Astrophotography equipment Q's

Hi Antony

Thanks for the pics, just have another question for you, what does the focal reducer do and how does it make a difference to the image.

Thanks

Hi John,

As the name suggests, the focal reducer is a special type of lens which reduces the apparent focal length of your system and, as a result, leads to a larger field of view.

With the C14, for example, we have a focal length of 3910 mm. With the f/6.3 reducer in place, we have an apparent focal legth which is now 2463 mm (ie. 3910x0.63). This reduction allows us to increase our field of view by about fifty percent in each dimension.

Focal reduction is especially important for scopes with a small field of view.

Oh I see
Just one more question. This might sound stupid but what is that big box attached to the Taurus tracker 3.

John,

I suspect you are referring to my CCD camera (SBIG ST-2000XM). As for the reducer and like all SCT reducers, it is round and threads on the back of the SCT. If you look at the first photo whose link I provide above, you will see it.

So that there is no misunderstanding, reducers for refractors are generally known as telecompressors (same function but slightly different name for whatever reason).

John,

Whatever means you use to attach the D80 at prime focus, you'll need a 40mm extension tube to fully illuminate the CCD and eliminate vignetting.

You will have to get a Nikon F-mount t-adaptor and something that fits your focuser and has the corresponding t-thread. Check the box of accessories that came with the LXD75, you may find that there's a focuser attachment with a t-thread in that. It'll be the only thing there that has a male thread on the end.

John,

If possible try and get the variable extender (as opposed to the fixed length one) so that you can customize to suit your needs and the particular object of interest.

I am certain the pricing is virtually identical between the two types of extenders.