| |
Main
Date: 27 Apr 2007 07:42:55
From: Jason H.
Subject: A nice sunspot group is evident.
|
A nice sunspot group is evident (I know these aren't great, just
letting others know that sunspots are up) I used the projection screen
method, hence the oblong shape from camera being off axis, NO FILTERS!
http://setisociety.org/sunspot26April07num2.jpg
In this next shot I had more trouble with the focus, but perhaps the
flower-petal-like bloom might be more apparent:
http://setisociety.org/sunspot26April07.jpg
60 mm Tasco, 9mm eyepiece (from Bill Burgess, this one didn't melt
like the stock Tasco one did on the Mercury transit) and 2x Tasco
barlow lens (slightly melted cylinder), Kodak EasyShare Z730 point &
shoot camera.
Regards, Jason H.
|
|
| |
Date: 03 May 2007 15:00:10
From: Rich
Subject: Re: A nice sunspot group is evident.
|
On Apr 27, 10:42 am, "Jason H." <exosea...@juno.com > wrote:
> A nicesunspotgroup is evident (I know these aren't great, just
> letting others know that sunspots are up) I used the projection screen
> method, hence the oblong shape from camera being off axis, NO FILTERS!
>
> http://setisociety.org/sunspot26April07num2.jpg
>
> In this next shot I had more trouble with the focus, but perhaps the
> flower-petal-like bloom might be more apparent:
>
> http://setisociety.org/sunspot26April07.jpg
>
> 60 mm Tasco, 9mm eyepiece (from Bill Burgess, this one didn't melt
> like the stock Tasco one did on the Mercury transit) and 2x Tasco
> barlow lens (slightly melted cylinder), Kodak EasyShare Z730 point &
> shoot camera.
>
> Regards, Jason H.
I saw that thing a couple days before, it looked huge.
|
| |
Date: 30 Apr 2007 10:23:39
From: Jason H.
Subject: Re: A nice sunspot group is evident.
|
On Apr 29, 12:52 pm, "Mick" <M...@nospam.net > wrote:
> "Chris L Peterson" <c...@alumni.caltech.edu> wrote in messagenews:4907331i3g8b7pk3ndapj1qbt57456u5ge@4ax.com...
>
> > On Sat, 28 Apr 2007 17:11:59 GMT, "Mick" <M...@nospam.net> wrote:
>
> >>It appears you had too much power for a 60 mm scope.
> >>If it was an F10 that means the maximum useable magnification was probably
> >>100 X's... not 200.
>
> >>Try it again with just the 9mm EP.
>
> > I'm not sure how you are coming up with 200x, but Jason is imaging, not
> > observing through the EP (good thing, no filters!) As such,
> > "magnification" is meaningless and can't be calculated.
>
> I said IF his scope is F10 then 200 X's is over the top
> for a 60mm scope. He said he used a 2 x's barlow with a 9mm EP.
> The quality of his images obviously suck as presented. Maybe this person
> is
> younger and new to this. How can you possibly disagree given my assumption.
>
> At 40 X's per inch of aperture...I rest my case.
Hello, it's F11.7, and I tried it both with and without the 2x barlow,
and at the time it looked better with it than without (I'm projecting
an image . It's possible that ideal magnification was somewhere
between using the 9mm (a disposable) and the 2x barlow (but I don't
have a 1.5 barlow and I don't want to toast my other eyepieces!)
Sorry but I'm no longer young (ouch), and I know my image sucked (as a
indicated in the first post "...I know these aren't great, just
letting others know that sunspots are up..".
Thanks for trying to help with a magnification suggestion though (I'll
have to use a calculator the next time I go out for visual) but
Chris's points are also very interesting and I'll have to keep them in
mind as I develop over time (I also have meager 6" refractor and 8"
SCT that I will apply his suggestions to, it seems that
experimentation is in order.)
Could you please post a superior image you have made of a sunspot
group USING THE PROJECTION METHOD and a 60 mm refractor so that I know
what to shoot for?
Jason H.
|
| | |
Date: 30 Apr 2007 18:10:40
From: Mick
Subject: Re: A nice sunspot group is evident.
|
> Could you please post a superior image you have made of a sunspot
> group USING THE PROJECTION METHOD and a 60 mm refractor so that I know
> what to shoot for?
>
> Jason H.
