Discover the Power of f/2.2 Astrophotography - the RASA Telescope

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Can you imagine capturing the cosmos in stunning detail without the hassle of long exposure times? Say hello to the RASA telescope, a game-changer in astrophotography! Join us on this enlightening episode as we sit down with Dave, our special guest, who breaks down what makes the Roe-Ackerman-Schmidt astrograph an essential tool for both seasoned astrophotographers and curious beginners. From its innovative design that positions the camera at the front to the ultra-stable focus system ensuring razor-sharp images, Dave explains how the RASA's F2.2 aperture revolutionizes how we capture the night sky. 

Explore how the RASA's shorter focal length and faster imaging capabilities are perfect for places like Pennsylvania, where clear nights are a rare gem. Discover the different sizes available to suit various budgets and how each model doubles the amount of light gathered, making it a versatile choice for anyone passionate about stargazing. With Dave's expert insights and practical tips, you’ll learn how the RASA telescope can elevate your astrophotography game, making those fleeting moments under the stars a lot more magical. Don’t miss out on this episode that promises to transform your starry-eyed adventures!

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Episode Transcript

Speaker 1 (00:00):
The kind of cool thing about the Rasa design is
because it's collecting light sofast you actually don't need to
be guiding always.
You can get away with normalsidereal tracking in most cases.

Speaker 2 (00:21):
Well, dave, thanks for bringing me out here.
You brought me out here tocheck out this Rosascope.
Now, I'm no expert in theRosascopes, but from what I know
, from what I've read, is thatthis is the type of scope that
you want to get if you just wantto do astrophotography, right.

Speaker 1 (00:39):
That's right.
This is a telescope that youactually cannot look through.
It only can be looked throughby a camera, and the place where
the camera goes is kind ofdifferent, in that it's up at
the very front, in the primefocus position, as opposed to
behind the telescope's mirror,at the back, like you would
normally see on like aSchmidt-Cassegrain.
Now, this is theRoe-Ackerman-Schmidt astrograph.

(01:02):
That's a mouthful it is.
It is the RASA, and the kind ofcrazy thing about this is just
how fast it is.

Speaker 2 (01:10):
It's an F2.2 telescope, which, so that means
like mostly like an SCT.
I have a Schmidt-Cassegrain,it's like a 10 or 11-inch one,
and that is an F10, right, andthis is an F2.2, so what does
that mean?

Speaker 1 (01:28):
So, basically every time you change the F ratio by
basically doubling the amount oflight.
Now, because we've gone verymany F ratios, it's extremely
fast when it comes to imagingand that's because the focal
length is that much shorter,that's right.

Speaker 2 (01:44):
So it's about the same size aperture, but the
focal length is that muchshorter, that's right.
So it's about the same sizeaperture, but the focal length
is shorter, so you can get morelight.
That's right.

Speaker 1 (01:49):
So this is only 620 millimeters of focal length.
An equivalently sizedSchmidt-Cassegrain is at about
2,800 millimeters of focallength.
The way you calculate the Fratio is you take the focal
length of the telescope dividedby the aperture of the telescope
.
So for this telescope you wouldtake the focal length of 620

(02:12):
millimeters and divide it by the279 millimeters of the aperture
.

Speaker 2 (02:18):
Okay, so that gets you the 2.2.
That gets you the 2.2.
So, in other words, compared tomy SCT of a similar size, less
exposure in order to get thesame amount of light and picture
.
Exactly Right.

Speaker 1 (02:31):
Yep, and so you know, for us here in Pennsylvania we
don't get a whole lot ofcloudless nights, yes, and so
that time that you have is at apremium.
And when you have a Rasatelescope, which does come in
three different sizes for threedifferent budgets, right, it
comes in the eight inch, this isthe 11 inch, and then there's a
36 centimeter version, which isapproximately 14 inches, right,

(02:54):
right, okay, and with each ofthose you get from the eight
inch to the 11 inch, you'regetting about double the amount
of light gathering power, andthat's just because of the
aperture, and that big step, youknow, also gets you that faster
image, okay.

Speaker 2 (03:10):
So then, what about the focusing?
I hear there's somethingspecial about how you focus on
this thing.

Speaker 1 (03:15):
Right, this is the V2 version and it has the ultra
stable focus system, whichbasically means that the mirror
in the back here is kept very,very Much in place when the
telescope is in motion.
So if you're looking at oneplace in the sky, you move to a
different place in the sky.
The Position of the mirrorstays the same.

