strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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I'm a refractor kind of guy, but this Criterion has me feeling a little dizzy. When I was 12 or 13 and realized, like a lot of us here, a 3" or 4" Unitron was never going to happen (never say never), I briefly turned my attention to the Criterion 6" Dynascope. A Newtonian reflector of all things. Of course at the rate I was acquiring wealth the RV-6 was also out of the question. I scotch taped the ad from a Sky&Telescope to a gallon wine bottle (no, I didn't drink the wine first), seeded it with a few coins, and kept it in my room. By the end of that summer I had a few more coins, but still about $198 shy of the $199.99 I needed. O K so I learned you can't culture money like sourdough... or can you? So 45 summers, and a few wine bottles (from wine I did drink), later I now actually have the 199.99! And there is an RV-6 for sale.
I'm sure a few of you have looked at the listing. I've been keeping a high bid presence, and have had some contact with the seller. Any observations or opinions about what you see in the listing. The seller seems to be quite precise (owns a machine shop... go figure) And has prepared a great visual presentation.
Besides having to look into the wrong end, is there something else I should know about the RV-6? The seller looked inside the drive motor cover at my request and found 182 imprinted there. I had read the manufacture date was (penciled) in there... true? Does 182 mean anything? Can anyone guess at a vintage? Does it look complete to those of you in the know? I suppose this will head north of the original selling price before the auction ends. I just want to be sure I'm getting the one used for that 1960 advertisement photo shoot, or at least one close to it.
I think it's been pretty well documented that the optics were pretty sweet in these instruments. Were some years better than others? Is there a good way to determine whether the mirror needs re-coating from across country? What is the best method to see a scratch in the mirror or coating? The seller mentioned in the eBAY copy about seeing one, but after blowing off the dust with solvent (his words), he can no longer see it. Should I ask what the solvent was? Please post away, I need your help 
other Keith
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 2296
Loc: Florida
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Lots of questions but here is a short answer. The RV6 was good in its time and is a good value today, if you're careful not to buy junk and willing to do some restoring. I wouldn't worry about vintage, because basically it was the same scope with minor changes over the years. The optics typically were very good to superior.
Plan on recoating and decide before you buy if you can afford this. The original scope was not perfect but a bargain in its day. The mount is just adequate and the drive while functional has lots of slop in the drive train.
Good luck on your venture.
Cheers, Bill
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
Tasco 10K 80mm/1200mm
Towa 339 Restored
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Jim Rosenstock
Post Laureate
Reged: 07/14/05
Posts: 3701
Loc: MD, south of the DC Nebula
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Bill pretty much nailed it. It's a great scope if you like that kind of thing. Should be a fun project, maybe take you back to your youth, huh?
The RV-6 currently on the Bay (selling out of Brattleboro Vermont) has an older-style mount (around the time of the Apollo program, they added "moon lander feet" to the mount) so this one appears to be pre-1968 or so...
The chances of this scope having an excellent primary mirror are quite good.
Most everything else about these scopes was a bit quirky, but quite usable.
Frankly, it would be a lot less bother to get a new, lightweight 6" f/8 Chinese Dob....but your're not that kind of guy, are you? 
So, get out there and start mowing lawns, young man....you have a telescope to buy! 
Cheers,
Jim
p.s. there's a great Yahoo Dynascope group that will be quite helpful with all your restoration questions, parts swapping, upgrade ideas, etc. Also, there were quite a few of these made; they turn up fairly frequently, so no need to go overboard with any one opportunity. Since they were made in Connecticut, more tend to show up on the east coast (just as many more Caves turn up on the Left Coast...) Make sure he packs it well for its cross-country trip!
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actionhac
professor emeritus
Reged: 08/09/08
Posts: 731
Loc: WA
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Hi Keith. A reflector! I think I did look at that on EB, nice photos, and I think it could be a older model with the serial plate on the OTA and mount.
Ask the seller if he could look at the numbers stamped around the drive motor, that will give you a date if it's original which it probably is.
RV-6's are great, better than the Edmund 6"f8 and you know for me to say that means it is REALLY good!
No doubt has a UPCO mirror (same as the Edmund) they hold up well over the decades but you could ask him to shine a light thru it to see if it is getting thin.
Thats a real classic, good luck.
Robert
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Robert,
I know, a lot of info gets lost in my verbiage. The seller found 182 stamped inside the drive motor cover. 182(0) ? 1(9)82 ? Does one of these "dates" seem likely? Were they ever marked month and year as in 1 82 = Jan. 1982?
