Focusing CCD cameras at f/3.3 is not for the light-hearted !
The extreme correction causes apparent curvature across the
field and makes it difficult to get pinpoint stars over the
entire pixel area. And this is exactly why the new Series IV
Professional Edition 'Stiletto' was developed!
Here's what Rob Bensko had to say about it:
"I finally had a few clear nights here for some imaging, so I went on a tear and got quite a few nice images. It was easy to focus with the Stiletto IV and the new screen, even at 3.3. I tested the Stiletto against diffraction spikes and are far as I can tell, you calibrated it perfectly. I'm passing along a few images for you to enjoy. Feel free to add any of them to your gallery if you like."
The Series IV Professional Edition incorporates our brand new
high resolution 'Black Chrome' ronchi screen. This is a 300 line/inch
black chromium ronchi grating etched on optical glass. It was
manufactured on the same machines used to etch integrated circuits.
The screen itself is calibrated to within .001mm of the factory spec
for your camera. The result is that even working with f/3.3 focal
reducers will be put in perfect focus in only seconds!
Series IV Standard and Pro Edition models are available for nearly
all 35mm, CCD, and Medium Format cameras. Using our modular approach,
you can go from one format to another on the fly,or easily upgrade
when you move to a different camera model or brand.
Check it out on our website along with Rob's pictures. Take advantage of our Red Tag sale while you're there!