Just wondering if anyone here is knowledgeable about telescopes as well as the macro side of things?
Reason being I have an odd scope which I need to rig up an eye piece to. Its an ex military scope with an image intensifier... The intensifier ends with a screen a bit over an inch in diameter. I can see a picture on it but I think it would be clearer through an eyepiece. (and I was told by the person I got the intensifier from that it needed an eyepiece on that end)
I've tried holding a couple of microscope eyepieces up to it, and a 5x eyepiece /almost/ came into focus but then I bumped into the end of the tube. I also tried a Nikon 38x eyepiece from one of their fieldscopes but I couldn't get anything in focus through that either... I have a Nikon 20x fieldscope eyepiece somewhere but cannot find it at the moment..
Any thoughts as to the sort of eyepiece I should be looking for?
If anyone is interested or thinks they could help I'll take some pictures of the end of the thing and post them up here!
Anyone know anything about telescopes?
Moderators: rjlittlefield, ChrisR, Chris S., Pau
-
rjlittlefield
- Site Admin
- Posts: 23597
- Joined: Tue Aug 01, 2006 8:34 am
- Location: Richland, Washington State, USA
- Contact:
Laurie,
Microscope eyepieces are designed to focus on an image that is formed inside the tube of the eyepiece, at the location of the field stop. At least some telescope eyepieces are the same way, though I don't know whether they all are.
It sounds like what you need is an eyepiece that is more like an ordinary magnifying glass, focusing on something outside its own envelope. Fact is, I'd be inclined to try an ordinary magnifying glass, or equivalently, one of your macro lenses, to get a feel for what might be required.
Hope this helps. I don't know much specifically about telescopes or image intensifiers -- just writing from general optics principles.
--Rik
Microscope eyepieces are designed to focus on an image that is formed inside the tube of the eyepiece, at the location of the field stop. At least some telescope eyepieces are the same way, though I don't know whether they all are.
It sounds like what you need is an eyepiece that is more like an ordinary magnifying glass, focusing on something outside its own envelope. Fact is, I'd be inclined to try an ordinary magnifying glass, or equivalently, one of your macro lenses, to get a feel for what might be required.
Hope this helps. I don't know much specifically about telescopes or image intensifiers -- just writing from general optics principles.
--Rik
I managed to find the 20x Nikon and that also didn't work.
What you say makes perfect sense. In the morning I will try out some of my macro lenses... (It's nearly 1.30am here and I've lugged the scope back to it's storage spot from where I cannot really try it out!)
I suppose thinking about it this is more of an image intensifier issue than a telescope issue, perhaps I should re-title the thread!
What you say makes perfect sense. In the morning I will try out some of my macro lenses... (It's nearly 1.30am here and I've lugged the scope back to it's storage spot from where I cannot really try it out!)
I suppose thinking about it this is more of an image intensifier issue than a telescope issue, perhaps I should re-title the thread!
If you have any Kellner eyepieces with any of your microscopes they usually focus in front of their barrel. The may be labled K10, K15, Ke10, or Ke15
Unitron used to have those with their microscopes. And as it happens they made astro scopes too. Some Kellners have a field stop at the focal point. You would want to remove that for this use.
Sometimes oculars that focus inside the tube are called negative and the ones that focus in front are called positive. The latter are as Rik says , magnifiers. Most microscope and telescope oculars have a field lens that increases the eyepieces light gathering power and then a virtual image is formed inside which is then magnified by the eyelens.
There are Kellner astro oculars too and there are others that focus in front of the first lens element. But I can't remember off the top of my head which ones are positive. Kellners are certainly the most common.
If you have a graphics magnifier that you lay on a surface and it focuses on that surface it will work too. five to ten X ought to be about right.
You could just mount a 10x hastings triplet or Belomo lens in the appropriate spot. Most negative oculars will give you some magnification if you look through them backwards. Or if you have some nice old lens that the field lens and field stop unscrew from the inside of the barrel , if you use only the eyelens it will be positive. But you may need to remove it from the barrel too because its focal point will be where the field stop is.
Night vision gadgets are a hoot! Be a little careful because most of them can bite rather hard. They have multi KV power supplies in them Make sure the ocular you apply is appropriately isolated and insulated.
Unitron used to have those with their microscopes. And as it happens they made astro scopes too. Some Kellners have a field stop at the focal point. You would want to remove that for this use.
Sometimes oculars that focus inside the tube are called negative and the ones that focus in front are called positive. The latter are as Rik says , magnifiers. Most microscope and telescope oculars have a field lens that increases the eyepieces light gathering power and then a virtual image is formed inside which is then magnified by the eyelens.
