How do you obtain proper focus on a webcam?

[Omaroo]

Hi all

Just thought I'd take the new ZenithStar 66ED out tonight for a spin and thought as I was setting up "time to use that ToUcam that's been sitting there since I bought it". So... this was going to be my first real go at imaging. I rigged it all up and.... well... think that it's really difficult to achieve good focus. How on earth do you guys do it? I haven't fiddled with these particular images in PhotoShop, but I have tried on others. Applying various sharpening algorithms simply overcooked the images and contrast looked horribly overdone. Is there a simple method? What's the secret of focussing with a webcam? Resolution is only VGA (640x480) so I suppose that great results are going to be hard to get anyhow. Focussing "on-screen" in real time is very difficult - I could not get any sharper that these are already - 10:1 focus control and all.....

Time to go DSLR I think. At least I can look at an image on the focal plane as I focus......

Any advice? :sadeyes:

Cheers and thanks everyone
Chris

[rat156]

Hi Chris,

A Hartmann mask will help, but only on points sources like stars.

Use one (star) close to your target, then move to the target, then don't play with the focus.

There's a link in IIS on how to make a Hartmann mask.

Cheers
Stuart

[Omaroo]

Thanks Stuart. I'll check this out. Looking at other ToUcam images of the moon on the net I don't think I did too badly now. Most of them are incredibly grainey and most are totally out of focus. Oh well - time to improve my own I guess.

Thanks
Chris

[[1ponders]]

What are you using to control your capture Chris? There is a free program called QCFocus (QuickCam) that you can use to both capture and focus. I have not used it but you could try it. I use K3CCDTools V3 which has a great focus assist built in. But as Stuart has says it is much easier to focus on a star, or if one is available, a mountain just peeking over the terminator and you focus on the mountain top.

At the FOV you are getting it is going to be tough to get a nice crisp image anyway. Try using a barlow, taking multiple higher res shots and then mosaicing them to capture that nice crisp large moon.

If none of these are options then you can focus as Stuart has says with a hartmann mask or even laying two pieces of dowel across the aperture in a cross.

Good luck with it.

[Omaroo]

I was just using the ToUcam software - VLounge, Paul. I was also using a 2x barlow - as such is the FOV through an f/6 66mm scope. I'll upgrade to a good quality barlow first I think (I'm using a 2" $25 special).

I have to say that I cranked up K3CCDTools and it scared the hell out of me. Where the heck to start? :sadeyes: It's a complex-looking app, which requires actually understanding the underlying principles first, I think. I will try QCFocus though. Looks good!

I'll give it a ...gulp....go though!

Cheers and thanks
Chris

[Ric]

Hi Chris, they have turned out very nice for your first real go.
You have captured some fine details and the moon is quite bright at the moment.

Top stuff

[Omaroo]

Thanks Ric :) We try, huh? The moon certainly is bright too. The poor little webcam had real problems initialising and coming to a stable image until I stuck a moon filter on. Whoops - should have included that in the folio..... :doh:

Cheers
Chris

[[1ponders]]

It does look a bit scary but stick to looking through the program settings (the hammer and screwdriver icon) for the video capture settings. That is where you set up the destination folder for your avi and the naming conventions.

Then check out the Video Source (exposure) (camera icon) for you exposure, gain and frame rate. Untick any check boxes for auto control. (If you have tracking then you can leave the autowhite balance set for the time being) Set your brightness to the middle, your frame rate to around 10fps (good for average nights) your gain to around 30%-40% and then drop your exposure rate until you get a nice even illumination. If it a bit burnt out in areas, drop your gain and reduce your exposure (eg go from 1/500 to 1/250) and then try adjusting your gain again.

See how you go from there.

[Omaroo]

Thanks Paul! :) I'll give it all a go!

Cheers
Chris

[Ric]

It's a bit off topic Chris but how is your bino-telescope progressing?

Cheers

[Omaroo]

The mirrors are underway with Mark, Ric. I have two matched 12" f/5 units in the works. I've ordered helical 3-vane spiders from the USA as well as Moonlite truss clamps. I've taken plenty of photos so that Mark and Paul can comment on dimensions - so I can then go and cad-up the box and secondary cages. Once that's done I'll get a mate of mine to turn them out on a Morbidelli CNC wood authoring machine. Should be nice! I then have to come up with push-button controls to wind the mirror co-collimation bolts in and out by stepper motors.

