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Any of you guys use a filter? (1 Viewer)
- Thread starter giosblue
- Start date
Hermann
Well-known member
This is a contentious issue, I think. Some people do, many others don't. The problem is that filters may "soften" the image quite considerably unless they're top quality. And how good a (large) filter is is something you can only judge by using it on the scope in the field and doing some careful comparisons.
Unfortunately good filters that have no or very little influence on image quality are expensive. I had my fair share of problems with filters that degraded image quality, so nowadays I only use (rather expensive) filters from the leading camera manufacturers (Nikon, Canon, Leica). No problems with those yet.
Hermann
Yes, top quality filters are expensive, but do you really need top quality?
If this is correct, why would you need a really expensive piece of glass just in front of the lens?
From Carl Zeiss.
Give your lenses a rub only once a year and in the rest of the time try to save them from receiving
fingerprints and other forms of fat mixed with weak acids.
Fingerprints and pollen are about the only contaminants which would have to be removed quickly to not
alter the coating. Both contain weak acids (”urine acid” in the case of the fingerprint).
Normal dust would have to accumulate into a real thick layer until it gets noticeable during nightly
observations to reduce contrast. A little more care is to be given during solar observation with narrow-
band-filters. That is about the only occasion when a lens should be kept free of
heavy dust build up.
Again - don’t overkill your lenses with
aggressive cleaning! We have run tests on this for 25 years.
The myriad of scratches due to wrong cleaning methods causes thousand times more damage to the
contrast than a heavy layer of dust! Series of parallel scratches on your objective can work like a
grating and even cause color error (!), while dust can only take some transmission away.
We have tested it on the sun during using a new, totally clean piece of BAADER AstroSolar Safety Film
against three years old AstroSolar filters, which had been left unprotected on purpose all the time.
There was absolutely no visible difference on image contrast or resolution, not even with the highest of
magnifications; between using a new or old and totally dust covered AstroSolar filter. At any magnifica-
tion, even when observing solar granulation image detail and contrast was exactly the same.
If this is correct, why would you need a really expensive piece of glass just in front of the lens?
From Carl Zeiss.
Give your lenses a rub only once a year and in the rest of the time try to save them from receiving
fingerprints and other forms of fat mixed with weak acids.
Fingerprints and pollen are about the only contaminants which would have to be removed quickly to not
alter the coating. Both contain weak acids (”urine acid” in the case of the fingerprint).
Normal dust would have to accumulate into a real thick layer until it gets noticeable during nightly
observations to reduce contrast. A little more care is to be given during solar observation with narrow-
band-filters. That is about the only occasion when a lens should be kept free of
heavy dust build up.
Again - don’t overkill your lenses with
aggressive cleaning! We have run tests on this for 25 years.
The myriad of scratches due to wrong cleaning methods causes thousand times more damage to the
contrast than a heavy layer of dust! Series of parallel scratches on your objective can work like a
grating and even cause color error (!), while dust can only take some transmission away.
We have tested it on the sun during using a new, totally clean piece of BAADER AstroSolar Safety Film
against three years old AstroSolar filters, which had been left unprotected on purpose all the time.
There was absolutely no visible difference on image contrast or resolution, not even with the highest of
magnifications; between using a new or old and totally dust covered AstroSolar filter. At any magnifica-
tion, even when observing solar granulation image detail and contrast was exactly the same.
John Dracon
John Dracon
Ron & Hermann - for years I didn't use filters on my spotting scopes, which were mostly B&L and Bushnell brands. Then as I acquired more expensive scopes, filters became more of an issue. I don't take pictures with my scopes but rather use the filters to protect the objective lens. Most of my viewing if of the terrestrial nature.
I have settled on HOYA HMC UV(0) made in Japan filters. In terms of expense I don't feel $30 postage paid is too expensive for a filter. Off or on I can see no difference in brightness, resolution, etc. But the protection and utility is there.
The Zeiss recommendation on cleaning lens makes good sense.
John
I have settled on HOYA HMC UV(0) made in Japan filters. In terms of expense I don't feel $30 postage paid is too expensive for a filter. Off or on I can see no difference in brightness, resolution, etc. But the protection and utility is there.
The Zeiss recommendation on cleaning lens makes good sense.
