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Questar Repair Bench – Q&A Thread

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#51 Optics Patent

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Posted 02 September 2019 - 11:21 AM

Alas, the mirror of the 1964 set had a bad chip on the back that turned into a crack on the front, and the set has been deemed unusable. 

 

I may transplant from one I have or keep an eye out.

The crack on the front goes only about 5mm from the aperture, and the thimble flange covers 3mm, so I wonder if it might be worth the investment in a recoat even if it means losing that chip.  I'll ask Cumberland if they might reconsider.  If I could find my spare optical set I picket up on eBay a few years back I might not worry.  I'll keep digging.

 

IMG 2521
 
Not pretty, but I've had plenty of good luck in this hobby, so can withstand the occasional bad luck.


#52 DAVIDG

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Posted 02 September 2019 - 12:17 PM

 I wouldn't get recoated unless you Foucault test to see if the surface is distorted. I have seen many optics were the damage looks like a small area but extends much farther into the optics surface and distorts it. It is very easy to doa  Foucault test on these small mirrors. All you need is a  LED, razor blade, a small block of wood to mount and battery to power the LED.  You did a wonderful jobs on the mechanical repairs. Some optical testing should go along with it. 

   As for coating on the corrector, on my 1961 version I had the MgF2 applied to both sides. It increased the contrast and transmission a bit and worth it to me to help improve the older style optics with the secondary on the front of the corrector.

 

                  - Dave  


Edited by DAVIDG, 02 September 2019 - 06:41 PM.

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#53 Old Don

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Posted 07 September 2019 - 12:10 AM

Ben,
What is the size of the Allen Head wrench used to adjust tension on the RA knob that  you show in the Q Zone video?



#54 Optics Patent

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Posted 07 September 2019 - 07:54 AM

The only adjustment is the small conventional slot screw recessed in the edge of the turntable.

The knob attaches to the pinion with a Bristol set screw.

#55 Optics Patent

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Posted 19 September 2019 - 11:06 AM

From this post about an Ebay acquisition:

 

"Re the finder knob, it works but not from the normal clock face 12 to 3 position. Instead it works from the 3 to 6 position. So would this be something for repair by Questar or Company 7?"

 

Don't send it in.  Get the small Bristol L-wrench (Ebay or Questar) and just loosen the set screw opposite the lever, adjust, and tighten.  As easy as it gets.  You'll want to visit this thread for most of the things mentioned here.

 

If you're ordering from Questar (call, don't email), consider if you want new eyepiece eye cups if any are damaged or worn. 

 

They can also send you a new replacement warning label so you can remove the damaged one, and replace if there is a fading shadow.

 

I'll bet that Mother's wheels polish or equivalent will impress you with how it can restore those purple surfaces (finish with plain car wax).

 

You'll need to deal with the finder mirror screws.  I did a post here about it, and also a 20-minute Youtube video on Questarzone.com. If you're not perfectly happy with the plating condition on the mirror, you may as well spend $30 and get it recoated like new.



#56 munirocks

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Posted 24 September 2019 - 03:41 AM

 

The crack on the front goes only about 5mm from the aperture, and the thimble flange covers 3mm, so I wonder if it might be worth the investment in a recoat even if it means losing that chip.  I'll ask Cumberland if they might reconsider.  If I could find my spare optical set I picket up on eBay a few years back I might not worry.  I'll keep digging.

 

 
 
Not pretty, but I've had plenty of good luck in this hobby, so can withstand the occasional bad luck.

 

I think the main mirror is held in place by the centre hole when mounted. The chip at the centre hole looks like it takes up a significant proportion of the hole circumference and might make it harder to hold the mirror square in the mount, even if the chip doesn't take up much of the exposed optical surface.


Edited by munirocks, 24 September 2019 - 03:42 AM.


