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Vintage Lenses - Spacers, Rings, & Things

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#26 Kasmos

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Posted 26 July 2020 - 04:08 AM

My 9TE was giving fairly sharp daytime views but compared to my Mayflower 814 and Manon I could see noticable purple and yellow fringing on the edges of details. So for the heck of it I opened it up this evening and took another look at the ring spacer.

 

It's metal, non magnetic, and silver where the black is nicked so I think it's black anodized aluminum. Keep in mind that this scope is likely from 1963. The rings in both my 60/800mm Crescent and cut down Mayflower 806? vari-power are metal and I thought they were both steel. Those two have a uncommon cell design that dates them circa 1959-61. I'll check them again as soon as I get a chance and report back. 

 

Tasco 9TE-Lens-removal.jpg

This photo was taken first time the lens was serviced after purchasing.

It's a bit of an illusion but you can still see that the ring is much thicker than most foil spacers

 

I was hoping to improve this lens and my first thought was to try the plastic ring from a Carton objective I have. The Carton shouldn't have one as it was done by a previous owner, who BTW, said the images were excellent. Anyway, instead I decided to make three spacers. One time I layered three pieces foil adhesive, but it's tedious and I'd probably need to stack 5 or so to match the thickness of the ring. Then I remembered I saved a aluminum soda can that I use for shim material.

 

I don't have a micrometer and it looks slightly thinner than the ring, but what's to lose? I can always put the ring back in.

 

Soda Can Spacers

Soda-Can-Spacers.jpg

First I cut some strips with sharp scissors and burnished all of the edges flat the best I could. I then marked where I wanted to fold them with a dull X-acto knife, then held them in tweezers at that line, and folded them. Then cut the excess length off and taped them to the edge.

 

Note. Before I made the spacers I checked to see if there would be room in the cell to tape them to the sides of the flint. I noticed that the lenses fit the cell perhaps too loosely. So when I taped the spacers to the flint it was now snug but the crown wasn't. Meaning they might not be aligned when tighted. Therefore, I removed them both and tape them together at the three places between the spacers. Now when it went back into the cell it felt nice. One reason I bring this up. If it turns out there's an improvement in performance, it might be the alignment of the lenses and not the new spacers.

 

First I set up the Mayflower 814, but since it was clouded over, my only (not so good) targets were limited to a parked car and a couple of street lights at approx. 1/4 mile away. It was late so instead of a true side by side comparision, I replaced the Mayflower's OTA with the Tasco. I might be wrong but my first impression is, the view in the Tasco now looked as color free as the Mayflower. Tommorrow I'll try setting them up side by side to see if it truely improved it's performance. fingerscrossed.gif If it did, I'll probably try it on a couple of more lenses I have.


Edited by Kasmos, 26 July 2020 - 11:50 AM.

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#27 GreyDay

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Posted 26 July 2020 - 04:59 AM

I did some measurements on the metal spacer ring using a micrometer. Values varied from .32 to .39mm as I rotated the ring 360 degrees and took several measurements twice just to make sure. Not much precision there.

Shocked! maybe not :)  who'd have thought there'd be misalignement caused by a nonadjustable part? Like most i've always assumed that the rings would be uniform.

Is this the reason we're not seeing newton rings in ring spaced objectives?

 

Great work Guido, DavidG already alluded to this earlier and now there's proof :)


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#28 Bomber Bob

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Posted 26 July 2020 - 08:43 AM

As usual, this post is Terra's fault:  She mentioned Jaegers & Baker Lenses...

 

My Dakin 4" F10 has an unknown-maker, but it's a Baker, with a 7mm metal band separating crown & flint:

 

PD4 S08 - Lens (Markings).jpg

 

(My camera gives the crown a mushroom-cap look, but it's normal.)  Elements have original pencil edge-marks.

 

The lens is kinda unusual, in that it weighs more than any of my other 4" lenses, including the new AT102ED.


Edited by Bomber Bob, 26 July 2020 - 08:46 AM.

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#29 PawPaw

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Posted 26 July 2020 - 08:46 AM

As usual, this post is Terra's fault:  She mentioned Jaegers & Baker Lenses...

 

My Dakin 4" F10 has an unknown-maker, but it's a Baker, with a 7mm metal band separating crown & flint:

 

attachicon.gifPD4 S08 - Lens (Markings).jpg

 

(My camera gives the crown a mushroom-cap look, but it's normal.)  Elements have original pencil edge-marks.

JW.....can you show us a pic from the side and the measurement of the spacer?  I have a 4" Baker lens in a Jaegers cell and  want to compare.

