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B&W Nano coated 46mm clear filters on Zeiss 8x42HT (1 Viewer)

Jerry,
I provided an exhaustive test on this binocular on Birdforum.
I identified the problems and said quite clearly this example is defective.

However, the design is first class and if it was made by someone like Nikon, would have no rival for wide field views.

What I object to is your personal comments, which started as soon as I joined Birdforum seven years ago.
I am not alone in being subjected to your personal comments.

This is my very clear reply to you.

B.
 
GoldenBear,
Post 31.

I have just had a long conversation with a senior optics lecturer.
He thinks that thin filters in front of the objectives will not affect field curvature in a binocular.

The most likely effect is wedge.
If there is a fair amount of wedge then the alignment of the two optics could be affected.
But I would think that with a high quality B and W filter any wedge is small.

However, flat glass elements behind the objective can and do have large optical effects depending on thickness, position etc.

I thought that maybe field curvature could be affected, but it probably isn't.

Hope this helps.

Regards,
B.
 
Binastro said:
Jerry,
I provided an exhaustive test on this binocular on Birdforum.
I identified the problems and said quite clearly this example is defective.

However, the design is first class and if it was made by someone like Nikon, would have no rival for wide field views.

What I object to is your personal comments, which started as soon as I joined Birdforum seven years ago.
I am not alone in being subjected to your personal comments.

This is my very clear reply to you.

B.
Click to expand...

Thanks for your response, I had not read about your earlier exhaustive
review of the binocular, and how it was defective.

I suppose then a good thing would be to just leave it at that.....

Jerry
 
The Zeiss Diafun had flat glass covers over the objectives as did the early (i.e non HD) Zeiss Conquest.

Gary.
 
GoldenBear said:
I have the exact same filters on my HT 8x42's and love them. I had them for a few months and so far have had no issues with condensation or fogging. I was more concerned that the flat filter surface may cause more glare or flares under certain light angles, but there's been no impact whatsoever.

Absolutely optically invisible as far as I can tell, and I compared them extensively in the field and against resolution charts. Much easier to clean the flat filter surface (especially with B&W's excellent nano coating). They also negate the need for objective covers (although I did but a pair of inexpensive pinch style caps the fit the filters for transport and travel).

Another nice advantage to the B&W fllter compared to most is that the metal frame is brass rather than aluminum which helps reduce he chance of seizing.

With regard to any effect on the image, if anything, when I first put them on I would swear the field curvature of the image became slightly less noticeable. No doubt it isn't optically possible for the filters to change the image in this way, but it sure seemed like it did to me eye.
Click to expand...

Golden Bear,

You are lucky with B+W filters that you can clean them. From experience with camera filters a lot of modern high quality multi-coated filters are impossible to clean without smudging. Leica and B+W are lucky exceptions; Nikon UV filters (L37c, now sadly not available as far as I know since the advent of digital cameras) are excellent but if they get dirty the only thing I can do is frisbee them into the nearest bin - or clean them so thoroughly that the coating comes off entirely!

Tom
 
Just to round out the question of how flat glass filters might or might not affect the ray paths I will add the following if it is of any interest or help:

Some Nikkor (name given by Nikon to their camera and enlarging lenses) telephoto/long focus lenses have flat glass plates at the camera mount end to prevent ingress of dust etc. They play no part in the optical train of the lens design. Similarly the AF-Nikkor 14mm f/2.8 ED lens - an ultra-wide design made with a view not only to 35mm full frame film cameras but also cropped (DX-sensor) format digital cameras - can take gel filters that you cut to slot into a female frame designed for this purpose at the camera end of the lens. I have used this and not noticed any degradation though I would check to see the gel isn't warped.

Tom

This is of no relevance to binoculars but I add it as there has been discussion of how various placements of such glass surfaces might affect the visible image.
 
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Tom,
Post 66.

There are many lenses that have rear small filters.
These are either drop in or screw in.
When a colour filter is not used, the clear filter needs to be in place, as the lens is computed to include the flat glass.
I suppose reasonable photos will result if the filter is left out.
I doubt that the thickness of the filters varies much to account for any colour shift.

The reasoning is that large front filters are expensive and add front weight.
I think that some fisheye lenses have rear filters. Also mirror lenses.
Yes, I have some that have a set of about four or five filters contained in the top part of the lens case.
With old lenses some of these cases have deteriorated so much that the foam has stuck to the filters, and it takes a lot of careful cleaning to get it off without damaging the filter.
I can't remember which old lenses I have with this set up.

Astro telescopes have filters that screw into the eyepieces, or for imaging are in a filter wheel.
This is not for me, as exposures are often ten hours or more in total, sometimes days.
The resulting images equal the old 200 inch Palomar telescope with modern 10 inch scopes and digital imaging.
10,000 plus images are stacked routinely.

Regards,
B.
 
Binastro said:
Tom,
Post 66.

There are many lenses that have rear small filters.
These are either drop in or screw in.
When a colour filter is not used, the clear filter needs to be in place, as the lens is computed to include the flat glass.
I suppose reasonable photos will result if the filter is left out.
I doubt that the thickness of the filters varies much to account for any colour shift.

Regards,
B.
Click to expand...

Does the presence of a filter glass on the ocular end similarly impact the image quality? There were yellow and gray filters included with the CZJ DF 7x40 and the Russian BPO 8x30.
Perhaps the impact is small at such low magnification, but presumably it exists.
 
It seems this thread has drifted badly from the OP of putting a filter on a Zeiss HT binocular.

