20 replies to this topic

[Mark Jones]

Our club just had a telescope donated by original owner's brother. It appears to be a Criterion 8" Newtonian, with 8x50mm finder, 1.25" focuser, RA motor, Dec axis has tangent screw. Mirror marked (on back) with ink stamp as 120971, mount serial number 4470. It is extremely clean and was in original box until recently.

Anyone know if the numbers on mirror and mount coincide to mfg in the early 1970's?

 

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[siriusandthepup]

A beautiful thing...

 

[CHASLX200]

 Mine was a killer on optics.

[deSitter]

Our club just had a telescope donated by original owner's brother. It appears to be a Criterion 8" Newtonian, with 8x50mm finder, 1.25" focuser, RA motor, Dec axis has tangent screw. Mirror marked (on back) with ink stamp as 120971, mount serial number 4470. It is extremely clean and was in original box until recently.

Anyone know if the numbers on mirror and mount coincide to mfg in the early 1970's?

Wow that's amazing!

 

-drl

[apfever]

Mark, first thing, be careful about taking things apart for investigation or service. Believe it or Not - Criterion used a lot of old discontinued metric bolts. You don't want to lose them. I'll get back to these at the end.  Try getting a purchase time from the brother that donated the scope. Any original paper work is a big plus too. 

 

I think it safe to say that the number 120971 is Dec. 9, 1971.  That might be just a date for the original blank, I don't know how Criterion labeled their 8" RV mirrors.  The 'serial' numbers on the RV series is a bit flaky. It started with good intent and some have found a consistency early on but that faded with time.  For the most part the serial numbers don't have any defined registry meaning and Criterion eventually dropped the numbering. 

 

The motor boxes started with the word "CRITERION" deeply engraved, then there was a small sticker, then there was nothing but a blank box. Somewhere in the run they used that blue riveted label for a short time. It is the least common label I've found on the RV series.  Catalog pictures and advertisements often used the same old pictures for years so those can be sketchy for dating.  Hopefully an original owner or documented scope with that blue label can come forward with a retail time.

 

Your best bet for a manufacture date is to have a Synchron motor for the drive. Criterion used two motors, a Synchron and a Haydon. The Haydon do not have a date. The Synchron motors have a manufacture date stamped at the end of a line of print that goes around the edge of the round motor cover.  There has been plenty of evidence that a telescope's manufacture date was usually 3 or 4 months after the motor date. Just about all the verified matches of motor dates and purchase dates have the scopes made within 3 to 6 months of the motors.  

 

The motor cover is held on with 5 small screws around the perimeter of the back plate. Those five screws are metric M4X.75 and they are NOT available by any normal retail. Remove the 5 screws, take off the cover, examine your motor, find the date if you have a Synchron. There are about a dozen discontinued metric bolts in different sizes in the motor box system,  and several more around the scope.

These old metric bolts are from the Japan Industrial Standard (JIS) system. Several of the JIS bolt sizes were discontinued as a standard after WWII when an international convention was held to standardize bolt threads.  The taps and dies for these threads are still common but it's a real pain to try making decent bolts at home. These old discontinued JIS bolts were not just in Criterions. They ended up splattered across a lot of telescope makers at the time...all over the world. My guess is that the remaining stock of the discontinued bolts dropped in value to peanuts and telescope companies had a hay day with the discounts.  Sometimes I could swear that most of the old JIS went strictly to telescopes - it seems. 

Edited by apfever, 26 March 2025 - 09:09 PM.

[Mark Jones]

Since I just picked up the donation today, I have not taken it apart and will be very careful. Thanks for the warning on the varied screw types.

 

I think the scope really does not fit the needs of our club, the scope needs love and care and probably has quirks that won't make it a friendly loaner scope. I told the owner that when I picked it up and he was OK with selling it to fund other club projects. 

 

It also came with Criterion eyepieces AR 18mm, 12.7mm, 9mm, 7mm and Ortho 6mm, and a CP4 Barlow. All are very clean and even have the original "waxed" paper wrappers. I will probably put up for sale in CN classified section.

 

I have too many telescopes in my garage already. Last count was I have 90 inches worth of aperture in my garage, ranging from 4" to 17.5" telescopes (all scopes less than 4" excluded).

