CN FORUMS ARCHIVE Telescope Reviews: Re: Miyauchi 20 x 100s

Here is a cut and paste of my article from back in August 03 comparing my "brand new at that time" Miyauche 20x100 semi-apo 45 degree prisms to the "Chinese clone" of the same binoculars offered by Burgess Optics. The Burgess model was the second release. I have not yet seen the new 3rd release which is supposed to have larger prisms and a somewhat different appearance.

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As many of you know I just acquired a pair of the 20x100 Miyauchi binoculars now being carried by Oberwerk at a price about $800.00 lower than what other dealers sell this binocular for. My only dilemma was: "Should I have gotten
the fluorite version instead?" It would have cost me $1000 more for some improved color correction - primarily a concern on the limb of the Moon, planets and brighter stars. As I see binocular astronomy as a pursuit of star fields at low power, I told myself the extra expense was not worth it to me.

At about the time that the Miyauchi binoculars arrived, I was advised by Bill Burgess that he had a revised and improved pair of the Burgess 20x100 Astros available for my evaluation and review. (I had previously tested the
prototype pair back in late April (03) with those being unacceptable based upon poor collimation, no coatings to most optical surfaces and undersized prisms or prism
housings. The last two faults essentially resulting in the prototype pair having no light gathering benefit beyond what we could see in a pair of 20x77 Miyauchi binoculars.) The new pair now had fully multi-coated optics with
properly coated prisms. The light cone cut-off issues were addressed as well (at least to some degree).

A combination of decent conditions, the arrival of the Burgess binoculars and a free Friday night on August 15th resulted in my departure to our club observing site some 60 miles north of New Orleans for the binocular evaluation.
My observing buddy, Frank Castagna, who participated in the earlier Burgess evaluation, came along with me for Act II. Frank brought his 20x77 Miyauchi that had been the comparator when we did the first evaluation in April, 03.

For the purpose of this testing, the Miyauchi 20x100's were mounted on my Light Speed Wagon alta-azimuth mount and the Burgess 20x100's were mounted on my Bogen 3036 tripod with Bogen 3063 fluid pan head. Frank had his 20x77 Miyauchis mounted on a similar Bogen tripod.

Conditions at our site were good - it was hot, it was fairly humid, but not too bad in view of what is typical down our way. The Milky Way was visible - not west Texas skies, but clearly seen. We would have about 1.5 hours of dark skies, followed by about an hour with the Moon rising behind the trees and then another 2 hours or so to continue observing the Moon and Mars and the stars in spite of the waning gibbous Moon.

Here are some general comments about the new pair of Burgess 20x100's -

1) The case externally was very similar to the first, but the foam padding and it's layout on the inside was much improved. As opened by the local dealer, the case lid did have two small dents on it's top surface, but the double
shipping boxes showed no sign of damage. Due to the construction of the case,it is likely that damage like this would be quite easy to cause but of little/no consequence to the inside contents.

2) Internally the case was found to have very dense foam padding and the binoculars fit them well. The overall appearance was much nicer than the first case. The eyepieces have their own separate little rectangular compartment, but are found to be somewhat susceptable to minor cosmetic damage due to the fact that they are packaged as pairs in a small plastic bag per pair. I tried to see if each of these 40 mm eyepieces would fit inside of 35 mm film canisters and they will not.

3) One of the first things I did was to measure the interpupiliary adjustment minimum distance. I found that they could be compressed to a minimum spacing of 60 mm, but no closer. This is 2 mm better than the prototype pair,
but not down to the 58 mm promised by Bill Burgess.

4) The eyepiece hinges moved very smoothly without any binding. The focus adjustment feel was very good, not too tight and not too loose. The eyepieces had a better look to them with some additional finishing on the field lens side and better looking coatings. A collar on one of the 20 mm eyepieces was a bit rough.