John
Thank you, giosblue, for an excellent and very helpful post. I wish it could be posted as a sticky on every BF optics forum dealing with the care of optics.
Scope objective lenses don't need protection except perhaps from salt spray and cleaning obsessed owners.
Filters don't help the image, add another condensation surface and don't really protect against damage from falls etc. They do keep fingerprints off the objective, which is probably their primary justification. A more effective alternative imho is a deep soft hood, which cushions the scope in case of falls and shields the objective against precipitation.
Scope objective lenses don't need protection except perhaps from salt spray and cleaning obsessed owners.
Filters don't help the image, add another condensation surface and don't really protect against damage from falls etc. They do keep fingerprints off the objective, which is probably their primary justification. A more effective alternative imho is a deep soft hood, which cushions the scope in case of falls and shields the objective against precipitation.
John Dracon
John Dracon
extudiant - Your posting puzzles me. 1. "Scope objectives don't need protection." Then why do they all come with caps? 2. "add another surface for condensation..." If the condensation falls on the filter, it won't occur on the objective lens. Of course how far the objective lens is recessed from the back of the filter could contribute to condensation on the lens, but this has never happened to me. (in over 60 years of spotting scope use) I would rather wipe condensation from a filter than my spotting scope lens. 3. How many deep, soft hoods to cushion blows from falling have you seen on spotting scopes? I've only seen one that fits that description.
Glass lens are surprisingly tough, but I have seen binoculars and spotting scopes with cracked objective lens from falls and other accidents. A filter in front would give some protection.
John
Glass lens are surprisingly tough, but I have seen binoculars and spotting scopes with cracked objective lens from falls and other accidents. A filter in front would give some protection.
John
Vespobuteo
Well-known member
read this test before getting a filter, even expensive ones can be bad...
http://www.lenstip.com/113.1-article-UV_filters_test.html
and low-quality filters can be horrible, this Tiffen-filter is a bad joke (12% light loss):
http://www.lenstip.com/113.24-article-UV_filters_test_Tiffen_72mm_UV.html
personally I don't use filters, for anything, not even for camera lenses, they were more relevant in the analog days,
(UV sensitive film etc.),
the only possible reason would be protection in very harsh environments,
just be careful so that the filter don't get stuck on the scope...
metal to metal can react and then you have a scope with a permanent filter mounted,
to me it seems like a more effective protection to pull out the sun-shade on the scope,
and much cheaper to.
http://www.lenstip.com/113.1-article-UV_filters_test.html
and low-quality filters can be horrible, this Tiffen-filter is a bad joke (12% light loss):
http://www.lenstip.com/113.24-article-UV_filters_test_Tiffen_72mm_UV.html
personally I don't use filters, for anything, not even for camera lenses, they were more relevant in the analog days,
(UV sensitive film etc.),
the only possible reason would be protection in very harsh environments,
just be careful so that the filter don't get stuck on the scope...
metal to metal can react and then you have a scope with a permanent filter mounted,
to me it seems like a more effective protection to pull out the sun-shade on the scope,
and much cheaper to.
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I think a decent filter is useful, particularly if you're seawatching etc and getting lots of salt spray on the lens. I don't notice any difference at 30x with my Hoya filter on, but there is a slight softening at 50x. If it bothers me in that instance I then unscrew it.
In transit, scope optics clearly need caps to protect the surfaces, but a filter does not really help much there. Hard rubber covers are the more suitable norm.
In service, filters do trap condensation, a bother when it happens on the inside surface of the filter. A hood gives more effective protection when it is damp and drizzling.
Admittedly, it is much easier to get a deep hood for my small ED50 than it would be for full sized scope, but it works well on the ED50.
The rubber hood together with a SoC provide good protection for the scope in the backpack and should also cushion falls in the field more effectively than an extra glass element.
I'd certainly put on a filter when birding someplace where blown sand or spray was common, to protect the optics surfaces. Elsewhere, I don't think filters add value.
I had a Leica Apo Televid objective lens destroyed by a Norfolk seawatch and rather wished I'd had a filter mounted, despite Leica replacing the lens for free afterwards. With the cost of scopes, tripods SoCs etc a few bob on a decent filter for those extreme occasions seems a reasonable investment.
