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Dynamax 8 image compared .

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#26 starman876

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Posted 14 February 2020 - 08:37 AM

I wish really good scopes would get this much attention cool.gif


 

#27 G-Tower

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Posted 14 February 2020 - 09:09 AM

Here, really good scopes get criticized and old 60mm achromats get praised...Questars, AP, Taks and others get ripped while a 60mm Tasco is the holly grail.lol.gif 


 

#28 highfnum

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Posted 14 February 2020 - 09:34 AM

nope the bad boys get

the attention !


 

#29 highfnum

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Posted 14 February 2020 - 10:01 AM

my dx8 with tweety bird

dx8tweety.jpg

 


 

#30 Chuck Hards

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Posted 14 February 2020 - 10:22 AM

I wish really good scopes would get this much attention cool.gif

 

 

Here, really good scopes get criticized and old 60mm achromats get praised...Questars, AP, Taks and others get ripped while a 60mm Tasco is the holly grail.lol.gif

 

I'm not aware of any "good" scopes getting ripped habitually here.  Brand name alone is not a guarantee of high quality.  It can improve your odds, but it's not a guarantee.   

 

 

Ecconomics:  Lots more folks who can afford a 60mm Tasco than a Questar, AP, or Tak.  Myself included.

 

Availability:  Lots more old Tascos on the market than Questar, AP, or Tak.

 

 

So please don't be angry with Cloudy Nights members.  They discuss the scopes that they want to discuss.  Start a thread on something if you don't see one already.  Not hard to do.

 

And actually we discuss AP, Tak, and Questar quite a bit!  Cloudy Nights has a dedicated Questar forum if you want more of that discussion.  And AP and Tak can be found in the Refractors forum.  

 

Plenty of discussion on those brands here on CN.


 

#31 davidc135

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Posted 14 February 2020 - 10:47 AM

Weren't the comments tongue in cheek? I think on CN scopes get the reputations they deserve. As for the Dynamaxes, when I bought my set I was looking for a challenge, and I certainly found one!  David


 

#32 tim53

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Posted 14 February 2020 - 11:00 AM

Weren't the comments tongue in cheek? I think on CN scopes get the reputations they deserve. As for the Dynamaxes, when I bought my set I was looking for a challenge, and I certainly found one!  David

Me too.  At least the one complete one I got from Chuck is reasonably fun to use, particularly for DSOs in a dark sky.  

 

My Tak FC76 would easily blow its doors off, if it had doors.


 

#33 starman876

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Posted 14 February 2020 - 11:03 AM

I'm not aware of any "good" scopes getting ripped habitually here.  Brand name alone is not a guarantee of high quality.  It can improve your odds, but it's not a guarantee.   

 

 

Ecconomics:  Lots more folks who can afford a 60mm Tasco than a Questar, AP, or Tak.  Myself included.

 

Availability:  Lots more old Tascos on the market than Questar, AP, or Tak.

 

 

So please don't be angry with Cloudy Nights members.  They discuss the scopes that they want to discuss.  Start a thread on something if you don't see one already.  Not hard to do.grin.gif

 

And actually we discuss AP, Tak, and Questar quite a bit!  Cloudy Nights has a dedicated Questar forum if you want more of that discussion.  And AP and Tak can be found in the Refractors forum.  

 

Plenty of discussion on those brands here on CN.

Chuck. We were teasing.  Sounds like you need a drink


 

#34 Terra Nova

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Posted 14 February 2020 - 11:07 AM

Looks like the venerable old (or not so venerable, old) DXs have again become the favorite punching bag of the Classics forum; in two concurrent threads no less!

 

https://youtu.be/Rsz1Aa890xc


Edited by Terra Nova, 14 February 2020 - 11:11 AM.

 

#35 Chuck Hards

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Posted 14 February 2020 - 11:11 AM

Chuck. We were teasing.  Sounds like you need a drink

I need the weekend to start!  ;)


 

#36 Chuck Hards

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Posted 14 February 2020 - 11:14 AM

Well I have a set of Celestron 8" SCT optics on the way.   This could be the year I attempt to transplant them into a DX8 tube.   There's more than one way to skin a CAT.  ;)


 

#37 clamchip

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Posted 14 February 2020 - 11:23 AM

Back when I flew antique freeflight model airplanes it was popular to take a 'not so hot' engine

from the era and rework the innards so it would burn up the sky.

