17 replies to this topic

[badback]

  Bet yer' wondering what's inside this crusty old box?  The lemons are a clue. Hmmm... ...

 

 

Did you guess it?

 

]

 

Here she is

 

 

At last, the super-freaky one.  So pretty, pretty.  

 

 

All the glass looked very good so... I took her for an optical joyride, and super-freaky she most definitely is.

Super-freaky MUSHBOMB that is! The worst optical joyride ever but, take a close look. Somethings missing.

 

 

Can you see the prob?

 

 

 

 

[badback]

Just Like a few Cray-Cray humanoids I know, this is obviously missing a few screws

Hmmm, very curious. Someone was uh... apparently taking it apart. We all know

why now don't we! The collimation must have been , and is still,  waaaaay off.

 

 

Regardless, here's her one undeniable attraction and the reason I was first drawn to her:

 

 

Still, she is a newish, shiny looking pile in desperate need of an alignment.

So...I will adjust her, take her on another optical joyride and see what she's got.

 

                     This will be my first step:

 

[

 

 

[markb]

Usually very rough correctors are the problem, Criterion used awful quality plate glass stock and a less than ideal grinding method on only one side to evade the patents. Primaries can, sadly, be quite good.Collimation only makes the best of an inherently bad image. But you could get lucky.

 

A Ronchi grating will quickly confirm if this is the issue.

 

No screws are missing, it looks like a pin spanner is used for retainer removal.

 

Good luck.

 

It is pretty, though. It must have been one of the earliest B&Ls..

[Riaandw]

Lemon tech the blue meanies.

[matt_astro_tx]

Beautiful looking scope. Any idea what year it is?

 

Hope you can get the optics dialed in. 

[deSitter]

Beautiful looking scope. Any idea what year it is?

 

Hope you can get the optics dialed in. 

 

It's a rebranded Criterion Dynamax, one of the saddest chapters in scope history. B&L bought out Criterion as the latter was about to expire in the mid-late 70s. The scope here with the blue and pebble grey finish is the same as the Dynamax 8. 

 

What David said about the primaries, imply that one of these scopes could be perfected by reworking the corrector and/or secondary. It would be wonderful to see one of these scopes perform as well as its good looks. And the bakelite tube would constitute a real advantage!

 

-drl

[matt_astro_tx]

Looks good for a 70’s model. 

[apfever]

I recognized the box right off the bat. I had a couple of them, both long gone. That retainer for the corrector does indeed screw off. The divots are for a spanner wrench set up. Earlier versions had the corrector held on with allen bolts. B&L slowly converted over the name especially on the eyepieces. The e.p.'s go from "Criterion" to " B&L Criterion" to just "B&L".   Bausch and Lomb was eventually bought out by Bushnell. I don't know when the ol' Dynamax finally faded from production. 

 

Did you get any eyepieces or accessories?

 

Here's a LINK.

There are several works in that string. My resto starts at about entry #185. I did complete the restoration and then some, and sold both scopes several years ago. I still have the documentation file with tons of pictures.

Edited by apfever, 13 May 2025 - 09:03 AM.

[Terra Nova]

It looks practically brand new!

[Kefka1138]

What a beast! Bummer the design/implementation is so troubled with these instruments because they look amazing. 

[clamchip]

One of these days someone will make a "Corrector replacement kit" or how about a "Corrector Exchange" where

we send it in, it gets doctored and sent back or used as a core like when you buy a replacement alternator for your car.

I hope it happens someday because there is so much good built into the Dynamax.

But really they aren't that bad. Half the time I'm limited by seeing when I have mine out. That's why they were made

as long as they were. About 200 power things start getting a little fuzzy. At 100X it's dreamy.

 

Robert

Edited by clamchip, 13 May 2025 - 12:32 PM.

[markb]

DavidG was refiguring one

https://www.cloudyni...g#entry13932799

 

If someone did do a corrector exchange. they certainly wouldn't need your old core! Rough, poorly chosen plate stock for blanks were most of the problem.

 

But I second the idea, it would be wonderful if someone could remake cures for these poor dynamax/B&L horror shows. Mine was my first new telescope purchase and it was money down the toilet.

 

It would be interesting to hear if anyone ever swapped in a Celestron or Meade corrector, etc.