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actionhac
professor emeritus
Reged: 08/09/08
Posts: 731
Loc: WA
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It could be. If so that would have been one of the last RV-6's they stopped making them for good in 1982, by that date the price was $359.95.
The EB RV-6 has serial plates on the mount and OTA which makes me think it is from the mid 60's, they started skipping things like that later on, and no leveling screws on the legs pushes it out of the early 60's.
Robert
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jeffg
member
Reged: 02/13/07
Posts: 66
Loc: Irvine CA
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I agree you'll probably have to spend some time restoring it. Sending the mirror off to be recoated is the first thing I'd do, then spend that time replacing bolts that have rusted or corroded. Check the counterweight and the dec shaft for rust spots as well. The drive is probably okay if it runs, but may need new cork for the clutch. You can find that at the hardware store as well.
I've never been one for restoring to original condition, so on my RV-6 I replaced the focuser with a Crayford, and put in a RACI Orion finder. That makes it much easier to use. Here's a picture of my restored RV-6 from 1968 vintage.
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Jeff
14", 10", & 4.25" Dobs
8" Schmidt Newtonian, C-8 SC, 8" LSC
6" Cave Student Model A, 6" Dall-Kirkham, 6" RV-6
5" Refractor & 80 mm Folded Refractor
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 2296
Loc: Florida
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Here's my 1960 vintage RV6 with Criterion camera holder. I bought it back then with paper route money.
Cheers, Bill
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
Tasco 10K 80mm/1200mm
Towa 339 Restored
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Jeff, Bill, Jim, Robert
Your scopes...they're...beautiful! I don't know what is happening to me. I've never felt this way about a reflector before. I would want to keep whatever I might find original in spite of its shortcomings. It would be great to see Jupiter this summer with some magnification.
Maybe its the seeing here but 120X is about all my best 60mm's can handle, 150X for the 65mm Nippon Kogaku & my 3 76mm scopes, The highest mag. 1 1/4" eyepiece I have is 12.4mm which only produces 66X in my 102mm Tak. That's as far as I've taken it. Hmmm, 15X per inch... I know it can do more. My largest aperture scope is an orange C-8. which handles 160X (20X per inch) before the image deteriorates. Maybe instead of a new scope I should be looking for some new real estate.
Back to the RV-6. I haven't paid enough attention to these in the last few years to know the going price. I see the one on the Indy Craigslist and think $300 would be a pretty great price if shipping weren't an issue/expense. Is that about what you would expect to get if you chose to sell yours?
other Keith
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actionhac
professor emeritus
Reged: 08/09/08
Posts: 731
Loc: WA
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Keith go to the CN classified and look at the Mizar reflector for $50.00.
Could be very nice, the classic Japanese mirrors were very good, fine polish by hand.
$300.00 would be a average price for a RV-6, any less is a good deal.
Robert
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desertrefugee
Pooh-Bah
Reged: 08/06/07
Posts: 1212
Loc: Arizona
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Keith, every classic telescope collector ought to have at least one Criterion in the herd.
(Here's mine):
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"Illimitable ocean, without bound, Without dimension, where length, breadth, and height, And time, and place are lost." - Milton
-Darrell
Reflectors - 76 to 305mm (f4.7 to f9.2)
Refractors - 50 to 120mm (f5 to f16.7)
Binoculars - 6x15 to 22x100
N. Phoenix, AZ
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trainsktg
Post Laureate
Reged: 08/23/05
Posts: 4586
Loc: Pacific Northwest
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I had both of my RV-6 mirrors recoated, one at Newport Glass and another at OWL. If I remember right, both cost less than $100 and that included insuring each mirror for $150 and shipping both ways. Worse case, if the scope is in good condition with a trashed mirror coating, I'd consider the $300 total worth the price. Good luck.
Keith (no Criterions in the herd yet  )
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He was a good little monkey and always very curious.
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Quote:
Worse case, if the scope is in good condition with a trashed mirror coating, I'd consider the $300 total worth the price. Good luck
Hi Keith,
$300 total price...do you mean scope, shipping, and recoating?
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trainsktg
Post Laureate
Reged: 08/23/05
Posts: 4586
Loc: Pacific Northwest
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Yes Sir. Scope, shipping and recoating. Now, we're all assuming the mirror needs recoating. My 3" f6 (UPCO mirror)from 1970 still has the original coating which is still in excellent contition because I've kept it sealed when not in use. This eBay scope may be the same.
Keith
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He was a good little monkey and always very curious.