 

Don



#30 Bomber Bob

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Posted 26 July 2020 - 08:48 AM

Shocked! maybe not smile.gif  who'd have thought there'd be misalignement caused by a nonadjustable part? Like most i've always assumed that the rings would be uniform.

Is this the reason we're not seeing newton rings in ring spaced objectives?

 

Great work Guido, DavidG already alluded to this earlier and now there's proof smile.gif

That is great detective work.  Now we know...  Thanks Guido!

 

I wonder if the vinyl rings are any better?


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#31 Bomber Bob

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Posted 26 July 2020 - 08:50 AM

JW.....can you show us a pic from the side and the measurement of the spacer?  I have a 4" Baker lens in a Jaegers cell and  want to compare.

 

Don

Got something better:  The Numbers from when I had the lens out of the cell...

 

Crown = 110x13
Flint = 110x17
Spacer = 110x7


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#32 oldmanastro

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Posted 26 July 2020 - 09:29 AM

As usual, this post is Terra's fault:  She mentioned Jaegers & Baker Lenses...

 

My Dakin 4" F10 has an unknown-maker, but it's a Baker, with a 7mm metal band separating crown & flint:

 

attachicon.gifPD4 S08 - Lens (Markings).jpg

 

(My camera gives the crown a mushroom-cap look, but it's normal.)  Elements have original pencil edge-marks.

 

The lens is kinda unusual, in that it weighs more than any of my other 4" lenses, including the new AT102ED.

A 7mm separation. It looks like a Clark objective design. Nice lens!

 

Guido



#33 oldmanastro

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Posted 26 July 2020 - 09:59 AM

I think that the Sears 6305 60mm f/15 had a ring spacer that I replaced. It is customary for me to keep things so it must be in my optical junk box. If it's there, I'll measure the thickness all around. 

 

Kamos idea of using aluminum soda can metal is excellent and I like the way it was placed bent at 90 degrees.

 

My guess with the use of the metal ring spacers in these small 60mm f/11 Towa refractors is that they provided a required spacing for a Fraunhofer design with precision thrown to the wind. These objectives are not even marked for positioning. Most of the people who bought these scopes didn't know anything about optics or optical quality. What they saw through them was ok. I knew nothing about star tests, Airy discs  or diffraction rings when in 1965 I received my 60mm f/11. For me this telescope worked like a charm and allowed me to see craters on the moon and the rings of Saturn plus a bunch of Messier objects. Optical quality? What was that at 13? One thing I can tell you is that my eyes had a much better optical quality then and maybe compensated for some of the telescope's shortcomings. 

 

I'll report back on the plastic ring spacer.

 

Guido


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#34 Kasmos

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Posted 26 July 2020 - 12:25 PM

Like most i've always assumed that the rings would be uniform.

Is this the reason we're not seeing newton rings in ring spaced objectives?

It's likely because they are spaced too far to create them. I have some objectives with 3 fairly thick foil spacers and they don't show them. The same goes for the soda can spacers above.

 

As usual, this post is Terra's fault:  She mentioned Jaegers & Baker Lenses...

 

My Dakin 4" F10 has an unknown-maker, but it's a Baker, with a 7mm metal band separating crown & flint:

My 4.25" f/15 Jaegers has a very thick spacer ring. I've never had it apart but it wouldn't surprise me at all if it's 7mm.

 

One other thing.

I realize that lenses are designed with a specific air space in mind, so If I had a micrometer I would have measured the average thickness of the ring and if needed then added some of the .003 adhesive foil I have to the soda can aluminum to match it. For now I want to see if the slightly thinner spacers make it work better. By using a ring it appears that Towa wasn't being very precise to begin with, so there's a chance that the lens could have been made in such a way that a slightly thinner than spec. spacer works better. 

 

Since it's very overcast today even daytime testing won't be as good as when it's sunny. Hopefully it will clear some and I can also test it tonight. 


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#35 GreyDay

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Posted 26 July 2020 - 01:48 PM

 I knew nothing about star tests, Airy discs  or diffraction rings when in 1965 I received my 60mm f/11.

All i know of star testing is i rarely understand what i'm seeing. If the disk is round and concentric it's good... if it looks like it's on fire the seeing is bad or i have tube currents/still cooling. I can tell pinched optics and astigmatism as they distort the disk enough for me to tell whats happening, beyond that things like under/over correction etc are beyond my understanding (should read more).

 

 

 My 4.25" f/15 Jaegers has a very thick spacer ring. I've never had it apart but it wouldn't surprise me at all if it's 7mm.