[YourNotSirius]

Since I just picked up the donation today, I have not taken it apart and will be very careful. Thanks for the warning on the varied screw types.

 

I think the scope really does not fit the needs of our club, the scope needs love and care and probably has quirks that won't make it a friendly loaner scope. I told the owner that when I picked it up and he was OK with selling it to fund other club projects. 

 

It also came with Criterion eyepieces AR 18mm, 12.7mm, 9mm, 7mm and Ortho 6mm, and a CP4 Barlow. All are very clean and even have the original "waxed" paper wrappers. I will probably put up for sale in CN classified section.

 

I have too many telescopes in my garage already. Last count was I have 90 inches worth of aperture in my garage, ranging from 4" to 17.5" telescopes (all scopes less than 4" excluded).

I believe that we have at least one of those in the garage. Actually, the OTA is the old man's bedroom. The mount is in the garage. I have never seen it assembled so I do not know anything about it but, having a grey tube I believe makes it from the late 1950s to early 1960s.

 

IF you want to find a new home for it you've come to the best place to do so. Depending upon where you are located will determine your results.

 

Q

[deSitter]

Mark, first thing, be careful about taking things apart for investigation or service. Believe it or Not - Criterion used a lot of old discontinued metric bolts. You don't want to lose them. I'll get back to these at the end.  Try getting a purchase time from the brother that donated the scope. Any original paper work is a big plus too. 

 

I think it safe to say that the number 120971 is Dec. 9, 1971.  That might be just a date for the original blank, I don't know how Criterion labeled their 8" RV mirrors.  The 'serial' numbers on the RV series is a bit flaky. It started with good intent and some have found a consistency early on but that faded with time.  For the most part the serial numbers don't have any defined registry meaning and Criterion eventually dropped the numbering. 

 

The motor boxes started with the word "CRITERION" deeply engraved, then there was a small sticker, then there was nothing but a blank box. Somewhere in the run they used that blue riveted label for a short time. It is the least common label I've found on the RV series.  Catalog pictures and advertisements often used the same old pictures for years so those can be sketchy for dating.  Hopefully an original owner or documented scope with that blue label can come forward with a retail time.

 

Your best bet for a manufacture date is to have a Synchron motor for the drive. Criterion used two motors, a Synchron and a Haydon. The Haydon do not have a date. The Synchron motors have a manufacture date stamped at the end of a line of print that goes around the edge of the round motor cover.  There has been plenty of evidence that a telescope's manufacture date was usually 3 or 4 months after the motor date. Just about all the verified matches of motor dates and purchase dates have the scopes made within 3 to 6 months of the motors.  

 

The motor cover is held on with 5 small screws around the perimeter of the back plate. Those five screws are metric M4X.75 and they are NOT available by any normal retail. Remove the 5 screws, take off the cover, examine your motor, find the date if you have a Synchron. There are about a dozen discontinued metric bolts in different sizes in the motor box system,  and several more around the scope.

These old metric bolts are from the Japan Industrial Standard (JIS) system. Several of the JIS bolt sizes were discontinued as a standard after WWII when an international convention was held to standardize bolt threads.  The taps and dies for these threads are still common but it's a real pain to try making decent bolts at home. These old discontinued JIS bolts were not just in Criterions. They ended up splattered across a lot of telescope makers at the time...all over the world. My guess is that the remaining stock of the discontinued bolts dropped in value to peanuts and telescope companies had a hay day with the discounts.  Sometimes I could swear that most of the old JIS went strictly to telescopes - it seems. 

They were used in MGs and the like - I bought 4 screws for $20 at a parts emporium in the UK.

 

-drl

[Kasmos]

I've seen JIS hardware for sale on a Vintage Japanese motorcycle restoration site

 

A quick search turned these up

 

https://www.kmcarbur..._VuAR4nX-ccMq0u

 

https://www.newcopro...ory&path=67_137

Edited by Kasmos, 28 March 2025 - 04:39 AM.

[deSitter]

I've seen JIS hardware for sale on a Vintage Japanese motorcycle restoration site

 

A quick search turned these up

 

https://www.kmcarbur..._VuAR4nX-ccMq0u

 

https://www.newcopro...ory&path=67_137

There was a 4x0.7mm JIS 4mm screw as well as the needed 4x0.75mm. The ones in the second link are 0.7mm pitch. JIS refers more to the screw profile than the pitch. I'd check the ones in the first link before buying as well. The ones I found in the UK had the pitch explicitly stated.

