34 replies to this topic

[BillP]

I recently acquired a Meade Model 140 2x Amplifier (i.e., Barlow) on the used market.  Initial field tests were quite outstanding for it, particularly at high magnification as it showed planetary details much better being more etched and higher contrast in appearance.  It even bested my TV 2x which was a surprise as that Barlow has held its own over the years against all others but the most premium.

 

So last evening I was out having some fun with my newly acquired set of RKEs doing a variety of observing and comparing how they rendered objects next to the Tak LEs.  I observed Mars, several doubles stars including colorful ones, a variety of rich star fields, open clusters, and the Ring Nebula.  Early on in the evening the seeing was not so great, but around 11pm it settled nicely so Mars was nice and detailed.  At that point I decided to get several of my Barlows and Barlow several of the RKEs, LEs, and XWs all to an effective 6mm focal length to see how they all compare.  In the process with, now with multiple Barlows set up with their individual eyepieces in them so I could switch them in and out quickly, it became readily apparent that Mars was looking a lot smaller in the Meade 2x setup compared to the others.  I gave a quick compare of the other Barlow setups and Mars looked a consistent size in those, so what was up!?

 

So last night I did a drift test of the Meade Barlow vs. the TV Barlow, both with the same eyepiece in them.  I know from my previous bench tests that the TV operates at 2.1x with my Tak LEs.  After getting the timings and doing the calculations, to my surprise the Meade 2x was operating at...1.4x !!!!!!!!!!!!!!!  Wow that is a low magnification!!  Today I did an indoor more controlled test and sure enough, the Meade Model 140 2x Barlow I have is operating at only 1.44x!  So guess that explains why it was looking sharper, because the magnification it was yielding was less so the exit pupil larger and brighter. 

 

The bad thing is that the magnification can be so far off from stated value.  But the silver lining is that I've always wanted a 1.4x Barlow but that is a low magnification that no one makes in a conventional Barlow housing, and now I have one!!    Morale of the story is to always always test your Barlows before assuming they are the magnification stated.  This one was the only one I had not bothered to test, and as a result I got fooled!

 

Edited by BillP, 04 November 2020 - 08:40 AM.

[MartinPond]

Odd how these things vary from spec.

I have a few Meade 126s, and to get 2X I add

a 1-inch tubing extension.  Also reduces vignetting range.

 

3 elements, and 1.4x?   Sounds like a excellent

 "short barrel conditioner" for eyepieces of 4 elements or less.

[Miranda2525]

I just went through some of my of observing records from 1999. I have a page with a 9mm Nagler type 1 which normally gave me about 170x when used in a 12.5" f/4.8 reflector. The records show when this configuration was coupled with the Meade #140 barlow, the magnification was 437x. I remember drift timing the barlows I had with that same telescope back then.

 

437x would be a magnification factor of 2.57x when used with the Meade #140 barlow. I also used to unscrew the element and use it on the bottom of the eyepieces, and it was close to 1.44x IIRC.

 

Maybe you did that and forgot?  Or maybe there are different versions of the Meade #140 barlow floating around?

[Lazaroff]

So last night I did a drift test of the Meade Barlow vs. the TV Barlow, both with the same eyepiece in them.  I know from my previous bench tests that the TV operates at 2.1x with my Tak LEs.  After getting the timings and doing the calculations, to my surprise the Meade 2x was operating at...1.4x !!!!!!!!!!!!!!!  Wow that is a low magnification!!  Today I did an indoor more controlled test and sure enough, the Meade Model 140 2x Barlow I have is operating at only 1.44x!

Is the field stop of the RKE you were using set below the external shoulder of the eyepiece? That would reduce the magnification of the barlow. 

 

I notice that in your drift test comparison you said you know from "previous bench tests" that the TV operates at 2.1X. Does that mean you didn't actually do a comparison of the Meade and the TV that night, but instead relied on your previous test of the TV? You need to compare the two barlows with the same eyepiece.

Edited by Lazaroff, 04 November 2020 - 10:31 AM.

[BillP]

So my Meade 140 2x Amplifier is actually operating at 1.4x.  Let's see how it does in other configurations...

 

Using an old GSO 2x Barlow and using a shorter 1" Barrel on that with the Meade 140 cell and it produces just 1.32x.