 

For now I want to see if the slightly thinner spacers make it work better. By using a ring it appears that Towa wasn't being very precise to begin with, so there's a chance that the lens could have been made in such a way that a slightly thinner than spec. spacer works better.

Do you get newton rings with the 7mm spacing on the Jaegers? or does this only work for close fitting elements? looking forward to the spacer results. i may have to start pulling my Towas out of storage smile.gif


Edited by GreyDay, 26 July 2020 - 01:49 PM.

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#36 GreyDay

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Posted 26 July 2020 - 01:55 PM

Can't help wondering if the Newt diehards are having a little giggle to themselves right now :)


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#37 Bob4BVM

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Posted 26 July 2020 - 03:05 PM

Can't help wondering if the Newt diehards are having a little giggle to themselves right now smile.gif

I am equally afflicted in both camps

Each has their own special sufferings :) 

Then there are the bino-scopes of either type. One has to decide how much suffering he can handle.

But as in many things , the greatest suffering yields the greatest gain...

Cheers

Bob


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#38 Bob4BVM

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Posted 26 July 2020 - 03:13 PM

Great thread !

Thx to all contributors.

 

Can anyone tell me what were the standard design spacer thickness for the Jaegers 6"F5 achromat ?

 

I have been chasing my tail trying different rotations of the C & F in mine, all the while not knowing if the spacers are even correct.

I bought the lens sans-cell, made a cell, and assembled it with spacers of 3-M sticky note paper.

It would be wonderful if i could at least nail down the proper spacer thickness, then proceed from there

I hope someone can help or point me to a resource for this lens.

 

CS

Bob



#39 Bob4BVM

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Posted 26 July 2020 - 03:18 PM

My 1957 Goto Hy-Score 452 (60x1200) lens has no spacers...

 

attachicon.gifGHS452 - Lens Before Cleaning S03.jpg

 

It's a contact doublet.  The alignment mark is original -- and critical.  A slip of just 1mm either direction hurts performance, which is a head-scratcher for me, as Goto uses a brass retaining ring on the eye-side of the lens cell:

 

attachicon.gifGHS452 - Lens Post Cleaning S03.jpg

 

No matter how slowly or carefully you thread the ring in, the 2 elements will move... and wreck alignment.  Once I figured that out, I taped the edges -- no more slips!

"I taped the edges"

omg, i cannot believe i hadn't thought of that with all my messing around with rotations, always wondering if it moved when i put it back in the cell...  Thank you Bob !

 

CS

Bob


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#40 Kasmos

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Posted 26 July 2020 - 03:28 PM

Do you get newton rings with the 7mm spacing on the Jaegers? or does this only work for close fitting elements? looking forward to the spacer results.

My understanding is they only show with very close or contacting lenses.


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#41 Kasmos

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Posted 26 July 2020 - 03:38 PM

"I taped the edges"

omg, i cannot believe i hadn't thought of that with all my messing around with rotations, always wondering if it moved when i put it back in the cell...  Thank you Bob !

 

CS

Bob

IIRC, I don't think any of the lenses I've taken apart had 'original' markings for aligning rotation. I tend to trust Davidg when he's said, that rotation shouldn't effect a properly made lens. That said, there seems to be plenty of folks in this forum who do it and swear it helped. My guess is that the lens that have arrows on both elements are not for alignment but are there for direction of placement.


Edited by Kasmos, 26 July 2020 - 03:38 PM.

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#42 oldmanastro

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Posted 26 July 2020 - 04:10 PM

I have the micrometer readings for two 60mm f/15 plastic ring spacers. Good news. They are consistently .10mm all around. I took many measurements twice in both rings making sure that the micrometer was calibrated. The metal ring spacer was .32 to .39mm. This is the spacer from the 60mm f/11. Notice the change in spacing with increasing focal length. Maybe it's nothing, just an observation. 

 

This discussion made me take out from storage the original objective of one of my Sears 3605s 60mm f/15s, re-space it to .09mm and try it again. I still cannot believe it is so bad. I was using the telescope with a replacement lens but being the way I am, the original objective is back again. Maybe I am beating myself on the head. Will let you know later after I retest if the weather allows.

 

Guido


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#43 GreyDay

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Posted 26 July 2020 - 04:24 PM

I am equally afflicted in both camps

Each has their own special sufferings smile.gif

Same here Bob, i have Maks, Newts and Fracs, no SCT's... just never got on with them :)

 

My understanding is they only show with very close or contacting lenses.

Hmmm.... so depending on the design changing out spacers may be pointless without DPAC to confirm optimal setup.


