ASTRO: Pelican nebula (IC 5070)

I used what remains of the nights here at +52 degrees north to test my QHY8
camera for the purpose I bought it for, which is recording emission nebulae
through an UHC filter.
I needed two nights to get the data for these 260 minutes, and I was imaging
well into dawn.

Unfortunately the Vixen reducer I used on my Skywatcher ED120 does not give
good stars near the edge of the field. Actually the stars are worse than
with the ED80, which surprises me as I thought that the ED120 was just an
"upscaled" copy of the ED80.

Taken from the middle of Berlin with a Skywatcher ED120 at f/5 on a G11
mount, 13x20 Minutes through an Astronomik UHC filter.

The picture can also be found at
http://ccd-astronomy.de/temp2/IC5070-260smallgut.jpg

Stefan

Stefan Lilge wrote:
I used what remains of the nights here at +52 degrees north to test my QHY8
camera for the purpose I bought it for, which is recording emission nebulae
through an UHC filter.
I needed two nights to get the data for these 260 minutes, and I was imaging
well into dawn.

Unfortunately the Vixen reducer I used on my Skywatcher ED120 does not give
good stars near the edge of the field. Actually the stars are worse than
with the ED80, which surprises me as I thought that the ED120 was just an
"upscaled" copy of the ED80.

Taken from the middle of Berlin with a Skywatcher ED120 at f/5 on a G11
mount, 13x20 Minutes through an Astronomik UHC filter.

The picture can also be found at
http://ccd-astronomy.de/temp2/IC5070-260smallgut.jpg

Stefan

My Lumicon UHC filter pases no H alpha or very little. No way it would
give a pink HII region. The Astronomik seems to give a much better
color balance.

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

"Stefan Lilge" wrote in message
...
I used what remains of the nights here at +52 degrees north to test my QHY8
camera for the purpose I bought it for, which is recording emission nebulae
through an UHC filter.
I needed two nights to get the data for these 260 minutes, and I was
imaging well into dawn.

Unfortunately the Vixen reducer I used on my Skywatcher ED120 does not
give good stars near the edge of the field. Actually the stars are worse
than with the ED80, which surprises me as I thought that the ED120 was
just an "upscaled" copy of the ED80.

really focal reduction and field flattening are two separate functions but
can be combined into a single unit.

for flattening, it really is design specific: you sort of need a flattener
specifically designed for the scope at hand and of course the spacing from
the flattener to the focal plane is critical. If you deviate from the
correct spacing then you can get results similar to what you are
demonstrating.

So maybe the only problem is that the spacing from the metal back of the
flattener to the focal plane needs to be tweaked a bit?

The big scopes like my AP refractors have standardized on the Pentax 6x7
flange to film distance of ~87.5mm

not sure what is done for smaller rigs but maybe the standard flange to film
distance of a typical 35mm camera of a bit less than 50mm is appropriate for
starters?

but I meant to say the image looks nice anyway

I was considering imaging the pelican with the PL39K this weekend but
decided on Sag instead....


"Stefan Lilge" wrote in message
...
I used what remains of the nights here at +52 degrees north to test my QHY8
camera for the purpose I bought it for, which is recording emission nebulae
through an UHC filter.
I needed two nights to get the data for these 260 minutes, and I was
imaging well into dawn.

Unfortunately the Vixen reducer I used on my Skywatcher ED120 does not
give good stars near the edge of the field. Actually the stars are worse
than with the ED80, which surprises me as I thought that the ED120 was
just an "upscaled" copy of the ED80.

Taken from the middle of Berlin with a Skywatcher ED120 at f/5 on a G11
mount, 13x20 Minutes through an Astronomik UHC filter.

The picture can also be found at
http://ccd-astronomy.de/temp2/IC5070-260smallgut.jpg

Stefan

Rick,

the Astronomik UHC has a similar bandpass for Halpha and OIII/Hbeta, so both
ends of the spectrum are almost equally matched. Colour balance is OK for
such a rather narrow filter.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Stefan Lilge wrote:
I used what remains of the nights here at +52 degrees north to test my
QHY8 camera for the purpose I bought it for, which is recording emission
nebulae through an UHC filter.
I needed two nights to get the data for these 260 minutes, and I was
imaging well into dawn.

Unfortunately the Vixen reducer I used on my Skywatcher ED120 does not
give good stars near the edge of the field. Actually the stars are worse
than with the ED80, which surprises me as I thought that the ED120 was
just an "upscaled" copy of the ED80.

Taken from the middle of Berlin with a Skywatcher ED120 at f/5 on a G11
mount, 13x20 Minutes through an Astronomik UHC filter.

The picture can also be found at
http://ccd-astronomy.de/temp2/IC5070-260smallgut.jpg

Stefan

My Lumicon UHC filter pases no H alpha or very little. No way it would
give a pink HII region. The Astronomik seems to give a much better color
balance.

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

Thanks Richard, I'll have to play with distances a bit. I'll probably get a
variable T-Ring...

Stefan

"Richard Crisp" schrieb im Newsbeitrag
m...

"Stefan Lilge" wrote in message
...
I used what remains of the nights here at +52 degrees north to test my
QHY8 camera for the purpose I bought it for, which is recording emission
nebulae through an UHC filter.
I needed two nights to get the data for these 260 minutes, and I was
imaging well into dawn.

Unfortunately the Vixen reducer I used on my Skywatcher ED120 does not
give good stars near the edge of the field. Actually the stars are worse
than with the ED80, which surprises me as I thought that the ED120 was
just an "upscaled" copy of the ED80.

really focal reduction and field flattening are two separate functions but
can be combined into a single unit.

for flattening, it really is design specific: you sort of need a flattener
specifically designed for the scope at hand and of course the spacing from
the flattener to the focal plane is critical. If you deviate from the
correct spacing then you can get results similar to what you are
demonstrating.

So maybe the only problem is that the spacing from the metal back of the
flattener to the focal plane needs to be tweaked a bit?

The big scopes like my AP refractors have standardized on the Pentax 6x7
flange to film distance of ~87.5mm

not sure what is done for smaller rigs but maybe the standard flange to
film distance of a typical 35mm camera of a bit less than 50mm is
appropriate for starters?