 

-drl

[Garyth64]

I don't believe the finder is the one that originally came with the scope.  That finder, is identical to my 6" Dynascope that is from about 1958.  It would match the finish on the main tube, but this tube is white.

 

I'd like to see more pictures.

Edited by Garyth64, 28 March 2025 - 08:33 AM.

[deSitter]

I don't believe the finder is the one that originally came with the scope.  That finder, is identical to my 6" Dynascope that is from about 1958.  It would match the finish on the main tube, but this tube is white.

 

I'd like to see more pictures.

I think the RV-8s I remember from brochures had the same finder as the RV-6. I seem to remember the only significant difference was the DEC slo-mo option for the RV-8. The grey pebble/whatever finish was characteristic of the Custom Dynascope pre-RV Criterion scopes. But Neil (apfever) says grey whatever finish RVs were also sold when parts inventory demanded it.

 

edit: Nope, 8x50 finder standard on the RV-8.

 

-drl

Edited by deSitter, 28 March 2025 - 09:02 AM.

[apfever]

I've seen JIS hardware for sale on a Vintage Japanese motorcycle restoration site

 

A quick search turned these up

 

https://www.kmcarbur..._VuAR4nX-ccMq0u

 

https://www.newcopro...ory&path=67_137

 

There was a 4x0.7mm JIS 4mm screw as well as the needed 4x0.75mm. The ones in the second link are 0.7mm pitch. JIS refers more to the screw profile than the pitch. I'd check the ones in the first link before buying as well. The ones I found in the UK had the pitch explicitly stated.

 

-drl

BIG points in the above.  Not all JIS are discontinued.  JIS is "Japan Industrial Standard" and still covers a lot of modern production. Only a few of the JIS thread types were discontinued.   M4X.7 is the current common hardware metric for a 4mm thread, which has 0.7mm per thread.  The discontinued JIS version is the M4X.75 which has 0.75mm per thread and the difference is enough to bind up.  M5X.8 is standard, M5X.9 was discontinued.  The discontinued M4X.75 and M5X.9 are what we get on our scopes.  I found the above links to be very elusive on what the pitch is. The links only give diameter and length up front.  Be careful and make specific inquiries of what you need if not distinctly posted. 

 

 

 

I don't believe the finder is the one that originally came with the scope.  That finder, is identical to my 6" Dynascope that is from about 1958.  It would match the finish on the main tube, but this tube is white.

 

I'd like to see more pictures.

 

I think the RV-8s I remember from brochures had the same finder as the RV-6. I seem to remember the only significant difference was the DEC slo-mo option for the RV-8. The grey pebble/whatever finish was characteristic of the Custom Dynascope pre-RV Criterion scopes. But Neil (apfever) says grey whatever finish RVs were also sold when parts inventory demanded it.

 

-drl

The RV-8 came with the larger finder which is usually white. Criterion did make all kinds of substitutions when inventory was low for the RV series. They used the fancier Dynascope series parts that had the frosty wrinkle grey/green finish. It is not surprising at all to see a Dynascope finder on an RV-8.  Criterion substituted entire 6" Dynascope OTA for the RV-6 when they ran short and I have one of those factory mismatches with a letter of confirmation - from Criterion - about the substitution.  Criterion might have used the smaller RV-6 finder to start with, and changed over to the larger one later on so someone might have an original small finder on the 8".  The tons of changes and substitutions during production make it impossible to confirm things unless someone has documented proof or comes forward as an original buyer with an uncommon configuration.  Image searches on the web can show what was most common or 'standard'. 

[Brachiopod]

BIG points in the above.  Not all JIS are discontinued.  JIS is "Japan Industrial Standard" and still covers a lot of modern production. Only a few of the JIS thread types were discontinued.   M4X.7 is the current common hardware metric for a 4mm thread, which has 0.7mm per thread.  The discontinued JIS version is the M4X.75 which has 0.75mm per thread and the difference is enough to bind up.  M5X.8 is standard, M5X.9 was discontinued.  The discontinued M4X.75 and M5X.9 are what we get on our scopes.  I found the above links to be very elusive on what the pitch is. The links only give diameter and length up front.  Be careful and make specific inquiries of what you need if not distinctly posted. 