 

Placing the Meade 140 cell directly onto an eyepiece barrel it produced only 1.2x.  Nice!  Will have to give that a test with star points to see if any significant aberrations pop up, but on the indoor test using the 10 Tak LE the entire FOV was nice and sharp.  Hmmm...this could be quite a nice find

[BillP]

Is the field stop of the RKE you were using set below the external shoulder of the eyepiece? That would reduce the magnification of the barlow. 

 

I notice that in your drift test comparison you said you know from "previous bench tests" that the TV operates at 2.1X. Does that mean you didn't actually do a comparison of the Meade and the TV that night, but instead relied on your previous test of the TV? You need to compare the two barlows with the same eyepiece.

No.  I should have clarified more.  Originally I had the 15 RKE in the 2.5x Powermate = 6mm effective -and- 12mm RKE in Meade 2x = 6mm effective.  So was planning to compare on-axis planetary performance on 2 effective 6mm setups.  It was during that compare that I noticed disk size differences when observing Mars.  So then I went in and got the TV 2x with the 12mm RKE and compared that to the view of the Meade 2x with the 12 RKE.  Since I knew from previous bench tests that the TV was close to 2x I should not be seeing a difference, but it was obviously smaller.  So then I drift times the 12 RKE with both the TV 2x and Meade 2x and got time difference to indicate that the Meade was operating around 1.42x.  Then today did indoor tests of TFOV and sure enough, then Meade is operating at 1.4x (1.44x to be exact).

 

ps - BTW, I like everyone else am prone to mistakes, but I believe I know a little about how Barlows operate relative to field stop locations, just check out the section on Barlows and Amplifiers in my book The RKE's FS is 3mm below the shoulder.  That difference in distance will make the Meade 140 2x I have operate at 1.41x instead of 1.44x (as bench tested).  So still 1.4x.

Edited by BillP, 04 November 2020 - 12:13 PM.

[Lazaroff]

Thanks for the clarification. Quite strange about that Meade barlow.

[BillP]

Indeed it is.  I was originally upset as was a pleasant surprise to find an older 2x surpass the TV 2x visually.  But then I got to thinking at just how nice this small magnification level will be to get my classic planetaries to small increment increases, so perfect for that job, which for me makes it much more than a pleasant surprise.  And given it is 3 elements (at least that what it says and not checked), then its correction should hold better for when I depart from its optimum magnification use.  We shall see.

[BillP]

Others have suggested that perhaps this Meade 140 I got used might have been tampered with - i.e., some previous owner replaced original lens cell with one from another Barlow.  I was actually thinking this could be the case.  Others have also sent me pics of their Meade 140 2x Barlow cells and theirs have the retaining ring visible on the field lens unlike mine.  So could be.

 

FWIW, I did disassemble the cell and it is indeed a triplet in a 1-2 design (doublet is the field lens).  So only 1 air gap and not a 1-1-1 fully air gap design like the Klee 2.8x.  Lens edges very nicely blackened.  All metal and glass so nothing economy about it.

 

Based on the various magnifications I am getting with the cell on different housings, I have calculated the focal length of this negative cell as a rather gentle -220mm.  Would be interesting to see how it performs as a low magnification OCA on a Binoviewer, which indeed it may have originally been?  It does not match how my WO OCA looks and magnification (1.6x) so perhaps from some other Binoviewer if not original with the Meade housing. 

Edited by BillP, 04 November 2020 - 02:58 PM.

[Starman1]

I had this Barlow back in the early '90s and didn't note that the magnification factor was that low.

Given its configuration, I don't think lenses could be installed incorrectly.

However, mine did not have filter threads on the top of the bottom section and could not thread into an eyepiece.

If it had, I'd have kept it.

So there must have been more than one generation of this one.

Is yours stamped "Japan" in the black upper section?

[BillP]

No Japan stamp on the unit, just the Meade box it came in.  Chromed barrel is rather heavy also as thicker than normal.  When you look at the threads that the cell threads into, they are standard 1.25" size but only for the depth that the cell screws in, then the threads continue but at a smaller diameter so the walls of that section of the barrel are correspondingly thicker.

Edited by BillP, 04 November 2020 - 05:52 PM.