(03:36):
Now, if you remember, in like aSchmidt-Cassegrain, the mirror
is actually what is moving toachieve focus.
Okay, the same thing ishappening here in the RASA
telescope.
The mirror is in motion to getfocus, but the ultra-stable
focus system allows it to stayin place in a very, very
rock-solid way.

Speaker 2 (03:54):
In this one, the light's coming in, bouncing off
the mirror, going through someoptics here, bouncing off the
mirror and going up to thecamera that's up there, correct
Right now.
Can that take any DSLR or anytype of camera or what it has?

Speaker 1 (04:08):
a T adapter which can be adapted to your DSLR camera,
mirrorless camera, and thenthere's a separate adapter, that
is, a 48 millimeter threadedadapter for your astronomical
cameras as well.
So, yes, you could have all ofthe different types of camera.
And here we have your Canonfull-frame, which it can handle.

(04:29):
That, which is prettyincredible, that it can handle a
full-frame camera.
Not all telescopes can do that.
This has a very no-transcript.

Speaker 2 (04:46):
And the camera's not actually going to be blocking
that much of the light, right?
Because it already has thesensor up there that's blocking
some of it and the camera justadds like a little bit.
It's not actually going to comeout in the pictures, right?

Speaker 1 (04:57):
Right, and even in a Schmidt-Cassegrain you would
have that central obstruction aswell, and Newtonian's the same
way.

Speaker 2 (05:02):
So let's say I actually go out and get
something like this Jesus, Sorryabout the chickens.

Speaker 1 (05:10):
If you're hearing chickens in the background, we
uh, we're out at the farm rightnow.
Yeah.

Speaker 2 (05:14):
Yeah.

Speaker 1 (05:14):
Getting a nice dark skies right, you gotta sacrifice
some things.

Speaker 2 (05:19):
So let's say we go out and and, and let's say I buy
this thing.
What kind of mount do I want toput it on, or what kind of
mount can I put it on?
So of course, with the 11 inchyou are going to need a pretty
substantial mount to place thison.
Um, but the kind of mount can Iput?

Speaker 1 (05:28):
it on.
So of course with the 11-inchyou are going to need a pretty
substantial mount to place thison.
But the kind of cool thingabout the Rasa design is because
it's collecting light so fastyou actually don't need to be
guiding always.
You can get away with normalsidereal tracking in most cases

(05:49):
and that's nice because you canhave a little bit less mount as
a result.
Now the weight capacity of themount needs to be correct for
the scope you have.
The bigger the scope, of course, the larger the telescope mount
, but the Precision of that isnot required as much as it would
be in a normal telescope,especially with an F-10

(06:09):
telescope like aSchmidt-Cassegrain.

Speaker 2 (06:12):
Now you're saying that this has a very wide field
of view.
So is this something that youdon't want to use for really
small stuff, or can you stilluse it for that really small?

Speaker 1 (06:22):
stuff collecting so much light.
The kind of amazing thing isyou can put very high megapixel
cameras on the telescope andstill collect enough light even
though those pixels are verysmall, and so you effectively
can digitally zoom in.
So you're right in there arebetter options for very small

(06:44):
objects, but you can actuallyget a pretty impressive digital
zoom cropping in even with thisvery wide field.
Maybe, if we have a chance, wecould start to do some of the
asteroid searching for ourselves.
Right, We've got a prettycapable telescope here and maybe
we can discuss trying to getsome of the software capable to

(07:06):
start looking for asteroids onour own.

Speaker 2 (07:09):
That would be quite the trek.
Well, yeah, this is the firsttime I've actually seen Rasa and
it's really cool.
You know, upgrade from an SCTand I'm actually looking forward
to hanging out with you a bitand taking some pictures.
I'm looking to see what.

Speaker 1 (07:24):
I can get, and now that we'll have some time this
summer, hopefully we have somenice clear skies and out here on
the farm we have some reallydark skies.
We can see some Milky Way, andeven though we can see Milky Way
and it is that dark, I cannoteven get away with a 30 second
exposure because it is sooverexposed, which is incredible

(07:46):
Nice.

Speaker 2 (07:47):
That's fantastic, so it's going to make it make a
really good scope for these guys.

Speaker 1 (07:52):
And we'll have to come back and show you guys what
an image looks like throughthis telescope in the months to
come.

Speaker 2 (07:56):
Yeah, looking forward to it.