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Sad Sack SCT - Criterion Dynamax 8

catadioptric classic equipment SCT
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#1 Bomber Bob

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Posted 02 May 2016 - 04:39 PM

My Dynamax 8 arrived today, between thunderstorms:

 

DX8 - Arrival S01.jpg

DX8 - Arrival S02.jpg

DX8 - Arrival S03.jpg

DX8 - Arrival S04.jpg

DX8 - Arrival S07.jpg

 

Very nice case, near pristine scope & mount, and 3 goodies!  We're off to a promising start...


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#2 terraclarke

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Posted 02 May 2016 - 04:42 PM

Looking good so far! Nice finder!

#3 Bomber Bob

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Posted 02 May 2016 - 05:25 PM

Y'all, there's not a scratch on it.  The power cord looks like it's never been unwound.  According to the Seller, a Los Alamos scientist had 4 DX8s, and this one was in a closet, apparently never used.  Assuming that's true:  Who buys 4 identical scopes?  Maybe the buy was a gov't contract for some research project, and the scientist was allowed to take these home.  Anyway, the feet on the case have no scuffs, and there are two sets, so it can sit horizontally or vertically.  Some of the thick foam panels are pulling loose from the sides, but they hold the 27 pound rig securely.


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#4 Bomber Bob

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Posted 02 May 2016 - 07:28 PM

The 3 Extras:

 

- A 50mm f/4 uncoated achromat in an all brass cell - possibly from a binocular?

 

- A 60mm FL eyepiece?  Uncoated lenses in an all aluminum heavy-duty housing with a 32.25mm barrel diameter.

 

- Yellow Packet containing 2 small plano-convex lenses, and a third lens that looks like a Barlow.  Soft-Lite Lens Company, Inc  New York City   Bausch & Lomb Made  Copyright 1933   Looks like this company made eyeglasses, visual aids, etc.


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#5 Bomber Bob

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Posted 02 May 2016 - 08:37 PM

At 27 lbs, there's no way the DX8 can ride on my Davis & Sanford tripod.  Guess I'll have to get a conventional wedge & tripod (and y'all know how I loathe the conventional!).

 

[That bonus unmarked (naturally, it's me!) 50mm lens is in a fancy brass cell, and would make a great large finder for my Mogey.  I'll have to do some kuldgifying, but that's not a problem.]

 

No star testing until Thursday, so I've got time to measure & collimate indoors.  The primary has a few flecks of black dust on it that could be from the interior blackening.  Its coatings look brand new.  There's a smudge on the corrector near the secondary holder, so it will get an exterior cleaning tomorrow.

 

Mechanically, I'm impressed by this DX8.  Construction looks & feels solid.  Unclutched, it moves easily on both axes, and the slo-mo's have the right stiffness and no backlash.  Can't wait to see if Criterion did as well with its optics.


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#6 Michael Covington

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Posted 02 May 2016 - 08:53 PM

I almost bought a Dynamax 6 in 1980 but was warned off it and bought a C5 instead.  Ever since, I've been wondering what Dynamax telescopes were really like.  Earlier, I had owned an RV-6, which was excellent, but I got out of astronomy for a few years and sold all my equipment.



#7 Bomber Bob

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Posted 02 May 2016 - 09:10 PM

Hate that you parted with your RV-6!  The DX8 is BB's final Classic Scope purchase​ - and I mean it.  I'd like to end the insanity on a high note.  [In the future, my buys will be cheap, damaged, classics that I'll restore to sell / trade / donate - like the Mayflower or the Stein Towa.]  I'll give this DX8 the benefit of the doubt for as long as possible.  I won't call it Sad Sack until I have to.  For now, it's almost as pretty on display as my Questar.


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#8 Michael Covington

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Posted 02 May 2016 - 09:23 PM

Yes... in the RV-6 era we had great optics and poor eyepieces.  In the 1980s and 1990s we had poor optics and better eyepieces.  I wish I had hung onto the RV-6 to pair it with a DeLite or at least a good orthoscopic!


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#9 terraclarke

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Posted 02 May 2016 - 09:24 PM

"The DX8 is BB's final Classic Scope purchase​ - and I mean it."

Boy I've heard that before! (And said it before! :lol: )

Good luck with that! :rofl:

Edited by terraclarke, 02 May 2016 - 09:25 PM.

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#10 Chuck Hards

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Posted 02 May 2016 - 09:40 PM

Oh, come on!  You didn't even look down the street with it?



#11 Bomber Bob

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Posted 02 May 2016 - 09:44 PM

Waiting on the B&L 1.25" adapter.  And, standing outside with this metal hulk would've been a Ben Franklin reenactment today!


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#12 orion61

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Posted 03 May 2016 - 01:52 PM

  That is the series of DX8 that I found to have the best optics, (of the 4 I have owned).

If you get tired of it, and since I have 2 of them, I might offer up my Rare DX6" in trade.. :flowerred:

I have been itching for another DX8. Great find buddy! I call dibbs.. :waytogo:

You are going to need to service the old girl because the grease will be dried and hard. The Dec Slow-Mo adjustment knob

will probably be murder to turn, :grin:  They get sticky over time, Criterion drilled the Dec adjustment rod holes so it was mounted at a slight bend. If you don't like the firm feeling the next size larger drill on the rod holes a bit will release the bend and make it easier to turn!

Also your DX8 will more than likely have significant image shift and need re-lubed. Some Super lube grease cut thinned

with some Mobile 1 oil will remove it. You would think thicker grease would make sense, but it will make it harder to shift.

Think Shoes stuck in mud..

Either Myself or the Dyna MASTER Gill can answer questions.... :bow:

Great find!

Duane


Edited by orion61, 03 May 2016 - 01:53 PM.

