A few noob questions...

[richmk3]

Hi guys.

Im currently saving to buy myself a Skywatcher 200p and mount. But me being me, I got itchy feet and recently brought myself a little stop-gap scope for my daughter and I to get started.

Its a Helios 114mm reflector with a 1000mm focal lenght on an eq mount. I picked this up 2nd hand for the bargain price of £50, and I have to say im quite impressed with the views of the moon.

Anyways, I have modded a cheap 640x480px microsoft lifecam and fitted it to the scope. My problem is two fold...

1. Why is the image so much closer than when viewed throu the 20mm eyepiece? And how can I improve this?

2. Why is the image quality so bad? Its in focus, just bad quality and appears to "boil" at the edges. Would a better quality 1080p webcam be any better?

Thanks for looking,

Rich.

[Laurie61]

HI, the cameras small chip size coupled to the scopes 1000 mm focal length create the same effect as using a short focal length eyepiece, so high mag image. This is probably also responsible for the boiling effect you see as you are magnifying the seeing conditions. This is turbulence in the atmosphere and it varies from night to night.   

[ronin]

Get a tape measure and measure the length of the actual tube.

If it is about 500mm then the design is a Bird-Jones, if the tube is about 1meter then it is a straight reflector.

The above information is relevant.

If the tube is long then I suspect the mirror is spherical, causes a bit of degridation in the image.

"Boiling" may be the atmosphere.

[richmk3]

Thanks for the replys guys.

Yes, the tube length is approx 500mm. Would it make any difference if the camera sensor were further away, ie had a longer tube where fitted into the ep?

Think I will try a better cam with a larger sensor.

[Leveye]

The turbulent air causes the "boiling" and intermittent distortion of the image you see. Later down the road you will find that by stacking only the less distorted images captured you can create a very well defined clear image of your subject. If your just doing the moon and planetary stuff centering the object should give you the best results with a budget scope. Welcome to astrophotography. Jump in the waters fine.

[richmk3]

Also just to add, I realise this scope will not give amazing results, and I dont expect miricals, but the visual views of the moon were very good.

[ronin]

Going to be very "unfriendly" here and say I would not bother trying, well not too hard anyway.

The whole tale will be:

The mirror will be something like a 500mm spherical mirror, giving a poor image - short and spherical are a bad combination.

The focuser will have a lens in it that acts like a barlow, thus going from about 500mm focal length to 1000mm. This "barlow" is not great and so it makes the image worse.

Imaging as said with a webcam is a case of focus image as best you can, take a movir (,avi file) and then process in Registax and select the best 10% (say) of the frames. These are stacked and the result "polished".

Give it a go and at least you will learn now things that you can use later. May as well get a bit of a head start.

Welcome to astrophotography. Jump in the waters fine.

You can tell the water is fine by the number of nice big sharks that are circling. :eek: :eek:

[richmk3]

Thanks ronin

As said the scope is only a stop gap, and somthing for my 5yr old to use until I get the one I want.

The wife takes a dim view of me blowing the best part of a grand on a scope and heq5 lol

£50 was deffo worth it just for the look on her face the first time she looked at the moon the other night and saw all the detail in the craters/surface.

Thanks again for the advice guys.