 

 

 

 

The RV-8 came with the larger finder which is usually white. Criterion did make all kinds of substitutions when inventory was low for the RV series. They used the fancier Dynascope series parts that had the frosty wrinkle grey/green finish. It is not surprising at all to see a Dynascope finder on an RV-8.  Criterion substituted entire 6" Dynascope OTA for the RV-6 when they ran short and I have one of those factory mismatches with a letter of confirmation - from Criterion - about the substitution.  Criterion might have used the smaller RV-6 finder to start with, and changed over to the larger one later on so someone might have an original small finder on the 8".  The tons of changes and substitutions during production make it impossible to confirm things unless someone has documented proof or comes forward as an original buyer with an uncommon configuration.  Image searches on the web can show what was most common or 'standard'. 

My 1969 RV8 has a dark gray crinkle finish 50mm finder which is original.

[Garyth64]

I only said, I didn't think the finder originally came with the scope.  If the company put a grey crinkle finder on a smooth white telescope, ok.  I was just trying to go from 1958 to 1971, and Criterion still used the same finders?  I think it is a stretch.

 

The RV-6 is not the same scope from 1958 Criterion 6" f/9 scopes.  There were many differences.

 

I know the topic is about the 8" scope, but for the mention of the RV-6 scopes, here is what my 1958 6" Dynascope looked like:

 

 

-a file photo

 

Here's a thread on the RV-6 scopes.

 

https://www.cloudyni...criterion-rv-6/

 

And one for RV-8 scopes:

 

https://www.cloudyni...ion-rv-8-mount/

 

So it is being said that a grey crinkle finder was put on a white scope?  I wouldn't want a different colored finder.  I would expect the scope to look like this:

 

-file photo

Edited by Garyth64, 28 March 2025 - 12:22 PM.

[Bill Griffith]

I love the serialization of DeLuxe Criterions!

Primary mirror diameter, build (year date) followed by a 3 digit serial no..

658069 and 861379 are the 2 DeLuxe that I'm the custodian of and a 1 No.31 cast pier that both models equatorial mounts slip into with legs attached.

The equatorial mount has the same serialization stamped on the mount. 

 

I found an odd the need to flip the equatorial mount 180 degrees to the legs for insurance in negating a tipping hazard.

 

The mirrors at prime are spheres.

 

 

Bill

Edited by Bill Griffith, 29 March 2025 - 09:34 AM.

[deSitter]

I only said, I didn't think the finder originally came with the scope.  If the company put a grey crinkle finder on a smooth white telescope, ok.  I was just trying to go from 1958 to 1971, and Criterion still used the same finders?  I think it is a stretch.

 

The RV-6 is not the same scope from 1958 Criterion 6" f/9 scopes.  There were many differences.

 

I know the topic is about the 8" scope, but for the mention of the RV-6 scopes, here is what my 1958 6" Dynascope looked like:

 

Criterion 03.jpg

 

file photo 01.jpeg

-a file photo

 

Here's a thread on the RV-6 scopes.

 

https://www.cloudyni...criterion-rv-6/

 

And one for RV-8 scopes:

 

https://www.cloudyni...ion-rv-8-mount/

 

So it is being said that a grey crinkle finder was put on a white scope?  I wouldn't want a different colored finder.  I would expect the scope to look like this:

 

Criterion 8.jpg

-file photo

How were the RV-8s optically?

 

Likely not many were sold - the RV market was first-time buyers. Those who wanted 8" probably went elsewhere.

 

DAVIDG, one of our optical experts, has a not-go-great opinion of the optics. My own RV-6 was certainly at least 1/8th wave with a near-perfect star test and able to show detail on a 7" of arc Mars (I watched said Mars pass over a 2nd magnitude star in Gemini, Mebsuta). I think my RV had a Coulter mirror however. David states with some authority that most RVs had spherical or nearly spherical (undercorrected) mirrors.

 

-drl

[Brachiopod]

I only said, I didn't think the finder originally came with the scope.  If the company put a grey crinkle finder on a smooth white telescope, ok.  I was just trying to go from 1958 to 1971, and Criterion still used the same finders?  I think it is a stretch.

