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

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

cdmackay said:
I have a note, relating to my 1978 Leitz Trinovid 10x22C, that says ""plain glass cover plates over objectives".

Not sure if that's true, however. Have other manufacturers done this, in the past?

I don't think they are field-changeable, so perhaps it's just a cost-saving measure by the manufacturer, i.e. it's cheaper to replace the plain cover glass, than part of the objective?

Or perhaps it wasn't true, and I noted it down in error.
Click to expand...

The Nikon 8x40 Classic Eagle focuses by moving the objectives and so is made waterproof by a sealed glass window in front of the objectives. I think the Swarovski 8x30 SLC is the same. There are other old bins like that. The original version of the Swift 8.5x44 Audubon roof-prism (before the 828HHS) had a window over each moving ocular lens to seal them, so eye-relief varied according to how focus was set! All of the above are models from yesteryear but I know of at least one current bin that has a flat glass in front of the objectives--the Pentax Papilio.

--AP
 
Alexis Powell said:
The Nikon 8x40 Classic Eagle focuses by moving the objectives and so is made waterproof by a sealed glass window in front of the objectives. I think the Swarovski 8x30 SLC is the same. There are other old bins like that. The original version of the Swift 8.5x44 Audubon roof-prism (before the 828HHS) had a window over each moving ocular lens to seal them, so eye-relief varied according to how focus was set! All of the above are models from yesteryear but I know of at least one current bin that has a flat glass in front of the objectives--the Pentax Papilio.

--AP
Click to expand...

The little Leupold Rogue 8x25 bins in my office desk at work are the same way... Flat glass over both objectives.
 
The Canon 18x50 IS and 8x25 IS have optical windows as do some of the others but not all.
The Minolta Mariners? also have front windows.

The 4 inch f/1.8 lenses were moving at 500 knots 250ft above the ground, terrain following.
Quite a ride.
Maybe some were angled forward. Usually there would be 3 cameras operating.
With image motion compensation.

The Wild 98mm f/1.4 lenses are marked with the focal length measured for each lens to 0.01mm at 80 metres.
I suppose these also had filters, so I don't know how the image scale was affected or the focus.

B.
 
cdmackay said:
I have a note, relating to my 1978 Leitz Trinovid 10x22C, that says ""plain glass cover plates over objectives".
Not sure if that's true, however.
Click to expand...

Yes, the Leitz 10x22 (and the 8x20 of the same style) had plain glass over the objectives.

Gary.
 
We are using B+W filter in our astronomical setups - they are slightly bigger (for Zeiss 135/2), but I think the conclusions carry over - we have measured transmission in the lab, in most of visible spectrum it's above 99% and we do not see any disturbance in image quality at all. This obviously doesn't test reflections (we use it when it's pitch dark) nor condensation issues (we use heating) but from purely optical throughput, the filters should be impossible to notice by eye at binoculars magnification.
 
The cover glass or optical window on the Minolta Mariner 8x32 here is uncoated.
The binocular is a mixture of single coats, multicoats and uncoated prisms.
The binocular is dim, but reputedly tough.

a c.2001 Canon 18x50 IS has purple coatings on the optical windows. Probably single coated or possibly double coated?

There is a new intercom panel about 25 metres away that I can't read with normal binoculars.
I tried a hand held 20x50 old Kowa spotting scope and couldn't read the small writing.
I thought I needed to set up a large spotter on a tripod
But the Canon 18x50 IS showed all the writing bar one word when I switched the IS on.

I then took 5 hand held photos with the pocket size Canon SX730.
All revealed the full text at 40x optical and 4x digital zoom.
With my eyes I would need a tripod mounted good 25x or 27x spotter to see the same detail.
This is really impressive for such a small camera.

But the Canon 18x50 IS did better than I thought.

B.
 
garymh said:
Yes, the Leitz 10x22 (and the 8x20 of the same style) had plain glass over the objectives.
Click to expand...

thanks Gary; do you recall the main reason for this?

Some have suggested to allow waterproofing, so that there's a fixed external element that's easy to seal, rather than a focussing objective.

But it occurs to me that the 1970s compacts, in particular, probably weren't waterproof/gas-purged anyway? At least, I don't have a note of mine being so.

Or just better sealing in general, e.g. to keep dust out?
 
Binastro said:
a c.2001 Canon 18x50 IS has purple coatings on the optical windows. Probably single coated or possibly double coated?

B.
Click to expand...

Canon uses optical windows on their 10x42 as well, perhaps to help protect the expensive objective elements which are very little recessed. It is a helpful indicator that sealing has been lost when these windows fog up.
 
The Visionking 5x25 binocular has green multicoated cover glasses.
I definitely would not call them optical windows, as one barrel in this sample has some of the worst quality optics I have ever seen.
This is a pity, as potentially this is a very useful 15 degree field binocular.

If I had the ability to buy it myself without help, I would buy 3 or 6 units and write off the poor ones, keeping hopefully one or more good ones.

I just measured the distance to the new build intercom panel (post 48).
It is 36 metres with the Leica rangefinder in bright sunshine.
So I made a very poor estimate of 25 metres by eye alone.
The performance of the Canon 18x50 IS and the Canon SX730 is impressive.
The writing is small text.

