So I Have This Vision

I have an Orion StarBlast 4.5" f4 reflector. It's far from
my best telescope, but I like scanning around with it. It's
nice for the Milky Way, open clusters, bright nebulas, and
even bright galaxies (e.g.; M81/82 and M94). It's particularly
nice for convenience - Easy to set up and easy to scan with.
It's easy to aim at low power, using a GLP. Almost as
natural as binoculars but with higher power available So... I
have this vision.

I'm considering the Orion Explorer II zoom EP. Yes. Zoom
EP's aren't the best, but... like... neither is the scope. The
7mm - 21mm focal length yields 21X-64X, which is about the
range the scope is good for. Yeah, you could double that if you
had to, and you still can with a barlow, but you're way out of
the sweet spot at that point.

Does anyone have the Explorer II? Is it that bad? I'm kinda
thinking there is an optimal magnification for every object in
a given scope, and that point tends to fall between available
EP's. Maybe the gain in hitting that point squarely would make
up for the optical deficiency of a zoom?

Or not. Comments?

Thanks and Regards,
-Larry Curcio

Does anyone have the Explorer II? Is it that bad? I'm kinda
thinking there is an optimal magnification for every object in
a given scope, and that point tends to fall between available
EP's. Maybe the gain in hitting that point squarely would make
up for the optical deficiency of a zoom?

Or not. Comments?

Thanks and Regards,
-Larry Curcio

My thinking is that there is no "optimal" magnification, rather there are a
variety of views which are different compromises between FOV and magnification,
brightness....

From my point of view, the difficulty with the Explorer Zoom is the small FOV,
30 degrees at 21mm, 43 at 7 mm. At 21X with this eyepiece the FOV is only 1.4
degrees. By comparison, the Orion Expanse 9mm provides a 1.32 degree FOV but
at 50X, the nearly the same FOV but over twice the magnification.

I would love to get my hands on one of those Starblasts, seems like it would
make a great widefield/RichField scope, and the eyepiece is at the right end of
the scope too. My thinking is to try to optimize a scope for what it does
best, in this case, Wide FOVs.

If you don't have a WideFov eyepiece, I would think that the 20 mm Expanse
would make a nice combination, almost a 3 degree FOV at 22X.

Jon

Yup. Agree agree agree. I saw the AFOV point
immediately after I posted :-)

Gotta say the low power limit of the StarBlast weighs
on me a bit now, but for low power and wide field, it's
great. It's good at what it does, but it's not exactly a
telescope.

The fork mount on my SCT is lousy for scanning. The
ALT axis is either too loose or too tight. As a result, it
encourages single axis searches. That's why the StarBlast
is such a relief. The real answer is a dob.

Thanks and Regards,
-Larry C.

Jon Isaacs wrote:

Does anyone have the Explorer II? Is it that bad? I'm kinda
thinking there is an optimal magnification for every object in
a given scope, and that point tends to fall between available
EP's. Maybe the gain in hitting that point squarely would make
up for the optical deficiency of a zoom?

Or not. Comments?

Thanks and Regards,
-Larry Curcio

My thinking is that there is no "optimal" magnification, rather there are a
variety of views which are different compromises between FOV and magnification,
brightness....

From my point of view, the difficulty with the Explorer Zoom is the small FOV,
30 degrees at 21mm, 43 at 7 mm. At 21X with this eyepiece the FOV is only 1.4
degrees. By comparison, the Orion Expanse 9mm provides a 1.32 degree FOV but
at 50X, the nearly the same FOV but over twice the magnification.

I would love to get my hands on one of those Starblasts, seems like it would
make a great widefield/RichField scope, and the eyepiece is at the right end of
the scope too. My thinking is to try to optimize a scope for what it does
best, in this case, Wide FOVs.

If you don't have a WideFov eyepiece, I would think that the 20 mm Expanse
would make a nice combination, almost a 3 degree FOV at 22X.

Jon