Hardin Optical DSH-10 report

I just received Hardin Optical's model DSH-10. This is a 10-inch dobsonian,
priced at under $500. I received it about 10 days after placing my order,
which was a lot faster than I was expecting.

The scope came in two boxes, one with the optical tube and optics (already
assembled and collimated), the other with the mount and hardware
(unassembled). Packaging was all very solid, and nothing was damaged.

The directions for assembling the mount were very well-done, with photos and
drawings. It took me about 15 minutes to put it together. An small allen
wrench is included for the wood screws, and the pre-drilled holes are not
too narrow, so fiddling with the allen wrench is not a pain. You need a
phillips screwdriver to attach the eyepiece holder and the rubber feet, and
a wrench to tighten the lock nut that holds the two parts of the rotating
base together.

The construction is impressive. The only weakness I could see was the black
plastic stripping used on the edges of the particle board: this is going to
come unstuck sooner or later, especially around the mount's cut-in handles.
The tube is metal, the finder is 8x50 with a decent mount, the secondary is
firmly mounted on a four-vane spider, and the 2" focuser seems fine. The
mount itself, while particle board, has been painted an attractive color
with Hardin's logo emblazoned on both sides, so the scope has a sleek,
professionally manufactured look. This might matter to your partner if you
are going to store it in plain view in your home, like I am.

The scope comes with a 1.25" adapter, a 2" 32mm "astrola" (I'm guessing a
plossl clone), and a 9mm astrola. A moon filter is included as well, a nice
little touch: most beginners never think to buy filters, and they can really
help observation. Plastic eyepiece and tube caps are included for all the
optics, including the scope itself. The paperwork includes a Messier chart,
moon map, eyepiece mag chart, catalog, and a nice manual with detailed,
easy-to-read instructions on collimation. You basically are ready to rumble.

My only wish so far is a handle built into the optical tube, but that would
probably comprise the construction (causing flex), so I can live without it.
I have not yet been able to test the optics, because we are still clouded
over in Chicago. When I do, I'll post a part 2, on optical quality and
observational ease of use. But this is looking like a very good buy for
$500.

Eric Martin

My only wish so far is a handle built into the optical tube, but that would
probably comprise the construction (causing flex), so I can live without it.

I screwed a handle to my 8-inch GS dob tube - very handy, and no flex
problems. I can lug the tube and base together for short distances.

I also added a handle to the base, and a steering knob to the front of
the tube, both well-used and recommended. The milk-jug washers helped
the az smoothness heaps; the spring tapes snapped pretty much
instantly and I replaced them with key rings, and hooking those
reduces the spring tension which works for me.

Good value, have fun.

Mark

On Tue, 18 Nov 2003 15:51:52 GMT, "Eric Martin" wrote:

I just received Hardin Optical's model DSH-10. This is a 10-inch dobsonian,
priced at under $500. I received it about 10 days after placing my order,
which was a lot faster than I was expecting.


I just purchased the same scope last Thursday. Mine is suppose to
arrive Friday according to UPS tracking. Reading your report makes me
think maybe I made a good decision. I'm just across the border in
Indiana and the weather is bad here too but the forecast for the next
three days looks impressive. Looking forward to reading your critique
of your scope. Of course I'm looking more forward to critiquing my
own...

Artisan

Congrats to all of you, good scopes, here's a link where those and their
close kin are the topic of discussion:
http://groups.yahoo.com/group/skyquest-telescopes/
Be sure to check the FAQ for answers to a lot of your questions.

Jim

"Artisan" wrote in message
...
On Tue, 18 Nov 2003 15:51:52 GMT, "Eric Martin" wrote:

I just received Hardin Optical's model DSH-10. This is a 10-inch
dobsonian,
priced at under $500. I received it about 10 days after placing my order,
which was a lot faster than I was expecting.


I just purchased the same scope last Thursday. Mine is suppose to
arrive Friday according to UPS tracking. Reading your report makes me
think maybe I made a good decision. I'm just across the border in
Indiana and the weather is bad here too but the forecast for the next
three days looks impressive. Looking forward to reading your critique
of your scope. Of course I'm looking more forward to critiquing my
own...

Artisan

Well, part 2 is not going as well as part 1. I brought the scope out tonight
to run it through its paces, and I've been having problems. I can't seem to
resolve stars down to points, which is something I figure I should be able
to do. They end up streaky across the middle, especially the brighter ones.
Is this coma? If so, shouldn't it be limited to one side? The brighter the
object, the more streaky it gets.

Mars was also poor...I could not get it down to a disk, more like a disk
with two ghost disks very closely overlapped. I was using the Pleiades star
field as a test as well...could not resolve down to perfect points, but
instead had the streakiness across the middle (not vertically). I called
Hardin, and they were very friendly and concerned, and suggested I check the
collimation. I brought the scope back into the house, and the collimation
was off...the primary needed some nudging, but basically it was sound, at
least to my admittedly unprofessional eye.

