BushnellVsHomebuilt-ShootoutV2

8/9/2019 BushnellVsHomebuilt-ShootoutV2

http://slidepdf.com/reader/full/bushnellvshomebuilt-shootoutv2 1/4

2010 3 3 Y E A R O L D H O M E B U I L T V S S T O R E B O U G H T 4-27-2010

I thought at first this was an Astroscan

clone, but it’s not really an exact matchfor an Astroscan. The Bushnell Voyager

is a 500mm F4.5 vs the Astroscan’s

380mm F4.2 The Bushnell has

collimnating screws for the secondary

mirror. The Astoscan none. The

Bushnell has by some accounts a

spherical mirror where the Astroscan is

a parabolic. But reviews can differ,

maybe depending on the model year.

Some have reported that both have

spherical mirrors and that the Bushnell

had better optics.

My homebuilt has a parabolic mirror

but suffers from some alignment issues

and needs a “real”spider. How do they

stack up in viewing. I took them out

for a quick peek of Mars and the

beehive and also looked at Saturn and

the almost full moon.

I started out by leaving the stock

eyepieces that came with the Bushnellin the car. I wanted to use my 40mm

Meade Plossl, a 25mm Celestron Plossl

and my University Optics 6mm Ortho.

These are a little bit better than the

lenses that came with the Bushnell.

I searched for Mars and the Beehive.

They are far apart now and a 40mm

won’t put both of them in the same

field of view anymore.

Mars of course looks small in thehomebuilt and in the Bushnell as well

with the 40mm. I was really just using

Mars to find the beehive cluster.

Although the friction ball mount is

really smooth, I had a difficult time

finding the beehive. I had to use the

more traditional homebuilt to locate it

and verify it’s position in relation to

Mars, before spending a few minutes to

finally find the beehive with the newerscope. A ball mount is a pain to sight

compared to a straight tube. The

Voyager is more of a hands on

telescope.

At times I needed to have a hand on

the scope to stabilize it, especially when

it gets aimed lower and the slippage is

to easy and causes the telescope to tilt

down and lose your target.

Being able to rotate the entire scope toadjust the position of the eyepiece is a

big plus when viewing. However

sometimes the Voyager has balance

problems and it’s mount is to slippery

to hold a position as it starts to slide

downward.

(The Bushnell Voyager cost me $75 at a

local pawn shop. “New in the box.”)

It’s not exactly an Edmond Astroscan Clone

F4 HOMEBUILT AND F4.5

HANDHELD AFOCAL STILL OF

MOON THRU BUSHNELL VOYAGER

SCOPE SHOOTOUT

BY GREG KNEKLEIAN TESTS CONDUCTED 4-27-2010 AND 4-28-2010



I finally found the Beehive cluster using

a 40mm eyepiece in the Voyager. The

40mm provided sharp stars and no

coma was evident with my eyes whichare far from perfect. The stars looked

sharp and like pin points all the way to

the edge. They were pin points all the

way to the edge with the homebuilt as

well. Even with alignment issues there

was little sign of coma in the homebuilt.

The homebuilt provided a brighter field

it seemed with the 40mm. This is pretty

low power for either scope. The stars

looked like they were on velvet

compared to a brighter sky on the

Bushnell. I wondered why the Beehive

looked better on the homebuilt. My

theory is the front glass and shorter

tube on the Voyager was picking up light

from a nearby streetlight. This caused a

glow and brighter appearance. A dew

cap that blocked light from sources

nearby might provide a darker view and

better viewing for the Voyager. Score

this first round for the homebuilt.I then dropped in the 25mm Celestron

eyepiece. At a higher power the sky

looked darker and the edge shifted

perhaps a bit to the Voyager. I wouldn’t

say the homebuilt had a bad view, but

the Bushnell seemed to have a more

pleasing view with the 25mm. I’m not

sure exactly what the difference would

be. The view looked brighter. Maybe

it’s time to re-coat the 33 year old

mirror in the homebuilt. Score round 2

for the Bushnell Voyager.