Lots to do..... :thumbsup:

Cheers
Chris

[Ric]

Excellent Chris, definately sounds like all systems are go.

Cheers

[sheeny]

Chris,

They look pretty good to me for first time shots!

You've already got some good advice here so I won't re-hash that other than to encourage you to get to know K3. Yep, it looks daunting when you first fire it up, but it's really not that bad. Just play with it a bit to get to know where things are and setup your camera, etc in the toolbox as Paul mentioned. It won't take long - it'll look like an old friend!:thumbsup:

BTW I'm assuming these images were stacks not single frames?

I'll throw a few tips in to complement the other stuff you have already:



You need a bit of room to move on your exposure meter. Aim for the brightest part of your image to be in the range 180 to 220. If the seeing is good, you can go to 220, but drop it a bit as the seeing deteriorates. It just gives you the opportunity to be more aggressive with sharpening (to compensate for the poor seeing) without burning out your highlights. It's never as good as good focus and good seeing, but... if your like me you try to extract as good an image as you can from the data you get.



Another technique I have found works for me is to make a focus adjustment and then just watch the preview for a while. If you are getting a few sharp frames every once in a while, then chances are your focus is as good as you'll get in those seeing conditions. I know when I was new to it, I was trying to improve the focus (i.e. get more sharp frames) beyond what the seeing would allow.

If you can work with the Hartmann mask, do that. But if you have only done a rough alignment (portable gear not permanent mount) and you don't have a parfocal EP/camera combination (as I don't when using filters on my ToUcam) the above method may help.

Al.

[Omaroo]

Thanks for your advice Al, and it looks like parfocal rings might be the next go.

[Omaroo]

Any better? This one fluked better focus I think. I had to reduce image quality to upload it here.

Mike - any chance of implementing links to image libraries via BB code?

[Ric]

Looks good Chris, the shadows and highlights along the terminator have come up very nice.

Cheers

[Omaroo]

Thanks Ric. Yep - it's better. I think that seeing will influence it now, so I just have to wait until I can try again..... dang cloud! :whistle:

[bluescope]

Nice images Chris !

I hooked up my SPC900NC the other night and did some images of the moon. I haven't been able to do any processing because the VLounge software outputs MPEG files and Registax won't read them or am I doing something wrong ?

Does anybody know of a good FREE converter to convert the MPEG's to AVI's ?

:thumbsup:

[[1ponders]]

Try Virtual Dub Steve, though you should be able to take straight from VideoImpression (not VLounge) to Reg.

http://www.virtualdub.org/

[Omaroo]

Steve - Thanks :)

I used VRecord - which is a component of the VLounge suite - and it outputs .AVI files natively.

Cheers
Chris

[bluescope]

Hi Chris I can't find any reference to VRecord in my VLounge software, maybe the SPS900NC has a different version to the ProII 840k.

Paul, I have donwloaded VirtualDub and will give it a try.

Thanks to both for your suggestions and help.

:thumbsup:

[Omaroo]

Latest...

[Ric]

Looking good Chris, you are picking up some of the finer details as well in that image.

Very nice

[RB]

Great work Chris, you're doing very well indeed.

:thumbsup:

[Omaroo]

Thanks guys :)

I took a series of segments last night, so hopefully today I'll tile it all and then shrink it back down to 640x480. Hopefully detail will appear more sprightly. :shrug:

Cheers
Chris

[iceman]

Look out - Chris is imaging! He'll never get that bi-newt finished now!

[Omaroo]

Hey Mike - fantastic idea! I could take stereo images..... :)

[Ric]

Does that mean that Mike will have to get IIS 3D glasses for us as well. :lol:

Cheers

[[1ponders]]

BTW Virtual Dub has a great recording facility as well. Weeelll if you are not used to using K3 that is :P

[ving]

hi chris, your pics look good to me considering you havent done any real processing on them. seeing will stop images from becoming really sharp, so maybe thats why they dont look as crisp as youd like. a little unsharp mask on them will work wonders. :)