11 replies to this topic

[deSitter]

Well I was playing with my 5x WF microscope eyepieces when I decided to figure out what the focal length was.

 

It's LOOOONG - about 50mm! And it's a classic Huygens.

 

I need to find an 0.5mm or so thick bushing to use it in a classic scope though - it's 23mm and I want something more elegant than tape. Actually a C-shaped tube of thin-walled copper would make for a tight fit. It should be 30 mils. Brass would be good. Can you buy brass sheet?

 

The AFOV is about 30 degrees, but that doesn't really bother me. With a 50mm eyepiece pair in a binoviewer you would get spectacular lunar views of absolute crispness in a long refractor. 50mm/16 = 4mm exit pupil even in a classic 76/1200mm scope, and only 24x.

 

Anyway a 5x microscope eyepiece provides an excellent route to very low power views in long refractors.

 

-drl

[Sleep Deprived]

Another one of my hobbies is model railroading.  They sell various thicknesses of brass for model building (brass locomotives and railroad cars are actually a thing!) at hobby shops.  Hobby shops are harder to find nowadays - you may want to try Amazon.

[deSitter]

Another one of my hobbies is model railroading.  They sell various thicknesses of brass for model building (brass locomotives and railroad cars are actually a thing!) at hobby shops.  Hobby shops are harder to find nowadays - you may want to try Amazon.

 

Thanks for the idea! Another thing - this eyepiece has RIDICULOUSLY long eye relief - you could use it with Coke bottle glasses - so no astigmatism!

 

-drl

[MisterDan]

-and zero lateral color. 

 

Plenty of 0.5mm brass sheet available via Amazon.

23mm microscope eyepieces are (or should be) 23.2mm, so 0.5mm should do well for a 24.5mm diagonal/port.

 

Best wishes.

Dan

[TOMDEY]

The magnification of a microscope eyepiece is (standard) 10 inches / f. So if yours is 50mm, that would likely be a ~5X~ eyepiece.  Same rule applies to loupes, magnifying glasses, etc.   Tom

[deSitter]

The magnification of a microscope eyepiece is (standard) 10 inches / f. So if yours is 50mm, that would likely be a ~5X~ eyepiece.  Same rule applies to loupes, magnifying glasses, etc.   Tom

 

Yes, I measured the f/l before I knew that The formula works!

 

If you want a millimeter version, just

 

F x Mag = 250mm

 

where F is in mm.

 

How I measured the f/l - I have a Vixen 6x30mm finder with no eyepiece. (Still looking.) I know the objective is 150mm f/5. It's very handy to have this lying around to test eyepieces on objects in the room. Just hand held. So I tried it on my eyepiece and came up with 3x. Meaning 50mm focal length. I guessed that was probably not an accident.

 

-drl

Edited by deSitter, 07 April 2025 - 04:00 PM.

[CharlieB]

I have used both .965 and microscope eyepieces in 50mm equivalent f.l.

 

Here are two of them.  The ASA labeled one is a .965 Huygen telescope eyepiece and the Nippon Kogaku (Nikon) 5x is, of course, from a microscope.  The NK 5x gives a superior view in sharpness, but the ASA gives a slightly wider FOV.  Neither are spacewalk views, to say the least.

 

The other Nikons are microscope eyepieces, with the 10x Kellner among my favorites,  Both the 8x and 15x Nikons give a fairly wide FOV.

 

 

Charlie

[TOMDEY]

Most "standard" microscopes feed their eyepieces nice and gently at around F/15 to F/18. If your telescope is faster than that... the imagery can be disappointing. Another effect is that the microscope feed provides more eye relief than does the telescope. Just somethings to keep in mind when using microscope eyepieces for astronomy.    Tom

[jragsdale]

I use these for microscope eyepieces, no retaining screw, just don't turn your diagonal upside down.

 

https://www.ebay.com/itm/114998649659

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Edited by jragsdale, 07 April 2025 - 09:18 PM.

[deSitter]

I use these for microscope eyepieces, no retaining screw, just don't turn your diagonal upside down.

 

https://www.ebay.com/itm/114998649659

 

Perfect! 2 on the way. I think the A-O scopes with the long drawtube will be able to do my binoviewer with these.

 

-drl

[Kefka1138]

Great post OP!

 

Microscope EP are really fun to experiment with for astro use - I personally enjoy the Zeiss products the most. However, I've spent fair amount of time viewing my old Layfayette's. The P15X are my favorites - very nice performance. I suspect they are Periplans. 

 

[RichA]

Another one of my hobbies is model railroading.  They sell various thicknesses of brass for model building (brass locomotives and railroad cars are actually a thing!) at hobby shops.  Hobby shops are harder to find nowadays - you may want to try Amazon.

Or buy brass shim stock from a tool house.