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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

New HT Observations (1 Viewer)

Troubador

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There have been dark skies and driving rain overhead for weeks but today the sky was brighter. Still cloudy but at least the clouds were pale grey.

In a birch tree we planted 30 years ago the birds were queuing up waiting for a turn on our feeders. In our garden we mostly get finches and tits (by the way YankeeBoys British Tits are like Chickadees) and there they were silhouetted against the sky.

With FL in one hand and HT in the other I checked out the dim outlines of the birds set against the pale grey clouds. Through the HTs is was as if someone had shone a torchlight on the birds. Through the FLs blocks of colour and wingbars were visible but the HTs revealed more saturated colours and nuances of colour shading. Subtle changes in texture were discernable. Swapping back to the FLs was like putting a grey filter in the way: the silhouette-nature of the view became more apparent.

This holds out the hope of seeing more detail in birds flying against a bright sky.

Merry Christmas to all BF contributors without exception.

Lee
 
I`m looking forward to trying the HT`s for actual Birding at some point, and comparing them to a 32mm FL, not their natural foil I know but thats what I have, and having already put a 42mm side by side the HT`s superiority was plain to see.

The most exciting new binocular I`v tried in ages after a somewhat underwhelming first go with the 32mm SV the other week.

Just to add I have no brand loyalty or preference, I`ll give any brand a home if I like them.
 
There have been dark skies and driving rain overhead for weeks but today the sky was brighter. Still cloudy but at least the clouds were pale grey.

In a birch tree we planted 30 years ago the birds were queuing up waiting for a turn on our feeders. In our garden we mostly get finches and tits (by the way YankeeBoys British Tits are like Chickadees) and there they were silhouetted against the sky.

With FL in one hand and HT in the other I checked out the dim outlines of the birds set against the pale grey clouds. Through the HTs is was as if someone had shone a torchlight on the birds. Through the FLs blocks of colour and wingbars were visible but the HTs revealed more saturated colours and nuances of colour shading. Subtle changes in texture were discernable. Swapping back to the FLs was like putting a grey filter in the way: the silhouette-nature of the view became more apparent.

This holds out the hope of seeing more detail in birds flying against a bright sky.

Merry Christmas to all BF contributors without exception.

Lee
Do you think some of the difference could be the aperture difference or is it all coatings and the bigger prism in the 42mm HT?
 
Troubador,
Thanks. That is as I'd hope, from a very simplistic idea of what higher transmission does. If transmission was increased from 92% to 96% for example, the untransmitted light, which "rattles around" in the binocular and causes image washout in situations such as you describe, would be cut in half, which ought to be easily noticeable.

Two caveats: The usual "everything else being the same", and some people's opinion that much of the image washout occurs in the eye, so improving the binocular might give less benefit than my numbers. Your observation suggests otherwise.
Ron
 
Do you think some of the difference could be the aperture difference or is it all coatings and the bigger prism in the 42mm HT?

Hi Denis

I'm a little unsure about your question. To be clear I was comparing an 8x42 FL with an 8x42 HT. I am assuming the difference is down to the Schott HT glass and possibly some tweaking of Zeiss's T* coatings.

Either way it illustrates that the HT is an undoubted step forward from the FL.

If I have not answered your question please feel free to rephrase it more fully and I'll have another go.

Lee
 
Hi Denis

I'm a little unsure about your question. To be clear I was comparing an 8x42 FL with an 8x42 HT. I am assuming the difference is down to the Schott HT glass and possibly some tweaking of Zeiss's T* coatings.

Either way it illustrates that the HT is an undoubted step forward from the FL.

If I have not answered your question please feel free to rephrase it more fully and I'll have another go.

Lee
You are right and that is what I thought it was. It has to be the glass and the coatings. They didn't change the prism size on the HT did they?
 
You are right and that is what I thought it was. It has to be the glass and the coatings. They didn't change the prism size on the HT did they?

Denis

I haven't read or seen anything to suggest the prisms have changed in size. The HTs are certainly longer than FLs despite the official specs, but I think the extra has gone into providing the objective lenses with a deeper recesses.

The HTs gave me cracking views of Jupiter and its moons last night.

Lee
 
The Zeiss video is IMO simplistic marketing BS. A larger exit pupil than the 5,25 mm of the 8x42 HT will extend the usable viewing time in twilight far longer than a minimal increase of 3% transmission.

If one consults the Schott catalogues, just about all non-HT optical glasses have a transmission of well over 99% for 25 mm light path at 546 nm (where the human eye is most sensitive). HT glass could only bring about a measurable improvement in the transmission if it were used in the prisms, which have a long light path but even then it would not result in a 3% improvement.

The Zeiss advertising in German uses a clumsy formulation, which translates to "Up to more than 95% transmission" so they probably mean it hits a camel's hump of 95% somewhere in the green like its predecessor, the FL.

John
 
I have to agree with John. In promotingf the HT's as the ultimate low light binoculars Zeiss appears to hope that no one will remember that they continue to make 56mm FL's, which will easily outshine the 42mm HT's in very low light. Even if 3% higher light transmission is conceded to the HT's, the 56mm FL's will still deliver 72% more light to the eye when the light level is low enough for the full exit pupils to be used.
 
I have to agree with John. In promotingf the HT's as the ultimate low light binoculars Zeiss appears to hope that no one will remember that they continue to make 56mm FL's, which will easily outshine the 42mm HT's in very low light. Even if 3% higher light transmission is conceded to the HT's, the 56mm FL's will still deliver 72% more light to the eye when the light level is low enough for the full exit pupils to be used.

I would expect that Zeiss means brightest 8x42 and 10x42, no?
 
I would expect that Zeiss means brightest 8x42 and 10x42, no?

James:

I am thinking the new HT is bright, but the link above shows the Zeiss guy
boasting the new HT is the very brightest of "all". Of course they are only
42mm. This advertising promotion, is just that.

Zeiss promotes these only for hunters, so you birders looking to use these
for birding, think about that, they may not work very well. ;)

I do think Henry is right, there are other 50 and 56mm binoculars that are
sure to be brighter. And that means not just Zeiss.

Jerry
 
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