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Well, I never got the first RV-6 on eBAY in Vermont which started this thread, nor the one on the D.C. Craigslist, but good ol' eBAY... I just now "won" one in Florida. Couldn't have been farther away and still conus! There goes my lawn mowing money! Thanks to all of you that were available to answer my questions. Can't wait to see what kind of newfangled telescope design this Newton character has come up with
other Keith
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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I saw that one!
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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BRisley
sage
Reged: 09/04/06
Posts: 345
Loc: SW Florida
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Well Keith, didn't know I was bidding against you. It is basically around the corner for me. Good luck with it.
Brian
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3 C-8's (2 OT 72/80 and SPC-8)
8" f5 Dob
Meade 4450 on EQ-2
Meade 4501 on EQ-2
Tasco 4.5" on EQ-2
Tasco Starguide 60GT
C-90/Cometron Sky Scanner 80 mounted tandem in a C-8 Fork
Cometron CO-62
Meade 11x80 Bino
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Quote:
Well Keith, didn't know I was bidding against you. It is basically around the corner for me. Good luck with it.
Brian
Thanks Brian. Sorry, that price would have been especially sweet with no shipping fees. The way things weirdly work, the next one to come along will probably be in my neighborhood and have your name written all over it!
other Keith
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johnfdean
Pooh-Bah
Reged: 06/04/06
Posts: 1031
Loc: southern tip of Illinois
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Hi Darrel,
I owned a 4" Dynascope for over 20 years. I finally gave it to a neighborhood kid when I realized I had stopped usig it. I still wonder if he made good use of it.
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Celestron C6 f/5 by Vixen with Polaris GEM
14" Tscope dob f/4.7 with Argo Navis
80mm Nighthawk on Eq 2
Celestron C-4 f/10 GEM
Sky Scout
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actionhac
professor emeritus
Reged: 08/09/08
Posts: 731
Loc: WA
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Nice scope Keith.
I can't wait to hear what a refractor guy thinks of a reflector!
152mm X 1219mm!
Robert
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Jae
professor emeritus
Reged: 04/13/06
Posts: 559
Loc: near Boston
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Quote:
I just now "won" one in Florida. Couldn't have been farther away and still conus!
other Keith
Keith,
Excellent ! Would love to hear what your thoughts are on it. I know I have really positive memories of the performance of my RV-6. It wasn't until I got a C8 that I fully appreciated how good the RV-6 was. I got my RV-6 after working a whole summer as a teen. 15 years later, I got a C8 - portable, powerful, great ads with Spock, Johnny Carson, etc.
My Super C8 Plus was excellent, as I was watching Saturn one hot, humid summer night, I thought the image couldn't be better. It was near perfect seeing conditions and to confirm how good a decision it was to buy the C8 I dragged the old RV-6 out. I couldn't believe it, my SCT was well collimated, etc but the RV-6 had a bit more contrast and a more pleasing image. The Cassini was vivid, crepe more clear, banding was more vivid. This was almost 25 yrs ago. Then 10 or more years later, during apomania, I sold the RV-6 ota and mount separately. A couple years ago, found my old ota for sale, so I bought it back from the guy. It needs new coatings, etc. so that's a project that I look forward to and compare it to another great C8 I have to see if it still holds. I've been told that a great C8 will hold it's own against an RV-6.
But the RV-6 legend continues.....
Jae
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Jae
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wfj
sage
Reged: 01/10/08
Posts: 258
Loc: California, Santa Cruz County
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Quote:
Hi Darrel,
I owned a 4" Dynascope for over 20 years. I finally gave it to a neighborhood kid when I realized I had stopped usig it. I still wonder if he made good use of it.
Depends on how you gave it to him. If it was just parking it with him - probably not.
Everytime I've had kids who really want to see things, then learn how to find things, then want to learn how to see things better ... when I give them a scope, they've made good use of it. Just checked - some still going strong after 8 years - one even got an accolade for the classic she'd received, kept, and used well.
Well worth the time and the scope. Take the time and care.
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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And yet another question... This new to me scope of unknown vintage comes with one 18mm eyepiece. It is a Bausch and Lomb. Would that imply that the vintage is early 1980's or whenever B&L bought out Criterion? Should I be concerned as it relates to quality, or were these scopes consistantly good throughout their production years? My personal preference is for older scopes from the 40's, 50's, and 60's, because just like their human counterparts of that vintage, THEY ROCK! 
other Keith
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teast
professor emeritus
Reged: 11/10/07
Posts: 500
Loc: Kentucky
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I wouldn't make any judgements until your RV-6 arrives. I, too, wanted one from at least pre-1975 but mine is probably 1979-80 vintage and performs like a champ. My eyepieces are labeled CRITERION, not BAUSCH & LOMB.
