taking the most detailed images over a small field of view. It was replaced by the more powerful Advanced Camera for Surveys.

 

Intensifier aided cameras were the hot ticket in the 1990s.


  • moshen likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics