pictures with the telescope

[ElPelado]

hi!
if i want to take pictures with a cammera(a normal cam, not CCD) and my telescope, i must take off the eyepiece or leave it there???
can someone help me?
and if i want to take a picture with a cheap webcam? take it off or leave it in its place??

[praesepe]

Hi ElPelado!

I've got quite experience at taking photographs with telescopes (during my holidays I've taken good shots of Mars opposition and Saturn before sunrise ). Basically, there are 3 systems to take shots:

- Piggyback: Mounting the camera on top of the telescope's tube. Ideal when you are trying to take high field photographs, but require a guiding system on the telescope and a few minutes of exposure, so it requires a good quality reflex camera.

- Directly attached to the focuser: By attaching the camera directly to the focuser with an adapter (T2), It can be a reflex, CCD camera or webcam (along with stacking software to improve the results, usually webcam sensors have low light detection, so images are less detailed ie. CMOS sensors)

- Through eyepiece projection: By taking photographs with a camera attached to the eyepiece. The problem is that there is a bit of "tunneling effect" with some eyepieces, specially when they're small, but it permits to use larger magnifications.

I hope this helps

[praesepe]

Here are two of my favourite photographs that I took during these holydays and that I wanted to share with all of you. I compared them to shots made on the same exact momment with Celestia.. they're really accurate!!




P.S.: Both images where processed with stacking software (Registax) and some Photoshop filters.

[t00fri]

Hi Praesepe,

pretty neat Mars CCD shots! Where did you get that red color from? How did you normalize the RGB weights of your CCD exposures? Did you orient it at the Celestia textures or is there some independent evidence you have for this distinctly RED Mars color?

Do you actually own a 2 Mpix CCD or was it part of your "holiday arrangement"?

Bye Fridger

[ElPelado]

I read many times that you can make a CCD from a webcam, but my question is: can i make a CCD from any webcam??

[mrzee]

I read many times that you can make a CCD from a webcam, but my question is: can i make a CCD from any webcam??

Web cams come in basicaly two flavours, CMOS and CCD. The cheap ones are CMOS and the more expensive (sometimes only marginaly) are generally CCD.

So, to answer your question, if the web cam is a CMOS type don't bother, the resolution and sensitivity is generaly poor though you can make it work to see an image.

The CCD based webcams are better for this. Look at the specifications, in particular the sensitivity (in lux, the lower the number the better), the resolution, the higher the better and if it's color or B&W.

There are cheap sources of CCD's (in Australia) and may be better suited depending on what you want to do, most provide a comp-video out, where-as webcams are digital encoded and connect sttraight to your PC.

There are other cool things that can be done using CCD's. Since the CCD element is sensitive to IR light it is quite possible to make an IR telescope. To do this get some exposed film (just take it out of the casing in daylight!) it is clear to IR but blocks visible light. Simply get the CCD to look through the film and an IR image will be viewed. To get lower wavelenght IR, ie heat maps, the CCD needs to be cooled from the back. Profesional setups like this can cost tens of thousands, a peltier effect device bonded to the back of the CCD can cool it to the required levels acheives a similar result. Finding a CCD camera with the PCB cut out exposing the CCD element's back is the hard part! It's better to use a B&W element for this as they are more sensitive and the color filters on the CCD don't realy work too well with IR.

Lots of fun things to experiment with and pretty cheaply too! Hope that anwers your question:)

Regards,

[praesepe]

Hi Praesepe,

pretty neat Mars CCD shots! Where did you get that red color from? How did you normalize the RGB weights of your CCD exposures? Did you orient it at the Celestia textures or is there some independent evidence you have for this distinctly RED Mars color?

Thanks!

As you know, CCD sensors are much more sensitive to the red part of the electromagnetic spectrum than the blues or greens so I always use a RGB ratio of 1:2.50:5 in the exposures, then I finally process the images with Photoshop comparing them to visual observations. In my Mars image series, the one on the left is the final result, the others are just variations in order to enhance surface details.

Do you actually own a 2 Mpix CCD or was it part of your "holiday arrangement"?

Yes I actually own it, I got it speccialy for this year's Mars opposition.

I read many times that you can make a CCD from a webcam, but my question is: can i make a CCD from any webcam??