Also, keep in mind that some of the RV-6 owners moved up to the cat line so the eyepieces could easily have been swapped between the two since I'm pretty sure they differed only in the labeling. I think you'll be happy with the optical quality. It's rare to find a poor RV-6 mirror.
-Tom
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Quote:
And yet another question... This new to me scope of unknown vintage comes with one 18mm eyepiece. It is a Bausch and Lomb. Would that imply that the vintage is early 1980's or whenever B&L bought out Criterion? Should I be concerned as it relates to quality, or were these scopes consistantly good throughout their production years? My personal preference is for older scopes from the 40's, 50's, and 60's, because just like their human counterparts of that vintage, THEY ROCK!
other Keith
So the eBAY seller has been so kind as to delay shipping while I thought I could perhaps let his scope go to a neighbor of his, (fellow CNer), (and save him the packaging hassle). In the meantime I had a great deal brewing in Wash. D.C. for what appeared to be an older scope with all the fixin's. That deal appears to have fallen apart with a cross-generational breakdown (father/son) not me, not mine! I gave the eBAY seller the go ahead to pack it. This he's done with a lot of trauma and riding of the learning curve.I think he probably has done a terrific job. He's ready to ship, gets it priced, and realized it will cost double what he had thought it would and what I had paid for. I'm not sure why I'm writing this. Perhaps I need a boost. If the vintage, (even though I have been assured by many shouldn't affect quality) were verified to be older I probably wouldn't be hesitating. So here are my options as I see them.
Call the deal off. He offered that because of the extra $90 shipping cost.
Have it shipped...$150 scope and $180 shipping. Hope it is a good specimen. OW.
If I call it off I'm actually going to make him keep $45 (1/2 of the shipping money for his efforts so far in packing)
I'm leaning toward just doing it because I know this extra cost took him by surprise and he's already been tortured enough learning about all the different size bubble wrap and where to find packing peanuts at 2 in the morning. I believe him to be a stand up guy. I'm not asking what you think he should do, but rather what should I do?
OK, I just need two of you to say DO IT! and I paypal him the extra. Just two. Sheesh, I never thought coming over to the dark side (reflectors) would be so difficult!
other Keith
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 2296
Loc: Florida
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A RV6 unseen for $150 plus $180 = $330? I don't think so. Why? Because these scopes come up for sale frequently and you probably can do better if you wait. Personally I think the scope if in great condition is worth $330 but the market prices are typically much lower than that. Good luck in any case.
Bill
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
Tasco 10K 80mm/1200mm
Towa 339 Restored
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albert1
Pooh-Bah
Reged: 01/01/07
Posts: 1367
Loc: Northern New Jersey
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I agree with Bill.
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Albert
1 Great 'ole Newt
4 Good 'ole Newts
2 Great 'ole Cats
1 Lousy 'ole Newt
One of these days I'll try a Refractor better than my 90mm finderscope
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Thank you Bill and Albert. I totally value your thoughts and advice. As is often (not always) the case I end up going the other way when given good counsel. I just sent off the additional shipping costs. It just seems like the right thing for me to do. Not smart, nor economical, nor frugal, nor preferred, nor... just right. Hey I just lost the squigglies!!! ... no... no they're still there! Oh well.
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 2296
Loc: Florida
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Good luck... hope you get a pristine RV6 if so the price will reasonable.
Bill
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
Tasco 10K 80mm/1200mm
Towa 339 Restored
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desertrefugee
Pooh-Bah
Reged: 08/06/07
Posts: 1212
Loc: Arizona
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That's taking the situation by the horns, Keith. I won't repeat your own words to you, but you recently gave me some advice that truly applies here.
And you followed your own advice (so I don't have to repeat it)!
Congratulations - and I hope this scope gives you many pleasurable hours under the stars.
--------------------
"Illimitable ocean, without bound, Without dimension, where length, breadth, and height, And time, and place are lost." - Milton
-Darrell
Reflectors - 76 to 305mm (f4.7 to f9.2)
Refractors - 50 to 120mm (f5 to f16.7)
Binoculars - 6x15 to 22x100
N. Phoenix, AZ
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albert1
Pooh-Bah
Reged: 01/01/07
Posts: 1367
Loc: Northern New Jersey
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That's right. Threethirty, shmethirty, whats the difference. Just don't pay the kids car insurance, boom, you got a free telescope  . It's a great classic scope and your gonna love it. Congradulations!
