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Photonis 4G P43 Intensifier Stills / Videos with Tak Mewlon 250

EAA NV
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#1 jdbastro

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Posted 08 July 2019 - 01:10 AM

I picked up another Photonis image tube recently.  This one has the more familiar P43 (green) phosphor vs the longer decay time and deeper green P22 tube that I have used previously.

 

As with other Photonis 4G (aka INTENS) tubes, this tube has a very smooth screen texture when viewing the sky at typical fast NV f ratios.

 

Sensitivity is pretty good though I have not yet done a direct comparison to a US made tube (like an L3 unfilmed) under dark skies.   One of these days.....

 

Finally made it to Mt Pinos over the weekend (first visit this year for me) and put this guy through its paces while connected to my Tak Mewlon 250/f12.

 

Here are some sample stills that I took (all single exposure, within 30 sec, low ISO):

 

1) M 13

M13 Glob Her Mew250 F12 10sec 50iso

 

2) M 92

M92 Glob Her Mew250 F12 10sec 50iso

 

3) M 4
M4 Glob Sco Mew250 F12 13sec 50iso

 

4) M 51

M51 Gxy Mew250 F12 25sec 50iso

 

5) NGC 5907

NGC5907 Gxy Dra Mew250 F12 25sec 50iso

 

6) NGC 7331
Ngc7331 Gxy Peg Mew250 F12 25sec 50iso

 

7) NGC 7332 & 7339

Ngc7332 7339 Gxys Peg Mew250 F12 30sec 50iso

 

8) M57 (at f48 with Omega Optical H&O LPF filter)

M57 RingNeb Lyr Mew250 F24 OmegaLPF 30sec 100iso

 

9) NGC 6888 (with Omega H&O LPF)

Ngc6888 CrescentNeb Mew250 F12 OmegaLPF 30sec 320iso

 

10) M27 (with Omega H&O LPF)

M27 DumbbellNeb Mew250 F12 OmegaLPF 30sec 50iso

 

11) Trifid (with Omega H&O LPF)

TrifidNeb Mew250 F12 OmegaLPF 30sec 100iso

 

12) Jupiter with moons and Red Spot (with narrow band Methane filter)

Jupiter Mew250 F48 Methane 4G 0.5sec 50iso

 

 

Also shot a few real-time videos:

 

1) M 13 and M 92 globulars

 

2) Jupiter in the Methane band (can you see the Red Spot?)

 

 

The Omega Optical filter is available on eBay at this link.


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#2 highfnum

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Posted 08 July 2019 - 06:49 AM

whats average exposure time?

 

what does H&O LPF filter stand for?


Edited by highfnum, 08 July 2019 - 06:50 AM.


#3 highfnum

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Posted 08 July 2019 - 07:00 AM

never mind about filter  I saw it   o3 and hydrogen Ha  depress  other freq 



#4 11769

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Posted 08 July 2019 - 01:21 PM

Really nice pics and videos. Actual Intens tubes are not the easiest to come by. What's the SNR and EBI on your tube?



#5 jdbastro

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Posted 08 July 2019 - 01:48 PM

whats average exposure time?

 

what does H&O LPF filter stand for?

On exposure time:

 

Rule 1 for me: Keep the camera ISO as low as possible.  This results in a 'richer' looking 'higher res' resulting still.  Given that, for my A7 III camera and the APS-C format relay lens that I was using (BE Meyers Dark Invader 702-DS relay), for Clusters - about 10 sec, for Galaxies - 20-30 sec, for nebulae with the Omega filter - 25-30 sec.

 

Rule 2 for me:  Screw exposure times over 30 sec.  If I can't capture the target in 30 sec, I generally don't pursue the target.  Reason is a combination of laziness and insufficient tracking accuracy since I don't have an auto-guiding system and I polar align with an Ipad and polar scope (Astro-Physics system).


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#6 jdbastro

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Posted 08 July 2019 - 01:51 PM

Really nice pics and videos. Actual Intens tubes are not the easiest to come by. What's the SNR and EBI on your tube?

Thanks.  Specs on the 4G P43 tube I have are:

 

SNR=30.35

EBI = 1.1 (US units)

Lum Gain = 57127 (US units)


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#7 Gavster

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Posted 08 July 2019 - 02:49 PM

Thanks.  Specs on the 4G P43 tube I have are:

 

SNR=30.35

EBI = 1.1 (US units)

Lum Gain = 57127 (US units)

It’s interesting that the green photonis 4g tubes generally have much higher lum gain than the white phosphor ones (which are typically between 30,000 and 40,000), not sure why...


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#8 Gavster

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Posted 08 July 2019 - 02:54 PM

On exposure time:

 

Rule 1 for me: Keep the camera ISO as low as possible.  This results in a 'richer' looking 'higher res' resulting still.  Given that, for my A7 III camera and the APS-C format relay lens that I was using (BE Meyers Dark Invader 702-DS relay), for Clusters - about 10 sec, for Galaxies - 20-30 sec, for nebulae with the Omega filter - 25-30 sec.

 

Rule 2 for me:  Screw exposure times over 30 sec.  If I can't capture the target in 30 sec, I generally don't pursue the target.  Reason is a combination of laziness and insufficient tracking accuracy since I don't have an auto-guiding system and I polar align with an Ipad and polar scope (Astro-Physics system).

I like your rules - I’ve found them a great help with my phone nv imaging where I generally use iso 50 or 100 and exposure times between 6-10 secs for clusters and galaxies and 15-30 secs for nebulae with my ha filter.


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#9 11769

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Posted 08 July 2019 - 04:22 PM

Thanks for the specs. Always interesting how narrow the spread is on Photonis specs. SNR is typically 30-32 and EBI hovers around about 1.5. Something tells me Photonis "tunes" their tubes before they leave the factory. Power supplies are digitally programmable, just like current US tubes. EBI is always "good" but not great. Don't think I've seen a Photonis tube with an EBI of 0.5 or less (again, US units). At 1.1, I think it's one of the lowest EBI Photonis tubes. Whatever they're doing with the photocathode, they're either trying to squeeze as much as they can out of it or if it's a NEA photocathode, it's seeing more thermionic emission than cesiated GaAs. 

 

As for the luminance gain, the WP used by Photonis is different than what L3 uses. Plausible their WP formulation emits fewer photons per electron than L3's formulation or fewer photons per electron than P43 (about 200 photons per electron at 6keV for P43).


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