It seems I think we all love the bad puddy tat's.

 

Robert


Edited by clamchip, 14 February 2020 - 11:26 AM.

 

#38 tim53

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Posted 14 February 2020 - 11:26 AM

Back when I flew antique freeflight model airplanes it was popular to take a 'not so hot' engine

from the era and rework the inards so it would burn up the sky.

It seems I think we all love the bad puddy tat's.

 

Robert

[Threadjack] I had friends who like to soak an old U-control plane in fuel, light it on fire, then fly it until it fell apart.  Good times. [/Threadjack]


 

#39 Terra Nova

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Posted 14 February 2020 - 04:23 PM

Well I have a set of Celestron 8" SCT optics on the way.   This could be the year I attempt to transplant them into a DX8 tube.   There's more than one way to skin a CAT.  wink.gif

https://youtu.be/QuoKNZjr8_U


 

#40 Terra Nova

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Posted 14 February 2020 - 04:24 PM

Back when I flew antique freeflight model airplanes it was popular to take a 'not so hot' engine

from the era and rework the innards so it would burn up the sky.

It seems I think we all love the bad puddy tat's.

 

Robert

I can still see the rising black smoke and smell the stink of burning plastic from when my brother used to burn his model airplanes in the backyard!


 

#41 oldmanastro

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Posted 14 February 2020 - 07:20 PM

Looks like the venerable old (or not so venerable, old) DXs have again become the favorite punching bag of the Classics forum; in two concurrent threads no less!

 

https://youtu.be/Rsz1Aa890xc

Poor old Dynamaxes and B & L 8000s and their smaller brothers. They have been beaten up quite often in so many reviews. My first SCT was a B & L 8000. It was useless at high powers but good enough for DSOs. I got in in 93-94 from Fred Pauli without a tripod and then mounted it in a Tuthill Isostatic mount (I think that was the name). Tuthill even called me to make sure that the mount was usable at my latitude. He was very happy to know that it worked down here. Later on I bought a used B & L 4000. It was not as bad as the 8000. In fact it gave pretty good images even at high powers. At that time I had a Coulter 8" f/7 Dobsonian and that one ran circles around the 8000 in terms of optical performance. I sold all three telescopes in 96 and got a used Celestron 8 GP. I hate myself for getting rid of the Coulter. It was an excellent telescope.

 

Psyquiatrists have a saying " past behavior predicts future behavior" and so I recently became the proud owner of another B & L 4000. Sometimes nostalgia is more powerful than reason.

 

Clear Skies!

 

Guido

Attached Thumbnails

  • BL40001.JPG

 

#42 Terra Nova

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Posted 14 February 2020 - 07:39 PM

Psyquiatrists have a saying " past behavior predicts future behavior" and so I recently became the proud owner of another B & L 4000. Sometimes nostalgia is more powerful than reason.

 

Clear Skies!

 

Guido

Boy that for sure Guido! As I always say, “Been there, done that, and I was dumb enough to do it again!”


 

#43 clamchip

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Posted 14 February 2020 - 07:53 PM

I really like my 4000 and I have a feeling I'd really like the 8000 too because they have

excellent mechanical construction, sweet focusers, and excellent drives.

I'm not sure how I'd feel about the 8's optical problem, I think I'd overlook it because it's

such a cool scope.

My 4 has the same problem, but you really don't notice it being half the aperture.

 

Robert 


Edited by clamchip, 14 February 2020 - 08:00 PM.

 

#44 starman876

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Posted 14 February 2020 - 07:59 PM

I really liked the way the one I had looked.   Good scope to look at not so good to look through.


 

#45 oldmanastro

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Posted 14 February 2020 - 11:02 PM

I really like my 4000 and I have a feeling I'd really like the 8000 too because they have

excellent mechanical construction, sweet focusers, and excellent drives.

