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What did you work on today?

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#4426 jtsenghas

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Posted 12 January 2020 - 04:26 AM

I hope your r&p is better then mine was... lol.gif

Actually,  that rack and pinion focuser appears to be surprisingly tight and linear in motion, despite being inexpensive. It has an all aluminum body and brass rack.  Two brass springs keep the pinion in tight contact with the rack. The guides hold the draw tube tightly enough without rocking and I shortened their length only a few millimeters. It's a LOT better than a similarly priced Orion focuser I once had that had a lot of plastic components. I found it on eBay. It wasn't from this vendor,  but appears to be identical. I see refractor focusers with the same body are also available. 



#4427 luxo II

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Posted 18 January 2020 - 04:24 AM

Cannibalised a sunshade for a car to make insulation for my OTA, the front section extended out to act as a dewshield. Adhesive Velcro tabs hold it in place.

Ready to try in the coming week as it appears the weather is finally improving.

#4428 jtsenghas

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Posted 18 January 2020 - 11:00 AM

Cannibalised a sunshade for a car to make insulation for my OTA, the front section extended out to act as a dewshield. Adhesive Velcro tabs hold it in place.

Ready to try in the coming week as it appears the weather is finally improving.

Nice!  Picture,  please? 



#4429 RFeaster

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Posted 19 January 2020 - 03:07 PM

Got tired of my 32mm Sirius plossl blacking out because the eyecup was too short, so I made a a new one.  [1] #217 & [6] #027 square o-rings super glued together.  Rough looking, but mission accomplished...

 

 

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#4430 ATM57

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Posted 21 January 2020 - 01:09 AM

I made a sub-aperture mask for my C14 with interchangeable apertures. The two main sub-apertures are 4.625” unobstructed. Either aperture of the mask can be blanked off for different visual experiments. I have some crazy ideas bouncing around in my head that I would like to try out. As an example, I’m looking forward to having a good hard “look” at how much of a “real” difference an obstruction makes for visual observing versus unobstructed, math equations, and computer simulations (contrast). I have extra blanks for future experiments and also a blank for a solar filter should the sun get active again. Still messin’ around… grin.gif

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#4431 jtsenghas

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Posted 21 January 2020 - 11:38 AM

I made a sub-aperture mask for my C14 with interchangeable apertures. The two main sub-apertures are 4.625” unobstructed. Either aperture of the mask can be blanked off for different visual experiments. I have some crazy ideas bouncing around in my head that I would like to try out. As an example, I’m looking forward to having a good hard “look” at how much of a “real” difference an obstruction makes for visual observing versus unobstructed, math equations, and computer simulations (contrast). I have extra blanks for future experiments and also a blank for a solar filter should the sun get active again. Still messin’ around… grin.gif

Comparisons on Jupiter in good seeing may be very useful.  That seems to me to be one of those targets that suffers most from a central obstruction.  Don't confuse loss of resolution from smaller apertures with the effects of central obstruction elimination.



#4432 ATM57

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Posted 21 January 2020 - 01:34 PM

Comparisons on Jupiter in good seeing may be very useful.  That seems to me to be one of those targets that suffers most from a central obstruction.  Don't confuse loss of resolution from smaller apertures with the effects of central obstruction elimination.

I agree, Jupiter is a good test object. Since I will be comparing the same size apertures, obstructed to unobstructed, this should be "apples to apples." I don't understand how a loss of resolution will come into play when both test apertures used will be 4". When testing, both test apertures will be loaded onto the same side of the C14 mask. The experiments will not be the same as when comparing diferent types, or sizes, of telescopes with differing degrees of optical correction, collimation, optical alignment, etc. I'm just having optics "fun" while, at the same time, keeping these old brain cells active smile.gif

 

Update: The pic shows the two 4" apertures for my contrast experiment. Still scope "hacking" after all these years...

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Edited by ATM57, 21 January 2020 - 08:09 PM.

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#4433 mark cowan

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Posted 21 January 2020 - 04:38 PM

I would do more of a blink comparison between opposing masks - the differences can be so subtle that this will guarantee you can see them.  I've done this kind of thing myself.