#57 Hosea100

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Posted 28 September 2019 - 10:47 AM

From this post about an Ebay acquisition:

 

"Re the finder knob, it works but not from the normal clock face 12 to 3 position. Instead it works from the 3 to 6 position. So would this be something for repair by Questar or Company 7?"

 

Don't send it in.  Get the small Bristol L-wrench (Ebay or Questar) and just loosen the set screw opposite the lever, adjust, and tighten.  As easy as it gets.  You'll want to visit this thread for most of the things mentioned here.

 

If you're ordering from Questar (call, don't email), consider if you want new eyepiece eye cups if any are damaged or worn. 

 

Hi Ben, well, I bought a set of Bristol wrenches and tried the ones that would fit in the set screw but it wouldn't budge. I left it alone since it works ok. I wrote the seller about the knob got that way but she hasn't responded...and probably won't. The eye cups are in good condition. The glue on the finder screws was not as "goopy" as shown in the pics.


#58 Hosea100

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Posted 28 September 2019 - 10:50 AM

Just a note to let you know I have learned a lot from your posts as I'm sure others have, too. I've watched your YT posts over and over and learn something new. Guess you CAN teach an old dog new tricks.



#59 Optics Patent

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Posted 28 September 2019 - 12:44 PM

Thanks for the kind words. It’s gratifying to know others are benefiting from my videos.

If you’re sure you have the L wrench in all the way then you can really apply some force. They tend to be tight and it’s scary when you’re doing it right. Go for it!

Edited by Optics Patent, 28 September 2019 - 12:45 PM.


#60 Optics Patent

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Posted 03 October 2019 - 03:24 PM

Slightly off-topic, but I can share that my Questar repair bench hobby has just expanded to camera lenses, specifically vintage Nikon manual focus lenses.  It uses some of the same skills, only a few of the same tools (Japanese "+" screwdrivers are different from Phillips, hollow rubber stoppers are used to unscrew rings, and little suction devices lift lens elements out of their housings), and mostly the confidence and judgment that cutting into a $2000 scope gives.  I'm playing with $50-100 lenses, but that can change.  Admiring credit to Richard Haw, who is a hobbyist who has documented the complete servicing of scores of lenses.  After scouring his detailed posts for some that are good for a beginner, I learned so much I did one I had that he hadn't done, and figured it out from the principles he teaches.

 

IMG 2704
 
This shows the lens (a 50mm f1.8) mostly disassembled but the individual lens elements not yet removed for cleaning.
 
IMG 2706

 

I'm using the nifty suction cup.  I might try it with corrector plates, but will test their weight capacity over a soft surface.  I also applied the hard-won lessons on reinstalling helicoids (the multi-start threads used in focusers with several ways to install wrong, and one to install right) that I learned from a Questar 700 project.

 

To keep this enough on topic, I've also found sources for cleaning and restoration of camera bodies such as the Questar-modified Olympus OM-1.

 


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#61 Gregory Gross

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Posted 03 October 2019 - 08:48 PM

Slightly off-topic, but I can share that my Questar repair bench hobby has just expanded to camera lenses, specifically vintage Nikon manual focus lenses....

This is not at all off topic, for me at least. I recently acquired a Praktina FX SLR specifically to attach to my '62 Questar. I was prompted to do so partly to try out film photography again (my last exposure [pun intended] to this was decades ago), partly to have a go at lunar photography with my Questar (see this past CN thread on mirror slap and shutter shock), and partly by the appearance of the Praktina FX on p. 28 of the November 1960 Questar booklet (this piece of Questar literature is accessible via Company 7).

Questar with Praktina FX

Alas, I have a habit of finding cosmetically beautiful but optically challenged vintage gear. Some of the lenses that accompanied this camera have signs of fungus. There are some other issues with the curtain shutter getting stuck with an obvious light leak as the result, issues that make me question how viable of a repair candidate this camera is. But at least it looks great when it's attached to my Questar!

 

I'll definitely have a closer look at Richard Haw's website. Thanks for sharing!




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