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Vintage Lenses - Spacers, Rings, & Things

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#51 oldmanastro

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Posted 28 July 2020 - 01:11 PM

I think you mean .01. I have few options. I could rob a plastic spacer from the Carton I mentioned earlier and see if that helps, or stack 3 layers of some foil adhesive I have that's .003. Then after that try 2 layers, then down to one.

 

Yes the Mayflower is difinitely the nicer of the two. Obviously a better objective and a much better focuser. I usally don't have not much interest in Towas but it was a orphan OTA that I got for a good price and thought if it's any good maybe I'd use it as a guide scope.... or worse case, for parts.

The plastic ring spacer has a .10mm thickness not .01mm. Both the metal and plastic spacers provide an ample space and this is the reason why we don't see Newton rings with them. The ribbon trimming tape that I got from Pep Boys is .10mm with the backing paper removed and it's gray. It feels like a metal tape but I'm not sure it is. The adhesive has a light grip that's perfect for our purposes.

 

 There are some good Towas around like the Sears 4454 80mm f/15. I have read that older 60mm Towas were of much better quality. They seem to have come downhill after the mid 60s. My first telescope was a 1965 60mm f/11 Towa. It's not great but ok.

 

Clear Skies,

 

Guido


Edited by oldmanastro, 28 July 2020 - 03:33 PM.

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#52 Kasmos

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Posted 28 July 2020 - 02:42 PM

My mistake, I automatically thought you were talking inches as my specs. of .003". 

 

Yes, many have mentioned how the larger Towas 76mm+ are better. As for the older 60mm's, my circa 1959-61 Crescent 60/800mm is also a under achiever with too much CA. Right now it has a replacemnt lens from a Celestron CO-60. I have a same era Mayflower (Towa) 60/400mm lens from a var-power scope that doesn't impress me and this 9TE is likely a '65. While it's not a big sample Towas aren't doing very well for me. The one exception might be the 60/1000mm Penncrest which looked good during the day, but due to some bad seeing, it could use more evaluation at night, but so far looks pretty good.

 

On the other hand my two Mayflower 814s are both great as is my Manon. 

 

 


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#53 GreyDay

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Posted 28 July 2020 - 03:51 PM

 There are some good Towas around like the Sears 4454 80mm f/15. I have read that older 60mm Towas were of much better quality. They seem to have come downhill after the mid 60s. My first telescope was a 1965 60mm f/11 Towa. It's not great but ok.

I Have a Towa 339(unbranded) 80x1200 and it gives good views. To get a good 60mm Towa you really need to aim for f15 or even the 60x1000 Carton objectives, there are Royal Astro's that perform well but honestly the 60x700 Towas are okay but not great. You can take comfort knowing that none of the Korean/Chinese 60x700's i've tried are anywhere near as good as the Towas.

 

The Kenko objectives are much the same, i have three 60x710 kenko's (2xPrinz330, 1Greenkat) that are just "okay" in performance maybe a touch better than the Towa's but not as good as the Kenko 60x910!

I have had a few 60x910 kenko's all performed really well. I kept one a Prinz 550 that was the best of the bunch that performs as well as my Carton 60x1000. I stopped buying 60's after buying a Telementor 2, that scope is probably as good as an achromat can get.

 

Has to be said though.. none of the best of my 60's has ring spacers! all foil tabs.


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#54 oldmanastro

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Posted 28 July 2020 - 03:52 PM

My mistake, I automatically thought you were talking inches as my specs. of .003". 

 

Yes, many have mentioned how the larger Towas 76mm+ are better. As for the older 60mm's, my circa 1959-61 Crescent 60/800mm is also a under achiever with too much CA. Right now it has a replacemnt lens from a Celestron CO-60. I have a same era Mayflower (Towa) 60/400mm lens from a var-power scope that doesn't impress me and this 9TE is likely a '65. While it's not a big sample Towas aren't doing very well for me. The one exception might be the 60/1000mm Penncrest which looked good during the day, but due to some bad seeing, it could use more evaluation at night, but so far looks pretty good.

