Astro Physics Reducer CCDT67 question

[Catanonia]

Reading between the lines, the Astro Physics CCDT67 reducer will work well on the ED80

but

Will it work on my SW EvoStar ED120 Pro Diamond Black refractor at 900mm F7.5

If it will, what is the trade off, do I loose focal length or is it gain / gain?

If I do use it, what will my F Stop be? I am calculating F5.05. Is this correct ?

Also if I get it, is it a straight fit, or do I need other parts to get it working ?

Many thanks

Cat

[Ben Ritchie]

Hi Cat, I have one which I use with both an 80ED and a 130mm f/8, so not that different to your 120ED.

Will it work on my SW EvoStar ED120 Pro Diamond Black refractor at 900mm F7.5

Yes, although (regardless of 'scope) it depends on the CCD size too. According to Roland the CCDT67 is good for chips up to ST-10 size, larger and you need the 27TVPH reducer (other makes are available ). If - guessing from your .sig - you're using a DSLR then I don't think you want a CCDT67

If it will, what is the trade off, do I loose focal length or is it gain / gain?

It reduces the focal length by approximately a factor of 0.67 (exact factor depends on reducer-CCD spacing, but is fairly tolerant of that - unlike a flattener it is not designed for any particular spacing).

If I do use it, what will my F Stop be? I am calculating F5.05. Is this correct ?

Approx 7.5*0.67 = 5.025, as above will vary slightly depending on spacing

Also if I get it, is it a straight fit, or do I need other parts to get it working ?

It's designed to work with the AP T-2 to 2" nosepiece, the other end attaches to the T-thread on a filter wheel etc. It's very easy to fit to a standard refractor focuser.

HTH

[Catanonia]

Many thanks mate,

Using a modded 350D dslr, so I guess will not be much use to me then and will reduce the focal length, trade off, don't get anything for nothing.....

Assume you not sold your ED80 yet or the 67 ?

[Ben Ritchie]

Using a modded 350D dslr, so I guess will not be much use to me then and will reduce the focal length, trade off, don't get anything for nothing.....

Yeah, I don't think it'll work for you - a reducer's good for getting more field of view from a small-chip CCD, with that DSLR you've already got a wide field and I don't think the CCDT67 covers it fully without vignetting and/or distortion.

Assume you not sold your ED80 yet or the 67 ?

Nope, not even had a query from Alan so things must be bad

[Catanonia]

Many thanks for you honesty mate as you know I was enquiring after your 67.

I really should learn to use what I have already

Yeah, I don't think it'll work for you - a reducer's good for getting more field of view from a small-chip CCD, with that DSLR you've already got a wide field and I don't think the CCDT67 covers it fully without vignetting and/or distortion.

Nope, not even had a query from Alan so things must be bad