Don't waste your time.
|
| | | |
Date: 30 Apr 2007 19:31:21
From: Sam Wormley
Subject: Re: A nice sunspot group is evident.
|
Mick wrote:
>> Could you please post a superior image you have made of a sunspot
>> group USING THE PROJECTION METHOD and a 60 mm refractor so that I know
>> what to shoot for?
>>
>> Jason H.
>
> Don't waste your time.
>
>
In to my plonker, yet another time, Mick. *Plonk*
|
| | | | |
Date: 01 May 2007 00:36:22
From: Dolly Swalerd
Subject: Re: A nice sunspot group is evident.
|
Why don't you just make a baader sun filter. The materials are cheap and you
could take afocal pics (direct images at the EP).
|
| |
Date: 28 Apr 2007 17:11:59
From: Mick
Subject: Re: A nice sunspot group is evident.
|
It appears you had too much power for a 60 mm scope.
If it was an F10 that means the maximum useable magnification was probably
100 X's... not 200.
Try it again with just the 9mm EP.
"Jason H." <exosearch@juno.com > wrote in message
news:1177684975.502903.258260@o40g2000prh.googlegroups.com...
>A nice sunspot group is evident (I know these aren't great, just
> letting others know that sunspots are up) I used the projection screen
> method, hence the oblong shape from camera being off axis, NO FILTERS!
>
> http://setisociety.org/sunspot26April07num2.jpg
>
> In this next shot I had more trouble with the focus, but perhaps the
> flower-petal-like bloom might be more apparent:
>
> http://setisociety.org/sunspot26April07.jpg
>
> 60 mm Tasco, 9mm eyepiece (from Bill Burgess, this one didn't melt
> like the stock Tasco one did on the Mercury transit) and 2x Tasco
> barlow lens (slightly melted cylinder), Kodak EasyShare Z730 point &
> shoot camera.
>
> Regards, Jason H.
>
|
| | |
Date: 28 Apr 2007 17:26:17
From: Chris L Peterson
Subject: Re: A nice sunspot group is evident.
|
On Sat, 28 Apr 2007 17:11:59 GMT, "Mick" <Mick@nospam.net > wrote:
>It appears you had too much power for a 60 mm scope.
>If it was an F10 that means the maximum useable magnification was probably
>100 X's... not 200.
>
>Try it again with just the 9mm EP.
I'm not sure how you are coming up with 200x, but Jason is imaging, not
observing through the EP (good thing, no filters!) As such,
"magnification" is meaningless and can't be calculated.
In this case, the image has a scale of ~2.5 arcsec/pixel, which is
undersampled for a good 60mm aperture scope. Ideally he'd have about
half this image scale (twice the current "magnification").
In practice, of course, the quality of his optics and seeing issues will
probably limit the value of seeking a higher resolution. Solar images
are seldom close to being diffraction limited.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
|
| | | |
Date: 29 Apr 2007 16:52:10
From: Mick
Subject: Re: A nice sunspot group is evident.
|
"Chris L Peterson" <clp@alumni.caltech.edu > wrote in message
news:4907331i3g8b7pk3ndapj1qbt57456u5ge@4ax.com...
> On Sat, 28 Apr 2007 17:11:59 GMT, "Mick" <Mick@nospam.net> wrote:
>
>>It appears you had too much power for a 60 mm scope.
>>If it was an F10 that means the maximum useable magnification was probably
>>100 X's... not 200.
>>
>>Try it again with just the 9mm EP.
>
> I'm not sure how you are coming up with 200x, but Jason is imaging, not
> observing through the EP (good thing, no filters!) As such,
> "magnification" is meaningless and can't be calculated.
I said IF his scope is F10 then 200 X's is over the top
for a 60mm scope. He said he used a 2 x's barlow with a 9mm EP.
The quality of his images obviously suck as presented. Maybe this person
is
younger and new to this. How can you possibly disagree given my assumption.
At 40 X's per inch of aperture...I rest my case.
|
| | | | |
Date: 29 Apr 2007 22:56:12
From: Chris L Peterson
Subject: Re: A nice sunspot group is evident.
|
On Sun, 29 Apr 2007 16:52:10 GMT, "Mick" <Mick@nospam.net > wrote:
> I said IF his scope is F10 then 200 X's is over the top
>for a 60mm scope.
That's not entirely correct. The focal ratio is irrelevant. A 60 mm
aperture scope is typically going to be good to around 100X, a limit
imposed by aperture only.
He said he used a 2 x's barlow with a 9mm EP.
