f/6.3 Focal Reducer mod??

[zakkhogan]

I have the Meade f/6.3 focal reducer, is it possible by use of an extension tube (i.e. a Glass less barlow) to increase the FOV to say that of an f/5 ?

I use the the reducer with Celestron CPC 800

Thanks

Craig

[michael.h.f.wilkinson]

The focal reducer does not grab more of the image plane than a 2" EP could. The F/6.3 reducer (I have one) yields an illuminated image circle of about 27-28mm, so combined with, e.g. a Panoptic or MaxVision 68 deg 24mm EP, or a 32mm Plossl, you get the maximum field of view possible with 1.25" EPs. 2" EPs might be able to get a bit more, but faster reducers (like the F/3.3 that Meade produced) are more about small CCD chips than about visual. You can change the effective reduction varying the distance from lens to image plane, but this may have an adverse effect on correction (field curvature, coma). I think you need to get the chip closer to the lens to reduce the focal ratio.

[zakkhogan]

Thanks Michael,

this is for photography, i currently use the f/6.3 with my Canon EOS 300D, so do you recommend just investing in f/3.3 reducer then?

*Just realized i posted in the wrong thread, if a mod could move it for me that would be great

[michael.h.f.wilkinson]

The F/3.3 illuminates just a 15mm circle I think, so it would vignette heavily, I am afraid.

[mindburner]

The focal reducer does not grab more of the image plane than a 2" EP could. The F/6.3 reducer (I have one) yields an illuminated image circle of about 27-28mm, so combined with, e.g. a Panoptic or MaxVision 68 deg 24mm EP, or a 32mm Plossl, you get the maximum field of view possible with 1.25" EPs. 2" EPs might be able to get a bit more, but faster reducers (like the F/3.3 that Meade produced) are more about small CCD chips than about visual. You can change the effective reduction varying the distance from lens to image plane, but this may have an adverse effect on correction (field curvature, coma). I think you need to get the chip closer to the lens to reduce the focal ratio.

hi I have been messing around with a Antares 6.3 focal reducer trying with some success to get it to play ball with my refractor. I have found that moving the CCD chip further away from the focal reducer increases the focal reduction as the image gets smaller?