help

I have here, my canon 400D attached via the t-ring and t-adapter into the visual back of the C11. Is it possible to insert the celestron eyepiece filters into the light path before it reaches the ccd?
Is this only possible when coupling the camera directly to the eyepiece?

Hi Karl

What you need is a tele-extender you put an eyepice inside then you can get higher magification



The Deluxe Tele-Extender for Schmidt-Cassegrain telescopes is a hollow tube that allows you to attach a camera to your telescope, with an eyepiece installed. By using the Deluxe Tele-Extender in combination with an eyepiece, you can increase your instrument’s effective focal length to well over 10,000mm! And this corresponds with a matching increase in image size. This technique is known as eyepiece projection photography. The following formula can be used to determine approximate effective focal length:

EFL = Telescope focal length/Eyepiece focal length x DF (the distance from the center of the eyepiece to the film).

The Deluxe Tele-Extender is used for high-power lunar, solar and planetary photography as well as for extreme terrestrial photography. It fits over the telescope’s eyepiece (even large eyepieces such as those in Celestron’s Ultima line), and connects to the visual back of the telescope. Optional counterweights will be necessary to properly balance the telescope when using the Tele-Extender.

To use the Deluxe Tele-Extender, remove the diagonal from your telescope and insert an eyepiece directly into the visual back. Place the Tele-Extender over both the eyepiece and the visual back, then attach your 35mm SLR camera to the back of the Tele-Extender, using a T-Ring. The Tele-Extender’s built-in safety device will help prevent your eyepiece from becoming accidentally dislodged.

There are a few things to keep in mind when using this accessory. First, the image you’ll see through your camera’s viewfinder will be upside-down. Secondly, due to the extremely high magnifying effect afforded by this accessory, extra care to prevent camera and telescope vibration, accurate polar alignment and use under good seeing conditions will all assist you in capturing high quality images.

Karl how are you getting with your polar alignment

I have here, my canon 400D attached via the t-ring and t-adapter into the visual back of the C11. Is it possible to insert the celestron eyepiece filters into the light path before it reaches the ccd?
Is this only possible when coupling the camera directly to the eyepiece?

Hi Karl,

It depends on what filters you have. Due to the size of the chip, you will need 2" filters. What I do is I have a 2" T-adapter which will fit into a 2" diagonal or 2" focuser or 2"-to-SCT-thread adapter. The 2" T-adapter looks like this: www.amazon.com/Orion-T-Adapter-Focusers-...lector/dp/B0000XMUOQ You simply screw the 2" filters onto the end of the T-Adapter, just like would screw the filters onto a 2" eyepiece.

If you have 1.25" filters, you can use a 1.25" T-adapter like this: www.telescopes.com/products/zhumell-univ...a-adapter-30842.html However, 1.25" adapters will block some of the light reaching the chip and cause vignetting; example here: www.peraltaskies.com/digicam/2004-04-28/TheStraightWall.jpg If you don't have filters yet and would like to buy them, my advice would be to make sure to get 2" ones.

Hope this helps,

WOOPS I must read the thread more carefully sorry Karl :oops: :oops: :oops:

Hi Karl,
I just cant see 1.25 inch filters working well with this camera, so I'll presume you are using 2 " filters, not using a diagonal and have SCT thread at the back of your scope.
There is a BORG adapter (2 parts) that allows any 2" filter to be placed between your t-threads and SCT scope, go to the bottom of the link here and you'll see the adapter explained.
www.videoastronomy.com/idas_filters.htm

As with most BORG solutions, its fairly pricey but its exactly what your looking for. I have the earlier 300D and this adapter and it works a treat with ALL 2" filters !.

How much is that eyepeice extender Carl?

I have the filters from the celestron case of eyepieces..