 

Oddly enough, there are a handful of decent ones that escaped the factory, but very few indeed. Hand figured? Sales demonstrator? Luck of the draw getting one good piece of glass out of that plate stock? Magical luck potion? Who knows.

 

I never had a clue what was wrong with mine, thinking it was my setup, until I started to learn how to use and read Ronchigrams- so that's why this telescope is so bad...

Edited by markb, 13 May 2025 - 03:29 PM.

[clamchip]

Interesting B&L changed Criterion's method of holding the corrector retaining ring on.

Also note the secondary holder assembly is different too, maybe just the cover.

Compare my photo to the previous:

Edited by clamchip, 13 May 2025 - 03:30 PM.

[Tenacious]

It's easy for me to feel the loss of others when their optical expectation falls short due to an apparent systemic quality control issue. 

 

There are a number of threads about these scopes - it seems that there are always some folks who praise their physical aesthetic, perhaps more than the C8 variants or Meade's 8" SCTs?  I don't necessarily disagree,     So, if you're one of the admirers, what captures your imagination?  Color scheme, fork/base design, better hardware, ergonomics, observatory in a trunk, etc................? 

 

Just curious..

[badback]

Usually very rough correctors are the problem, Criterion used awful quality plate glass stock and a less than ideal grinding method on only one side to evade the patents. Primaries can, sadly, be quite good.Collimation only makes the best of an inherently bad image. But you could get lucky.

 

A Ronchi grating will quickly confirm if this is the issue.

 

No screws are missing, it looks like a pin spanner is used for retainer removal.

 

Good luck.

 

It is pretty, though. It must have been one of the earliest B&Ls..

I have another BLUE MEANIE that I last looked through, for a few hours, maybe

10 years ago. I' was aware of their probs even then. but surprisingly found the

views to be ok.  ​ OK, OK.  I'll go and look again.

 

"No screws are missing; it looks like a pin spanner is used for retainer removal."

 

Oopsie! Sorry. No thinking here , just taking pics. I did find it strange for that ring

to be attached by only two screws. Thanks for the heads up. .

 

I suspect the ring was probably never removed, but based on some minor ring

scratches on it (see photo) it appears there was an attempt made. The wretched

views from this scope probably prompted that attempt. I'm thinking the factory

views really sucked so the owner attempted to adjust the secondary, which made

matters even worse. What a frustrating, miserable waste of...(fill in blank)

After all that it was......TIME TO PARK IT

 

I will collimate it soon and get back with you all.

[badback]

Beautiful looking scope. Any idea what year it is?

 

Hope you can get the optics dialed in. 

Beautiful looking scope. Any idea what year it is?

Nope.

Hope you can get the optics dialed in.
Dialed in for these particular scopes equals mediocre. 

Thanks for your interest and comments.

[badback]

I recognized the box right off the bat. I had a couple of them, both long gone. That retainer for the corrector does indeed screw off. The divots are for a spanner wrench set up. Earlier versions had the corrector held on with allen bolts. B&L slowly converted over the name especially on the eyepieces. The e.p.'s go from "Criterion" to " B&L Criterion" to just "B&L".   Bausch and Lomb was eventually bought out by Bushnell. I don't know when the ol' Dynamax finally faded from production. 

 

Did you get any eyepieces or accessories?

 

Here's a LINK.

There are several works in that string. My resto starts at about entry #185. I did complete the restoration and then some, and sold both scopes several years ago. I still have the documentation file with tons of pictures.

Did you get any eyepieces or accessories?

 

Here's what she came with:

 

Great link. Thanks

[DAVIDG]

  This has been beat to death but for anyone new to the party here is why no matter how well you collimate  a DX8 that you will never get a good image. The facts are that the method and the glass Criterion used could never  make a good corrector plate.

   I have around 8 of these correctors that I purchased over the years from a person that worked for Criterion and bought out what was left of Criterion when they went out of business. These are not rejects but production "quality" correctors. A couple are AR coated..

  The Schmidt curve is not symmetrical. Here is a picture showing it. It should looked like the upper left all the way around the corrector. 

 

  Here is how these telescope test in Double Pass Autocollimation. The wave front shows a large amount of spherical aberration, roughness and astigmatism.

 

                   - Dave