I'm not sure how I'd feel about the 8's optical problem, I think I'd overlook it because it's

such a cool scope.

My 4 has the same problem, but you really don't notice it being half the aperture.

 

Robert 

I think you hit the right note Robert. They are cool scopes. I like the 4000 a lot and this one has good optics, not excellent but good. I can pump power above 150x and can see an Airy disc and a good diffraction ring around it when focusing a star. One thing that has to be right is the collimation and I mean critically right. I never had the 6000. In a recent interview from another thread Fred Pauli mentioned that they were made with better quality control. I never knew what became of my 8000 in the Isostatic mount.

 

Guido


 

#46 markb

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Posted 15 February 2020 - 01:00 AM

B&L fixed, apparently, the corrector issues when they brought out the 8001.

 

I vaguely recall a 6000 fix at that time, but 1) am not sure and 2) if they did, I don't recall if they bothered to rename it, as they did with the 8001. The 8001 was, I believe, out when I bought my 6000, but they did not yet have the upgraded replacement yet.

 

An older astromart ad with otherwise accurate information stated that they brought out a 6000 Pro. These may have in the source of the reports of decent 6000 s, but, again, it could be wishful viewing. My 6000 is consistent with the reports of Dynamax 8 problems, and I have no doubt those issues are shared by the 6in Dynamax as well, at least until Bausch & Lomb finally attempted to correct the manufacturing issues, first on the 8, and, possibly, later on the 6. The 4 was also improved at some point, but never seems to have achieved a consistent reputation, the reports at that the time, that I remember, varied widely. I saw a frightening bad dpac image while poking around.

 

I am not going to spend the time researching old ads, perhaps someone accurately recalls what they did with the 6-inch scopes at that time. I suspect the astromart advertiser was correct.

 

I do have to say, though, the blue and white Dynamax was a good-looking scope, and the color scheme used on the B&Ls was attractive as well. Pretty but not useable.


Edited by markb, 15 February 2020 - 11:24 AM.

 

#47 G-Tower

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Posted 15 February 2020 - 01:22 AM

Looked through an 8001 many years ago and no B&L did not fix the issue. They would have been better off subcontracting Celestron to make them. All they did was add the word pro and change a 0 to a 1. So the myth continues...


 

#48 DAVIDG

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Posted 15 February 2020 - 11:00 AM

"B&L fixed, apparently, the corrector issues when they brought out the 8001"

. Over the years there is person that worked at Criterion and B&L that comes to Stellafane and sells parts at the swap tables. He bought out much of the remaining parts when they went under. I have purchased many Criterion parts from him over the years. This included a handful of  8" and 4" correctors. Each was still in the  factory wrapping and also some were AR coated. That indicated to me that they were typical of production quality.  You don't spend the money AR coating reject parts.  Every single one when tested was a lumpy mess. He told me that the they never changed the production method used when B&L took over. So I doubt that Criterion/B&L fixed the problem with the both the method they used to fabricate the correctors and the quality of the glass they used.

   Here is  a typical 4" corrector that I'm testing in front of spherical mirror. You can see how badly figured it is. Every DX-8 and Criterion/B&L 4 that I tested has had major optical errors of similar magnitude.  

   As I said before photographs at the improper magnification will not show optical errors, this includes low power images of the Moon. So people get a false impression that they a have a "good" one. Any one of these that is stated to be "good" needs to be bench tested and the results of the test shown before I will believe that they actually have one that is truly diffraction limited or better. 

So far all the actually test data shows the opposite. 

            - Dave 

 

 

4corrector.jpg


 

#49 clamchip

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Posted 15 February 2020 - 11:10 AM

When I bought my 4000 it was unusable.

Most of that was due to the secondary being off the optical axis.

The 4000 corrector has a lot of room to move around and is held down by a rubber O ring.

Rough handling can easily knock the corrector out of alignment.

I'm not sure how the 8's are built, just something to be aware of when buying or using a

Criterion/B&L SCT.

Robert 

 

post-50896-0-15440000-1494094222_thumb.jpg


 

#50 CHASLX200

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Posted 15 February 2020 - 11:48 AM

Never saw a 5".


 


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