[Thomas_M44]

Others have suggested that perhaps this Meade 140 I got used might have been tampered with - i.e., some previous owner replaced original lens cell with one from another Barlow.  I was actually thinking this could be the case.  Others have also sent me pics of their Meade 140 2x Barlow cells and theirs have the retaining ring visible on the field lens unlike mine.  So could be.

 

FWIW, I did disassemble the cell and it is indeed a triplet in a 1-2 design (doublet is the field lens).  So only 1 air gap and not a 1-1-1 fully air gap design like the Klee 2.8x.  Lens edges very nicely blackened.  All metal and glass so nothing economy about it.

 

Based on the various magnifications I am getting with the cell on different housings, I have calculated the focal length of this negative cell as a rather gentle -220mm.  Would be interesting to see how it performs as a low magnification OCA on a Binoviewer, which indeed it may have originally been?  It does not match how my WO OCA looks and magnification (1.6x) so perhaps from some other Binoviewer if not original with the Meade housing. 

This is very odd!

 

I also have the 140 Meade triplet Barlow mentioned, which I purchased new in 1993 or 1994. It's unmodified and in near mint condition.

 

I'm avoiding the Post Office as much as possible these days to mitigate Covid risk, otherwise I'd be tempted to mail it to you for your comparison and inspection.

 

If nothing else, I need to take the 140 out sometime soon, and compare directly with my own TV 2X.

 

I'll chime in once I get a chance to take a look.

 

BTW: I wish TeleVue would make a 1.25-inch Powermate with something like 1.5X

Edited by Thomas_M44, 04 November 2020 - 06:07 PM.

[duri_jk]

Hi Bill
Your measured magnifications as well as look of the barlow element reminds me my Astro Engineering AE AC555 barlow.
It is rated as 1,5x when screwed on eyepiece, but I measured 1,27x. It is very close to your. When I screw it on Baader Q-Barlow body I get 1,51x
It has weight of 28 grams, black barrel height 19,2mm, total height including top thread section 24.1 mm. You may check it your has the same dimensions.

When I change the distance between EP and barlow by 25mm, magnification changes by 0.2x.

I think it's the same barlow as "William Optics 1.25" 2x Barlow Nosepiece for Binoviewers" - item E-BINO-B2.

 

Juraj

 

[Starman1]

I hope it isn't.  The WO E-Bino-B2 added so much chromatic and spherical aberration to their binoviewers it made the binoviewers almost unusable.

Their binoviewers worked fine with other brands of OCAs.

Edited by Starman1, 25 January 2021 - 07:40 PM.

[UrbanAstroLA]

That looks very different from the Meade Model 140 I used to have.   Sharing so there's a comparison reference image in the old thread.

 

I think it's possible that the barlow element was swapped.   The Meade 140 that I've used was excellent and had unique blue-green-purple coatings, with one of the more notable aspects being how large the clear aperture was.  IIRC, it was Japan stamped.

 

[ubernator]

I just went through some of my of observing records from 1999. I have a page with a 9mm Nagler type 1 which normally gave me about 170x when used in a 12.5" f/4.8 reflector. The records show when this configuration was coupled with the Meade #140 barlow, the magnification was 437x. I remember drift timing the barlows I had with that same telescope back then.

 

437x would be a magnification factor of 2.57x when used with the Meade #140 barlow. I also used to unscrew the element and use it on the bottom of the eyepieces, and it was close to 1.44x IIRC.

 

Maybe you did that and forgot?  Or maybe there are different versions of the Meade #140 barlow floating around?

I know of at least 3. I had a Chinese one That was significantly larger than any others I have seen.  Recently got a Chinese or other wise not origin stamped one with a scope that was the "normal" size because I bought a Japan chrome stamped one here shortly after and they were identical in proportions (but not optics or coatings) . I also had acquired a normal sides chrome stamp japan in the past. So at least 4 of them have gone through my hands, and none stood out as being so low of a power. And ALL of them had lenses that went to the edge unlike what BillP has pictired, though it is possible that that funky oversized one had the smaller lenses, it was a long time ago.

 

and I have not seen the earlier Japan ones with the Japan stamp in the black body. So there are several versions of this Barlow, and probably more than one version of the chrome Japan stamped one, as mine has yellow-orange lettering, not as orange as some Taiwan series 4000 plossls, but definitely more orange'y than my other series 4000 Japan stuff, or the Chinese 140 that came with my scope package, that I sold to a friend after getting the Japan one.

