Astrophotography With A Reducer - 3 - Above Us Only Sky.....

Jun 2: Astrophotography With A Reducer - 3

Another step forward - I think!

After the disappointment of discovering the flaring on photographic images produced with my 0.5x reducer mounted on my Meade LX-90 ACF telescope, I sought the assistance of Bintel's expertise. They realised from the images I showed them that the problem was not axial tilt, it was the inability of the camera to maintain the optimum back-focus distance for this particular reducer.

So the 0.5x reducer is now allocated to visual observing duties only!

For my LX-90 and Canon 60D, Bintel recommended a Lepus 0.62x telecompressor from Optec, complete with a tube-spacer which is custom built for my camera on my telescope.

Needless to say, it's been mainly cloudy since the new device was delivered three days ago, so I tried a simple daytime test today on power lines about six kilometres away:

1. No Diagonal, No Reducer:

f/10 - estimated FOV= 1.0° x 0.67°

2. No Diagonal With Reducer:

f/6.2, no obvious vignetting. Estimated FOV= 1.4° x 0.92°

3. With Diagonal, No Reducer:

f/10, inverted image

4. With Diagonal, With Reducer:

f/6.2 inverted image, no obvious vignetting

So the Optec 0.62x reducer focuses well inside the LX-90's focusing range, as did the 0.5x reducer but it remains to be seen whether the image flaring experienced with the 0.5x reducer will be eliminated.

It should be eliminated, of course - because the 0.62x Optec reducer has been specifically designed for my telescope and my camera but it seems it may be a while before I can verify that, judging from the long-term weather outlook!

The focusing was satisfactory both with and without the diagonal but it remains to be seen whether the diagonal can be utilised in night sky conditions.

Equipment:

LX-90, Optus Lepus 0.62x Telecompressor, Canon 60D. No Diagonal. Camera points horizontally.