Recent content by LensBoii

I'm up early updating my computer. So here are some updates while I wait. I did some exact measurements for tuning collimation of lenses in the eye tube cartridges. There were different sized gaps because of the way lenses in general are made. Exact lens mounts for a single lens can cost...

Dollond did a lot of research and development of eyepieces and had an early zoom lens I think. They also made highly-corrected telescopes for military use. A useful set of data is in this paper, from which you can draw some conclusions: link

I did some more observations and testing. The eyepiece is not really a Ramsden configuration but looks like a stretched out Huygens eyepiece. I'm basically reverse engineering at this point to recover lost information. Huygens eyepieces work really well with focal ratios of f/10 and slower...

I have a pleasant surprise! I was wondering why I was getting such good image quality from this telescope, especially sharp focus and colours. I finally managed to be a bit tougher with the objective lens mount - and it does turn apart to release the glass within. Polishing the lens in...

Great points @Heym SR20 ty. I've gotten some muscular memory after practising for a week for focus. It just happens automatically now, even without looking through the eyepiece. I agree that this is much faster and field-expedient than setting up with a tripod. Years of holding long metal...

A beautiful piece of kit.

Update with experimental results - useful if you want to know any telescope better. Plus the method. Some older vets might have known, but it's written here now. Results: (correct for 20:20 or 6/6 vision) Magnification = 19.94x +/- 0.7x Field of view = 1.63 degrees +/- 0.004 degrees (98...

Thanks for confirming my suspicions @caberslash . I might as well leave this up for the lens data I measured and geometry for people coming in from Google searches in 2123 :lol: Now I have an excuse to beat up on this one, use it hard and experiment with lenses and carry it in a chunk of PVC...

Beautiful

Thank you @caberslash for this excellent writeup, and for all those who commented. I read the whole thread with interest while working on my own telescope. I added lens specifications and a geometrical optics model. It might be useful to restorers or tinkerers. The drawing is to scale. I'm...

Thank you @finnbear270 and @Heym SR20 ! Indeed I used that writeup before I added my contributions and measurements. My writeup is geared towards geometrical optics and lens specifications and my other thoughts. Maybe I should cross-reference my writeup with theirs.

Eye Relief end-on Closed showing stitching on leather and knurling Order of assembly: Objective to body, Sun shade to body, first draw tube, second draw tube, lens cartridges x2 (containing 4 lenses total) to Eye tube, Eye tube to the second draw tube, Eye relief to Eye tube. (With...

Hi all, I made an introduction post last night. I'm writing up my investigation into a deer stalking telescope I got in the year 2000. I believe it is the number #3 model from Ross London, without a serial number, circa 1900 AD. I believe it's an imitation made in India. It's quite...

Hello!

Hi!