 

I recently acquired a Meade Model 140 2x Amplifier (i.e., Barlow) on the used market.  Initial field tests were quite outstanding for it, particularly at high magnification as it showed planetary details much better being more etched and higher contrast in appearance.  It even bested my TV 2x which was a surprise as that Barlow has held its own over the years against all others but the most premium.

 

So last evening I was out having some fun with my newly acquired set of RKEs doing a variety of observing and comparing how they rendered objects next to the Tak LEs.  I observed Mars, several doubles stars including colorful ones, a variety of rich star fields, open clusters, and the Ring Nebula.  Early on in the evening the seeing was not so great, but around 11pm it settled nicely so Mars was nice and detailed.  At that point I decided to get several of my Barlows and Barlow several of the RKEs, LEs, and XWs all to an effective 6mm focal length to see how they all compare.  In the process with, now with multiple Barlows set up with their individual eyepieces in them so I could switch them in and out quickly, it became readily apparent that Mars was looking a lot smaller in the Meade 2x setup compared to the others.  I gave a quick compare of the other Barlow setups and Mars looked a consistent size in those, so what was up!?

 

So last night I did a drift test of the Meade Barlow vs. the TV Barlow, both with the same eyepiece in them.  I know from my previous bench tests that the TV operates at 2.1x with my Tak LEs.  After getting the timings and doing the calculations, to my surprise the Meade 2x was operating at...1.4x !!!!!!!!!!!!!!!  Wow that is a low magnification!!  Today I did an indoor more controlled test and sure enough, the Meade Model 140 2x Barlow I have is operating at only 1.44x!  So guess that explains why it was looking sharper, because the magnification it was yielding was less so the exit pupil larger and brighter. 

 

The bad thing is that the magnification can be so far off from stated value.  But the silver lining is that I've always wanted a 1.4x Barlow but that is a low magnification that no one makes in a conventional Barlow housing, and now I have one!!    Morale of the story is to always always test your Barlows before assuming they are the magnification stated.  This one was the only one I had not bothered to test, and as a result I got fooled!

 

Meade 140 2x Barlow (web).jpg

That front lens does not look like a normal 140 as volvonium just pictured. 

 

And my previous chrome stamp Japan 140 did not best my TV 2x when I had both (sold the 140 with my smoothie set long ago and the TV barlows were stolen out of my car June 2018 along with most of my premium 1.25 stuff that was in a doskocil XL case with my pronto). So I can't compare now.  

 

But I did compare my current one to a 2x parks Japan (pre GS3) and did not see any drastic power difference for sure.

 

I also remember my 140 threads not being compatible with eyepiece threads hence no 1.5x trick, but that could be mixed with my televue memories as they were definitely not compatible with filter threads. It was a long time ago.

 

But I just tested My current one and it is compatible for the 1.5 trick....

 

Meade 140 has too many iterations to keep track of lol

 

That looks very different from the Meade Model 140 I used to have.   Sharing so there's a comparison reference image in the old thread.

 

I think it's possible that the barlow element was swapped.   The Meade 140 that I've used was excellent and had unique blue-green-purple coatings, with one of the more notable aspects being how large the clear aperture was.  IIRC, it was Japan stamped.

 

Is yours stamped in the chrome or the black?

 

We should compare ours sometime

[duri_jk]

I hope it isn't.  The WO E-Bino-B2 added so much chromatic and spherical aberration to their binoviewers it made the binoviewers almost unusable.

Their binoviewers worked fine with other brands of OCAs.

My fault, I meant 1.6x version, housing looks the same, magnification matches, but it's just my assumption (and I know what ****-u-me might lead to)

I tested AE AC555 yesterday and it performed good enough for me to keep as fine tuning barlow for special occasions. No chromatic aberation, slight spherical when used directly on EP. Test EP was APM UFF 18mm.

AC555 + EP ~ 1.26x

AC555+Q-barlow body + EP ~ 1.49

AC555+Q-barlow body + 25mm extension tube + EP ~ 1.7x

I also did a combination of:

Q-barlow body + AC555 + 25mm extension tube + Q-barlow optical element. Final magnification was 4.34x and image was surprisingly usable. I expected foggy, mushy, distorted something, but it was good (not excellent nor bad).

