Neximage settings

[robindurant]

I had a go with my Neximage Cam on Saturn last night and got poor images. I do not really know what the difference is between the Brightness & Gain controls and what does Gamma do to the settings. Also what is the reason for various shutter speeds. I just got as good a picture as I could on the PC screen and gave it 400 seconds. The info on the manufacturers spiel is useless to a newbie to imaging, Can anyone give me a few tip as to how to start out on this AVi route to imaging

[geppetto]

Robin

Has your neximage had a long exposure mod done to it?

Generally with the settings, set the brightness to about half way and the

gain to minimum (less noise) and the gamma to minimum.

Then alter the shutter speed till you get a decent image on the pc screen.

If you can't quite get it right using the shutter speed, you can tweak the

gain up a bit to compensate.

Trick is to get a live image on the pc that is slightly darker than you might think to set it,

as stacking later on ups the brightness levels.

The shutter speeds set the time that the shutter is open

A fast speed will let less light in so is OK for brighter targets

The gamma settings even out the brightness range making your image less contrasty.

The gain setting is like the ISO setting on a normal camera. Usefull but can introduce noise at higher settings

Good luck with it

[robindurant]

Thanks Geppetto for your fast reply and a helpfull one too.

There has been no mods on the Camera as it is new out the box. To get a good visual image on the Laptop I had to set the Brightness to 70% Gain 40% and shutter speed to 1/10th which seemed to me a little slow and the FPS to 5 Without these settings I could not get a visual image on the screen at any other settings such as reducing the Gain. If I set the shutter speed to 1/25th all I got was a small dark yellow blob. Saturation made no difference to the image shown at all. ALSO It it OK to set the focus on an adjacent star such as Regulus. I tried using a Hartman mask which focused well on the star but I did not get chance to see if it had worked on Saturn ( not getting a good result)

Thanks again for your help, it is most appreciated.

Robin

[geppetto]

Probably easier to focus on a star then move over to Saturn for a tryout Robin.

I use a Toucam but these webcams share a lot of similarities.

Thing is there's no right or wrong way, it's a case of trying different combinations

of settings till you find the right one.

I presume youv'e switched off the full auto.

Also on your camera I think theres another auto setting for the gain and shutter speed.

Might be worth setting that to auto when your focused on Saturn to see what the camera's

software reckons the ideal settings to be.

[robindurant]

Thanks again, I will give it a try as soon as the clouds roll back.

Robin

[MartinB]

Robin, start off by having the brightness and gain settings high to make life easy getting it on the chip. Use Saturn to focus, not a bright star. You have a perfect focussing aid in Cassini. Don't know if you are using a barlow or not. Obviously the barlow makes things dimmer but best to use one to increase the image scale. Achieve a rough focus on the burnt out image then start to dim it down. shutter speed shouldn't really be longer than 1/25 sec. brightness at half, then as much gain as you need. The stacking will sort out the noise. Play around with gamma if you want but as Phil says, ok to leave it off. You want the image to be dim but bright enough so that you can see Cassini. Only in the best seeing will you have cassini constantly visible. The norm is for it to shimmer in and out of focus. Just keep tweaking the focus to a position that puts it in focus as much as possible - a frustrating business! If seeing is good capture at 5fps but if focus is very variable you are better off with 10fps and doing a manual selection later using "virtual dub" 400secs is probably too long since Saturn rotates pretty fast but not sure about this. I normally stick to 120 secs.

Have a look at the Planetary imaging with a toucam primer in the learning zone. Most of the stuff in there applies to your camera as well