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Albert
1 Great 'ole Newt
4 Good 'ole Newts
2 Great 'ole Cats
1 Lousy 'ole Newt
One of these days I'll try a Refractor better than my 90mm finderscope
Edited by albert1 (07/19/09 06:15 AM)
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Jae
professor emeritus
Reged: 04/13/06
Posts: 559
Loc: near Boston
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Keith,
Glad you did it. I would have done the same thing. I can "feel" the right thing to do and I just do it.
Jae
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Jae
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Quote:
That's right. Threethirty, shmethirty, whats the difference. Just don't pay the kids car insurance, boom, you got a free telescope . It's a great classic scope and your gonna love it. Congradulations!
I wouldn't have found this group of maniacs had I still had kids at home. Not only could I not afford admission, I would have had to compete with them for the dial-up connection. And without their empty bedrooms for storage... Now that you mention it Albert.. how am I gonna pay MY car insurance?
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clintwhitman
Caveman
Reged: 01/01/07
Posts: 2425
Loc: ValVerde CA(SoEasyaCavemanCanD...
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Hi Keith,
I wanted to say My CaveCritter as Lew Named it, Was a 1965 or so Cave 6" mount and OTA. I purchased it for $40 but it had no optics  I had an RV 6 Someone left outside in oxnard. The mount took the brunt of a few years of the beach. Rusted and busted!!! So I started to re build it then the cave showed up. It was to tempting so the optics from the Rv 6 ended up in the cave. The secondary holder and primary cell in the RV6 is better built than Cave, faster cooling, better finder, nicer to adjust the secondary. But the Cave OTA, Focuser (Sky micro) and mount are lightyears better than the RV-6 so it seemed like a match made in the heavens. After shortening the tube, Re mounting a few thing she snaped right into focus. All in all I have not been over whelmed with the quality of the primary mirror from the RV-6 but then again I am compairing it to some awsome optics that come around here!! The colimation process with this scope alway leaves me scratching my head a little which may mean the mirror figure is a little whacky... Anyway thats my experience with the Cave Critter. One other thing if you need parts for an RV 6 I have a few floating around...
(aveman
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Clint&Debbie Whitman (aveman
1960s 6"F15 Jaegers-Unipons by John Pons on a Byers 812, 1947 4" F15 TINSLEY, 1965 10" F8 CAVE, 1950 5CM & 6.5CM Nippon Kogakus (the twins), 1960s UNITRONS a 152 restored a 160 numbered green lens original mint a 114 original 50s mint, 1950s UNITRON M100 100mm F15 OTA, WO 80mm Florite, ASTROPHYSICS 155 EDFS on LOSMANDY G11, a bunch of Tascos,Sears Mayflowers The list goes on Add infinitum.
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Quote:
Nice scope Keith.
I can't wait to hear what a refractor guy thinks of a reflector!
152mm X 1219mm!
Robert
Well it came on Thursday and was missing a few nuts and bolts but otherwise looks good. The mirror looks good, but the eyepiece is way wrong, up near the top! There was even a spider inside. Preston fear not, you gotta get one of these things, come on over...it's always dark here!
I haven't looked at the R&P focuser but is rolls down from the mid-point. i assume there is a shim or pressure pad of some material to tighten it? I have focused on some fir tree needles at 2000' (so clear and bright!) but only with the focus racked out, the brass sleeve pulled out, and the ep just in the sleeve. Does that seem about right? Reflectors weren't designed for terrestrial viewing at less than infinity like refractors were? Or are there longer brass sleeves to put in? Unlike Rod's Criterion, I think this one may be dated by the finder scope. The tube has certainly yellowed in a mere 30 years Can't wait to get a clear night and try this out!
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Finder. Pulling that electrical tape is gonna hurt!
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Anyone have a theory why I have a second set of screws in the tube. The mirror is held by the set closest to the end. The other set isn't doing anything at the moment.
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 2296
Loc: Florida
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Any RV6 thread and I just gotta post a pic of my restored 1960 model.
Bill
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
Tasco 10K 80mm/1200mm
Towa 339 Restored
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Compressorguy
sage
Reged: 03/14/09
Posts: 219
Loc: North Carolina
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"Anyone have a theory why I have a second set of screws in the tube. The mirror is held by the set closest to the end. The other set isn't doing anything at the moment."