 

On the other hand my two Mayflower 814s are both great as is my Manon. 

Changing from english to metric took some time at least for me. It requires a new measurement mindset. That Kenko looks quite nice. It has good a good quality mount. 

I replaced the lenses of the bad Towa 60mm f/15 with a Meade lens that work very well. Another problem with the Towas is the collimation. Apparently the end of the optical tube where the objective cell threads is not machined too well and the cell ends up misaligned. There's no way that it will fall in collimation. One way I have found around it is to place a plastic strap behind the cell. Then unthread the cell a bit so that it is loosens up a bit and moves sideways on the threads. Then I push the plastic strap against the cell in the right direction to correct the collimation using a Cheshire. It works and stays put for quite a while. It's a crude way to do it but I don't want to drill and tap anything.

 

Guido


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#55 oldmanastro

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Posted 28 July 2020 - 03:57 PM

I Have a Towa 339(unbranded) 80x1200 and it gives good views. To get a good 60mm Towa you really need to aim for f15 or even the 60x1000 Carton objectives, there are Royal Astro's that perform well but honestly the 60x700 Towas are okay but not great. You can take comfort knowing that none of the Korean/Chinese 60x700's i've tried are anywhere near as good as the Towas.

 

The Kenko objectives are much the same, i have three 60x710 kenko's (2xPrinz330, 1Greenkat) that are just "okay" in performance maybe a touch better than the Towa's but not as good as the Kenko 60x910!

I have had a few 60x910 kenko's all performed really well. I kept one a Prinz 550 that was the best of the bunch that performs as well as my Carton 60x1000. I stopped buying 60's after buying a Telementor 2, that scope is probably as good as an achromat can get.

 

Has to be said though.. none of the best of my 60's has ring spacers! all foil tabs.

I built a Carton 60mm f/17 from a lens I got from Sheldon Faworski. It's the best 60mm I have. Excellent optical performance. This is it on the Sears 6305 mount.

 

Guido

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#56 Kasmos

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Posted 28 July 2020 - 04:22 PM

This Kenko is also a 60/710mm.

 

The mount looks nice but it was completely unfunctionable when bought it. I thought it was just stiff grease but when I disasembled it I found that many areas of the machining didn't match up. Because of that one of the major issue was that the tube holder wouldn't rotate more than a few degrees in the york arms. I had to take it apart and re-assemble it many times over the course of a very long evening to correct all of it's problems. I took photos so maybe I'll post it in it's own thread. The other problem is this particular model doesn't have controls for azimuth. Some did so they could be added if I found the parts from one. They appear to share a history with Atco so parts from a Atco mount might also work.

 

I also have a Carton 60/1000. I have all of the parts for the OTA (Objective and tube from Sheldon), but I never got around of putting it together. Too many projects going on with new scopes coming in to interrup it, but that's now stopped!


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#57 Bomber Bob

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Posted 28 July 2020 - 04:43 PM

really need to try / test a Carton objective...  Chuck has had some under-performers...


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#58 GreyDay

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Posted 28 July 2020 - 06:17 PM

really need to try / test a Carton objective...  Chuck has had some under-performers...

Mine works well it's Carton branded on the focuser so i trust it's pedigree, no CA except on the brightest etc, Not quite up to Zeiss standard can't say it's better than my Asahi but it's no slouch, performance is on par with 60x910 kenko scopes if a touch better.. most of the time there's nothing in it just "presentation" if you know what i mean?... no real night/day differences no extra detail maybe just better contrast but a more pleasing view it just "feels" nice to use.

 

I do wonder about under performing objectives, it's like the assumption that every 60x1000 is Carton or every 60x800 is of AsahiPentax origin because of focal length. This leads to Towa producing 60x800's and 60x1000's like the Penncrest/JC Penney scopes that sometimes don't perform as well?

