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Good counterweight solution for DSLR with Q3.5

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#1 TerryWood

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Posted 16 February 2019 - 06:24 PM

I found a very good alternative for counter-balancing a DSLR with your Q3.5. This may have been mentioned before, but I missed it if so. I screwed on a 95mm metal dewshield and added a old Celestron C-5 counterweight kit to the the front. Now it balances perfectly with one small counterweight. I'm gearing up to take some Moon shots tonight. Here are a few pictures of what I'm talking about.

 

V/R

 

Terry

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#2 TerryWood

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Posted 16 February 2019 - 06:25 PM

Another angle.

 

V/R

 

Terry

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#3 TerryWood

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Posted 16 February 2019 - 06:26 PM

And my target in the distance (the Moon).

 

V/R

 

Terry

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Edited by TerryWood, 16 February 2019 - 06:28 PM.

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#4 agmoonsolns

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Posted 16 February 2019 - 07:00 PM

Where did the metal screw-on dewshield come from? Very clever solution Terry!


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#5 Toddeo

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Posted 16 February 2019 - 07:49 PM

Ace Select 78mm x 95mm Screw in Metal Lens Hood for Mirror Tele Reflex Camera Lens with 95mm Filter Thread
by DS.DISTINCTIVE STYLE
5.0 out of 5 stars    1 customer review 
Price: $25.99 & FREE Shipping. Details

 

Go on Amazon. Another  member here has posted- after getting his. Seems to screw on very good.


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#6 SteveJF

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Posted 17 February 2019 - 12:08 AM

I use the same Ace hood with a 12oz velcro exercise ankle weight:

https://www.amazon.c...0?ie=UTF8&psc=1

 

The exercise weight stays on securely and are available in several different sizes. 

 

The Ace hood is well made and has a very good fit.  It doesn't jam even at sub zero temperatures as I initially feared.  

 

Steve


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#7 TerryWood

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Posted 17 February 2019 - 01:12 AM

Hey that's a great idea too, thanks! 

 

V/R

 

Terry



#8 Optics Patent

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Posted 17 February 2019 - 09:35 AM

This seems superior to the original Questar counterweight. Except for the adjustable effect. Perhaps more than one mounting location for the weight would do it. Probably not needed.
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#9 TerryWood

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Posted 17 February 2019 - 10:49 AM

I like the fact that it slips right onto the rim of the dew shield and can be slid around if needed. Those little counterweights are great and can be stacked if need be, but you probably won't need more than one. I also like that they're shiny and match the Questar. I like the asthetics.

 

V/R

 

Terry


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#10 Optics Patent

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Posted 17 February 2019 - 01:51 PM

I’d have the urge to do this with something in tungsten. Small and dense.
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#11 TerryWood

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Posted 17 February 2019 - 02:18 PM

Now we're talking! It would be cool if it were a round, globe shaped weight that screwed into the weight holder too. Like a big, shiny ball bearing with a short stem. V/R Terry

#12 munirocks

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Posted 21 May 2019 - 02:25 PM

Part of the trouble with balancing binoviewers and large eyepieces (like the 13 mm Ethos) in the top eyepiece holder (as opposed to a camera along the axial port) is that the eyepiece weight is off-axis. This means that the counterbalance also needs to be off-axis (underneath) in order to avoid 1) the balance changing with the altitude of the target and 2) potential rotation of the optical tube in its ring mount when viewing targets in the extreme east or west in equatorial mode.

 

The brass-ringed UV filter and lens hood that I have on the front of my Q allow pretty good on-axis balance at many useful astronomy-related altitudes, but I wanted a universal off-axis detachable, adjustable balance solution that worked at all altitudes, even for vertical zenith and horizontal terrestrial viewing. I don’t have a proper machine shop, so my efforts are restricted to what I can saw, file, and drill by hand, preferably with what I can find laying around in the garage. Here’s what I’ve come up with.

 

Brass-ringed B+W UV filter for permanent protection of the front Q corrector. 68 grams.

 

Lens hood. This is a Fittest aluminum tube, 95 mm threads, male at one end, female at the other. 140 grams.

 

SkyWatcher mounting ring, 101 mm inner diameter. I reduced this down to 98 mm (the outer diameter of the Fittest lens hood) by removing the felt, adding a rubber sheet (cut from a bicycle inner tube and attached with double-sided tape), and re-sticking the felt. 167 grams.

 

Steel hollow curtain rail, cut to fit, 138 grams. The front end is bolted to the SkyWatcher mounting ring. The ring is threaded so you can adjust the bolt and locknut to get the amount of compression on the rail just right (to remove slop but still allow rotation for flat storage) without coming out of adjustment.
The rear (finder) end of the rail is cut and filed to a special shape that interlocks with the Q’s finder mirror bracket without touching or damaging the finder mirror itself or the finder solar filter. The finder is not useable with this system because it looks through the middle of the curtain rod. But then the finder does not focus with binoviewers or Ethos 13 anyway so no great loss. (I now know what the inside of a curtain rod looks like under high two-eyed magnfication. And what a sight it isn’t.)

 

The moveable counterweight is a couple of large magnets taped together, along with a steel plate to help contain the magnetic field on the non-rail side of the magnet. I can re-position the magnet anywhere along the rail. The magnets and plate are 440 grams, cannibalised from a broken double-sided window cleaning kit. They are ridiculously, seriously, dangerously overpowered. I have to tilt them onto the rail gently one edge at a time for fear of thwacking the scope out of collimation. I might consider replacing the curtain rod with a proper non-magnetic solid rail and counterweight set, but one would have to figure out how to attach/drill/file/shape the finder end of the solid rail so it fits around the finder mirror and finder solar filter without touching them. Probably something involving swans. (What, no Bleak Expectations fans out there? Over in the Stargazers Lounge that last sentence would’ve been really funny.)

 

To check the balance at any time, rotate the Dec knob back and forth to see if there is any difference in resistance between the up and down directions. They should be equal.

 

The system seems to work well for my Ethos 13 mm and WO binoviewers.

 

Edit: It turns out that my WO binoviewers have a swan logo on the nose cap! How re-happified a bit some more am I? Harry Biscuit would be so proud of... oh, never mind.

questar_counterweight_1_downsampled.jpg

questar_counterweight_2_downsampled.jpg

questar_counterweight_3_downsampled.jpg


Edited by munirocks, 21 May 2019 - 02:29 PM.

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