>The quality of his images obviously suck as presented. Maybe this person
>is
>younger and new to this. How can you possibly disagree given my assumption.
>
>At 40 X's per inch of aperture...I rest my case.
Because he isn't using 40X per inch of aperture. Your calculation is
related to visual use of the scope, where magnification has a real
meaning. This is imaging, and magnification is meaningless. You need to
consider image scale, and this image could stand a little more
(something like more magnification, not less). The problem with these
images probably has little to do with how much he's pushing a small
aperture.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
|
| | | |
Date: 29 Apr 2007 12:12:28
From: Paul Schlyter
Subject: Re: A nice sunspot group is evident.
|
In article <4907331i3g8b7pk3ndapj1qbt57456u5ge@4ax.com >,
Chris L Peterson <clp@alumni.caltech.edu > wrote:
> On Sat, 28 Apr 2007 17:11:59 GMT, "Mick" <Mick@nospam.net> wrote:
>
>> It appears you had too much power for a 60 mm scope.
>> If it was an F10 that means the maximum useable magnification was probably
>> 100 X's... not 200.
>>
>> Try it again with just the 9mm EP.
>
> I'm not sure how you are coming up with 200x, but Jason is imaging, not
> observing through the EP (good thing, no filters!) As such,
> "magnification" is meaningless and can't be calculated.
You can give meaning to "magnification" if you decide on some image
scale representing a magnification of one. If you're shooting using
standard 24x36 mm film, the image scale of a 50 mm normal lens would
be a reaonable choice to represent 1x magnification. If you instead put
the film at prime focus of a telescope with, say, 2000 mm focal length,
that would provide a "magnification" of 40x. This terminology is
nonstandard, I'm aware of that, however one can put meaning to the
term "magnification" even in astrophotography.
> In this case, the image has a scale of ~2.5 arcsec/pixel, which is
> undersampled for a good 60mm aperture scope. Ideally he'd have about
> half this image scale (twice the current "magnification").
>
> In practice, of course, the quality of his optics and seeing issues will
> probably limit the value of seeking a higher resolution. Solar images
> are seldom close to being diffraction limited.
>
> _________________________________________________
>
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
|
| | | | |
Date: 29 Apr 2007 14:26:00
From: Chris L Peterson
Subject: Re: A nice sunspot group is evident.
|
On Sun, 29 Apr 2007 12:12:28 GMT, pausch@saaf.se (Paul Schlyter) wrote:
>You can give meaning to "magnification" if you decide on some image
>scale representing a magnification of one...
And there are several other definitions of "magnification" used by
optical designers that can apply as well. But on the whole they aren't
used by imagers, or in situations like this post describes, because they
are not useful and simply attempting to use them requires far too much
explanation to avoid confusion.
The main points here are:
(1) Whatever was meant by 200X, it tells us nothing about whether the
image obtained was beyond the optical capabilities of the scope.
(2) Images like this need to be analyzed using image scale
(arcsec/pixel).
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
|
| |
Date: 27 Apr 2007 21:23:22
From: Jason H.
Subject: Re: A nice sunspot group is evident.
|
I montaged for side-by-side comparison purposes (of course introducing
more losses) my (meager Tasco 60mm) shot with a SOHO satellite shot
taken the same day with the MDI (Michelson Doppler Imager) in the
following (the upper is the SOHO image rotated and converted to black
& white for comparison:
http://setisociety.org/sunspotcombinedwithsoho42607.jpg
My shot is oblong because the camera is so off-axis from the
projection screen, but I'm happy to see that by just using the
projection screen method (instead of filters) many of the ghostly
marks on mine actually turned out to be something :^)
Regards, Jason H.
On Apr 27, 10:42 am, "Jason H." <exosea...@juno.com > wrote:
> A nice sunspot group is evident (I know these aren't great, just
> letting others know that sunspots are up) I used the projection screen
> method, hence the oblong shape from camera being off axis, NO FILTERS!
>
> http://setisociety.org/sunspot26April07num2.jpg
>
> In this next shot I had more trouble with the focus, but perhaps the
> flower-petal-like bloom might be more apparent:
>
> http://setisociety.org/sunspot26April07.jpg
>
> 60 mm Tasco, 9mm eyepiece (from Bill Burgess, this one didn't melt
> like the stock Tasco one did on the Mercury transit) and 2x Tasco
> barlow lens (slightly melted cylinder), Kodak EasyShare Z730 point &
> shoot camera.
>
> Regards, Jason H.
|
|