I then left the scope outside for a good hour (I had left it out for an hour
before starting as well), and went back out. Better, but still no perfect
star points. (I don't think I've ever really seen an airy disk...when I rack
out of focus on all my scopes, I get the growing fuzzball).

I brought out my 3" refractor, just to make sure the seeing was not the
issue. The refractor wasn't as bright, of course, but it resolved better; no
streaks, a little mushy. Hardin told me to try again tomorrow, and call
them. They even briefly mentioned swapping out scopes, something I don't
want to do, of course. What bothers me is that I can't quite diagnose the
problem. Can anyone here, given the symptoms I've given?

Thanks, Eric


--Eric

I think I figured something out, that hadn't occured to me: the streaking
(which some call flaring) that I was seeing in bright objects is prolly due
to my own astigmatism, which is more pronounced in one eye, but not enough
in either that I wear glasses.

I did a final optical check on the scope, which had now been out for three
hours and fully acclimated to the cold evening. Saw Saturn, Orion Nebula,
resolved the Trapezium with ease, Pleiades again, and noticed that the
brighter the object, the more the flare, which moved with my eyes, only on
one axis. I checked these symptoms on a Google search of this newgroup, and
yep...personal astigmatism.

So, maybe it's time to get some contact lenses....

Eric

I own one of these.

What I did for a handle is to use a flat webbing luggage strap and a 8
inch piece of 1 inch conduit.

Run the strap around the tube fore and aft of the altitude bearings,
and through the conduit. This makes a nice handle for the tube with no
holes and the strap spreads the load around the tube when you lift it.

"Eric Martin" wrote in message
. com...
I think I figured something out, that hadn't occured to me: the streaking
(which some call flaring) that I was seeing in bright objects is prolly
due
to my own astigmatism, which is more pronounced in one eye, but not enough
in either that I wear glasses.

What size eyepiece were you using Eric?. I went through some considerable
expense to correct for my astigmatism, but it only kicks in at exit pupils
of greater than 3mm (wider fields of view), and as you note, the stars have
to be pretty bright to make the flaring objectionable.

Turns out after the expense that I rarely use my corrective lenses at the
eyepiece.... even with the 1.6 degree field I get at 6mm exit pupil using a
35mm Panoptic in my 10" F5 with Paracorr. I also have a 24mm Panoptic which
gives a 4mm exit pupil with the Paracorr in place and flaring isn't too
objectionable except on bright objects. My next jump up is a 13mm Nagler T6
which is under my 3mm exit pupil limit at 111x when used with the Paracorr
and there's no astigmatism at all (that's followed by 9mm and 7mm NT6s, for
160x and 205x, with a barlow for even higher powers).

To put that in perspective, given my eyepiece set, that equates to
astigmatism in two eyepieces used for wide fields of view at magnifications
of 60x and 40x. These low magnifications and wide fields are used primarily
for galaxy hunting, and observing the large bright open clusters, the former
of which are not, and the latter of which are, subject to the astigmatism of
my eyes. So, only for the bright clusters do I bother with my corrective
lenses.

Turns out that's a pretty small number of objects.

Exit pupil = focal length of eyepiece / focal ratio of telescope, or
Exit pupil = aperture / magnification


-Stephen

Thanks for the detailed post. I was using 32MM and a 17mm. The flaring was
evident in both, but not in the 3" refractor (obviously because things were
less bright). I only used the 9mm for some Saturn views, so no flaring.

It was when I could make the flares move by moving my eyes that it dawned on
my thick skull that it was me, not the mirrors. And a search in this group
brought up the same big two symptoms: flaring on bright stars at low power,
and ghosting of planets.

I should point out that the flaring was not THAT objectionable: I had just
bought the scope, this was the first night out, and so I freaked a little
bit, paranoid about the optics, but it was really because I've never had
this kind of light grasp before, so I didn't notice flaring in my earlier
scopes. That, and the fact that it's been about a decade since I've
seriously observed, so my eyes are certainly more astigmatic.

You mentioned paracorr, which is a coma-corrector, yes? Interesting...do you
think it's worth me getting one for the bigger eyepieces (my scope is the
same as yours:" 10: f/5).

Thanks, Eric

"Eric Martin" wrote in message
. com...

You mentioned paracorr, which is a coma-corrector, yes? Interesting...do
you
think it's worth me getting one for the bigger eyepieces (my scope is the
same as yours:" 10: f/5).

I only bought one to correct coma _after_ getting some pretty expensive
well-corrected, wide-field eyepieces.

To put that into a dollar and sense perspective....

XT10: $650 (before Hardin et al)
35mm Panoptic: $365
24mm Panoptic: $295
13mm NagT6: $280
9mm NagT6: $280
7mm NagT6: $280
2" Visual Paracorr: $295

That's $1795 in eyepieces and accessories, and $650 for the scope ;-).

I'd hold off until you are more intimate with the optics in your scope, and
more certain of your future as an amateur astronomer. Me? I'll be moving up
to a larger reflector with a faster mirror, and the accessories above will
make the transition with me.

- Stephen