 

Assuming the C14 is well collimated and corrected and your sub-apertures are well aligned there's no difference between opposing sides of the entrance pupil.


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#4434 ATM57

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Posted 21 January 2020 - 05:18 PM

I would do more of a blink comparison between opposing masks - the differences can be so subtle that this will guarantee you can see them.  I've done this kind of thing myself.

 

Assuming the C14 is well collimated and corrected and your sub-apertures are well aligned there's no difference between opposing sides of the entrance pupil.

Nice idea. My C14 is, in focus, star collimated and is very well corrected with smooth optics. I'm probably being more critical than needed using a single side of the mask for the experiment. The apertures are easily changed out in mere seconds (3 to 5) when not using the brass knobs which were a bit of overkill. I even made a 2.5" mask to remind me of my first telescope which was a Sears refractor. I saw a lot of things with that first scope when I was stationed in Alaska. I will try to see them again just for the memories and the fun factor. cool.gif Using the GoTo mount will make my searches for these targets much, much, easier than my beginner struggles trying to find objects with an EQ mount over 40 years ago! I wonder if they will still look as good as they did then (doubtful)? 
 


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#4435 megachriops95

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Posted 26 January 2020 - 05:12 PM

Flocked the new tube for my 6" mirror rebuild.

 

The difference in blackness is great. Hopefully I notice a big difference in my light polluted skies. I used the Mcmaster Carr velvet sheet with double sided carpet tape. Tedious but I got it in there finally.

 

 

 

Flocking.jpg

 


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#4436 ATM57

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Posted 27 January 2020 - 12:48 AM

I finished more apertures for my experiments. My tests are similar to Robert E. Cox’s visual diffraction effects shown in the September 1960 issue of Sky & Telescope, Gleanings for ATM’s, pg.166.  I will run similar obstruction/diffraction tests but my real purpose for all of this is a bit different. I will keep those purposes under my hat for now. wink.gif  This could be a total waste of time but it is an old itch I have to scratch. grin.gif

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#4437 luxo II

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Posted 27 January 2020 - 12:58 AM

Adapted a case to hold a 2" diagonal, turret and the eyepieces I actually use...

 

 


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#4438 petertinkerer

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Posted 27 January 2020 - 11:46 AM

Star tested my newly completed 6 inch F8 binoscope on the trapezium stars.  ABCD nice and sharp at 210 magnification, E star clearly visible and the C star slightly elongated, so maybe a hint of the F star.  So pretty happy with that and when the seeing is better I hope to clearly separate the F star. The 1 degree view with 20 mm GSO 62 degree AFOV eyepiece was glorious.


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#4439 don clement

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Posted 27 January 2020 - 12:05 PM

After having looked at an antique ammeter of mine I came up with an idea for my Coulter 17.5" truss tube conversion. I would use a solenoid to release a spring loaded Turcite pad so that stiction using the Teflon bearing pads could be controlled by push button.

 

Don 

 

IMG_3471Web.jpg

 

IMG_3469web.jpg


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#4440 bcarter1234

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Posted 27 January 2020 - 06:40 PM

Star tested my newly completed 6 inch F8 binoscope on the trapezium stars.  ABCD nice and sharp at 210 magnification, E star clearly visible and the C star slightly elongated, so maybe a hint of the F star.  So pretty happy with that and when the seeing is better I hope to clearly separate the F star. The 1 degree view with 20 mm GSO 62 degree AFOV eyepiece was glorious.

Peter,

 

Congratulations, you are doing better than I have managed so far from a light polluted driveway. I continue to try but have not yet managed to see F in a binoscope of 150mm or less. I refuse to give up though. If you are willling, share your observations in the "15 Amazing Minutes with M42" Thread over in Deep Sky Observing.  

 

Oh yeah, since this is "What did you work on" here is a picture of the PVC adapter turned to save 18mm of back focus for binoviewers on the 13.1" Dob.

20200126 123920 resized

 

Installed in the focuser.

20200126 123353 resized
 

E shows up and F plays hide and seek in them at 200X plus. F should be readily visible once I get the mags down and the resulting brightness up just a bit. Something closer to 125-150X seems to make F easiest to see from the driveway. The more I play the more I think a 12.5" binocular telescope could be my most used instrument, in combination with a smaller binocular telescope for wider views of course.   

