Webcam imaging

[Peter1]

Anyone any tips on focusing when yor webcam is connected to telescope and laptop. It seems to be difficult to focus using Image on laptop. Captured a few AVI's and ran through registax. Seems the focus

was'nt quite right. Attached images taken with Skymax 90, cheap webcam and free laptop.

Peter

[riklaunim]

Note - don't post BMP files as they are big.

For focusing you can set faster framerate and shorter exposure. I used also motofocus with SkyWatcher newtonian, which allowed me to focus without shaking the telescope (and easily looking at the laptop screen)

[Peter1]

Thanks for the tip I will give that a try. I've edited the pics.

Peter

[Glider]

Nice pics Peter.

I too suffer with my focusing and am constantly tweaking it throughout the night. Sometimes I shoot the same avi 2 or 3 times and just nudge the focus a little in between, then select the best and delete the rest. Shake of the mount can be a problem making focusing on the laptop a problem. A motor focuser can help. I also removed the relatively small knobs of the focuser and fitted much larger ones. This makes small adjustments feel more positive if you see what I mean.

If you set the higher frame rate for focusing this does work but don't forget to put it back down again afterwards. I'm not sure what camera you have but on my SPC900 at higher frame rates the camera starts to apply compression to the frames and you loose quality. This might not be a problem for you depending on what camera you have.

Posting bmp's is fine but just watch the size, that's all.

[Peter1]

The webcam is a PC Line with lens removed. I made up a nose piece consisting of a part of an SLR adaptor that came with an eyepiece set

and a cap cut down to size it seems to work ok. But I found it tricky to focus. Never thought about the frame rate though thought I had set it at 30fps will check and see if it can be increased.

Peter

[Glider]

Nice one, you should publish what you've done on the DIY thread.

High frame rate is OK for focusing but the important thing is to put it back to 5 fps when capturing your AVI so you don't loose quality.

[Peter1]

Thanks for the tip that is usefull. May do that once I have satisfacory results from setup.

Peter

[jgs001]

The issue with the frame rate is only relevant if the webcam has a USB 1 interface. If it supports full USB 2 you can run at whatever speed you can manage without compression risks. See if you have something in the software that allows you to magnify the image and use that. Also, go for more exposure on screen than you need, without burning it out, it's actually easier to focus if it's a bit brighter (especially if the lappy is on battery as it's probably dimmed the screen).