5) The overall external paint finish on the binoculars looks good. I noticed that the "gold ring" separating the binocular main barrels from the prism housings in the first pair is now black. The paint in the prototype seemed to
be a little warmer of a silver with a hint of gold tone, these are more pure silver in color.

6) The dewshields fit well, pull out well and do not slip. There is adequate separation between the barrels and the dewshields so that even if the dewshields are cocked somewhat in pulling them out or pushing them in they
cannot touch each other. However the inside of the dewshield is not painted that well, the spray is very light in some places and the black does not cover the silver
or gray primer surface completely in some places.

7) Looking down into the barrel, I noticed that the paint internally has been improved greatly. It is a nice flat black now over a nice ribbed internal surface. The prototype's internal paint was a glossy black.

8) I was surprised to notice a partial arc on an internal surface. Perhaps a prism or the first surface of the petzval pair? Imagine a nickel centered on top of a quarter. This arc would represent the limb of the nickel and would extend for some 100 to 120 degrees, always the same consistent distance from the outer limb of the element. There was also a small sleek or scratch on this
surface closer to the center of this element. This was on the right barrel. Checking the left barrel, I found an identical scratch (for lack of a better term). This one, however completed a full circle. It is not a reflection, it
is easily noticed if you look for it and whatever it is, it is not supposed to be there. It is possible that this is some sort of residual mark left from the previous prism support structure prior to recent revisions and this pair
did not have the prisms repolished and coated. I will assume that this is an isolated incident and that other revised pairs do not have this fault and that future newly built pairs cannot have this fault.

9) Looking at the exit pupils in a bright light (20 mm eyepieces), I found some cutoff, approximately the 3:30 to 5:30 position on the right eyepiece and from about 7:00 to 8:00 on the left eyepiece. When racked in to achieve focus
at infinity, this cutoff became progressively smaller and finally disappeared on the left. It was still visible on the right but was extremely minor.

Here are some general comments about the Miyauchi 20x100's

1) My pair came in with a pair of the 26x eyepieces and the pair of 37x eyepieces with the 20x eyepieces being on backorder. I also noticed that the two26x eypepieces probably come from two different production runs as the labeling on the top collar of each is different. Optically however they do work as a pair.

2) The Miyauchis are slightly shorter (about 1/2" than the Burgess). They are about 3 lbs lighter than the Burgess.

3) The Miyauchi utilize 1.25" plus a fraction eyepieces. Like the Burgess, each eyepiece has two grooves in the barrel with an 0-ring in each groove. This keeps the eyepieces firmly in their receptacles. While 1.25" eyepieces
will fit and can be snugged up via use of something like Dymo label tape on the eyepiece barrels, most will not come to focus. I know my TeleVue 24mm Panoptic will not, not even close. I do however have a pair of old Brandon 7/8"
eyepieces in black anodized barrels which did come to focus. These eyepieces are equivalent to 22 mm eyepieces and will yield 22 x with a 2.35 degree field with
the Miyauchi. (note - extensive experimentation with different eyepieces was not very rewarding. Additionally there are stops at the bottom of the eyepiece recepticles which will limit field. Bottom line - the stock Miyauchi eyepieces work best.)

4) The Miyauchi front barrels and dewshield are closer to each other than what was found with the Burgess binoculars. It is possible to touch one dewshield with the other one when pulling them out and pushing them in, so be careful.

5) Looking at the objectives and into the body of the Miyauchi, I was immediately impressed by the fit and finish. Very first rate. While the Burgess is good, the Miyauchi is in a whole different league. Very, very nice!

6) The carry handle on the Miyauchi is only connected in one place. I like the handle on the Burgess much better. The Burgess handle attaches in two places and is not going to break or snap. Not so sure about the Miyauchi handle.
In a way it is a moot point as I will be removing the handle anyway and attaching a red dot finder in it's place.

7) The overall fit and finish of the Miyauchi is very nice. I will say however that looking at the binoculars externally, the Burgess is slightly better looking at the front end with slightly longer and better separated
dewshields being a plus and the Miyauchis are better at the eyepiece end with eyepieces with a much better finish and with larger diameter barrels.