It is my understanding that they are for repositioning the mirror (move it closer to the focuser)to shorten the focal length for astrophotogrphy use. This would reduce the focal ratio, lessen the exposure times and help the camera setup achieve focus. I'm no expert but I did stay in a Holiday Inn Express. Someone please correct me if i'm incorrect.
--------------------
Scott
1976 Cave 10" Deluxe f/6
Late 70's Meade 628 6" f/8
1950's Selsi 80mm X 910mm f/11
1960's Lafayette 60mm X 800mm f/13
2005 Meade 10" LX200GPS f/10
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teast
professor emeritus
Reged: 11/10/07
Posts: 500
Loc: Kentucky
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Quote:
I'm no expert but I did stay in a Holiday Inn Express.
- Same here, Scott! The explanation I heard was that it was for prime focus astrophotography rather than reducing the focal ratio - 
-Tom
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teast
professor emeritus
Reged: 11/10/07
Posts: 500
Loc: Kentucky
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Quote:
I haven't looked at the R&P focuser but is rolls down from the mid-point. i assume there is a shim or pressure pad of some material to tighten it?
If the RV-6 has a weak point, it's the R&P focuser. It does the job, but just barely. I shimmed mine with some thin cardboard (cereal box) in order to get more traction but it still had a lot of slop in it so I replaced it with a JMI RCFMini1 which works great. If you can get yours snugged up using shims then go for it.
Quote:
I have focused on some fir tree needles at 2000' (so clear and bright!) but only with the focus racked out, the brass sleeve pulled out, and the ep just in the sleeve. Does that seem about right?
The brass sleeve is actually two brass sleeves, one inside the other. Did you have both extended or are they flush with each other? You can extend the drawtube by pulling the inner sleeve out from the outer one.
By the way, the electrical tape was probably put on the finder to prevent marring the tube with the adjusting screws. Some clear bumper pads might do the trick and not take away from the looks as much.
-Tom
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Quote:
"Anyone have a theory why I have a second set of screws in the tube. The mirror is held by the set closest to the end. The other set isn't doing anything at the moment."
I'm no expert but I did stay in a Holiday Inn Express. Someone please correct me if i'm incorrect.
Wow, I need to start getting out more.
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Hi Tom,
There is the brass focuser with the grooves cut in, and a 2 3/8" brass sleeve that slides into the focuser. Looking out about 3 miles to some trees I need the focuser fully extended, the brass sleeve pulled out to near the falling out point, and then the 18mm eyepiece can be flush to the sleeve. Anything closer, and I need to slide the eyepiece up as well. Not a good move in the dark over a hard surface! I'm on grass, still in the light. Are you saying there are 2 sliding/removable sleeves?
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teast
professor emeritus
Reged: 11/10/07
Posts: 500
Loc: Kentucky
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Now that CN is back online I can answer your question  .
No, I was referring to the outer brass tube (the "rack") as one of them and the inner brass sleeve as the other. In my mind I envision the focuser as the black crinkle housing attached to the tube. Just a terminology glitch in my mind.
For near focus (3 miles as compared to infinity) I recall having a similar situation although perhaps not quite as extreme as your description. Newts aren't typically used for terrestrial viewing since they invert the image so the drawtube won't be as long as you might be used to with a refractor.
Are you sure that the primary mirror is being held in by the set of screws closest to the back end of the tube? If it's actually held in by the upper set that could explain a bit of your situation. I think once you turn it to the sky you won't have a problem. Keep us posted.
-Tom
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 2296
Loc: Florida
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Quote:
Anyone have a theory why I have a second set of screws in the tube. The mirror is held by the set closest to the end. The other set isn't doing anything at the moment.
If I read your comment correctly, the second set of screws are likely there to fill the holes that someone drilled to move the mirror forward for prime focus photography. They moved the mirror back to the original position to facilitate visual use. Cheers, Bill
--------------------
RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
Tasco 10K 80mm/1200mm
Towa 339 Restored
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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OK focuser, rack, sleeve, eyepiece... got it. I had a few moments to catch Jupiter through the clouds last night. Yes the mirror is attached closest to the end (farthest from the secondary). At infinity, the B&L 18mm eyepiece that came with was just focusing, using most of the available (rack out) travel. A 12.3 mm Meade Plossl had plenty of movement in and out to focus. The image of Jupiter wasn't real crisp, but I'm sure the mirror needs collimating. Not bad for starters! I'll have to be looking for used tools to do that.
