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ED50 "55mm filter can be attached to objective lens" (1 Viewer)

Some people use clear-glass filters on the objective lenses of spotting scopes to protect them against the elements. I did this many years ago but stopped because of slight image degradation & the tendency of the lens/filter sandwich to fog up under humid conditions.

A high-density sun filter suitable for viewing eclipses is another potentially useful filter type for a spotting scope.
 
Thanks for the info fugl!... actually I was wondering about that with the recent Transit of Venus... next time (for Mercury!) I will have one for sure... now, why it says 52mm filter when the ED50 is 50mm?
which one should I get?....
and of those high-density sun filters you know which kind, reference, number, should I get?... 14 is a good number in welding glasses!
thanks again!
Diego.
 
filter for Nikon ED50

Hi Diego,

Don't bother with a filter for the ED50, if you want to give the objective lens greater protection buy a cheap 55mm screw-in lens hood (mine is about 22mm deep).

Cheers,

Mark
 
50mm is the diameter of the objective lens; the filter thread which goes round that is 55mm.

I've seen those rubber collapsible lenshoods recommended here; presumably do a job reducing risk of flare as well as protection. Of course if the problem is seaspray the filter might start to look like a more attractive option.
 
I have one of those ,It is 55mm standard filter size..It came with the scope (bought used),but I never use it..If I had to use the scope in extreme conditions,though,I would be happy to have it at hand and compromise whatever minute image degradation,to protect the objective from dust,sand ,salt water or large amounts of bird poop....Collapsable Hoods wont protect from mist or dust..I used to own some ,from old camera lenses,they are kind of cool and they will reduce reflections and flare...although I dont find the ED50 specially prone to glare from the objective ,even in harsch ,frontal light,( those AR coatings are really,really good.)..I get some reflections from the ocular side ,now and then, Now that I use the 27X DS..A little bit worst, in that regard,than the MC WA oculars,but not a big deal
 
The idea of a protective front glass is appealing, but the space between it and the lens will fog up in the messy conditions often found on a sea watch.
A flexible screw-on shade helps protect the front lens from little upsets more effectively than another piece of glass and metal, imho. If salt spray is a problem, a rinse after use is probably a good idea.
 
A linear polarizing filter can be a good option when viewing into the sun over flat water (e.g. shorebirds on a marsh with the light in their direction).

Or you can wear polarizing sunglasses (with a scope that uses a porro prism system).
 
COLOMBIA Birding said:
and of those high-density sun filters you know which kind, reference, number, should I get?
Click to expand...

Diego,

For viewing the sun you can make up your own filter from AstroSolar film from Baader Planetarium. It has 99,99% absorption and excellent optical properties.
An alternative would be a glass filter from Thousand Oaks. Using anything other than a specifically designed filter would endanger your eyesight.

I got up before 5 am to view the recent Venus transit and it rained :-( .
I shall now have to wait another 105 years!

John
 
Thanks all for your comments here... I now understand which kind of filters are possible and what for they are...
I still have the original lens cap and works really well; also ordered the cleyspy case so that offers more protection in the field now.
Those screw-able filters and protections would fog immediately here birding in the Andean Choco of Colombia for example so not eager on getting anything like that ;-)
saludos!
d.
 
Last edited:
John Russell said:
Diego,

For viewing the sun you can make up your own filter from AstroSolar film from Baader Planetarium. It has 99,99% absorption and excellent optical properties.
An alternative would be a glass filter from Thousand Oaks. Using anything other than a specifically designed filter would endanger your eyesight.

I got up before 5 am to view the recent Venus transit and it rained :-( .
I shall now have to wait another 105 years!

John
Click to expand...

John, I am less than an amateur at astronomy but got the amazing Venus transit some days ago and was SUPERB!.. saw it through my Swaro EL bins using welding filter no.12 that protects perfectly and enjoyed it a lot!...
guess for the next transit (Mercury though!) will build a filer to try to make some photographs!
cheers, Diego.
 
John Russell said:
Diego,

It seems #12 is a bit risky and optically not very good for use with bins or a scope.
Here's a useful link:- http://www.oneminuteastronomer.com/999/choose-solar-filter/

John
Click to expand...

Thanks for the input John.. we actually used no.12 filters because our Venus transit here in Colombia was only visible at the end of the day when sunlight had lost loads of intensity... but you are right, should be no.14 for regular sun watching!...
Actually here the Venus transit was so late in the day, that friends at the beach in the N Caribbean coast of the country enjoyed it naked eye (https://fbcdn-sphotos-a.akamaihd.ne...x720/292635_10151176911523135_104187791_n.jpg - Photo by Fernando Ayerbe)!!
 
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