The old Leica 7x monocular rangefinder has very nice optics.

I recall that one of the Swift binoculars has optical windows.
At least I think so.

B.
 
If it really is true that a cut up Post-it stuck on an objective lens cannot be noticed - see this post - then all this quibbling about filters has got to be...what's that term again... BB stacking? :cat:
 
Binastro said:
The Visionking 5x25 binocular has green multicoated cover glasses.
I definitely would not call them optical windows, as one barrel in this sample has some of the worst quality optics I have ever seen.
This is a pity, as potentially this is a very useful 15 degree field binocular.

If I had the ability to buy it myself without help, I would buy 3 or 6 units and write off the poor ones, keeping hopefully one or more good ones.

I just measured the distance to the new build intercom panel (post 48).
It is 36 metres with the Leica rangefinder in bright sunshine.
So I made a very poor estimate of 25 metres by eye alone.
The performance of the Canon 18x50 IS and the Canon SX730 is impressive.
The writing is small text.

The old Leica 7x monocular rangefinder has very nice optics.

I recall that one of the Swift binoculars has optical windows.
At least I think so.

B.
Click to expand...


Binastro:
You can save your babble about some cheap junk china visionking 5x25 binocular, as that really does not apply to this thread.

Your reference to an optical window does not apply here, no real meaning.

Jerry
 
Jerry,
You are wrong.

The Visionking 5x25 is potentially a very good design and very useful, if it was made properly.
Without any changes to its specification it would be a fine binocular. If it said Leica or Zeiss on it, people would appreciate what it does.
But 5x binoculars are not popular.

The problem with the Visionking 5x25 is that the sample here has faults in the glass. Either the glass material is poor on one side or it is just pressed glass and not accurately ground and polished.
The star images on the faulty side are good. It is the resolution that is very poor.

It might be wise if you actually examined one carefully, before giving unfounded opinions.

It also has flat glass windows in the front, and this thread is about flat glass windows in the front.
How does this not apply?

I also do not appreciate your unwarranted personal comments.

B.
 
I just tried the Visionking 5x25 in late afternoon.
Fairly clear but failing light.

Within seconds I saw a herring gull, a pigeon and a small far away bird flying through the enormous 15 degree field.
This is 4 times the area of many binoculars used here.
These birds would have had less than half the time seen if I had been using a normal binocular.
One would not have been seen at all.

It is just a pity that the resolution of this binocular is so poor.
But this has less effect in failing or low light as my eyes have less resolution.

If a major maker, such as Leica, Zeiss or Nikon made it to the same specification, I would be interested.
Particularly Nikon, as the price would be reasonable.

This Visionking 5x25 is a great design, let down by poor manufacture.

B.
 
Patudo said:
If it really is true that a cut up Post-it stuck on an objective lens cannot be noticed - see this post - then all this quibbling about filters has got to be...what's that term again... BB stacking? :cat:
Click to expand...

It's a different problem. Something that masks the objective has the potential to reduce brightness or alter performance very slightly by masking off parts of the lens that perform better (near the center axis) or worse (near edges of the lens) or that do not work well together. The effects will generally be subtle. A filter has the potential to produce distortions, aberrations, reduced resolution, reduced contrast etc as it allows light to pass through but potentially be redirected in a pathological way. Painting opaque black spots on a lens will generally have little visible effect as compared to painting it with translucent spots of petroleum jelly or the like. Filters are more like the latter.

--AP
 
Mark,
Post 56.

In view of your comment, I tried to remove the glass multicoated front covers from the Visionking 5x25.
I peeled back the rubber armour, but there is no obvious way to remove the front glasses, about 38mm aperture.

I could smash the glass, but this would let slivers of glass into the focus mechanism and risk cutting myself.
I don't have a glass cutter. With one I could make circular cuts and remove most of the front glasses.

The reason why I would remove the glass covers is to see whether the poor optical performance is due to these front glass covers, or to the binocular glass elements behind the covers.

I agree with Alexis in post 57.
Filters, optical windows, and glass covers can degrade optics.
Some of the early Hoya filters I have are very poor quality and degrade optics.

Masking the objectives is quite different.

Regards,
B.
 
Mark9473 said:
All somewhat interesting, but it wouldn't hurt to re-read the title of this thread...
Click to expand...

In a discussion about the merits of filters i.e. flat glass elements, the introduction into the discussion of binocular models that come factory-fitted with these elements doesn't seem out of place.

Lee
Moderator
 
Binastro said:
I just tried the Visionking 5x25 in late afternoon.
Fairly clear but failing light.

Within seconds I saw a herring gull, a pigeon and a small far away bird flying through the enormous 15 degree field.
This is 4 times the area of many binoculars used here.
These birds would have had less than half the time seen if I had been using a normal binocular.
One would not have been seen at all.

It is just a pity that the resolution of this binocular is so poor.
But this has less effect in failing or low light as my eyes have less resolution.

If a major maker, such as Leica, Zeiss or Nikon made it to the same specification, I would be interested.
Particularly Nikon, as the price would be reasonable.

This Visionking 5x25 is a great design, let down by poor manufacture.

B.
Click to expand...

Yes, it seems I am correct, just cheapo china junk, you just admitted it.

Enjoy your binoculars in good health.

Jerry
 
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