Connecting a webcam to an unguided/untracked DOB

Scooter · #1 21-02-2008, 04:30 PM

Hi Folks,

Just a quick one to ask about the relative merits of connecting a webcam up to a manual 12” Dob. Doable or don’t bother?

Guess my thinking was connect it up and then view via the image on a laptop rather than through the eyepiece. Now that means the image needs to be real-time and at least equivalent to what I would see with an eyepiece visually. Was wondering if this was doable say with an entry level cam like the Phillips 900NC or a high end cam like the mailincam (sp?)

Wasn’t just about capturing images as I was thinking about say having something like starry night in one window and cam output in another and then manually moving the scope against the software etc. Also then would be able to stream the image so I could show remote people the view through the scope (thus needs to be at least as good as visual). Now I know that the high end cam this was (sort of – not quite real-time maybe??) doable due to high lux and short exposure but what the cheapy cam like?

If I get some added benefit of being able to capture images great

If I understand it right the cam is equivalent to a < 4mm lens yeah? So I am not gonna really be able to do anything manually am I in terms of finding an object and then keeping in view unless I reduce magnification is that right?

Anyway just wondered if it was worth it (that Philips at < $90 looks good as I don’t actually have a webcam so I could justify the spend somewhat for normal webcam uses

) and what peoples thoughts were (especially those with the Philips cam – how do you think it would go replacing observing via eyepieces?). Mind you that high end cam looks the goods for my light poluted back yard......

Thanks in advance

Scott

iceman (Mike) · #2 21-02-2008, 04:32 PM

Hi Scott

Something here just for you

Astrophotography with a Dob

A few years old, but still relevant.

Scooter · #3 21-02-2008, 06:07 PM

Thanks Mike. Actually read it allready (your site and the community are great

) and got a pretty good idea of whats going on now, just needed a little clarification.

First up what are the relatative mm equvilants of say the 900NC and the Malincam? I know I have no problems manually tracking with my 6mm eyepeice but if the 900NC was like a 3mm ep then I wouldn't bother (because as per above not interested in imaging just replacing the ep with a realtime image on the lappy etc.).

From my understanding every cam/ccd combo etc will have a different ep mm eqivilent so I was just interested in what these were for both the 900nc and a higerend unit like the mailincam (yeah - being lazy will try google later

)

Messing around with the A70 afocally I know I could rig up something and then use the stream from the A70 to view from the lappy rather than the ep but the A70 is like 15fps and not a performer in low light thus when I have messed around I can see say 4-5 moons in the ep for Saturn but the A70 will only show 1 (if any) thus the second question was for realtime capture is something like the 900nc gonna be better than the naked eye in the eqivilent ep? I.e if the 900nc is equivilent to 4mm ep then if I see 4 moons in a 4mm ep can I expect to see 4 moons on a single fram from the 900nc (or much better say in the case of the mailincam).

That make better sense than the first post

Scooter · #4 21-02-2008, 11:31 PM

Ok Done some more reading and re the relatative mm equvilants (most web stuff saying the 900nc is between 7-10mm) and found this site:-

http://www.newastro.com/wodaski/pick_a_camera.htm

Check out the actual download version at http://www.newastro.com/newastro/dow...cdCalcFree.asp
as it is pretty cool. Allows me to put in the specs on my GSO scope and save it (has a comprehensive list anyway) and output the details for the 900nc.

So now I know it would give me a 6.2 x 8.3 arcmin FOV with just the camera and scope (with visual aids as well which is pretty cool) so I guess I now need to work out how that translates as eqivalent ep mm.

Found http://www.megastronomy.150m.com/New-QCUIAG/ which has some info etc.

Anyway looks like the cheapy will show me what I am seeing and would be OK for streaming bright objects but darker objects need a much more sensitive cam for realtime viewing.

Oh well might get the 900nc for a play

jjjnettie (Jeanette) · #5 22-02-2008, 08:29 AM

Or you could save up and get a Gstar-Ex.
http://www.myastroshop.com.au/products/gstarcam.asp

erick (Eric) · #6 22-02-2008, 08:54 AM

I've been very tempted Jeanette - but I think an Argo Navis has to come next.

Scooter · #7 22-02-2008, 10:01 AM

Hey Erick - you read that marathon thread on cloudy nights about setting circles? http://www.cloudynights.com/ubbthrea...l/fpart/1/vc/1

I reckon this is a great mod (and can look pretty professional too) and as it essentially is the manual equivilent to the argo (ok - it needs to be coupled with some software but thats easy enough) could be worth doing as it is cheap to implement and should be indicative of the experiance you will get with the more expensive argo solution.

Know I plan to do it ASAP