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teast
professor emeritus
Reged: 11/10/07
Posts: 500
Loc: Kentucky
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IIRC, the inner brass sleeve has vertical slots cut into it to permit a kind of "compression" (for lack of a better term) adjustable fit, to hold the eyepiece in place without a set screw. You should be able to lift the eyepiece up slightly, exposing a bit of the barrel without danger of it falling out too easily. This may give you a bit more draw for focusing. Do your eyepieces fit snugly in the sleeve or do they automatically slide down flush with the top of the sleeve?
-Tom
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strdst
scholastic sledgehammer
Reged: 03/23/08
Posts: 830
Loc: Oregon USA
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Tom,
The eyepieces are quite snug. I was lifting the ASP 18mm to get a far off terrestrial image. Looking at Jupiter last night I was able to leave it flush with the sleeve and just rack out fully. Although the first light wasn't sharp, I was pretty impressed with how bright things were... you know compared to my 3" and 4" toy refractors. I also remembered I have a classic orange C-8 in the spare bedroom I never even think to take out anymore. I remember I've never been impressed with the C-8 for planetary sharpness, but it's pretty great for the globulars. Maybe this RV-6 can bridge the gap between my refractors and the 8" SCT.
other keith
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BRisley
sage
Reged: 09/04/06
Posts: 345
Loc: SW Florida
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Glad it arrived in good shape.
Brian
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3 C-8's (2 OT 72/80 and SPC-8)
8" f5 Dob
Meade 4450 on EQ-2
Meade 4501 on EQ-2
Tasco 4.5" on EQ-2
Tasco Starguide 60GT
C-90/Cometron Sky Scanner 80 mounted tandem in a C-8 Fork
Cometron CO-62
Meade 11x80 Bino
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teast
professor emeritus
Reged: 11/10/07
Posts: 500
Loc: Kentucky
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Keith,
Keep in mind that newts will perform better after some cool down time. Set it up an hour ahead of time to let it start stabilizing to the ambient temperature. Tube currents can dull an image and make it "swim". Collimation is also important, as you've already mentioned.
It'll take some learning on your part since you've mostly used refractors in the past. Once you get a feel for it though, I think you'll be amazed at how well it can perform. My RV-6 at a dark site has given me some absolutely stunning views of the Orion nebula, Andromeda, planets and even some comets. Have fun, ask questions and keep us posted!
-Tom
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StarmanDan
sage
Reged: 08/27/07
Posts: 391
Loc: China Spring, Texas
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Welcome to the RV-6 crowd! Looks like your newest addition is in better shape than mine. I acquired mine from a friend whose grandfather had his stashed in the garage for the past 30 odd years. The bakelite tube was cracked in a couple of spots, the focuser was seized up, mount was rusted, mud daubers and spiders had made home in the tube and the mirror coatings were nearly non-existent. To my amazement, the clock drive still worked! Had the mirrors recoated, cleaned up the focuser, tube and the rust, replaced the cork in the clutch and I'm now working on restoring the tube. Even in its present state, the scope is usable and delivers excellent images for being a spherical f/8 mirror. I'm sure you won't be disappointed.
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"Starman" Dan Doyle
Texas Astronomical Society of Dallas
Central Texas Astronomical Society
8" LX200GPS w/ST80 guidescope, Canon 350D+DSI Pro
150mm f/8 Sky Watcher Refractor
10" f/4.5 Homemade Dob
RV-6 Criterion Dynascope
http://darcstar.wordpress.com
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deSitter
Carpal Tunnel
Reged: 12/09/04
Posts: 2925
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StarmanDan,
The mirrors were parabolic - a 6" f/8 sphere would have noticeable SA, and mine had none - NONE. It was a great mirror.
-drl
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 2296
Loc: Florida
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Ahhha...The old RV6 spherical vrs parabola raises its head once again. I've never tested my original mirror due to its excellence. However I bought a 2nd RV6 mirror and it tested spherical with an excellent smooth surface. The test facility said a 6 inch at f/8 is very forgiving with little detectable SA. Haven't tried the mirror yet visually. The guy doing the testing said he "believed" most if not all RV6 mirrors where spherical at least the ones he's tested.
Bill
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
Tasco 10K 80mm/1200mm
Towa 339 Restored
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DAVIDG
Carpal Tunnel
Reged: 12/02/04
Posts: 1985
Loc: Hockessin, De
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My RV-6 that I purchased new in 1976 had basicly a spherical mirror with a broad turned edge. I refigured it to an excellent parabola. I've test many a RV-6 mirror and handful of RV-8's. The RV-6 are almost always undercorrected and every RV-8 was a sphere.
