Criterion Dynamax 8

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Brand and Model:Criterion Dynamax 8
Price ($USD):700
Type:Schmidt-Cassegrain
Attributes: un-checked Go-To un-checked PEC
Aperture:203mm (8")
f Ratio:f/10
Focal Length:2030mm
Finder:50mm
Electric Power:110v ac
Mount:Fork
Tripod:
Weight (lbs):lbs.
Dimensions (w/h/d):
Description:
Vote Highlights Vote
Criterion Dynamax 8
I have 2 Criterion Dynamax 8 scopes that I picked up for chump change on A-Mart. They are in excellent condition. One is a 1976 model and the other is a 1979 model. Read my review of these scopes on Astromart in the "Cats" section. Both of these scopes have excellent optics. The 76 model has shown incredible detail inside Jupiter's red spot. I have seen shades of white, red, orange, and brown. Views of deep sky objects in both scopes have the tiniest star images you can imagine with great contrast and resolution. I had to tweak the 79 model to get it to perform at this level and that is explained in my review. This review is also on Cloudy Nights.

I use a telrad on them and when I am in a lazy mood I just use the settings circles with great success. Tracking is excellent and very quiet. They also have an 8X50 finder on each one. The bakelite tubes are very strong and attractive.

The mount is very steady provided the legs are not extended to a high position. I extend them an extra foot or so from the lowest point .

Any 2" Diagonal threaded for SCT will screw into the back of a Dynamax 8. Any SCT f6.3 focal reducer will thread into the back of a DX8. Any skylight filter dust seal will also screw into the back of a DX8. This in turn will allow any Meade or Celestron visual back to thread into the back of the dust seal.

I have an 80mm f6 Nighthawk achromat that does not provide sharper views on stars than the DX8 scopes. It is a sharp refractor, but no sharper than the views I am getting with my WELL COLLIMATED Dynamax 8 scopes.

Mark

Overall Rating: 10
Optics:10 Mount:9 Ease of Use:10 Value:10
Weight: 5 (Veritable Vote)
Date:
By: SCT8Swanson
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=595784

Criterion Dynamax 8
It is still a good workhorse, although there isn't a good way to re-coat the mirror or even open it.

Overall Rating: 8
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.95.132)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=472793

Criterion Dynamax 8
I actually own a Dynamax 6 SCT - excellent optics (diffraction limited), stout mount with jewelled controls, but will not fit standard SCT tripods - very easy to use, and I got an incredible deal on mine so value is sky high. Overall, a very nice tabletop scope with lots of features and good optics.

Overall Rating: 8
Optics:8 Mount:7 Ease of Use:9 Value:10
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.141.110)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=452921

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)
Date:
By: Anonymous (xxx.xxx.137.106)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=411800

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)
Date:
By: Anonymous (xxx.xxx.240.203)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=37933

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
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.117.20)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=37932 

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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 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
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.142.144)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=37931

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
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.1.248)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=37930

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
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.254.199)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=37929

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
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.71.135)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=37927

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