Another important measurement concerning both binoculars relates to "field of view" and this is based upon eyepiece field stop/field lens measurements and the field stop within the eyepiece receptacles on both binoculars. In short,the Burgess should give you a slightly larger field of view. Here's why -

With the Miyauchi both the field stop on the 26x eyepieces and the field stop within the eyepiece receptacles measures 20.5 mm in clear aperture. Working out the math knowing the focal length of the system, this yields a max field
size of 2.35 degrees. Dropping to the 20x eyepiece cannot increase the true field size any further, even if it has a larger clear aperture field lens as the binocular eyepiece field stop is 20.5mm.

With the Burgess, even in spite of smaller diameter eyepiece barrels, the field stop diameter of the 20x eyepieces is 22.5 mm and the eyepiece receptacle
has a field stop diameter of 23 mm. So with the 20x eyepieces the actual true field by my measurements (mathematically, not on the stars) is 2.58 degrees.
Burgess is talking about a 16x eyepiece in the near future. It would give you a 6.25 mm exit pupil and a 2.64 degree field assuming a field stop that can take advantage of the binocular eyepiece field stop diameter of 23 mm. 0.2
degrees isn't much, but I know it is important to some of you.

Field testing was done using a 20x77 Miyauchi as a comparitor to both the Burgess 20x100 and the 20x100 Miyauchi (non-fluorite). The 20x100 Miyauchi was
used with a pair of 26x and 37x eyepieces. The 20x100 Burgess was used with the 20x and 40x long eye relief eyepieces, as well as the low power pair from
the 20x70 Miyauchi yielding 25x when used with the Burgess.

Results -

Similar views with low power in the 100 mm binoculars, both showing fainter stars than the 20x77 Miyauchi. There was little to distinguish between the 100 mm pairs at low power. When the higher power Miyauchi eyepieces yielding 25x were used in the Burgess, Frank immediately complained about collimation. This was something he had suspected at 20x. I too could see the collimation problem with the 25x eyepieces. Double images were separated horizontally
(left-right rather than up-down or diagonally). Ignoring the collimation issue, both of the 100 mm binoculars exhibited good sharpness and both held good images close to the edge of the field of view. The Miyauchi exhibited better contrast than the Burgess and could reach stars
marginally fainter, perhaps a .1 to .2 maginitude advantage. Chromatic aberration was acceptable, about equivalent to a very good rich field achromatic refractor in both the 100 mm binoculars.

The Burgess produced a ghost image when Mars was viewed; the Miyauchi did not have this ghost image when Mars was viewed. The brighter portion of the Veil Nebula was easily seen at 26x in the Miyauchi 20x100's and confirmed by Frank
when he came over to check it out. It could be found witin the Burgess, but was fainter with the contrast gradient not being as good; this was using the Miyauchi eyepieces yielding 25x in the Burgess. It could also be found with
the 20x77 Miyauchi at 30x, but was fainter still.

Switching to the 40x long eye relief eyepieces with the Burgess and the 37x eyepieces with the Miyauchi, the Moon was observed. Both binoculars exhibited a fair amount of chromatic aberration around the Moon's limb; this was
expected. On the Moon the detail was very nice and sharp. The chromatic ring around the limb of the Moon was seen to a lesser degree on-axis. The collimation problem with the Burgess was pronounced on the Moon with the 40x eyepieces, the Moon being like two interconnected Olympic rings. With the Miyauchi 20x100's the collimation was fine

In regard to the Burgess collimation problem - it was pronounced at 25x and 40x though I did not notice it at 20x on star fields. This was the second pair and they arrived well packed in a good case with no sign of shipping damage.
If a large binocular like this is non-user collimatable, it should be built in such a way that adjustment is needed very rarely. If a large binocular like this needs occasional collimation, it has to be user adjustable with good and clear instructions provided. If a large binocular like this falls out of collimation easily and has to be
sent in for dealer or manufacturer adjustment, it will likely be rejected by most potential users. Collimation could be lost again on the return from the dealer to the owner.

