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Wallace the 6 inch f/2.8 telescope, building it, and hiking with it

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Re: Wallace the 6 inch f/2.8 telescope, building it, and hiking with it

#21

Post by chantepierre »

helij wrote: post #16
chantepierre wrote: post #7

Earlier quoted context omitted.

Hi ! It is quite easy, with 2 tilt screws at the secondary cage, and the primary cell floats on three heavy duty springs. I can shake it and nothing moves, this is my first criteria. I collimate with a cheshire tool but always finish on a star at medium power (since this telescope realistically does not reach high power, since it would need 2mm eyepieces which are the opposite of wide field views). I use it with Expl…

Barlow!?

Well, I could, but checking collimation at 1-2D magnification for an instrument used at 0.16D provides no observable advantage once star collimation was done. My rule of thumb is to star collimate at a higher power than actually used to observe

Re: Wallace the 6 inch f/2.8 telescope, building it, and hiking with it

#22

Post by chantepierre »

mybbor wrote: post #13
dylan604 wrote: post #10

Earlier quoted context omitted.

> cabinet makers were building the most impressive wood frames You say impressive, but my mind reads that as heavy even if they looked amazing

Yeah! I meant impressive more in the “big sturdy woodwork” sense, not lightweight. They had to hold a heavy mirror and still move smoothly enough to aim by hand. The Dobsonian design, plus Teflon on Formica bearings, made big aperture amateur telescopes way more accessible to hobbyists. From what I gathered it was definitely a “bigger is better” kind of thing, and weight seemed pretty secondary.

We still do it ! But the designs have evolved, see : https://www.youtube.com/watch?v=SWhxCwHVPms

I'm planning this kind of build for my 16". It's still a dob, still uses teflon against formica and a wood structure, but the ability to move it easily indeed became a desirable feature.

Re: Wallace the 6 inch f/2.8 telescope, building it, and hiking with it

#23

Post by chantepierre »

giantg2 wrote: post #17
zonkerdonker wrote: post #4

Very cool project and video documentation, really inspiring! As someone who is mechanically inclined and has a decent amount of tools/3D printer, is there any DIY telescope that you would recommend to build as a first foray into the field? I've never done much with optics, and after reading through a few of your posts, it looks both incredibly challenging and very rewarding.

Just go down the rabbit hole like I have over the past year... Find thick glass on Facebook, build a cutting jig, build a kiln to fuse it, etc. I'm still planning to build an 18".

Very nice, are you documenting this somewhere ?

Re: Wallace the 6 inch f/2.8 telescope, building it, and hiking with it

#24

Post by chantepierre »

petee wrote: post #8

Beautiful, like I needed a new crossover of hobbies; btw could this fill a 220 format frame? You also could save a lot of weight by boring out your plywood base and still be plenty rigid

I'm sorry, I did not find what you meant by a 220 format frame. Is it a film photography type ?

Re: Wallace the 6 inch f/2.8 telescope, building it, and hiking with it

#25

Post by hebrox »

robotswantdata wrote: post #14

Very cool project. Been taking my dwarflab mini on hikes instead of the 12” dob ;) , not the same at all but enjoy getting dark sky and some great astro shots.

I want to start looking at the sky with my kids. Would be nice to have something portable like the dwarflab mini. How would you rate it? Does it capture planets in some detail?

Re: Wallace the 6 inch f/2.8 telescope, building it, and hiking with it

#26

Post by platinum95 »

chantepierre wrote: post #24
petee wrote: post #8

Beautiful, like I needed a new crossover of hobbies; btw could this fill a 220 format frame? You also could save a lot of weight by boring out your plywood base and still be plenty rigid

I'm sorry, I did not find what you meant by a 220 format frame. Is it a film photography type ?

220 is a roll film, essentially the same as 120 film, just a longer roll. It's 6cm wide, and picture format depends on the camera/lens, varying from 6x4.5 up to 6x7 (and beyond, for panoramic shots).

So for use with your telescope, it'd need to produce an image circle that'd cover at least 6cm.

Re: Wallace the 6 inch f/2.8 telescope, building it, and hiking with it

#27

Post by chantepierre »

platinum95 wrote: post #26
chantepierre wrote: post #24

Earlier quoted context omitted.

I'm sorry, I did not find what you meant by a 220 format frame. Is it a film photography type ?

220 is a roll film, essentially the same as 120 film, just a longer roll. It's 6cm wide, and picture format depends on the camera/lens, varying from 6x4.5 up to 6x7 (and beyond, for panoramic shots). So for use with your telescope, it'd need to produce an image circle that'd cover at least 6cm.

Thanks for the clarification. I don't think so, my largest eyepiece has a field stop of 39mm, and I'm taking advantage of the fact that edge illumination falloff is not perceptible in visual astronomy when the f/D ratio is low.

Re: Wallace the 6 inch f/2.8 telescope, building it, and hiking with it

#29

Post by chantepierre »

thenthenthen wrote: post #28

Very cool, any pictures of the images it produces?

Sadly not as I exclusively practice visual astronomy.

Here is a nebula, NGC7000, drawn by an excellent observer, which appears that way (very wide field, but a bit dimmer than their drawing) :

http://www.astrosurf.com/magnitude78/serge/images/NGC7000_10...

My advantage despite the low diameter is the ability to frame such huge objects !

Re: Wallace the 6 inch f/2.8 telescope, building it, and hiking with it

#30

Post by robotswantdata »

hebrox wrote: post #25
robotswantdata wrote: post #14

Very cool project. Been taking my dwarflab mini on hikes instead of the 12” dob ;) , not the same at all but enjoy getting dark sky and some great astro shots.

I want to start looking at the sky with my kids. Would be nice to have something portable like the dwarflab mini. How would you rate it? Does it capture planets in some detail?

Not good for planets IMO as 150mm focal length and a small 30mm aperture. Binoculars or small desktop DOB is better with kids for planets. The mini is amazing for deep sky objects for the price
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