Edited by duri_jk, 28 January 2021 - 04:23 AM.

[CrazyPanda]

That looks very different from the Meade Model 140 I used to have.   Sharing so there's a comparison reference image in the old thread.

 

I think it's possible that the barlow element was swapped.   The Meade 140 that I've used was excellent and had unique blue-green-purple coatings, with one of the more notable aspects being how large the clear aperture was.  IIRC, it was Japan stamped.

 

This is what my 140 looks like as well. Got in the mid 90s. "Japan" is stamped on the chrome barrel.

 

One thing that stands out is how good the blackening/baffling is in the Meade #140.

I recently got an APM 2.7x Coma Correcting barlow to replace my Meade #140 binoviewer setup. I was just going to use the T-2 threaded portion of the APM barlow when I noticed how much better the Meade was. Here's a comparison:

 

APM barrel - poor stray light control:

 

 

Meade #140 barrel - outstanding stray light control:

 

 

As such, my APM lens cell is living in the Meade #140 barrel.

I wonder if a similar situation happened with Bill's #140, where someone used the #140 just for its excellent blackening/baffling, but wanted a different cell in it for whatever reason.

 

Also, I know for a fact that the Meade 2x barlow is definitely at least 2x.

 

I've done planetary imaging with both a 2x PowerMate, and the #140. When I use the #140 like a normal barlow and my planetary camera (whose sensor is 12mm back from the shoulder), the multiplication factor is much higher than my 2x PowerMate. I would estimate that for a standard eyepiece inserted into the barlow, the multiplication factor would be very close to 2x.

Edited by CrazyPanda, 27 January 2021 - 11:52 PM.

[thecelloronin]

Sorry to resurrect an old thread, but does anyone have an educated guess as to which Barlow cell BillP actually has attached to his 140? 

[CeleNoptic]

Bumping this older thread because I'm wondering too if Bill was able to figure out which cell was used with the body of his Meade #140   Any updates?

[Mike B]

The #140 Barlow I posted in my “CNC gleanings” thread is as others (above) have described:

* “JAPAN” stamp at the upper edge on the chrome barrel;

* no stamps or origin markings seen on the upper black portion, nor on the black lens housing;

* the field end of the optic is NOT as BillP’s pics show, but rather exactly as Volvonium’s pics show (post #15)

 

So at this point I’d guess that mine is a factory-original model 140. As soon as our current atmo river runs dry, I’ll try to get some EP trials in this Barlow & will post results…. If it hasn’t floated off! 

[Mike B]

Looking at the pics BillP posted, now I’m wondering if the lens cell he has on his might be this?:

1.6x Glass Path Corrector for Binoviewers 1.25"
TS Glass Path Corrector for Binoviewers 1 1/4".
Manufacturer : TS Optics
SKU : TSO-TSGWK16

 

Anyone recognize his lens cell?

Edited by Mike B, 14 March 2023 - 06:27 PM.

[gnowellsct]

Looking at the pics BillP posted, now I’m wondering if the lens cell he has on his might be this?:

https://www.apm-tele...inoviewers-125 

Anyone recognize his lens cell?

Says "404 not found"

 

I'm also wondering how we're defining "lens cell" for the purposes of this discussion... 

 

Greg N

[Mike B]

Post modified to remove link… Photo & text supplied in lieu of.

 

im referring to “cell” as the threaded-on metal section of blackened finish, which contains the optics. I don’t believe there are any other optical components elsewhere within the Barlow’s tube.

[CeleNoptic]

Looking at the pics BillP posted, now I’m wondering if the lens cell he has on his might be this?:

DA224218-AFF9-4D0C-9086-C9F9816D9865.jpeg

1.6x Glass Path Corrector for Binoviewers 1.25"
TS Glass Path Corrector for Binoviewers 1 1/4".
Manufacturer : TS Optics
SKU : TSO-TSGWK16

 

Anyone recognize his lens cell?

 

As Bill mentioned above (post #8) the original Meade #140 Barlow must be a 3-element ones. Are the three located in the single nosepiece which is removable?  I doubt that the 1.6x TS GPC has more than 2 elements, but I may be wrong. The number of elements isn't that hard to check by reflections under a bright light source (e.g. led light).