I centered Saturn and with the 40mm

with both scopes. At that low power

Saturn didn’t look like much, so I quickly

dropped in a 6mm UO Ortho, which

may be overpowered for these

conditions.

The Bushnell had a bit of flaring on one

side of ring. The disk looked okay with

no details. Clearly this is not a

planetary scope.

The homebuilt wasn’t any better and

actually worse. I’ve seen Saturn better

with the homebuilt in the past. Flaring

was evident on both sides and I had

more problems getting a focus with the

homebuilt. I think it’s due to the

alignment issues in the homebuilt. I’d

say the Bushnell had a slight edge here,

but it’s so small and both views were

not appealing with the 6mm. I’d call it

more of a tie and a poor one at that for

the 6mm and Saturn. it was to cold out

to continue and bring out the other

telescopes to see what was up with the

sky conditions. I moved on toward the

moon.

The moon was at about a 45 degree

angle. Anything more than 30 degrees

from the zenith seemed to cause the

Bushnell to be off balance and start to

tilt downward. It’s mount was toosmooth and not sticky enough. The

eyepieces made it less balanced. Even

without an eyepiece it would fall and go

off target. This needs some

modification or to be safe and take your

hands off the scope you should only aim

it up within 30 degrees of the zenith.

This aiming problem makes the cheap

homebuilt shacky mount preferable to a

ball mount. The ball mount is smooth,

but I need a way to “fix” the mount into

a position and lock it. I’m sure there

are many ways to modify this. Perhaps

even a small elastic tension tie down

strap would do it by increasing friction.

Or I could modify the pads to add more

Stickiness to the mount.

I wanted to take a photo of the moon

and the beehive if I could. I knew these

would be pretty bad, but give a rough

idea of what could be done. I did hand-

held which is bad enough with a normal

scope. With the ball mount and thetelescope moving, it’s even more

difficult. I was holding the telescope

and trying to put pressure on the top of

the ball to keep it on target or cradling

it’s tube from below. Then holding the

Canon EOS with the other hand I’d

hope to get a handheld shot, with one

hand on the camera. Needless to say

this was very difficult and challenging.

You’d want to fashion some kind of

funky mount to this telescope to attachit to a real mount for any serious

attempt to use this. I’m sure some kind

of unique ring contraption could be

made. A pair of rings perhaps that

intersect with a mount that squeeze the

scope and hold it in position.

I took a shot of the beehive, well part of

the beehive in the lens. It was

impossible to hold the camera still for 2

seconds at 3200 ISO and it was alsoimpossible with the time constraints to

get a good focus. The image shows a

little of the wide field of view. The

moon was a little easier, because it’s a

fast exposure. But this lacked much of

the detail you’d actually see live in an

eyepiece. The photo is not a really

good representation of what you can

visually see looking at the moon with

this little telescope.

On the next page I’ll show a couple

basic attempts at the beehive through

the Bushnell scope. This taken through

the 40mm Meade Plossl. These are

poor photos but may give you a rough

idea of the field of view.

At Low Power - Both perform very well



Beehive through 40mm - blurring is due to the inability to hold the camera and telescope still for 2 seconds. Just a rough idea. Canon t1i at 3200 ISO.



A Second Night

(My neighbors lawn light shined like a

spotlight on my eyes. ) The next night

the sky looked clear again, so I decided

to take a second look this time only

with the Voyager and some eyepieces.