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#44 DAVIDG

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Posted 26 July 2020 - 07:00 PM

Same here Bob, i have Maks, Newts and Fracs, no SCT's... just never got on with them smile.gif

 

Hmmm.... so depending on the design changing out spacers may be pointless without DPAC to confirm optimal setup.

 I have read many time that people found better performance by playing with the spacer thickness but show no proof. As I have said the air space is optical element just like the glass so when you change the thickness your changing total correction of the lens. 

   You need to bench test the lens to see what is really going on. If the figure has zones, changing the spacing isn't going to help. It is only if the lens is slightly over or under corrected that changing the spacing may help but you have to look at the test results in Green Red and Blue because they all interact and just because you changed  the spacing and  the correction looks better in Green light it doesn't mean that you didn't throw off Red and Blue. 

   The bottom line is if  you want truly meaningful results you have to bench test and confirm the results vs  guessing.

 

                     - Dave 


Edited by DAVIDG, 26 July 2020 - 07:51 PM.

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#45 oldmanastro

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Posted 27 July 2020 - 02:43 PM

I remember when Chinese made achromatic refractors invaded the market in the late 90s. Quality was very variable with some people reporting excellent optics while others received useless telescopes. One of the major complaints was spherical aberration and people started to change the spacing between the objectives. Some indicated that they were successful but I never saw any related images. Then a Russian made optical corrector called Chromacor came to the market. The cost was almost the same as that of a Chinese achromat and even more but some people bought it. This Chromacor devise corrected the spherical and as a result also a lot of the chromatic aberration and people swore by it. 

 

Suiter's book mentions something about testing refractors for SA using a central obstruction in front of the objective while doing a star test. I tried it once with my former 150mm f/8 achromat. The results were not easy to interpret. The the telescope gave pretty good images but I sold it mount and all. I was tired of hauling mount and telescope.

 

It's interesting that neither the metal ring spacers or the plastic ones provide any visibility of the Newton rings. When I substituted the plastic spacer in the 60mm f/15 with the .10mm individual spacers (same thickness as the plastic one) , then the Newton rings appeared. It seems that even though the plastic spacer has an equal thickness all around it, there are areas where it is bent and disrupts the spacing. The "new" spacers at least improve things in these lower end Towa 60mm scopes. 

 

I retested the original lenses of the second Sears 6305. It's just bad. There must be something really bad in one of the elements. There's no way this lenses will throw a usable image. 

 

Here's an image of the metal vs plastic spacers.

 

Clear Skies

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  • Pastic60mm ring.JPG

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#46 GreyDay

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Posted 27 July 2020 - 05:21 PM

 This Chromacor devise corrected the spherical and as a result also a lot of the chromatic aberration and people swore by it.

 

It's interesting that neither the metal ring spacers or the plastic ones provide any visibility of the Newton rings. When I substituted the plastic spacer in the 60mm f/15 with the .10mm individual spacers (same thickness as the plastic one) , then the Newton rings appeared. It seems that even though the plastic spacer has an equal thickness all around it, there are areas where it is bent and disrupts the spacing. The "new" spacers at least improve things in these lower end Towa 60mm scopes. 

 

I retested the original lenses of the second Sears 6305. It's just bad. There must be something really bad in one of the elements. There's no way this lenses will throw a usable image.

The "Chromacor" brings back memories, never had one myself but a friend with a Helios(skywatcher?) 6 inch had one and swore by it. Personally i think a scope objective should be able to stand on it's own two feet, and be judged that way. It's one of the reasons i don't own a ED scope, paying out so much money for a scope that needs flatteners or EP's that cost as much as the scope itself because of SA is a bit of a joke. obviously there are ED scopes that show no field curvature but they're beyond  my disposable income. Until scope manufacturers start making "visual" ED scopes that aren't so fast they're picky about EP's i'll wait :)

 

Interesting that the individual spacers work in the 60/f15, i'll have to give it a try. I have a few 50 and 60mm scopes with plastic rings it'll be interesting to see how they perform. I'll probably start with Tasco 66TE's as i have a couple of "donor" scopes i can mess with.

 

Sad about the 6305, I had a Prinz330 (60x710) that wouldn't give a good image no matter what i did, i bought a second OTA and compared the elements, it looked like the first had had its crown replaced as it was thinner than the second i bought. A past owner probably broke the original crown and replaced it with another of the wrong figure. Some people eh? i couldn't sell a scope like that...