The reason why the RV-6 give nice images is because a 6" f/8 sphere is just over a 1/4 wave, and if you polish on it for about 5 minutes and put a little correction on it, the wave front will drop below a 1/4 wave.
A spherical 8" f/8 is well above a 1/4 wave and needs to be parabolized to produce a good image.
- Dave
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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics
Engineering = Taking what you have and making what you need.
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teast
professor emeritus
Reged: 11/10/07
Posts: 500
Loc: Kentucky
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Criterion advertised the RV-6 as parabolic with 1/10th wave accuracy. Considering this was during the 50's, 60's and 70's, the claim could be interpreted in several different ways. I am assuming that the description applied to the mirror surface but who knows ?
I believe this was pretty standard terminology before Strehl ratios came along. Some who have their mirrors tested find that they are spherical while others find them parabolic and exceeding the specified standard. What really matters most is does it perform well. Mine sure does !
-Tom
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rmollise
Post Laureate
Reged: 07/06/07
Posts: 4553
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Quote:
Ahhha...The old RV6 spherical vrs parabola raises its head once again. I've never tested my original mirror due to its excellence. However I bought a 2nd RV6 mirror and it tested spherical with an excellent smooth surface. The test facility said a 6 inch at f/8 is very forgiving with little detectable SA. Haven't tried the mirror yet visually. The guy doing the testing said he "believed" most if not all RV6 mirrors where spherical at least the ones he's tested.
Bill
At f/8, a spherical mirror will function tolerably well. It will certainly not be a barn-burner. Just OK.
It can ALMOST meet the 1/4 wave criterion (you really need to be at f/10 to do that with a sphere), but CANNOT be better than that, no matter how smooth and well-made the sphere. The 4.5-inch Tasco (Towa) reflectors all had good spherical mirrors, and did OK--good on the deep sky, quite useable on the planets. That is not "blow your doors off," though...
I would guess that those RV-6s that perform well on the planets (one of the scope's hallmarks) are parabolic. Lots of weird stuff went down over the long run of these scopes, between the glory days and the B&L debacle, but I do know Upco, Criterion's supplier through at least the sixties, made some good mirrors. 
--------------------
Uncle Rod
Rod's New Book:
Choosing and Using a New CAT
Available now!
Edited by rmollise (08/05/09 06:27 PM)
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rmollise
Post Laureate
Reged: 07/06/07
Posts: 4553
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Quote:
The reason why the RV-6 give nice images is because a 6" f/8 sphere is just over a 1/4 wave, and if you polish on it for about 5 minutes and put a little correction on it, the wave front will drop below a 1/4 wave.
An undercorrected mirror is an undercorrected mirror, which does not mean it was left a sphere. A plain sphere at f/8 will produce average images.
--------------------
Uncle Rod
Rod's New Book:
Choosing and Using a New CAT
Available now!
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deSitter
Carpal Tunnel
Reged: 12/09/04
Posts: 2925
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Rod has an excellent point. I'm sure the parabolizing on these was perfunctory, but they probably had real masters who knew how to do it fast without overcorrecting. A perfect parabola can be made in an hour or less by a master from a 6" f/8 sphere. I have a 4.5" f/8 sphere and I can see the residual SA in this otherwise perfect mirror, and I don't remember seeing any in my RV-6, so that was one they probably hit out of the park.
-drl
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Steve40
member
Reged: 10/15/06
Posts: 24
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Just to chime in---
I purchased an RV-6 in the late 1960's as a high school graduation gift to myself! It was terrific! Many years later, as a high school physics and astronomy teacher, I guided many students through grinding, polishing, and figuring 6 inch mirrors.
Just for fun, I put my RV-6 mirror on the foucault tester. It blanked out evenly and smoothly all over---a beautiful sphere! No hint of parabolization I could see.
Steve
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 2296
Loc: Florida
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The thread is becoming very interesting! I've written this many times before so I'll be concise this time:
I had my 6 inch f/8 triple element oil spaced 1989 vintage Astro Physics refractor set up in my yard viewing Jupiter. I loved this scope and wish I still had it. A kid in the neighborhood brought over a 70ish RV6...The RV6 side by side to the refractor provided a more contrasty, clear view of the planet. Gulp... Long story short, sold the AP and restored my 1960's vintage RV6. Spherical or paraboloid the RV6 delivers fantastic performance at a very economical price.
Bill
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
Tasco 10K 80mm/1200mm
Towa 339 Restored
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