In talking to Bill Burgess on Saturday, he felt like the factory had possibly torqued the collimation screws too much in the binoculars shipped. They did this to prevent collimation slippage. He had backed off the torque and
recollimated this pair. He wanted to see how they traveled with less tension on the prisms. Obviously that did not work out. Others shipped in this batch, I believe 7 or 8 pair, have not apparently had collimation issues. Bad luck for me, I guess.

Flaws/damage to some of the internal optics as seen in this pair (arcs on the same prism facing in both barrels) is likely an isolated problem and hopefully has little effect on performance, although I have no explanation for
the ghost image of Mars seen in the Burgess and not seen with the Miyauchi.

Minor gripes - incomplete, poor paint job to the inside surfaces of the dewshields. Minimum interpupilary spacing is still too large for some observers. No containers for eyepieces not in use and no caps for eyepieces. Bill
Burgess tells me that these binoculars will have eyepiece cannisters in the near future.

Regarding the Miyauchi 20x100's. They really performed as well as I hoped they would. While not fluorite models, I can live with the chromatic aberration I saw on the Moon. Mars was colorful too, but Mars is a telescope object,
not a binocular one. It needs magnification and plenty of it. I liked the feel of the focus adjustment on the 100 mm Miyauchi, better than the loose feel on my 20x77 Miyauchi. I also see less flaring of stellar images, especially
near the field edge on these as compared to my 20x77 Miyauchis. If and when I write a review for Excelsis, these will receive a "10" as they are better than a "9" and I have no ability to give it a "9.5" score.

Final comments -

I believe, that if finally executed correctly with the price staying in the $1000.00 range, the Burgess 20x100's can do very well offering the avid binocular observer an alternative to the similar Miyauchi 20x100's but at a much
lower price. These can be great binoculars. This is especially true considering the extra eyepieces and the case. A non-fluorite 20x100 Miyauchi, even considering the new discount price of $1995.00 from some dealers (now a few hundred dollars more) has a real price of about $2700.00 if you add a second eyepiece pair and a good case (Pelican
1550 is recommended).

In their current form the Burgess 20x100's with 45 degree prisms have faults that once again results in my rejection of the pair I tested. (Prism sleeks or scratches as represented by unusually uniform arcs on both sides and the
continued problem with collimation). Keep in mind that the binocular observer willing to pay these prices is a picky breed and things such as the prism imperfections/arcs seen and the collimation problems will not be overlooked.

In talking to Bill Burgess, you can expect continued improvements to this model in his product line and expansions to the product line with similar
binoculars both larger and smaller. He is in a better position to talk about what is planned, however there are a lot of goodies coming down the pike. I look forward to being able to evaluate some of the new toys coming soon.

In respect to the Miyauchis. I am very happy with the pair I tested. It is very possible that I could have received a pair with poor collimation. I wish the field size was a little larger, it is advertised as 2.5 degrees, but by
measurement it can only max out at 2.35 degrees and this is even if you could drop down to a lower power eyepiece. (Subsequent testing and measurement on the sky does show that I do get 2.5 degrees, so there is truth in advertising!) Even if I could find a pair of eyepieces with a larger field lens/field stop, I am not about to modify the binocular eyepiece receptacle field stop. It may not help anyway if opening it up reveals the edge of a prism or some other mechanical obstruction underneath it. I also wish the built-in dewshields on the Miyauchi were just a tick longer, 0.75" to 1" is all I ask. Dewshields with a little less wobble pulling out would be nice. The action and proportion of the shields on the 20x77 are perfect, they should have modeled on those.

Let me know if anyone has any questions.

Best regards,

Barry Simon

Edited by BarrySimon615 (10/03/04 11:13 AM)

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