camera focus

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camera focus

Postby john hayhurst » Mon Jan 02, 2017 5:57 pm

I have just bought a celestron 130, when I connect my canon 500d I loose focus it won't adjust enough to focus it any idea's please.

john
john hayhurst
 
Posts: 2
Joined: Mon Jan 02, 2017 5:45 pm

Re: camera focus

Postby Gfamily2 » Mon Jan 02, 2017 9:03 pm

Hi and welcome.
Newtonians can suffer from this as the prime focus from the mirror is often located inside the focuser, and for use with a dSLR you need to get the image on the sensor.
There are a few things you can do -
One option is to replace the focuser with a low profile one that will allow you to gain focus.

Alternatively, you could move the main mirror forward by enough to get the prime focus on the camera sensor - however, this will lose you some light as the secondary mirror is likely to be too small to capture all the light in the light cone.

A third option, and probably the best to start with, is to use a Barlow lens, as that has the effect of producing an image outside the focuser. Unfortunately, this will reduce the field of view you can capture, but if you're imaging the Moon and planets this won't be a problem, and you can mosaic images of larger objects.
Scopes: Meade 8" SCT, Skywatcher 127mm Mak
For imaging: Pentax K5, Asda webcam, Star Adventurer (new toy)
For companionship: Mid Cheshire Astronomical Group.
Gfamily2
 
Posts: 253
Joined: Thu Jun 25, 2015 10:38 pm

Re: camera focus

Postby john hayhurst » Tue Jan 03, 2017 7:32 pm

Hi Gfamily2
Thank you for reply, looking at my options I think the barlow lens is the first thing to try.
I'm new to Astronomy I have always had an interest watching it on tv now having a go myself.
Again thank you for your time.

john
john hayhurst
 
Posts: 2
Joined: Mon Jan 02, 2017 5:45 pm

Re: camera focus

Postby Gfamily2 » Tue Jan 03, 2017 8:08 pm

john hayhurst wrote:Hi Gfamily2
Thank you for reply, looking at my options I think the barlow lens is the first thing to try.
I'm new to Astronomy I have always had an interest watching it on tv now having a go myself.
Again thank you for your time.

john

It's a great challenge - but can be very satisfying when it comes together.
Do you have a local astronomical society? It'll be well worth seeing if you have one nearby; I'm learning a lot from the other members of the one we go to.
Scopes: Meade 8" SCT, Skywatcher 127mm Mak
For imaging: Pentax K5, Asda webcam, Star Adventurer (new toy)
For companionship: Mid Cheshire Astronomical Group.
Gfamily2
 
Posts: 253
Joined: Thu Jun 25, 2015 10:38 pm


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