There are Kellner astro oculars too and there are others that focus in front of the first lens element. But I can't remember off the top of my head which ones are positive. Kellners are certainly the most common.
If you have a graphics magnifier that you lay on a surface and it focuses on that surface it will work too. five to ten X ought to be about right.
You could just mount a 10x hastings triplet or Belomo lens in the appropriate spot. Most negative oculars will give you some magnification if you look through them backwards. Or if you have some nice old lens that the field lens and field stop unscrew from the inside of the barrel , if you use only the eyelens it will be positive. But you may need to remove it from the barrel too because its focal point will be where the field stop is.
Night vision gadgets are a hoot! Be a little careful because most of them can bite rather hard. They have multi KV power supplies in them Make sure the ocular you apply is appropriately isolated and insulated.
-
Joseph S. Wisniewski
- Posts: 128
- Joined: Fri Aug 15, 2008 1:53 pm
- Location: Detroit, Michigan
Hey, my first photomicrography.net post 
Oddly enough, although not a major expert in either microscopes or telescopes, I've got enough experience with both, and general knowledge of both, and optical design experience, to hopefully contribute something useful here.
Rik nailed it, almost all microscopes and telescopes put the focal plane inside the eyepiece tube. For microscopes, the standard used to be 10mm inside the tube. This was handy for having different manufacturer's stuff be parfocal. For telescopes, eyepieces are not parfocal across manufacturers, and it's often up to the scope owner to parfocalize his eyepieces by adding rings of tape, or commercial clamp-on rings. But in general, the focal plane is closer to 5mm from the tube.
Additionally, telescope eyepieces are 31.75mm (astronomers are barbarians and call it "1.25 inches"),slightly larger than microscope eyepieces at 30mm.
So, basically everything favors the astronomer. The smaller microscope eyepieces fit and lock into the telescope eyepiece tubes, and astronomers are used to parfocalizing their own eyepieces. The fact that you can't parfocalize the microscope eyepieces on this night vision scope tells me it's one of the rare devices that uses an eyepiece with a focal plane deeper inside the tube than a microscope does.
Can you saw a few mm off the scope's tube?
My Meade 1.25 inch eyepieces are parfocal with each other, and my Wild 20X microscope eyepiece (a league above the Meade Plossls) needs to be spaced out about 5mm to be parfocal.
There's one other key difference. Microscope eyepieces are typically "tuned" to counter a microscope's aberrations: mild curvature of field, severe chromatic aberration. Telescope eyepieces are typically optimized for mirror optics, greater curvature of field, problems with comma, nearly zero chromatic aberration. When I use the microscope eyepiece on the telescope, it overcorrects CA: bright stars near the periphery are "rainbows". dim stars vanish. But oh, the center sharpness...
Oddly enough, although not a major expert in either microscopes or telescopes, I've got enough experience with both, and general knowledge of both, and optical design experience, to hopefully contribute something useful here.
Rik nailed it, almost all microscopes and telescopes put the focal plane inside the eyepiece tube. For microscopes, the standard used to be 10mm inside the tube. This was handy for having different manufacturer's stuff be parfocal. For telescopes, eyepieces are not parfocal across manufacturers, and it's often up to the scope owner to parfocalize his eyepieces by adding rings of tape, or commercial clamp-on rings. But in general, the focal plane is closer to 5mm from the tube.
Additionally, telescope eyepieces are 31.75mm (astronomers are barbarians and call it "1.25 inches"),slightly larger than microscope eyepieces at 30mm.
So, basically everything favors the astronomer. The smaller microscope eyepieces fit and lock into the telescope eyepiece tubes, and astronomers are used to parfocalizing their own eyepieces. The fact that you can't parfocalize the microscope eyepieces on this night vision scope tells me it's one of the rare devices that uses an eyepiece with a focal plane deeper inside the tube than a microscope does.
Can you saw a few mm off the scope's tube?
My Meade 1.25 inch eyepieces are parfocal with each other, and my Wild 20X microscope eyepiece (a league above the Meade Plossls) needs to be spaced out about 5mm to be parfocal.
There's one other key difference. Microscope eyepieces are typically "tuned" to counter a microscope's aberrations: mild curvature of field, severe chromatic aberration. Telescope eyepieces are typically optimized for mirror optics, greater curvature of field, problems with comma, nearly zero chromatic aberration. When I use the microscope eyepiece on the telescope, it overcorrects CA: bright stars near the periphery are "rainbows". dim stars vanish. But oh, the center sharpness...