 

The origin of any telescope's objective is questionable, they're mostly interchangeable and do get damaged/messed with over time. We all look for the manufacturers stamp on the focuser and if we see Astro,Hino,Goto etc we expect a level of performance somewhat better than Towa but.... we all know that Towas are okay they work but they're sometimes crap.. one of a bad batch etc. Knowing there are Towa 60x1000's out there calls into question the quality of any 60x1000 that doesn't have a proven Carton origin. Nobody will be able to tell unless they DPAC :)


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#59 PETER DREW

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Posted 28 July 2020 - 06:25 PM

Just to add to the mix, I'm currently refurbishing a Towa 80-1200.   It has the usual two plastic spacers gives the same view as in #4 and presents a textbook artificial star pattern at focus at 400x using 3mm on a Nagler 3-6 zoom. 


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#60 clamchip

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Posted 28 July 2020 - 07:56 PM

The Towa 339 is Towa's flagship and they proudly put their name on the focuser.

These are excellent, even with a plastic spacer.

Robert

 

post-50896-1407427716982_thumb.jpg


Edited by clamchip, 28 July 2020 - 08:03 PM.

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#61 oldmanastro

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Posted 28 July 2020 - 11:07 PM

I got my Towa 339 in the form of the Sears 4454 a few years ago locally from the original owner. It had all the accessories except the diagonal and had been stored for years. The lenses had fungi growing between the elements. That's nothing uncommon here if you leave the telescope in boxes for extended periods. I had to disassemble the objective and found one spacer resting on the bottom rim where the flint element rests in the cell. The other spacer was located right below the retaining ring. There was no spacer between the lenses indicating that someone took them out and incorrectly reassembled the lenses. Both rings had been deformed and could not be used as spacers so I made some spacers out of the ribbon material that I have mentioned before and placed them on the cleaned lenses. The result was very good with the telescope providing a very nice star test after collimation. Even though the star test is very good the test that I get from the Sears 76mm f/16 Astro Optical is a tad better. 

 

The image shows the 4454 using a clock drive for a 6305 60mm. It works on the 4454 with no undue stress on the motor.

 

Guido

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#62 GreyDay

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Posted 29 July 2020 - 09:58 AM

The Towa 339 is Towa's flagship and they proudly put their name on the focuser.

These are excellent, even with a plastic spacer.

Robert

I just pulled out my 339, it shows newton rings! looks like plastic spacers with no foil evident. So even plastic ring spaced objectives can show newton rings if well executed smile.gif

 

EDIT: i tried to photograph it with my iphone but only picked up glare from the light.


Edited by GreyDay, 29 July 2020 - 10:00 AM.

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#63 JHub

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Posted 29 July 2020 - 01:28 PM

Greyday'

 

Any chance you know the thickness of the lens spacers on the Kenko 60x710 objectives? I'm trying to revive one that's missing the spacers.

 

John



#64 GreyDay

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Posted 30 July 2020 - 04:23 AM

I'll take a look this afternoon when i get some freetime :)



#65 GreyDay

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Posted 30 July 2020 - 05:44 AM

just checked my Prinz330, the foil spacers fold over the side of the flint, they measure 0.05mm. they don't look original to me but they do show newton rings smile.gif

 

Edit: After playing with this objective i'd say the foil spacers in this objective are wrong..! They're more like acetate (plastic) than foil though they are shiny like foil.  They barely space the elements and dont touch both elements at the edge, the pressure is at around 3mm in from the edge, so it feels like the spacers are loose at the edge but make contact around 3mm in. I hope that makes sense? The objective is also very sensetive to pressure from the retaining ring, if you overtighten even a little the centre moves to one side like the bubble in a round spirit level.


Edited by GreyDay, 30 July 2020 - 06:34 AM.