You astro types should go, and to a site like Cloudy Nights or other. Binastro, take notice......

Birdforum is about birding and terrestrial viewing.

Jerry
 
The Barr and Stroud CF41 7x50 binocular has an internal colour filter wheel with 4 positions.
Green, yellow, grey and surprisingly an empty position.
So I suppose there cannot be much impact with a single thin internal filter, perhaps if positioned correctly.

There is an example of a cover protective glass in front of the prism, rather than the objective.
The Russian Monocular, half a binocular, Combo 12x40/20x60 has two bayonet mounted barrels.
The very short 40mm barrel and the long 60mm barrel.
The rear part of the instrument has a clear glass cover just in front of the prism.
It does not seem to impact optical performance.
I mainly used the 20x60 option.

Etudiant,
I suppose there is a slight impact with rear mounted filters, but if high quality I don't think one notices it.

Regards,
B.
 
NDhunter said:
It seems this thread has drifted badly from the OP of putting a filter on a Zeiss HT binocular.

You astro types should go, and to a site like Cloudy Nights or other. Binastro, take notice......

Birdforum is about birding and terrestrial viewing.

Jerry
Click to expand...

Jerry,
Please relax and don't try to become the arbiter of what is suitable for discussion. Here at BF thread drift is not a big deal. It happens all the time and there is no need to get upset by it.
I asked because I'm really interested whether the extra glass of the ocular filters impacts the image. Binastro has optical expertise and experience, so his insights are valuable to me, as well as to many others here, even if they seem less so to you.
 
SeldomPerched said:
...You are lucky with B+W filters that you can clean them. From experience with camera filters a lot of modern high quality multi-coated filters are impossible to clean without smudging. Leica and B+W are lucky exceptions...
Click to expand...

I feel your pain when it comes to the difficulties of cleaning filters sometimes. I have found that ROR is super effective for easily cleaning all glass multicoated filters, even the ones that seem to tenaciously hold on to oil. Luckily, the latest top-end filters from several brands are using oleo/hydrophobic coatings to make them as easy to clean as binoculars that have such coatings.

--AP
 
Alexis Powell said:
I feel your pain when it comes to the difficulties of cleaning filters sometimes. I have found that ROR is super effective for easily cleaning all glass multicoated filters, even the ones that seem to tenaciously hold on to oil. Luckily, the latest top-end filters from several brands are using oleo/hydrophobic coatings to make them as easy to clean as binoculars that have such coatings.

--AP
Click to expand...

Thanks, Alexis; handy tip.

Tom
 
NDhunter said:
It seems this thread has drifted badly from the OP of putting a filter on a Zeiss HT binocular.

You astro types should go, and to a site like Cloudy Nights or other. Binastro, take notice......

Birdforum is about birding and terrestrial viewing.

Jerry
Click to expand...

Be careful what you wish for. I'm sure a lot of Birdforum viewers would rather hunters begone from the site than astronomers.

I don't share this view myself - hunters put their gear through a lot more hard use/abuse than most birders, and have valuable input to offer regarding durability and longevity in tough conditions. But from what I can see, the viewing situations and conditions that hunters use their binoculars in, and the types of binoculars that are used by hunters, are different enough to those experienced/used in mainstream birding that I'm not sure how useful the dedicated hunter would actually find this forum.
 
Patudo said:
Be careful what you wish for. I'm sure a lot of Birdforum viewers would rather hunters begone from the site than astronomers.

I don't share this view myself - hunters put their gear through a lot more hard use/abuse than most birders, and have valuable input to offer regarding durability and longevity in tough conditions.
Click to expand...

Patudo has it right, hunters have a lot of insights to offer regarding outdoor and nature observation gear.
However, I think that in the US, the hunting community can teach the larger birding community as well. Hunters and their organizations remain enormously more clear headed and effective in their efforts to maintain and improve the needed environment and habitat essential to allow hunting to continue, with fees, lobbying and volunteer work. It would be wonderful if that energy and dedication were welcomed and emulated by the birding community.
 
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Robert Moore said:
The B+W 46mm XS-Pro Clear MRC-Nano 007 Filter is a simple, clear filter with a 1x filter factor and is designed to provide general protection for your lens. This optically clear filter does not affect overall image quality while helping to reduce dust, scratches, moisture, and other elements from damaging your lens.

99.8 percent light transmission so I am only losing .02% and they are optically excellent. I just want to keep this Zeiss HT in absolute new condition since they don’t make them anymore.
Click to expand...

Robert, did you give any consideration to the fact that the filter doesn't have 42 mm clear aperture?
 
I do hope we should all know the fact that any filter will change the view as designed
by the original designer of the optic. The view will be degraded much of the time.


This has been mentioned several times above.

Jerry
 
Mark9473 said:
Robert, did you give any consideration to the fact that the filter doesn't have 42 mm clear aperture?
Click to expand...


Well I can’t measure the clear aperture now because I no longer have the 8x42 HT. I traded the HT with the filters for a Leica 7x42 Ultravid HD plus. I really liked the HT and said I would never sell it but I find I enjoy the view through my 7x42 Leica BN so much I decided to get the HD plus to compare with the Leica BN. So now I have two 7x bins and the 10x Zeiss SF.
 
No need to measure it, I have done so, it's 40.7 mm. I was just asking if you took into consideration the fact that you were giving up some aperture.
Or let me rephrase the question: had you been aware that you were cutting the aperture, would you still have been so enthusiastic about these filters?
 
Last edited:
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