Yes, you can. As mrzee said, webcams come with two types of sensors, CMOS (low light sensitivity and low resolution, ie Quickam Express, and easy versions) and CCD (high light sensitivity ie. Phillips Vesta Pro, Phillips ToUcam, QC VC, QC Pro, ect.). Check these links for comparison:

Quickcam Express shots: (CMOS)
http://www.astrocam.org/qcexpress.htm#E ... 20d'images

Vesta Pro shots: (CCD)
http://www.astrocam.org/philips.htm#Exemples%20d'images

[t00fri]

Hi Praesepe,

pretty neat Mars CCD shots! Where did you get that red color from? How did you normalize the RGB weights of your CCD exposures? Did you orient it at the Celestia textures or is there some independent evidence you have for this distinctly RED Mars color?

Thanks!

As you know, CCD sensors are much more sensitive to the red part of the electromagnetic spectrum than the blues or greens so I always use a RGB ratio of 1:2.50:5 in the exposures, then I finally process the images with Photoshop comparing them to visual observations. In my Mars image series, the one on the left is the final result, the others are just variations in order to enhance surface details.

Do you actually own a 2 Mpix CCD or was it part of your "holiday arrangement"?

Yes I actually own it, I got it speccialy for this year's Mars opposition.

After the 'Pathfinder' people have finally managed to convince me of their orange-brown Mars color, I still would like to understand why Mars looks so preculiarly red in visual observations from Earth!? Your color setting matches exactly my personal impressions, although visually, Mars is so bright that the exact color is hard to pin down.

What is the size of your telescope that you use with the CCD? Looks like not so small...

Bye Fridger

[selden]

Fridger,

Remember that praesepe applied corrections to the RGB channels. It could be that those corrections aren't precisely right for his particular camera.

[t00fri]

Fridger,

Remember that praesepe applied corrections to the RGB channels. It could be that those corrections aren't precisely right for his particular camera.

Selden,

I agree with you, of course, but still there is something striking:
Both Praesepe and I apparently have the same visual impression of the color of Mars: some clear 'rose-pinkish' tone, no sensation at all of yellow-orange-brown.

Praesepe, has represented his visual impression in the color corrections of his CCD shots. So I can see it and compare it with what I think Mars looks like...

Perhaps Chris has also an opinion about it, given his excellent refractor? But he -like me- is probably too far north for really great 'vistas' ...

Bye Fridger

[ElPelado]

some time ago i bought a Genius web cam.
months later, a lightning storke(?, what verb should i use with lightning??) near my house and parts from the computer stop working: modem, mouse, keyboard, mother board... and the cam. after reading about ccd cameras from a web cam, i opened it to see whats inside. but i have a question: how can i know if it was a ccd or cmos??? i chekeced the box and manuals and it doesnt say.

i have an other question: does anybody know if i can fix it? may be its burned, but someone told me that it may be not burned. can i do something?

[mrzee]

Hi ElPelado,

Correct phrase is "lightning strike" but everyone knows what you mean:)

Unfortunately lightning strikes on electronics tend to be pretty fatal even the surges generated from a strike many km's away do great damage.

Visual inspection of the sensing element can to a trained eye determine the type of technology used in manufacture. The better approach however is to get the part number of the device and do a search for it. This will give you both the type and interfacing details. If the camera doesn't work in another PC then the best bet is to get another one. Electronics fails in overvoltage due to excess power (ie heat), the two effects are it will either have fused components (shorted together) or blown (opened circuit). Either inside the device renders it either non functional or partialy functional depending on what/where the failure occured. If the sensing element is fine but the support chips are damaged then they need to be replaced.
No matter which way you go it involves replacing SMD components (very tricky) or making your own interfacing hardware (even more tricky!). The only real chance you may have is if the device had overvoltage protection devices in built as part of the design. These are either SMD fuses, diodes or varistors (transorbs etc). You can either bypass or remove to check if they are faulty. Knowing which to remove and which to bypass is critical. Be warned it requires good understanding of electronics, a circuit diagram, good test equipment, no garantee's and a high probability of shorting the USB power supply on your PC if things aren't done correctly.

Recomend you call insurance company first to see if you're covered. Then visit your local computer store and get another one whether you are covered or not it will probably be cheaper in the long run unless you are very lucky.

Regards,

[praesepe]

After the 'Pathfinder' people have finally managed to convince me of their orange-brown Mars color, I still would like to understand why Mars looks so preculiarly red in visual observations from Earth!? Your color setting matches exactly my personal impressions, although visually, Mars is so bright that the exact color is hard to pin down.

Looks like we've got the same impressions about what Mars look like. I always notice the reddish (i'd also say pinkish tint in some cases) color that I try to represent in Photoshop. I'd say that I'm not the only one that
perceived it, I've seen lots of astrophotos on the net that reflect the same effect...

What is the size of your telescope that you use with the CCD? Looks like not so small...

Well, actually I've got two newtons, (D=114,D=250). As you suppose, I used the last one to take the photographs