 

The RV-6 is not the same scope from 1958 Criterion 6" f/9 scopes.  There were many differences.

 

I know the topic is about the 8" scope, but for the mention of the RV-6 scopes, here is what my 1958 6" Dynascope looked like:

 

 

So it is being said that a grey crinkle finder was put on a white scope?  I wouldn't want a different colored finder.  I would expect the scope to look like this:

 

 

I do have the grey crinkle finder on mine and it was original. I think that it was one of the first RV-8s off the line since I got it in 1969. I never actually thought about it, but White would make so much more sense. I know that there was a big delay in getting it shipped from Criterion, so maybe they were just grabbing any parts they had to finish the scopes at that time and I got a finder from the "deluxe" version.  I should post a picture of it, let me drag it outside...

 

[Brachiopod]

Here is what I have, crinkle finder and all. Note the 2 different sized counterweights, that was an RV8 thing. Not everything is original on mine, I lost the DEC slow mo knob because I had an extension attached for years. The clock drive motor is new. The clock drive cover is off an RV6 because I lost the original 40 years ago when I took it apart to fix the motor. One of the legs broke from people stepping on it and I bought a replacement off another RV8 that was being parted out.

I always thought that the optics were good, on a good night Jupiter's moons are little balls. It is probably a spherical mirror, but the focal length is long so I've never tested it.

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[apfever]

I only said, I didn't think the finder originally came with the scope.  If the company put a grey crinkle finder on a smooth white telescope, ok.  I was just trying to go from 1958 to 1971, and Criterion still used the same finders?  I think it is a stretch.

 

The RV-6 is not the same scope from 1958 Criterion 6" f/9 scopes.  There were many differences.

 

I know the topic is about the 8" scope, but for the mention of the RV-6 scopes, here is what my 1958 6" Dynascope looked like:

 

Criterion 03.jpg

 

file photo 01.jpeg

-a file photo

 

Here's a thread on the RV-6 scopes.

 

https://www.cloudyni...criterion-rv-6/

 

And one for RV-8 scopes:

 

https://www.cloudyni...ion-rv-8-mount/

 

So it is being said that a grey crinkle finder was put on a white scope?  I wouldn't want a different colored finder.  I would expect the scope to look like this:

 

Criterion 8.jpg

-file photo

Me too!!   I don't think the mismatch was a good idea but they did it without discretion both ways. 

 

Here ya go folks. A good example of verified odd looking Criterion substitution and not only that, they did this without prior notice to buyers at least in this case. Either RV-6 or RV-8 won't matter, they are both the same series with the same base concept of value. Mark Jones (OP) might be interested in knowing that "RV" stands for Real Value.  I bought this scope from the original owner with factory documentation of the substitutions, and I still have it. The finder was damaged and repaired but it is obvious that the smaller RV finder is original to the tube (owner verified). The larger Deluxe finder requires a different mount that would have left other holes in spite of the repair. This has the rare jumbo OTA rings. They are not the Deluxe rotating rings or the regular RV-6 rings. The tube is obviously Deluxe Dyna. The bolt on stuff is RV. The secondary assembly is all RV instead of the Deluxe figure 8 spider. The serial numbers are 2361 on the OTA  and 2349 on the mount which is closer than any other RV I've seen in person but has no relation to scope size or date. The picture is from the original owners ad.  Criterion's statement about the substitutions touted superior aspects of the Deluxe Dyna OTA even though it was basically just a tube swap, and they had the gumption to close with "We assume these substitutions will be satisfactory".  

 

Criterion knew no bounds on flip flops and swaps with the RV series. 

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Edited by apfever, 28 March 2025 - 03:43 PM.

[CHASLX200]

I think the RV-8s I remember from brochures had the same finder as the RV-6. I seem to remember the only significant difference was the DEC slo-mo option for the RV-8. The grey pebble/whatever finish was characteristic of the Custom Dynascope pre-RV Criterion scopes. But Neil (apfever) says grey whatever finish RVs were also sold when parts inventory demanded it.

 

edit: Nope, 8x50 finder standard on the RV-8.

 

-drl

RV8 has that junky mount the 6 did.  Really bad with a 8" F/7.