Hello All-
I recently picked up a high angle prism eyepiece with a solar filter for my gurley transit. while i'm not a stranger to antique equipment, i have never used one of these before. i set up this weekend to play with it, and immediately noticed that there's a lot of difference between the opacity of this tiny smoke glass filter and the objective lens filters i used to do sunshots with on a modern TS. in the fraction of second i let myself flirt with seeing the sun through this thing (and that peripherally), it looked so bright to me i figured i had better ask. Best i could tell, i wouldn't be able to see the entire disk anyway (...?)
Could i please get some comments on the intended use of this thing (aside from the obvious)? I guess it's just not clear to me when compared with the modern experience of seeing a whole, softly glowing solar disk to shoot.
I would experiment with something a lot less bright at first, like a light bulb indoors.
What you may have is just a right angle prizm
I wouldn't use an eyepiece filter.
We have an old Mountain Transit with an eyepiece filter but I'm not using it to look at the sun.
Objective filters are safer.
yeah, i actually did look at a lightbulb first - that's what made me wary. thanks for the reply and confirmation. im wondering what these folks used to do way back when if this is what they had...
my feeling exactly. i started looking into one a while back (pun intended) just out of curiosity. not planning on doing any work with it or anything....just interest and fun. thanks for the help.
It would be great for observing Polaris which you can do right around dusk or a little before.
that is one thing i want to play with. Im at about 32 1/2 N Lat, so, while it could be higher, i can still get a good crick in my neck without the prism.
> I would experiment with something a lot less bright at first, like a light bulb indoors.
>
> What you may have is just a right angle prizm
I am a horrible person. The thought of this made me LoL
My first sun shots were taken indirectly using an attachment made from a clothes hanger to hold a piece of paper 1.5± ft from the eyepiece to adjust and cast and image of the sun and crosshair on.
That can not be done with a TS because direct sight of the sun will damage the IR receiver in the scope.
I have two solar filters for my Sokkia guns and they are so dark that a light bulb can barely be seen.
> Hello All-
>
> I recently picked up a high angle prism eyepiece with a solar filter for my gurley transit. while i'm not a stranger to antique equipment, i have never used one of these before. i set up this weekend to play with it, and immediately noticed that there's a lot of difference between the opacity of this tiny smoke glass filter and the objective lens filters i used to do sunshots with on a modern TS. in the fraction of second i let myself flirt with seeing the sun through this thing (and that peripherally), it looked so bright to me i figured i had better ask. Best i could tell, i wouldn't be able to see the entire disk anyway (...?)
>
> Could i please get some comments on the intended use of this thing (aside from the obvious)? I guess it's just not clear to me when compared with the modern experience of seeing a whole, softly glowing solar disk to shoot.
My Gurley Solar Transit has the eyepiece filter for use when taking a direct solar observation. The little filter swings out of the way so that you have a clear view in order to point to your sight line point. Then you swing the filter back in place to observe the sun. The sun should appear as a bright yellow orb when the scope is oriented on it.
Dagnabit, did I spell prism thataway again?
hi charles -- that is how this one works as well. what got my attention very quickly was just how *bright and intense* the image is through this thing. it made me think it wasn't filtering out anywhere near enough magnified solar light. scared me that it might do some serious damage. that's why i asked if they are even safe to use. so, based on what you are saying, you use/have used this thing at least several times and your eyes are ok? i might add that this is an older make of prism and solar filter; newer ones may be darker......
> hi charles -- that is how this one works as well. what got my attention very quickly was just how *bright and intense* the image is through this thing. it made me think it wasn't filtering out anywhere near enough magnified solar light. scared me that it might do some serious damage. that's why i asked if they are even safe to use. so, based on what you are saying, you use/have used this thing at least several times and your eyes are ok? i might add that this is an older make of prism and solar filter; newer ones may be darker......
I've taken many solar observations using these filters and have not suffered any negative reprecussions doing them, I just turned 80 last month and had eye surgery 13 years ago to have a cataract taken off my right eye, which is not the eye I use when running instruments. I use my left (master) eye for this. They did my left eye too, a couple of years later, but this was only to balance my eyes out to make both eyes the same and eliminate my having to wear glasses, other than dime store reading glasses. Anyhow, these filters are made especially for this purpose. Some may think that a welding helmut filter will suffice, but this is a no-no. The design is not the same and there are articles published warning against using a welders helmut filter glass to perform a solar observation. These filters have been in use since the day of the Solar Compass and as far as I know, haven't changed, or if so, very slightly. The GLO/BLM used them for many years performing their cadastral surveys.
My Gurley Solar Transit has both a regular eyepiece filter and the additional 90° eyepiece filter to use when the sun is too high to see through the regular eyepiece. One is a yellow image and one is a green image. My old Ainsworth transit with a Young & Sons Solar Attachment filter doesn't look any different when looking at the orb than the ones on the Gurley. When I bought some Lietz T-60D theodolites for my crews to use, I had the solar reticle put in and ordered all the 90° prism eye pieces necessary for the scope and vernier eyepiece in order to do solar observations. If I remember correctly, the scope eyepiece filters depict a red image.
very helpful. thanks for the reply. no substitute for experience.