Camera to telescope

[Notts star]

Hi could you help me i just bought a t-ring to join my camera to my telescope it fits ok but i CAN NOT FOCUS on anything i have tryed with the moon and its just a white shape im i doing something wrong or do i need to add something

[Cornelius Varley]

The problem is that the camera is too far away from the point of focus of the telescope. This can be easily cured by using a barlow lens to move the point of focus further away from the telescope.

Peter

[Starlight 1]

I think you have to put a barlow in to get focus .

[Notts star]

How do you do that the t-ring i have got screws on to my focuser so when i put the barlow in i cant fit the camera to the t-ring

[Veracocha]

You need an extension tube to increase the distance between the camera and the secondary.

[Cornelius Varley]

You need an extension tube to increase the distance between the camera and the secondary.

That won't work. The camera is too far away from the secondary to start with. By using a barlow lens the point of focus is moved further away from the secondary and the camera will be able to focus.

Peter

[Cloudwatcher]

The Skywatcher x2 Deluxe Barlow Lens is threaded to fit a T-ring. Just screw it on and attach to your camera.

HTH.

[DoctorD]

Hi

My understanding is that the addition of a Barlow will move the focus point away from the primary and a reducer will move it towards the primary.

This is why reducers often need significant inward focus which cannot always be acheived, whereas a Barlow can always be used but may need extension tubes.

You could try racking the focuser fully out and then holding the camera near the focuser to see if you can acheive focus - if you can then all you need is an extension tube.

Hope this helps

Paul

[Cornelius Varley]

Hi

My understanding is that the addition of a Barlow will move the focus point away from the primary and a reducer will move it towards the primary.

This is why reducers often need significant inward focus which cannot always be acheived, whereas a Barlow can always be used but may need extension tubes.

You could try racking the focuser fully out and then holding the camera near the focuser to see if you can acheive focus - if you can then all you need is an extension tube.

Hope this helps

Paul

The majority of reflectors. except those specifically designed for astrophotography, is that there is insufficient inwards focuser travel, this problem is well documented on the site. The solution is to use a barlow lens to move the point of focus further away from the telescope or physically move the primary mirror either by shortening the tube - not recommended or by using longer collimation and locking bolts.

Using an extension tube on a reflector just moves the camera further away from the point of focus.

Refractors usually have the opposite problem- not having sufficient outwards focuser travel, a short extension tube is usually all that is needed to fix this.

Peter

[Veracocha]

The op says he has attached the camera to the tube already and can't get focus, this is without any form of extender/barlow. Therefore I can't understand how the camera can be too close?

[DoctorD]

Hi Peter

Thanks for the explanation, I agree that a Barlow would help in this situation.

Apologies if I confused matters.

Clear skies

Paul