#66 DAVIDG

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Posted 30 July 2020 - 07:38 AM

just checked my Prinz330, the foil spacers fold over the side of the flint, they measure 0.05mm. they don't look original to me but they do show newton rings smile.gif

 

Edit: After playing with this objective i'd say the foil spacers in this objective are wrong..! They're more like acetate (plastic) than foil though they are shiny like foil.  They barely space the elements and dont touch both elements at the edge, the pressure is at around 3mm in from the edge, so it feels like the spacers are loose at the edge but make contact around 3mm in. I hope that makes sense? The objective is also very sensetive to pressure from the retaining ring, if you overtighten even a little the centre moves to one side like the bubble in a round spirit level.

 What your describing with the element not touching at the edge is that one of the elements is flipped. In a typical fraunhofer design which 98% of these small achromats are, the two inner radii are almost the same  but slightly different enough that  they only will touch at the edges,  even will no spacers.  

   You will  still get an image that comes to focus and looks OK when the element is flipped, that is why people don't question the image quality but when you get the elements in the correct position the image will be much sharper.

 

              - Dave 


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#67 GreyDay

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Posted 30 July 2020 - 12:15 PM

 What your describing with the element not touching at the edge is that one of the elements is flipped.

Thanks David, i'll take another look at it soon. It's not really high on my list as it barely gets used, I only opened it up to take a peek at the spacers and the rest of the objective is pretty poor with feint scratches and worn coatings. If i remember correctly this particular scope was bought for it's mount and tripod so not a high priority :)



#68 JHub

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Posted 30 July 2020 - 12:20 PM

Thanks for your replies  GreyDay & DAVIDG.

 

John



#69 Kasmos

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Posted 30 July 2020 - 01:33 PM

just checked my Prinz330, the foil spacers fold over the side of the flint, they measure 0.05mm. they don't look original to me but they do show newton rings smile.gif

 

Edit: After playing with this objective i'd say the foil spacers in this objective are wrong..! They're more like acetate (plastic) than foil though they are shiny like foil.  They barely space the elements and dont touch both elements at the edge, the pressure is at around 3mm in from the edge, so it feels like the spacers are loose at the edge but make contact around 3mm in. I hope that makes sense? The objective is also very sensetive to pressure from the retaining ring, if you overtighten even a little the centre moves to one side like the bubble in a round spirit level.

IIRC the original spacers in my 60/710 Kenko were thicker than normal and also folded over the edges of the flint, but wouldn't show Newton rings.  I removed them and tried foil since they were glued crooked. I might try making some new ones today. 

 

BTW, my Manon also has what appears to be slightly thicker spacers folded over the edge of the flint. It works great so I'm not touching them.


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#70 strdst

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Posted 30 July 2020 - 02:22 PM

 

 

The Kenko is among my prettiest scopes, so it would be nice if it performed as good as it looks.

attachicon.gifKenko-Palm.jpg

Chris,

 

My experience as well. This one is (perhaps) a Sans&Streiffe 601. The focuser label was loose in the case. The case is labeled S&S but the seller was a collector/tinkerer not unlike myself so it's quite possible the label and case were not original. I have a bad habit of allowing parts from unfinished projects (as most of mine are) to mingle within my telescope community.

 

They are good looking telescopes and the mounts are not common. Is your Kenko cell serial numbered?

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#71 Kasmos

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Posted 30 July 2020 - 02:36 PM

Chris,

 

My experience as well. This one is (perhaps) a Sans&Streiffe 601. The focuser label was loose in the case. The case is labeled S&S but the seller was a collector/tinkerer not unlike myself so it's quite possible the label and case were not original. I have a bad habit of allowing parts from unfinished projects (as most of mine are) to mingle within my telescope community.

 

They are good looking telescopes and the mounts are not common. Is your Kenko cell serial numbered?

I have a habit of jumping form project to project myself, but slowly they are getting there.

 

They say they are worth a thousand words so....

