KAF-3200ME Note

Technical Note
KAF-3200ME CCD
April 15, 2002

An effect of the microlens on the 3200ME CCD has been reported that the user should recognize as normal for this CCD. Images captured at fast focal ratios may show a small spike (similar to a diffraction spike seen in images taken through Newtonian scopes) on bright stars. In our view the additional Quantum Efficiency of the new CCD is clearly worth this difference:


ST-10E image of Mizar Enlarged 300%	ST-10ME image of Mizar Enlarged 300%

The bright double star Mizar was imaged through the same 5.1" F/6 EDF Astro Physics refractor with the ST-10E and ST-10ME cameras within minutes of each other. The stars in both images are saturated with the brightest star of the pair beginning to bloom underneath in both frames. The enlarged ME image on the right shows the vertical "spikes" from the top of the stars. Otherwise the images appear nearly identical with virtually the same FWHM in the horizontal direction. Greater variations in star sizes caused by seeing were observed using a single non-ME camera. The ST-10ME star image is brighter than the non-ME due to the higher QE of the CCD.


ST-10E image of Alcor Enlarged 300%	ST-10ME image of Alcor Enlarged 300%

The two images of Alcor, above, are from the same frames as Mizar. The Alcor images are not saturated and no diffraction spikes are seen. Reports we have received from customers who have upgraded from the ST-10E to the ST-10ME have been very favorable for the ST-10ME's increased sensitivity. We also feel that the additional QE made possible by the microlens version of this CCD far outweighs this small effect, and we continue to recommend the ME version as the ST-10 model of choice. But the choice is the customer's. We view the decision as similar to the ABG vs. NABG choice for the ST-7 and ST-8 cameras. The non-ABG versions have much higher sensitivity but no anti-blooming protection so some blooming will occur. In the case of the ST-10XME, one gets higher sensitivity but small spikes on bright stars at fast f/ratios. We will continue to offer the customer the choice of the ST-10XE using the KAF-3200E CCD, so long as it remains available from Kodak.

ST-10ME User's Comments:

"I have an ST-10ME. While it is true that the spikes do exist, I have decided that for me, they are not objectionable, considering the increased sensitivity."
- Tom Carrico http://www.ccdargo.com

"After a wait of a year the camera finally arrived and Hey Presto the sky cleared. What a light sensitive piece of kit. This is my first image taken this morning with the camera mounted on the16" LX200 and comprises 80 minutes L (1x1) and 10 minutes RGB (2x2) at F6.3. Digital development applied to the L in Maxim. The image is at www.gordonrogers.co.uk" - Gordon Rodgers