Criterion Dynamax 8

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Criterion Dynamax 8
Mine was terrible. (From '70s) Star images 10 arseconds in diameter.
There was a large strain in the corrector plate. It was totally outperformed
by an 80mm Unitron finder. Sigh

Overall Rating: 1
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Criterion Dynamax 8
Very poor optics. Cardboard/fiber tube. Poor mount. Looked pretty!

Overall Rating: 1
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Criterion Dynamax 8
I bought a Dynamax 8, used, in 1981, and it has been a tolerably good
all-around telescope. I've gone through about a dozen scopes in that
time and it's the only one I've kept all along. The main reason is
that it is very robust in the sense that it's easy to take apart, tune
up, and put back together (which I do about once a year). It's not what
is called "portable" these days, but in the last 18+ years it's been to
mountains in Alaska and Hawaii, beaches in the West Indies and Panama,
and deserts from the Mojave to the Sahara. IMO, a tough little telescope!
It's not ideal for extended astrophotography due to it's periodic error.
Many folks run down the fiberboard tube, but it seems to be durable and
much more thermally friendly than metal ones. The optics in mine were OK
though I did refigure the mirror a bit when I realuminized the primary ca.
10 years ago. Just had about 75 people look through it at a Venus-Jupiter
conjunction party last week ... never have to worry about damage from
unskilled hands, there's even a big "FOCUS" label ... 18+ years old and
still going strong, what's to complain about?

Overall Rating: 7
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Criterion Dynamax 8
pretty poor overall

Overall Rating: 1
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Criterion Dynamax 8
I just bought a Dynamax 8" SCT. It seems to perform fine. In a comparison to my friend's 8" Meade Dobsonian, there was little difference in optics. What I wouldn't mind though is a manual Can anyone help? TmcPherson @sd68.bc.ca

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Criterion Dynamax 8
The Dynamax SCT we used was first used during our public skyshows at Behlen Observatory (University of Nebr., Lincoln). It never gave outstanding images, and showed some noticable astigmatism. One night, we brought the RV-6 with us to help with the crowds, and the RV-6 totally blew the Dynamax away (Criterion should have given up on the Dynamax and stayed with Newtonians). Needless to say, the RV-6 got a lot of workout at public nights, while the Dynamax sat in the equipment room at the University collecting dust.

David Knisely

Overall Rating: 3
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Criterion Dynamax 8
Worst optics and images I've ever seen. Junk. I heard later ones (post 1975 or so) got somewhat better.

Overall Rating: 1
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Criterion Dynamax 8
Run - don't walk away from this one!

Overall Rating: 3
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Criterion Dynamax 8
I'd say that an 8 rating is a little bias but I have had real good luck with mine. Purchased in 1980, the only real problems I ever had was the drive corrector went bad on me very early in the game. The periodic error is noticable but on short wide field exp. piggy back things work out fine. I have seemed to master its short comings. It is very durable and mine has taken some pretty hard knocks and came through o.k. I have never done any rework to the main optical assy and have always enjoyed the great views of Jup. and deep sky objects in-general.
The only work I have done is to add a self-designed fine adjustment to the eq. wedge assy for easy polar alignment. The mount could have been some what more robust. The manual had some great advice on maintaining the scope-still got mine. All in all, the scope is probably in better shape then i am after 20 yrs.

Overall Rating: 8
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Criterion Dynamax 8
I have used a dynamax 8 since 1980 with good images until recently. Now I get bad ghost images during eyepiece projection photography.

Overall Rating: 7
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Criterion Dynamax 8
I had two of these in the early 70s. The first one was so bad (pits were not ven ground out of the corrector plate) they took it back and gave me a different one. It was only terrible. I should have returned it too. Bought a C8 a year later. Everything about this scope was poor: optics, mechanics, finish, fit, clock drive, wobbly forks, you name it. My paint even peeled off all the aluminum parts. From a distance it looked good tho!

Overall Rating: 1
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Criterion Dynamax 8
As with other SC's from Bausch & Lomb, the later ones were a little bit better than their earlier ones, culminating with their aluminum-tube 8001 model, which apparently was quite good (see reviews elsewere on this site). I bought mine in 1988, and star images are quite good. Star tests show a turned edge along with some roughness. Nevertheless, platetary images show a lot of detail, with crisp images. It does not perform quite as well as my Vista V812GP (Skywatcher 120),but it's close. I've taken it up to 700x on M13 on some very good nights with excellent seeing - it was like being in a spaceship! Negatives - the fork mount is wobbly and the motors have a large periodic error. It uses it's own type ot thread for the star-diagonal.

A good purchase if you can star-test it first.

Overall Rating: 7
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Criterion Dynamax 8
hi , i just bought a dynamax criterion 8,
and i dont have the manual .
i saw your comments on the net,
for this telescope .
is it posible to get a copy ,
any help welcome .

hydroplus@videotron.ca

Overall Rating: No Vote
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Criterion Dynamax 8
I have the later B&L 8000 model built in the mid 1980s. I bought mine in 1990 off of Pauli's Optical. They had purchased the unsold inventory of B&L when they went out of business. I like this scope. It does not have as good of optics as the newer Meade and Celestron models but I only payed $550 for it. It came with a plastic carrying case and I built a wood tripod for it. With my heavy tripod there is no wobble at all and I find the fork mount sturdy. I have photoed the moon and have had no trouble picking up all 4 stars in the trapezium using the ASP 30 mm eyepiece that came with the scope. The scopes best performs using the 18mm eyepiece producing 117x. As the power increases the performance of the scope degrades. At 300x the images of Jupiter are not crystal clear even on the best days. However, at the lower powers I have had very satisfying veiws of deep sky objects. M-13 is fantastic showing hundreds of individual stars. I am thinking of purchasing a drive corrector for it to photograph deep sky objects. This scope was still in the box when I bought it and included all of the manuals.