I decided to break out the eyepiecesthat came with the Voyager, a 27mm

Plossl and 5mm Ramsden. The 27mm

had a few specks on the lens, some kind

of black machined flecks. I didn’t

attempt to remove them but hoped to

ignore them. The lens didn’t perform

very badly, but the ball mount now,

seemed to be more of a hassle. I need

to modify the design to allow a way to

“Fix” the Voyager into position. (Maybe

a small spring lever with a sticky rubberpad will do the trick.) It becomes more

apparent when you’re swapping an

eyepiece and find you have to hold on

the scope while fumbling for the higher

powered eyepiece. The 27mm wasn’t

as bad as I thought it would be. It held

up pretty well against the regular

Meade 40mm Plossl and seemed to be

a pretty good match. I looked forward

to finding the flaw with the 5mm. First

I put the University optics 6mm back in

to compare. Either due to sky

conditions or weaknesses in the scopes

optics I could not get a good sharp

image with the 6mm. It was almost

there at times, but it seemed like coma

or some kind of poor optics plagued

the University Optics. I imagined the

5mm would be worse. Dropping the

5mm in, I was surprised. It still didn’t

produce the perfectly sharp image I was

used to seeing in much better scopes,

but it was sharper than the University

Optics 6mm. Either this 6mm is poor

compared to what it should be doing

or the Ramsden is not a bad eyepiece,

especially for a cheap one. I wanted to

push it further toward 200x and tried

to put the Ramsden into a Meade 2x

shorty barlow. I was surprised to find

the eyepiece would not fit in the

barlow. The eyepieces for this

telescope are a little bigger than a stock

1.25 eyepiece. There barrels are slightly

oversized. They are also shorter in the

length of the tube which fits into the

focuser tube. The Voyagers eyepiece

holder has a plastic sleeve or stop

inside that limits the depth that an

eyepiece will fit into the focuser as

well. This matches the short eyepieces

that come with the scope, but limits the

depth a normal eyepiece will fit into the

focuser. This shows that the design is

either cheap or trying to force you to

buy their own accessories, like an

oversized 2x barlow. Not a good

marketing move in the long run.Dropping a 25mm Celestron Plossl this

second night surprised me at how poor

it seemed to perform. The cheap

27mm Bushnell seemed better than the

Celestron 25mm this second night.

(Clearly I need to test this with a

Televue eyepiece sometime soon.)

CONCLUSION

These are small rich field telescopes.Neither one will set the world on fire,

but if you want to go out and check out

some open star clusters with a

comfortable posture, these can do the

job. I think they are better for star

clusters than binoculars, unless you

have a fancy binocular stand of some

sort. The ergonomics of a small

newtonian are difficult to beat.

They aren’t suited well for planets. Ithink it’s almost silly to use a very short

focal length eyepiece and barlow with a

rich field to look at planets. Just get a

longer focal length scope for those.

They are both easy to deploy which

makes them a good scope for a quick

Astronomy fix.

Weight: Without the tripod, my

homebuilt is longer and might look

heavier. The homebuilt OTA is actually

a lot lighter. I prefer holding my

homebuilt under an arm viewing

compared to the Voyager held like a

baby. I haven’t tried the”strap” that

comes with the Voyager yet, it’s size

makes it feel like a light bowling ball.

With both telescopes, you’ll get a quick

setup.

For ease of viewing if you have a

platform you can whip around the ball

mount and make very quick minor

adjustments with the super smooth ball

on felt setup. When it’s balanced the

Voyager’s ball mount is great. But it

needs a locking mechanism for more

serious work. They are both fun to

deploy.

I also like this design which is free of a

spider. I wonder at times if I have

something against spiders. Maybe it’s

from reading to much about SCT’s,

Questars and Maksutov telescopes in

the old days or something. Most of my

scopes have no spider.

Maybe my next scope won’t have one

as well. Hmm. . . should it be a

Questar, a Mak Newt or some other

exotic design? Maybe a long focal

length offset mask Newtonian for

planetary viewing. . . I could just build a

mask for a regular Newt and get rid of

secondary obstructions. . . .

4 inch Bushnell Voyager sits nextto a Celestron Nextar 4SE

Documents

BushnellVsHomebuilt-ShootoutV2