Kenko-Objective.jpg


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#72 PawPaw

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Posted 30 July 2020 - 04:46 PM

This has become a very informative thread and will be bookmarked by myself for future reference.  A few months ago I acquired a 50mm Polaris branded (Unitron 750) and last week I finally took a close look at the performance of the lens.  I started out with terrestrial testing compared to a known quality lens of 58mm and found the Polaris images to be soft and mushy.  This is a fraunhofer 50mm with foil spacers and I was unable to see any Newton rings.  So today I removed the objective and found a prominent fingerprint smear on the eyepiece side of the flint....Usually not a good sign. The spacers were still intact but noticeably degraded with the foil dull with the paper base showing through in spots. I went ahead and made orientation marks in case they were correct and  after a thorough cleaning I assembled the lens as removed with the original spacers and  still no newton rings.  The Crown side toward the sky had some degradation of the AR coating so that made me believe the orientation of the lens had been that way for some time.  Makes me think It could have left the factory that way.   The flint looked correct so I flipped the crown and eureka Newton appeared.  Unable to get the rings centered there was no doubt the foil spacers needed replaced so using the micrometer I fashioned new ones of similar size as the originals.  I used this method to fashion the new spacers:  https://www.cloudyni... unitron find

 

I used .003 foil spacers and adjusted via a CFL light to center the rings.  Unable to test, at least tonight due to weather, I focused on a terrestrial object and found much better sharpness.....weather permitting this weekend I will to a comparison star test with my known performers.  I have found photographing the Newton rings can be difficult but one method I use is to reflect the CFL off a light colored background with a shade between the light and objective.   This helps me photograph the rings.  They look off center from the photos but visually checking side to side they are centered.

1st pic before cleaning 

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Edited by PawPaw, 30 July 2020 - 04:56 PM.

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#73 PawPaw

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Posted 31 July 2020 - 03:59 PM

Instead of posting this in "what did you do to your telescope today"  I thought it more appropriate to share it here.   Ever since I acquired my first Unitron that needed cleaning/new spacers I have been looking to confirm definitively what foil spacer thickness Unitron used.....Or Nihon Seiko asked their contractors to use.  Today while removing the lens from my recently acquired Unitron 128 for cleaning and respacing one of  the foil spacers actually fell out intact.  Keep in mind this is a 60mm lens and it is possible other apertures from NS required a different foil size.  This one measured as close to .003" as you can get........you could call it .0029 but for all practical purposes this is the first definitive measurement I have been able to get on a unitron lens spacer. 

 

The  main reason I removed the objective is the Newton rings were off center and the sky side of the crown needed cleaning plus the flint had some mold blooms.  Looking forward to clearer skies for testing.

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#74 clamchip

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Posted 31 July 2020 - 05:01 PM

Besides other things I collect micrometers!

I just want to point out my 'Favorite' shown here by nurse Mendy.

It will make you lazy because it's a direct readout, the little windows

display the thousandths, and it has ten thousandths on the hub.

Made by Slocomb, these were popular so plentiful on places like

ebay.

Super accurate, and a ten thousandths mike, and like I said it works

so well you won't be able to go back to a conventional mike.

Robert

 

post-50896-0-22878800-1581559100.jpg


Edited by clamchip, 31 July 2020 - 05:07 PM.

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#75 GreyDay

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Posted 31 July 2020 - 10:00 PM

Today while removing the lens from my recently acquired Unitron 128 for cleaning and respacing one of  the foil spacers actually fell out intact.  Keep in mind this is a 60mm lens and it is possible other apertures from NS required a different foil size.  This one measured as close to .003" as you can get........you could call it .0029 but for all practical purposes this is the first definitive measurement I have been able to get on a unitron lens spacer.

I wondered if there may be different thicknesses of foil due to focal length but at .003" it appears to be the same for 900mm as 710mm.

 

I'm not sure how the math works for achromatic elements, my understanding is the 4 surfaces (1&2 crown,3&4 flint) usually have surfaces 2&3 that define the air space between crown/flint as almost identical radii, with surface 1&4 determining the focal length? maybe someone who knows how element design works could confirm or correct?

 

if i'm correct then surfaces 2&3 could be the same across many focal lengths? just guessing i know too little about the design:)




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