Overall Rating: 7
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Criterion Dynamax 8
I bought my Dynamax 8 about 1981. I injoyed it for many years. I later wanted
a larger scope about 1989 I bought a Meade 2120 It is ok but I get more detail
from my old D8 than the 10 inch Meade.
J Smith
Fort Worth,Texas

Overall Rating: 7
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Criterion Dynamax 8
I had one in the late 1970's and after using for several years gave it away to an amateur who could not afford a telescope. I probably didn't do her a favor because it was a poorly made telescope and performed poorly. Giving it away was too good for it. I did have very good luck with an RV-6 though.

Jeff

Overall Rating: 3
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Criterion Dynamax 8
I have bought my dynamax about 15 years ago from a collegue. I had to adjust the secondary mirror (which is a tedious) task. Nevertheless up till now I was reasonable content with it. The motor comes loose from time to time, but that's a matter of fixing the screws tight. The fork is OK. I have made my own equatorial mount on a sturdy demountable wooden structure. Nowadays it seems as if I can't focus the stars for 100% any more. The just out of focus images have dotted stars on several rings which are not perfect cicular. So the diffraction rings are visible only not circular. It wonder whether it is the mirror, the correction plate or the secondary mirror. I hope to find out soon. I am working on a Foucault test, to measure the mirror more detailed. When the tube is exposed to sunlight for longer times (weeks) than some deposit might show-up on the inside of the correction plate. Just cleaning with a little soap and water does the job. There might be some deposit on the two mirrors as well. My former collegue has made beautiful pictures with it. So I think the two mirrors have to be recoated again. The locks on the declination and hour axes have to be readjusted. To much weight on the tube is a slight problem. Then the whole scope becomes a little wobbly. I have a manual, which I intend to put through the scanner, so anyone interested could get a digital copy.
A major draw back is the relative long cooling time of the scope. The longer it stays in the open air the better the images. I do mainly visual observations. and on very cold and clear skies in the Netherlands (which has heavenly light pollution!) I can reach sometimes magnitude 12 - 13. M13 is still a problem I can't resolve the stars, maybe it is also my eyes.

Overall Rating: 5
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>I've had mine for about 3 years and have never had a manual.  I would appreciate it if you could send me a copy of the electronic version to uffda@ns.sympatico.ca

Thanks
Criterion Dynamax 8
I've had my Dynamax 8 since '85 with mount. I paid $400 at the time.

When I first got the scope I took it apart cleaned it then re-aligned the mirrors. I also placed black flock paper on the inside wall. I added an inside
sleeve of black flock paper that goes up halfway in the baffle tube. This seem
to cut down on scattered light. Later on I added an adapter available from pauli's optical that changes thread size to Meade/Celestron specs. This allowed
me to add a zero_shift focuser. All and all I've been pleased with the images.

I must admit sometimes I feel that I'm lucky because so many people have
complained about this scope. I believe the later models were better than
the eary models.

As for observations -- Great red spot on jupiter -- no problem
Resolving M13 -- no problem
split Saturns ring no problem
Owl nebula, M73, M57 ditto

Its true images are not as crisp as in a refractor but what SCT with 33% obstruction is? The motor track is fine for visual I have not tried to take
long exposures so I dont know if it's good for that. Mount is very stable.

My biggest complaint is the declination knob and friction lock. It goes soft
real easy. I replaced declination screw with a thumb screw to keep pressure up.
Also telescope does need some time to cool down. Focuser was a little soft
thats why I added a zero_shift focuser.

When scope is well aligned and weather permits I have seen central airy disk and one outer ring on star image.

If you get one make sure you test it first and don't overpay for it.
But in my opinion its not has horrible as others have made out to be.
Well at least not the one I have.

Overall Rating: 7
Weight: 1 (Unreliable Vote)
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Criterion Dynamax 8
This, unfortunately, was my first telescope that I begged my mother to buy me when I was a teenager. She wanted to get the less-expensive RV-6 Newtonian instead, but stupid kid that I was, I was convinced this scope was vastly superior. As usual, Mother Knows Best! Using it was an exercise in frustration. It was impossible to polar align, because at that time Criterion did not offer a tripod and wedge as an option, so you had to use the cheap tabletop legs that came with the scope that were hard to adjust, and balance it precariously on a crate. There were no coatings on the corrector plate, so the images were disappointingly dim. It had terrible astigmatism and was only good for relatively low powers. I sold it a few years later, and never bought another telescope for years. Too bad we didn't have the Internet back then to help us avoid inferior instruments like the Dynamax. I'm glad that the later ones were better, but this scope put me off astronomy for years!

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Criterion Dynamax 8
I had a dynamax 8 in the late 1970s. It had the worst
optics I've ever looked through. Star images were 10 arcsec
across. That is not an exaggeration, it just barely split
Polaris.

The problems were not due to collimation. The corrector
had a huge optical strain running accross it like a river.

The mount was springy too. It did have a nice 50mm finder
and nice AC drive corrector.

I've heard that there are a few OK dynamax 8s around.
However I believe mine is the norm.

-ad

Overall Rating: 1
Optics:0 Mount:3 Ease of Use:4 Value:1
Weight: 1 (Unreliable Vote)
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