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L3 Filmless vs. Thin Film ULT.. Impressions requested...

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#26 jdbastro

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Posted 23 July 2016 - 03:08 AM

I have done side-by-side comparisons of an ITT thin-film Ultra P43 (green), an L3 unfilmed P45(white), an L3 unfilmed P43 all with similar performance specs.

 

Don't have any videos, yet.  The comparisons are all based on eyeball observations.

 

This is what I have seen using a 1X NV objective:

 

When pointing each of the three tubes (MX10160 format) into the forest at Mount Pinos, Calif, BOTH unfilmed tubes showed greater definition of tree branches and rocks on the ground in the deep dark shadows of the forest.  The thin-filmed Ultra tube showed less contrast in the deep shadows and overall exhibited a faint glow / haze on all terrestrial targets (tree branches, the ground) as if someone had placed a translucent (not transparent) film in front of the objective on the NV monocular housing.  All three tubes had the same type of housing with the same front objective.

 

When pointed at the sky the difference between the thin-filmed and unfilmed tubes was less obvious.  In fact the only difference I could see was that dimmer stars appeared sharper in my unfilmed tubes because there is a resolution difference between the thin-filmed vs unfilmed tubes - both unfilmed tubes have 72 lp/mm resolution vs. 64 lp/mm resolution in the thin-filmed Ultra tube.

 

I suspect that a video might not demonstrate the visual differences because although they are obvious visually, they are subtle enough, such that  a camera may not have adequate dynamic range to capture the contrast differences.

 

I have not yet attempted a comparison between the three tubes in a telescope yet.

 

One final note, a while back I did a similar comparison between my thin-film Ultra tube and an L3 unfilmed tube with an SNR that is 4 points lower than the thin-filmed tube.  The lower SNR unfilmed tube still showed better contrast and detail in forest deep shadows and sharper faint stars.  This lower SNR unfilmed tube also has a resolution of 72 lp/mm.

 

I'm pretty much sold on unfilmed tubes.  Wish they could be had in MX10130 format (for PVS-7's).



#27 Sarkikos

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Posted 23 July 2016 - 09:06 AM

 

You mean both are white phosphor?  
Mike

 

Both tubes are P43(G), not P45(W)!

 

 

Sorry.  The description under the video did not make that clear to me.  The wording was ambiguous to someone - like me - who does not have prior knowledge of these things.  

 

 

There are slight differences in the P43 phosphor used by ITT and L3.

 

No mention of green or white anywhere.  And the video being in b&w added to the misunderstanding.

 

So it is ITT P43 Thin-filmed Green and L3 P43 Unfilmed Green?  

 

And P43 is always green, while P45 is always white?

 

I wish everyone would be very specific when they discuss these gizmos.  There are NV newbs - like me - who are trying to understand this stuff.

 

Mike


Edited by Sarkikos, 23 July 2016 - 09:15 AM.


#28 Sarkikos

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Posted 23 July 2016 - 09:19 AM

 

Aren't the L3 Unfilmed P43 and ITT P43 both green tubes?  
 
Mike

 
 
In the hot linked video, Contrasting attributes of L3 unfilmed with ITT thin filmed, both the L3 and ITT tube use P43 phosphor!

 

 

So the answer is "Yes, they both use P43 phosphor, and P43 phosphor is GREEN."  

 

Mike


Edited by Sarkikos, 23 July 2016 - 09:20 AM.


#29 cnoct

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Posted 23 July 2016 - 09:43 AM

Both tubes used in the video are P43(G), not P45(W)!

There are several 'green' phosphor types e.g. P20, P22, P39, P1/P39, P43 etc...

Simply identifying the phosphor as 'green' is ambiguous, where as identifying the phosphor by the correct designator is as specific as one can be.

#30 Sarkikos

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Posted 23 July 2016 - 10:29 AM

Green is not ambiguous.  White is not ambiguous.  To someone who does not understand exactly what the numbers mean, P20, P22, P39, P1/P39, P43, P45, etc. ARE ambiguous!  Obviously, the best protocol is to always use the colors with the numbers.  Many readers of these threads - or iTube videos - will not immediately understand that P43 is green and P45 is white.  That knowledge is not intuitively obvious!

 

See, I can use an exclamation mark, too!   :grin:

 

Please understand that to the great unwashed throngs of non-NV amateur astronomers, the numbers don't mean much.   Green and white we do understand.  We need to be taught what the numbers mean.

 

Mike


Edited by Sarkikos, 23 July 2016 - 10:34 AM.


#31 Sarkikos

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Posted 23 July 2016 - 10:37 AM

Now, getting back to the video ...

 

The L3 Unfilmed P43 and ITT Thin-filmed P43 are both green tubes.

Looking at the video, the major difference I see between the two images, is that the L3 Unfilmed P43 appears a little brighter.  The ITT Thin-filmed P43 has a bit more contrast to my eye, but that could be because it is not as bright, as if it were stopped down slightly.  (And I need to keep in mind that both tubes are green, though the video shows them as b&w.)

It would be difficult for me to choose one over the other, judging from the video.

 

Any comments?

Mike


Edited by Sarkikos, 23 July 2016 - 11:11 AM.


#32 Foobaria

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Posted 02 July 2018 - 09:21 PM

I've heard the unfilmed tubes don't last as long since the film was introduced to protect the plates from photonic/electronic damage.   Is that true or did they find a way around this problem? 

 

I have done side-by-side comparisons of an ITT thin-film Ultra P43 (green), an L3 unfilmed P45(white), an L3 unfilmed P43 all with similar performance specs.

 

Don't have any videos, yet.  The comparisons are all based on eyeball observations.

 

This is what I have seen using a 1X NV objective:

 

When pointing each of the three tubes (MX10160 format) into the forest at Mount Pinos, Calif, BOTH unfilmed tubes showed greater definition of tree branches and rocks on the ground in the deep dark shadows of the forest.  The thin-filmed Ultra tube showed less contrast in the deep shadows and overall exhibited a faint glow / haze on all terrestrial targets (tree branches, the ground) as if someone had placed a translucent (not transparent) film in front of the objective on the NV monocular housing.  All three tubes had the same type of housing with the same front objective.

 

When pointed at the sky the difference between the thin-filmed and unfilmed tubes was less obvious.  In fact the only difference I could see was that dimmer stars appeared sharper in my unfilmed tubes because there is a resolution difference between the thin-filmed vs unfilmed tubes - both unfilmed tubes have 72 lp/mm resolution vs. 64 lp/mm resolution in the thin-filmed Ultra tube.

 

I suspect that a video might not demonstrate the visual differences because although they are obvious visually, they are subtle enough, such that  a camera may not have adequate dynamic range to capture the contrast differences.

 

I have not yet attempted a comparison between the three tubes in a telescope yet.

 

One final note, a while back I did a similar comparison between my thin-film Ultra tube and an L3 unfilmed tube with an SNR that is 4 points lower than the thin-filmed tube.  The lower SNR unfilmed tube still showed better contrast and detail in forest deep shadows and sharper faint stars.  This lower SNR unfilmed tube also has a resolution of 72 lp/mm.

 

I'm pretty much sold on unfilmed tubes.  Wish they could be had in MX10130 format (for PVS-7's).




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