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#13 starman876

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Posted 03 May 2016 - 05:01 PM

Hate that you parted with your RV-6!  The DX8 is BB's final Classic Scope purchase​ - and I mean it.  I'd like to end the insanity on a high note.  [In the future, my buys will be cheap, damaged, classics that I'll restore to sell / trade / donate - like the Mayflower or the Stein Towa.]  I'll give this DX8 the benefit of the doubt for as long as possible.  I won't call it Sad Sack until I have to.  For now, it's almost as pretty on display as my Questar.

interesting. In the same sentence you say your last and what you will do with future buys. You need to pass that doobie around :lol:



#14 Bomber Bob

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Posted 03 May 2016 - 05:22 PM

Uh, I think Dr. J has already been tokin...

 

Buys for myself are donebuys for others are okay.  I'll be retired soon, and I enjoy taking the sad sacks, restoring them, and finding good homes for them.  Not going for a sainthood, but good deeds won't hurt, either.


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#15 Bomber Bob

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Posted 03 May 2016 - 05:23 PM

Based on the corrector number (740205) my OTA is the 205th made in 1974.  I'm hoping that was a good year at Criterion.  And, the 1941 base number means it's the 941st DX8 made.


Edited by Bomber Bob, 03 May 2016 - 05:25 PM.

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#16 starman876

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Posted 03 May 2016 - 05:38 PM

Based on the corrector number (740205) my OTA is the 205th made in 1974.  I'm hoping that was a good year at Criterion.  And, the 1941 base number means it's the 941st DX8 made.

they really made that many?



#17 Bomber Bob

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Posted 03 May 2016 - 05:51 PM

Criterion stopped numbering around 1980, and Masvingo's DX8 has base #4844 - the 3844th OTA made --> http://www.cloudynig...e/#entry6454462   All that before B&L absorbed a once proud company...


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#18 Gil V

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Posted 03 May 2016 - 06:20 PM

Dying to hear how well the scope images. Was that an E-bay scope? I seriously considered it...

#19 Bomber Bob

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Posted 03 May 2016 - 07:51 PM

Was that an E-bay scope?

 

Yes, and as I posted earlier, I didn't check the ad until the T-15:00 point, as I expected it to be at least $400 -- more than I'd pay for the Sad Sack of SCTs.  But $250?  Sure!  A beautiful piece of hobby history, even if the images stink on ice.  Also, I thought, if the Mystery Mak 6 is a good performer, I'll paint it gray, and put it on the DX8 mount! 

 

Before cleaning the corrector (front face), I verified that the secondary assembly is centered, and found an alignment mark that I've duly recorded.  After cleaning, I can see black paint flecks / dots on the rear side.  Apparently, the flat black interior sheds.  There are a few larger flakes on the primary, too.  I won't take her apart just yet, but y'all know me - I gotta have clean optics.  Anyway, just as with my Tinsley, I won't bother unless the optical quality is worth the effort.  (Once I saw what the Tinsley could do, I was motivated!)

 

It'll be a dirty dog shame if this well-built rig has lousy optics.  It moves as easily as my Questar, and has a similar feel at the controls.  It's stout, and should damp out vibrations quickly.  The 8x50 finder is among the best I've owned.  Overall, it looks built for science - for serious space studies - like my Telementor.  But if the views are Tanzutsu... Well, it can always sit on my desk.


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#20 terraclarke

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Posted 03 May 2016 - 11:04 PM

"Apparently, the flat black interior sheds."  Not a good sign! 

 

(dogs shed!)

 

Hey, in any event, I do know of a nice bridge they have for sale in up in New York City. :lol:

 

Seriously, tho. Keeping fingers crossed that you got a fluke- meaning a good one. ;)


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#21 DAVIDG

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Posted 04 May 2016 - 08:42 AM

 You really need to bench test it to see what is going one. I'll be happy to help anyone that want to refigure their optics. It's really not that hard and the result will be appreciated for years to come with what you can see vs missing out on using a scope with poor optics.

 

                  - Dave 


Edited by DAVIDG, 04 May 2016 - 10:56 AM.

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#22 rolo

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Posted 04 May 2016 - 02:44 PM

I finally found a victim (buyer) for my DX8. He's a loco buyer...oops, I mean local buyer.  He 's aware of their optical limitations but like myself he appreciates the beautiful design and historic value.


Edited by rolo, 04 May 2016 - 02:46 PM.


#23 bremms

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Posted 04 May 2016 - 02:59 PM

There is a D8 bashing thread over on the CAT/ Cass forum.. getting ugly. Worked on one for local guy back in the 80's it was OK. (early one.) About the same as the C8 of a friend, but not a premium scope.



#24 DAVIDG

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Posted 04 May 2016 - 03:01 PM

Mine is sitting patiently on my optical bench waiting for it's turn to be refigured. I got a couple of ideas of how to refigure the corrector to  get it to be optically smooth, then refigure the secondary to the correct the total system so it nulls.

 

                   - Dave  


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#25 Bomber Bob

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Posted 04 May 2016 - 04:56 PM

Got ready to collimate my DX8, until I saw yet another Big Flake of black paint on the mirror:

 

DX8 - First Cleaning S03.jpg

 

Good Grief!!  That won't do.  So, I took off the corrector, and gave these optics a proper cleaning.  The engraved outer ring is held on by 8 small screws:

 

DX8 - First Cleaning S02.jpg

 

Criterion put a handy alignment mark on the corrector and the inner cell.  4 small cork bits shim the glass, keep it centered, and keep it from contacting the aluminum ring.  I marked the locations with a pencil before removing them.  As you can see, the corrector & secondary had paint debris, too.

 

DX8 - First Cleaning S04.jpg

 


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