 

Take care,

Brent


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#4441 soldevilla

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Posted 28 January 2020 - 06:02 AM

not only today, but these last weeks.

 

Designing and printing several field rotators for friends

 

49453783288_3aaccad4ac_k.jpg

 

49453786298_4e75ebfdd3_o.jpg


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#4442 jtsenghas

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Posted 28 January 2020 - 07:09 AM

not only today, but these last weeks.

 

Designing and printing several field rotators for friends

Cool! Are these motorized for astrophotography? 


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#4443 soldevilla

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Posted 28 January 2020 - 12:55 PM

Cool! Are these motorized for astrophotography? 

the second one will have a motor. But I need to do tests before to know if the precision is enough for to derotate images with an azimutal mount. Maybe I must to design a four one lol.gif


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#4444 jtsenghas

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Posted 28 January 2020 - 01:59 PM

The neat thing is that if you use short exposures and stack,  even if you have a bit of error on drift and rotation,  if both are intermittent and approximate from manual adjustments,  this will still be a lot better than stacking exposures with much more image rotation.  It's amazing how much software compensates. 


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#4445 skround

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Posted 28 January 2020 - 03:26 PM

3 of the 12 flanges for the 6 truss beams for the 800mm project, been turned. A local school helped by machining these in their workshop.

 

a.JPG

 

This is the drawing for reference:

 

aa.JPG

 

What's missing here is that to shed some weight will taper the inner wall of the cylindrical section


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#4446 Pinbout

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Posted 28 January 2020 - 06:31 PM

augmented reality 

 

just testing the link

 

it needs to opened on a smart phone.

 

and point it at your wife. lol.gif lol.gif lol.gif


Edited by Pinbout, 28 January 2020 - 06:35 PM.

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#4447 Bob4BVM

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Posted 29 January 2020 - 02:41 PM

3 of the 12 flanges for the 6 truss beams for the 800mm project, been turned. A local school helped by machining these in their workshop.

 

attachicon.gifa.JPG

 

This is the drawing for reference:

 

attachicon.gifaa.JPG

 

What's missing here is that to shed some weight will taper the inner wall of the cylindrical section

Interesting, truss-end flanges !

How will this install & interconnect ?

Since the design is so close, can you alter the flange geometry  a bit to allow a single thru-bolt interconnect, thereby creating a tru triangle at the truss junctions ?

 

Drawing below illustrates what I mean. I might have shared this somewhere in your 800mmF3.3 build thread...

 

CS

Bob

tube insert for true truss structure.png

dob truss pole single-bolt-lap joint.jpg


Edited by Bob4BVM, 29 January 2020 - 02:58 PM.


#4448 skround

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Posted 29 January 2020 - 07:34 PM

Interesting, truss-end flanges !

How will this install & interconnect ?

Since the design is so close, can you alter the flange geometry  a bit to allow a single thru-bolt interconnect, thereby creating a tru triangle at the truss junctions ?

 

Drawing below illustrates what I mean. I might have shared this somewhere in your 800mmF3.3 build thread...

 

CS

Bob

attachicon.giftube insert for true truss structure.png

attachicon.gifdob truss pole single-bolt-lap joint.jpg

Here's a rendering of the installation - bolts not shown. All the bits are pretty much done. I see a point in your concept which is valid for portable dobs by  using half the bolts and making the assymbly.

 

For our 800mm the transportabikity is not a priority as it will be possibly assembled an handful of times.

 

x.JPG

  

Cheers, Michele


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#4449 Other_Mike

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Posted 30 January 2020 - 02:42 AM

Added mounting brackets to my recently-built filter holder so it can hang off of my rocker box within easy reach.

It will get stained and sealed to match the rest of the scope at a later date.  And, I need to work on memorizing the order I keep them in, so I don't have to grab five different filters until I find the one I wanted in the first place.

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#4450 mcmaker

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Posted 31 January 2020 - 06:10 PM

Finished making aluminium motorized barndoor mount. I designed it for a scrap Vixen controller and steppers, it perfectly tracked 55 mm lens for over 70 seconds, I hope for 2 minutes with 135 mm lens ;)

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