Dark Image on Sun

I just bought an adaptor for my Kodak DX3500 digital camera to fit my Celestron
8i. When viewing the sun on the camera's digital viewer, I get a dark spot on
the sun as shown in the picture here. I do am using a sun filter.

http://home.comcast.net/~haroldpiser/Files/Sun.gif

What is causing that and how can I eliminate it?

Harold

It looks like vignetting. The adapter is too small to pass the whole
image to the telescope. This is a common problem. You could look for
another adapter with a fancier optical component, but don't be
surprised if you have trouble finding one that fits. Maybe someone
else knows that combination better than I, but I don't have an
experience with it.

Saul Levy


On Wed, 15 Sep 2004 21:31:14 -0600, Harold Piser
wrote:

I just bought an adaptor for my Kodak DX3500 digital camera to fit my Celestron
8i. When viewing the sun on the camera's digital viewer, I get a dark spot on
the sun as shown in the picture here. I do am using a sun filter.

http://home.comcast.net/~haroldpiser/Files/Sun.gif

What is causing that and how can I eliminate it?

Harold

One question I have is what EP were you using? It looks to me like you
have the shadow of the secondary there. This would be caused by using an
EP with too large a focal length. My guess is you used a 40mm ep for
this shot.

Craig

In article , Harold Piser
says...
I just bought an adaptor for my Kodak DX3500 digital camera to fit my Celestron
8i. When viewing the sun on the camera's digital viewer, I get a dark spot on
the sun as shown in the picture here. I do am using a sun filter.

http://home.comcast.net/~haroldpiser/Files/Sun.gif

What is causing that and how can I eliminate it?

Harold

Is a sun filter polarized?

Most polarized filters are incompatible with digital cameras. For digital
you need a circular polarized rather than linear polarized.

That is what it looks like to me.

BP

"Harold Piser @attbi.com" haroldpiserremove wrote in message
news
I just bought an adaptor for my Kodak DX3500 digital camera to fit my
Celestron
8i. When viewing the sun on the camera's digital viewer, I get a dark spot
on
the sun as shown in the picture here. I do am using a sun filter.

http://home.comcast.net/~haroldpiser/Files/Sun.gif

What is causing that and how can I eliminate it?

Harold

On Thu, 16 Sep 2004 14:56:46 GMT, ETX_Astro_Boy
wrote:
Craig,

Thank you for your reply. That shot was taken with a 32mm. I tried a 25mm but
that too gives me a dark area. I have a 15mm, but that magnifies the sun too
much to get a full disk.

Does it make any difference if I use a diagonal? The diagonal makes it easier to
see the viewer on the back of the camera.

Harold


One question I have is what EP were you using? It looks to me like you
have the shadow of the secondary there. This would be caused by using an
EP with too large a focal length. My guess is you used a 40mm ep for
this shot.

Craig

In article , Harold Piser
says...
I just bought an adaptor for my Kodak DX3500 digital camera to fit my Celestron
8i. When viewing the sun on the camera's digital viewer, I get a dark spot on
the sun as shown in the picture here. I do am using a sun filter.

http://home.comcast.net/~haroldpiser/Files/Sun.gif

What is causing that and how can I eliminate it?

Harold

Saul,

Thank you for your reply. The lens ring on the camera is 27mm. I had to buy a
27mm to 37mm adapter to fit the eye piece. The adopter has no optics.

Harold

On Wed, 15 Sep 2004 21:32:30 -0700, Saul Levy wrote:

It looks like vignetting. The adapter is too small to pass the whole
image to the telescope. This is a common problem. You could look for
another adapter with a fancier optical component, but don't be
surprised if you have trouble finding one that fits. Maybe someone
else knows that combination better than I, but I don't have an
experience with it.

Saul Levy


On Wed, 15 Sep 2004 21:31:14 -0600, Harold Piser
wrote:

I just bought an adaptor for my Kodak DX3500 digital camera to fit my Celestron
8i. When viewing the sun on the camera's digital viewer, I get a dark spot on
the sun as shown in the picture here. I do am using a sun filter.

http://home.comcast.net/~haroldpiser/Files/Sun.gif

What is causing that and how can I eliminate it?

Harold

On Wed, 15 Sep 2004 21:31:14 -0600, Harold Piser wrote:

I just bought an adaptor for my Kodak DX3500 digital camera to fit my Celestron
8i. When viewing the sun on the camera's digital viewer, I get a dark spot on
the sun as shown in the picture here. I do am using a sun filter.

http://home.comcast.net/~haroldpiser/Files/Sun.gif

What is causing that and how can I eliminate it?

Harold


Are you doing this afocally? If so you're not lineing up the camera
quite right. Keep trying. Try backing off the lens a bit or moving it back
a hair. It takes a bit of practice to do afocal.

Tom

On Wed, 15 Sep 2004 21:31:14 -0600, Harold Piser
wrote:

I just bought an adaptor for my Kodak DX3500 digital camera to fit my Celestron
8i. When viewing the sun on the camera's digital viewer, I get a dark spot on
the sun as shown in the picture here. I do am using a sun filter.

http://home.comcast.net/~haroldpiser/Files/Sun.gif

What is causing that and how can I eliminate it?

Harold

Cool, MY setup is not radically different than yours.

http://users.bigpond.net.au/wanglese...Astronomy.html

Go to my sun links.

I have the same 37mm adapter, and a Televue eyepiece adapter

I'm using a 32mm eyepiece most of the time

Couple of tips I've found:

1: use "sports" or "night" mode

2: use self timer to prevent camera shake

3: "zoom" in to make sure you have the focus correct (use the LCD to
"digitally zoom"), then zoom back out to take your shots

4: make sure the camera is "centered" on the eyepiece.

5: keep at it, and take lots of shots.

if you want to email me directly, feel free.

I'm upgrading my camera to a 7630.

--

Find out about Australia's most dangerous Doomsday Cult:
http://users.bigpond.net.au/wanglese/pebble.htm

"You can't fool me, it's turtles all the way down."

Harold,

did you have the camera zoomed in at all? Also, what kind of adapter do
you have for the camera/ep combo? Scopetronix sells a few and I've had
good luck with the Digi-T system they sell with my Casio QV-3500 EX
camera.

Craig


In article , Harold Piser
says...
On Thu, 16 Sep 2004 14:56:46 GMT, ETX_Astro_Boy
wrote:
Craig,

Thank you for your reply. That shot was taken with a 32mm. I tried a 25mm but
that too gives me a dark area. I have a 15mm, but that magnifies the sun too
much to get a full disk.

Does it make any difference if I use a diagonal? The diagonal makes it easier to
see the viewer on the back of the camera.

Harold


One question I have is what EP were you using? It looks to me like you
have the shadow of the secondary there. This would be caused by using an
EP with too large a focal length. My guess is you used a 40mm ep for
this shot.

Craig

In article , Harold Piser
says...
I just bought an adaptor for my Kodak DX3500 digital camera to fit my Celestron
8i. When viewing the sun on the camera's digital viewer, I get a dark spot on
the sun as shown in the picture here. I do am using a sun filter.

http://home.comcast.net/~haroldpiser/Files/Sun.gif

What is causing that and how can I eliminate it?

Harold