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Astrophotography with 76mm/300mm focal length/f4 reflector telescope?


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Hey everyone, hoping someone can provide me with some insight on this situation.

I have always been fascinated by the night sky, but only recently bought my first telescope which is a Celestron Firstscope 76mm/300mm focal length/ f4 speed reflector telescope. The telescope itself works brilliantly with any eyepieces I have, but I have tried using a modified webcam and a telescope cam and I hardly get anything when hooked up through the eyepiece. The telescope just doesn't want to focus with a cam attached. I have tried using a couple of different programs including sharpcap 2, messing around with settings including settings provided by very helpful users of this website with no luck. I'm wondering if my little f4 is too fast for imaging, but I have seen youtube vids that people have taken with the same or similar telescope with fairly good results.

I feel like I could be missing something very basic here, being a beginner and what not.

Thanks in advance for any advice! 

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What are you trying to image? I assume from the focal length and aperture of the scope you are after deep sky objects rather than planetary imaging?

If you cant reach focus, you may not have enough back focus. Meaning you need more distance between the focus tube and the camera chip. 

I would also advise against using a webcam for imaging DSOs as from what i have seen they do not produce nice images at all and may put you off all together. You may want to consider buying a DSLR or maybe borrowing one from a family member or friend to try.

Can you provide a link to the exact scope you are using please? That way we can see what we are dealing with here :)

Callum

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Have you tried holding your webcam (you have already modded it and removed the lens) very steady and very very slowly pulling it back out of the focuser unit (having first set your focus tube to it's furthest in position and pushed the webcam right in and then already wound the focus back out slowly as far as it will go) can you see whether you are running out of back focus? Or is it that you did that in reverse and you ran out of in focus travel?

Once you know in what direction you need more focus travel you can then consider your options.

If you can get focus be fun on the Moon :-)

Do you have aa link to the webcam you bought as I remember now you bought a second one?

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As ikose7 says, it's quite likely that the focuser doesn't have enough travel, either inwards or outwards. It's quite a common problem with scopes primarily designed for visual use. The easiest way to check this is by sighting on a distant object in daylight. You could also try removing the diagonal if you are using one. 

f4 certainly isn't too fast for imaging, faster is generally better for imaging DSOs. However, any optical distortions that the scope produces will show up more in images than through the eyepiece, imaging is less forgiving of equipment visual.

Webcams are good for lunar and planetary imaging but not much good for imaging DSOs.

Hope that is some help.

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I am interested in planetary imaging but I realize with this kind of telescope It will be far from amazing by any means, I'm really interested in everything the night sky holds. I have a Logitech c270 and a cheap telescope cam. The USB telescope camera is just a cheap 0.3mp webcam that slides into the eyepiece holder, i'm not expecting anything great but the USB cam won't focus and neither will my Logitech webcam. I tried slowly pulling both cameras outwards to achieve focus with no success while observing the moon.

I will be buying some better kit in the future, telescope and camera. I think the DSLR is the way to go eventually.

Thanks for the quick response!  :smiley:

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I think you are right about the focus travel, either inwards or outwards. If the focus problem is inwards then there isn't any way to remedy that is there? Might be worth making some kind of extension tube to see if it the focuser needs more outwards travel then buy one if it works?

This isn't a big deal as i'm not expecting much from such a small telescope, for regular viewing I was pleasantly surprised how good it is.

Thanks again, really appreciate the advice!

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I have a really cheap 3x barlow lens, which I didn't care about breaking. I popped out the lens, so it's just a tube now that will neatly house my USB telescope cam, hopefully if the issue is not enough outwards focus this will fix it. When I get a chance I will try it out, it will add about 3" of outwards focus.

Thanks for all the help!

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It might be too much outward it is a fiddly case of working out what you need in or out and then trying with what you have to find the sweet spot.

You can't be much out can you work out what the distance difference is between the webcam that worked and this webcam?

Good luck.

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It's just really strange, I set up my telescope outside and had the webcam running. I tried it with and without the Barlow tube and it wouldn't focus either way. Lots of beginners telescopes from Orion and Celestron seem to ship with smaller eyepieces and a Barlow, but the 76mm Firstscope ships with 20mm & 10mm eyepieces which only give 15x/30x magnification but work fine. Eventually I would like to get a DSLR when I upgrade to a bigger telescope.

Thanks for the help everyone! :smiley:  

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You don't say what mount you're using. For DSOs which need long exposures, your mount would need to track and preferably auto-guide, such as the SW HEQ5 Pro mount which is expensive. If you don't auto-guide you can take shorter exposures (subs) of brighter DSOs such as the Dumbbell Nebula which I managed to take with 30 subs. Better with more!

I don't know your scope or how heavy it is, but if it's just that you'll be using, look into an Astrotrac. It might not be able to take the weight though, plus the DSLR.

Many nebulae emit in hydrogen alpha so you would need to have the IR filter removed from the DSLR ('modded') to pick up much of the light. Or take images of galaxies, globular clusters, reflection nebulae etc.

As has been said: DSLRs or dedicated CCD cams for DSOs. Webcams or cams like the ZWO ASI 120 for planetary. But planets are small and need longer focal length scopes, unless you go for the Moon.

Alexxx

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Hey everyone, hoping someone can provide me with some insight on this situation.

I have always been fascinated by the night sky, but only recently bought my first telescope which is a Celestron Firstscope 76mm/300mm focal length/ f4 speed reflector telescope. The telescope itself works brilliantly with any eyepieces I have, but I have tried using a modified webcam and a telescope cam and I hardly get anything when hooked up through the eyepiece. The telescope just doesn't want to focus with a cam attached. I have tried using a couple of different programs including sharpcap 2, messing around with settings including settings provided by very helpful users of this website with no luck. I'm wondering if my little f4 is too fast for imaging, but I have seen youtube vids that people have taken with the same or similar telescope with fairly good results.

I feel like I could be missing something very basic here, being a beginner and what not.

Thanks in advance for any advice! 

This scope is probably designed as a visual scope so the focuser does not have enough inward travel for imaging . Some folks move the primary mirror up the tube to bring the focus point more outwards but I doubt if this would be a practical proposition for a short and fast Newt such as yours.

A.G

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I've got a 80eq refractor a Starshoot usb cam 5mm high power and T510NG color digital camera. My refractor is a slow f11@900mm fl and images just as good as my Z10 reflector but, reflector has to be spot on collimated. This is a must to be able for the light path to hit the sensor, if it's off you won't get an nothing but, a bright disc.

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