WebCam Photography

CCD vs Film? Lots of time vs no patience? Alright, this is your place to discuss all the astrophotography what's and what's not. You can discuss about techniques, accessories, cameras, whatever....just make sure you also post some nice photos here too!
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Razsky
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WebCam Photography

Post by Razsky »

Hi there!

I was reading up on this article on astrophotography with a webcam. I always thought the webcam shd be attached onto the len itself. Boy was i shocked when i realised that the webcam shd be attached directly onto the scope, without the lens.

If that is the case, does that mean that the magnification of the photo is based solely on the webcam?

How do i determine the magnification then? Is there a formula that i can apply?

Hoping to try out some simple astrophotography with a lousy webcam that i found. Will appreciate any advises!



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Zephyrus
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Post by Zephyrus »

Well, I briefly went through the article as well. I believe that he stated that he used a barlow and his 10mm eyepiece for the actual taking on the planet. You probably misunderstood him as he said "ToUcam is inserted the same way as an eyepiece into the telescope eyepiece holder or Barlow as shown. Note that an eyepiece is not used". The author probably just means that no eyepiece was inserted in the photo that he posted with the webcam inserted in the telescope.

In fact, as you read on, you'll find out that he an 10mm eyepiece as well as a 2x barlow for the actual taking. One last note, these type of cameras are only suitable for lunar and planetary imaging. There are commercially available ones such as the Meade LPI and the Celestron NexImage Solar System Imager. I have the Meade LPI (got it from acc at $30), and it has an magnification equivalent to that of a 6mm eyepiece.

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weixing
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Re: WebCam Photography

Post by weixing »

Hi,
Razsky wrote: Boy was i shocked when i realised that the webcam shd be attached directly onto the scope, without the lens.
This is call prime focus which is the most common method for taking Astrophoto.... The scope become the lens of the webcam in this case.
Razsky wrote:If that is the case, does that mean that the magnification of the photo is based solely on the webcam?
I think field of view is more suitable than magnification. The field of view is depend on the focal length of the scope and the size of the sensor... same as the crop factor in non-full frame DSLR.
Razsky wrote:How do i determine the magnification then? Is there a formula that i can apply?
There is a formula that will determine the field of view that the webcam cover... the simplified version:
Field of View = 57.3 x (w / F) degree
w is the width or height of the sensor in mm and F is the effective focal length of the scope in mm.
Razsky wrote:Hoping to try out some simple astrophotography with a lousy webcam that i found.
Lunar and planetary astrophotography is very suitable for webcam that can take avi video as long as you can found a way to connect the webcam to your scope.

Have fun and have a nice day.
Yang Weixing
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Razsky
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Post by Razsky »

Thanks for the replies!

That means for the prime focus method, the only way to "zoom in" on the object is via the webcam's software?
Lunar and planetary astrophotography is very suitable for webcam that can take avi video as long as you can found a way to connect the webcam to your scope.
I read somewhr that i can mount the camera onto a standard film canister. Abit of DIY there but it should work right?


I am still very new to this. Thats why i am experimenting on a lousy webcam before moving on further. If you guys got any lobangs on 2nd hand webcams then pls inform me!

Thanks again!
Kai Long

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weixing
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Post by weixing »

Hi,
Razsky wrote: That means for the prime focus method, the only way to "zoom in" on the object is via the webcam's software?
To increase the magnification, just use a barlow. Barlow will increase the focal length of the scope and thus, increase the magnification.

Have a nice day.
Yang Weixing
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aquillae
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Post by aquillae »

Razsky wrote:
I read somewhr that i can mount the camera onto a standard film canister. Abit of DIY there but it should work right?
It should work, I did it this way too when I first started doing webcam imaging. Just try your best to have the film canister's opening area parallel to the webcam's sensor surface.
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Razsky
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Post by Razsky »

I tired to take some shots of the moon. Weather was kinda bad but i was able to record about 30secs of videos for each picture.

Video captured with Iris and processed in RegiStax5.

My 1st Astro photos!

Image

Image

I am still very new to registax. Kinda feel that the shots are abit over processed. Comments are welcomed!

Btw, i didn't manage to secure the webcam using a film canister. I just roughly pointed the webcam at the centre and taped it in place.

I am planning to purchase a cheap webcam ($30+) that is able to take videos at higher resolutions. What do you guys think of that?

Thanks!
Kai Long
Last edited by Razsky on Tue Apr 14, 2009 1:28 pm, edited 1 time in total.
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Sam Lee
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Post by Sam Lee »

Hahah , i thought you were kidding when you said you'll be trying some webcam shooting that day.
Pretty bad weather that day but your images turns out quite well.

Maybe you can think of ways to mod your webcam such that it can sit nicely with the setup so that you can do your focusing with ease.

Regards,
Sam
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Razsky
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Post by Razsky »

Hehe. Trying to use the film canister for the securing. Do you know of any place where i can get these film canisters? Only got 1 of it.

Anyway, i did try to image Saturn. Sadly though, all that appeared on my screen was a big white dot. Fiddled with the focusing knob over and over but just could make saturn show. Do you think is may be my exposure settings of the webcam?

One more thing, i notice the "halo" around the moon edges. Cant seem to get rid of it. Do you guys know what causing it?

Thanks!
Kai Long
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rcj
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Post by rcj »

Hi Kai Long,

Good attempt on the webcam shots. Have noticed that the moon shots are oversharpened and a bit too bright. You may need to play around with the webcam capture software and tone down on the gain. If it has a histogram function, the peak of the histogram should be on the left side and then taper down gently towards the right. Play around with the exposure settings too, as usually, for the moon, and even saturn, it is better to underexpose it than overexpose which you will end up with saturated highlights which cannot be recovered or remedied through post processing software. A good point to start is 30 or 15 fps, with exposure shorter than the reciprocal of the frame rate. Gain should be around 30-40% depending on transparency conditions and object of interest. If there are default sharpening or deconvolution algorithm imposed during capturing by the software, do disable them. And if you are shooting the moon, one good choice on reducing throughput bandwidth is to shoot in greyscale if there is such an option. If Saturn looks like a white blob, it is definitely overexposing. Sometimes this is good when we want to find the planet, but once we "zero in" on the object, one will have to adjust the capture settings until you are able to see features on the planet. This assumes your image scale is large enough, which it may not be the case for Saturn on your system at the moment. Perhaps you need to add a barlow (2x or 3x) but this means you need to track the object better before it goes out of the narrower FOV.

The way to go, is to keep experimenting with the settings, and keep a log book, and in time to come, you will be able to obtain near perfect settings for each object at a given imaging focal length per external weather condition/location.
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