Russ
Russ
henry link
Well-known member
In that position the filter is more than just "seen", it becomes part of the objective lens group. If it's perfectly flat (not easy to do) it will be relatively harmless, but if it isn't flat it acts like a poorly figured lens. A high magnification star-test will reveal how much and what kind of wavefront error it adds.
Saxatilis
Well-known member
Tarsiger,
I had the same bad experience just after buying my first ED Opticron spottingscope.... on a seawatching day with southerly winds in my region I never got to eliminate completely the marine aerosol traces from the scope' lens.:C
Since then I always carry a B+W 86mm filter in my backpack that can apply to my Nikon Ed 82 whenever necessary
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This is the reply I got from Kowa when I asked them.
The 883 is a tough piece of equipment that can take quite a lot of abuse.
However, it is still a precision optical instrument and does require a little bit of care, the front lens objective is a case in point.
We produce a protective filter which I would highly recommend to anybody, it can protect the lens from scratches or possible coating damage which can be expensive to repair/replace and means you are without use of your scope for a few weeks – Not a good scenario.
The filter is designed for the scope and has a special oil and water repellent coating, this coating helps in poor weather and cleaning , its particularly useful for use in and around the coast where you might get salt spray, which can be harmful to lens coatings.
No downsides.
95mm protective Filter £169 inc VAT.
It can be easily ordered from any Kowa stockist, they may have to order it for you however.
We carry it from stock
The 883 is a tough piece of equipment that can take quite a lot of abuse.
However, it is still a precision optical instrument and does require a little bit of care, the front lens objective is a case in point.
We produce a protective filter which I would highly recommend to anybody, it can protect the lens from scratches or possible coating damage which can be expensive to repair/replace and means you are without use of your scope for a few weeks – Not a good scenario.
The filter is designed for the scope and has a special oil and water repellent coating, this coating helps in poor weather and cleaning , its particularly useful for use in and around the coast where you might get salt spray, which can be harmful to lens coatings.
No downsides.
95mm protective Filter £169 inc VAT.
It can be easily ordered from any Kowa stockist, they may have to order it for you however.
We carry it from stock
Very interesting input, thank you very much and good on Kowa.
This is the first instance I know of where a manufacturer offers a custom designed protective filter. All other scope filters I've seen are simply pieces of glass of varying quality.
Pinewood
New York correspondent
Hello Saxatillis,
B+W filters have a very good reputation. The question for some is when is the filter necessary.
Happy bird watching,
Arthur Pinewood. :hi:
Rotherbirder
Well-known member
Personal experience leads me to differ on this one, I'm afraid. The catastrophic failure of a shoulder strap caused my Leica APO62 to hit the floor from several feet. It connected with the ground objective-end first. Had it not been fitted with a filter, serious damage would have resulted. As it was, the frame/rim of the filter absorbed the shock, shattering the filter itself but leaving the valuable objective completely unscathed. The cost of a replacement filter stung much less than 'the unthinkable' would have!
As for visible, detrimental optical effects of filters, I must admit that I consistently see none - zilch, nada - that I can attribute directly to the filter rather than light, weather or other prevailing conditions.
As you may have gathered, I would never use my scope without a decent filter, no matter what the circumstances.
Saxatilis
Well-known member
Hello Pinewood
the main trouble for me is the sea spray (marine aerosol) that tends to deposit on the scope lens, only when seawatching with a certain kind of south winds...well under these conditions I use the filter, don't want to worry anymore about that.
Away from the sea and the seawathing I never use it, and always remains in my backpack.
The B+W 86mm filter decreases very very little the quality of the Fieldscope lens, you hardly find diffeneces
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Good on you!
Happily have not had any such close calls, but am optimistic the rubber hood on my ED50 would similarly protect its objective. That hood flares out to a 100mm diameter and adds 45mm to the length of the scope, which provides some cushioning.
Lewis Haank
Member
I just ordered a Swaro ATX 25-60x85 and will take it on a Hawaii trip in 10 days. Seems like protecting the lens with a filter when birdwatching at the beach would be wise. But what filter to get? The Swaro tech data lists the objective filter thread as M 87 x 0.75. I looked the b h photo website and it lists 86mm and 94mm filters but no 87.