help desperately needed

[stopusinmyid (Tammy)]

hi all,
I have finally got my Celestron NexImage camera and need advice. I can't seem to get clear crisp pictures. I'm guessing the brightness might need adjusting on camera settings to start with but even so how do I get better quality? I have played around with the settings in Registax and just can't figure it out. The pictures look better when I reduce the size but could still be better. Here are some of my finished shots

[darbyvet (Carl Darby)]

Hi Tammy,
those are great shots for a first time with the Neximage. I think your major issue is with focusing.The images are slightly out of focus and unfortunately that cant be fixed with registax.It is hard to focus with the neximage.I usually increase the frame rate to 10 fps and keep fiddling with the focus until I get as sharp an image as i can then I go back to 5 fps for capture.You can also use a bahtinov mask to focus on a nearby star.If you do that there is a really cool program (Bahtinov frame grabber) that helps you to get the best focus.
Set the gain and gamma to minimum and play with the brightness and saturation to get an image which is slightly darker than you think it should be. Once you stack the images your final image will be brighter.I think a couple of your images are overexposed.
There is a lot of trial and error with the neximage.I used to take several AVis and varied the exposure and brightness to get a feel for the correct exposure.
With your large aperture scope you may be able to use a higher frame rate than 5 fps, but I would start with 5fps and sometimes the neximage gets a little temperamental at higher frame rates.

Here is a quick guide to using the neximage.There is also a yahoo group for neximage camera users.

When I used to image Jupiter I used one of the moons to focus-You adjust focus until the moon is as small as possible and then move to the planet.

http://www.nexstarsite.com/download/...thNexImage.pdf

[alistairsam]

hi,
to start with, the focus does seem out.
do you have sufficient in-focus?
have you tried the different modes if available, outdoor, indoor, turning off automatic gain control?
are you imaging by prime focus without an eyepiece?

[Poita (Peter)]

As others have said, it looks like it is mostly a focus issue, a Bahtinov mask is cheap and can really help get the focus nice and tight.

[Amunous (Michael)]

i have the neximage as well. first time i used it i had the partner looking at the laptop while i kept the scope on the moon and did the focus out or in as needed untill it was crisp. if your focus is all the way out and thats the image your still getting, try getting an extension tube for the focuser as that will give a bit more play, if its all the way in then you may not be able to use it on your dob.

[renormalised (Carl)]

Yep, focus

This is where a Robofocus comes in handy because you can focus your scope without having to leave the lappy to do it. That way, you can keep an eye on what you're doing without having to get up and twiddle the focus knobs all the time.

[renormalised (Carl)]

Still, really nice shots

[midnight (Darrin)]

Tammy,

Couple of things I found with my original setup - 8"SN and Neximage was :

1. Focus. Does your OTA have a single speed focuser or dual?
2. Consider increasing your F ratio. It was recommended to me by a fellow IIS member to change from my native F4 to something like F7 by placing a black piece of material over the front of the scope and cut away say a 2" hole. The moon is bright and you don't change the magnification but my focusing was easier. I got sharper images that way.
3. Neximage. Your images appear over exposed. Back off the exposure and reduce the gain if possible.

Good luck!!

Darrin...

[stopusinmyid (Tammy)]

Thanks guys,
Went out last night for a few hours viewing. Played around with the settings as suggested. Our image of Saturn and Jupiter are a lot clearer then before. Haven't processed any as yet, had to work today. Shall sleep well tonight.
We have a 2" crayford focuser with the 10:1 fine tune, not sure if that's what you refer to as dual focuser. Still learning the language.
Stupid me didn't think to write down what settings I was using for the different shots to use as a guide next time. I put the moon filter in for a couple of shots but yeh don't know which ones .
Yeh we are imaging without the eyepiece. Tried adding the barlow to it also as the link suggested for planets but they just couldn't seem to get picture in the screen of laptop after lining it up with viewfinder.
All in all it's been fun and cold . Here's a shot of the moon behind clouds just before it went out of view using digital camera held up to eyepiece

[darbyvet (Carl Darby)]

Tammy,
the crayford 10:1 is a dual focuser.You can use the outer knob to make very fine adjustments to focus which is usually what you need for planets.It is very useful to write down your settings as you learn.You can use a regular moon filter that makes the moon look green especially if the moon is really bright or you can use a red filter.
I like to keep the gain as low as possible and adjust the brightness.Remember gain=grain-The higher the gain the grainier the image.

I would no use a barlow yet.It is harder to focus with a barlow and the image will be dimmer.
Once you are ready to use a barlow i would suggest getting a flip mirror.What this does is allow you to use an eyepiece to get the image of the planet centered in the field of view and then you flip the mirror to direct the image to the camera.I will take a pic of my imaging train.If you are using a Dob you may have to adjust the balance of the scope to accomodate the weight of the imaging train.