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#47 Kasmos

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Posted 28 July 2020 - 02:42 AM

It's been very overcast for the last 2 days so it really wasn't the best day for checking the 9TE's images. Even so I didn't see any improvement from using the three new spacers. It still looked like it had the same amount of CA to me. The left and right edges of the brackets used as a target on a power pole had the same purple fringe on the left and a yellow fringe on the right. Some parts on the pole showed more color than others but it's really noticable on things in the field of view that are out of focus. Too bad I'm unable to take a photo to illustrate it.

 

By comparision the Mayflower set up next to it looked color free. I have to say given the amount of CA it's surprising how otherwise the image isn't so bad, but to me the color is annoying. I haven't had a chance to try it at night on a astro object but I would assume that the CA would really spoil the views. I don't know how much time I'll continue to put into it but I'll probably go two more rounds of trying some thinner spacers and see if it helps. Who knows, maybe it wouldn't bother someone else as much?

 

9TE-Test.jpg

The Mayflower is used as a bench mark to shoot for. 


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#48 oldmanastro

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Posted 28 July 2020 - 09:28 AM

It's been very overcast for the last 2 days so it really wasn't the best day for checking the 9TE's images. Even so I didn't see any improvement from using the three new spacers. It still looked like it had the same amount of CA to me. The left and right edges of the brackets used as a target on a power pole had the same purple fringe on the left and a yellow fringe on the right. Some parts on the pole showed more color than others but it's really noticable on things in the field of view that are out of focus. Too bad I'm unable to take a photo to illustrate it.

 

By comparision the Mayflower set up next to it looked color free. I have to say given the amount of CA it's surprising how otherwise the image isn't so bad, but to me the color is annoying. I haven't had a chance to try it at night on a astro object but I would assume that the CA would really spoil the views. I don't know how much time I'll continue to put into it but I'll probably go two more rounds of trying some thinner spacers and see if it helps. Who knows, maybe it wouldn't bother someone else as much?

 

attachicon.gif9TE-Test.jpg

The Mayflower is used as a bench mark to shoot for. 

Nice pair of 60mm scopes! The Mayflower is my favorite of the two. The 9TE seems to be mounted in a sturdy Unitron altazimuth mount. Experimenting with spacers is interesting even if one ends up returning the original spacer to the objective lens. The ring spacer is definitely irregular so I would return to the aluminum can spacers if thinner ones don't work. Try something that's near .10mm. 

 

The early Chinese achromats were found to have spacers made of what appeared to be  a rubbery tape not unlike electrical tape. They were sticky and made the job of separating the elements quite difficult. 

 

Plastic ring spacers, if not bent, can be left in place but I still think that three well placed spacers are better. Manufacturers probably saved money using plastic or metal ring spacers. No time consuming procedure to place three small spacers in each lens.

 

Guido


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#49 Kasmos

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Posted 28 July 2020 - 11:57 AM

Nice pair of 60mm scopes! The Mayflower is my favorite of the two. The 9TE seems to be mounted in a sturdy Unitron altazimuth mount. Experimenting with spacers is interesting even if one ends up returning the original spacer to the objective lens. The ring spacer is definitely irregular so I would return to the aluminum can spacers if thinner ones don't work. Try something that's near .10mm. 

 

The early Chinese achromats were found to have spacers made of what appeared to be  a rubbery tape not unlike electrical tape. They were sticky and made the job of separating the elements quite difficult. 

 

Plastic ring spacers, if not bent, can be left in place but I still think that three well placed spacers are better. Manufacturers probably saved money using plastic or metal ring spacers. No time consuming procedure to place three small spacers in each lens.

 

Guido

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.


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#50 Kasmos

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Posted 28 July 2020 - 12:56 PM

Yesterday I also tested the Kenko again. It's lens had also disappointed me. IIRC It's spacers were slightly thicker than I'm use to and I believe were glued down unevenly. (I really need to take notes). Anyway, I repalced them awhile ago with the standard .003 material I have. First look then and yesterday was like Meh. So even thought it looked right I flipped the lens and found out very quickly that the lens had been in correct. Flipped it back and when I checked the view again it somehow seemed better. Not up to the Mayflower's standards, but better? It's CA wasn't annoying like with the 9TE, just a slight amount of purple and not quite as sharp as the Mayflower. I think I'll do a bit more experimenting on it too. The lens has too much side to side space in the cell and maybe that isn't helping any. BTW, when I did changed the spacers I couldn't get a normal ring pattern. 

 

Kenko-Test.jpg

I use the Unitron mount since it's easy to swap out OTAs, and yesterday I must have done it at least six times. 

 

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

Kenko-Palm.jpg


Edited by Kasmos, 28 July 2020 - 01:01 PM.

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