Deep Sky (Prime Focus)

Here the whole telescope serves as a tele photo lens. The then very long focal length requires a stable mounting of the telscope. The mounting should be equipped with an electronic motor drive that in conjunction with alignment of the mount with the rotational axis of the earth points the telescope on the same stars for the time of the exposure. The stars will then be points on the film. Exposure time under a dark sky is 40 minutes. If a depp sky filter is used to reduce sky glow the exposure time can be increased to 2 hours.

For my photography I use hypersensiticed Kodak Ektar 100. Hypersensitication is done for 6 hours in 10% H2 90% N2 forming gas at 60 deg. C and 1.5 bar.

Tests of the new Ektar 200 have shown very nice results. Hypering times are down to about 2hours at 60deg. C and 1.5 bar which makes it much easier to hyper the film on demand. Film grain of the Ektar 200 is nearly equal to the Ektar 100. Exposure times hoever are about half.

Storage of hypered film of the Ektar series is difficult. After 3 to 4 days the film must have been exposed and developped. Otherwise the colorbalance will suffer considerably.

These are some results
M31

M31 - (128K)

Photo : G. Gottschalk, 33cm, f4 Newton, Ektar 100 hyp, 2 hours exposure.

M33

M33 - (342K)

Photo : G. Gottschalk, 33cm, f4 Newton, Ektar 100 hyp, 2 hours exposure.

NGC 6946

NGC6946 (64K)

Photo : G. Gottschalk, 33cm, f4 Newton, Ektar 100 hyp, 2 hours exposure.

Cocoon nebula. Hidden Hills Observatory, 90min, 13" f4 Newton, Kodak PPF400.
Processing:

NGC 253.  Hidden Hills Observatory, 90min, 13" f4 Newton, Kodak PPF400. (Red and green streaks from airplane)
Processing:

Dark nebula Barnard B91 and other nebulosity. A region east of the Lagoon nebula. 6/99 Hidden Hills Observatory, 80min, 16" f4 Newton, Kodak PPF400.
Processing:

Eagle nebula Messier M16. 7/99 Hidden Hills Observatory, 120min, 16" f4 Newton with 2x Barlow, Kodak PPF400.
Processing:


'Three Fingers' central region of Eagle nebula Messier M16. (Enlargement from previous image) 7/99 Hidden Hills Observatory, 120min, 16" f4 Newton with 2x Barlow, Kodak PPF400.
Processing:


 

M1

M1 - (197K)

Photo : D. Hartmann, 45cm, f8 Newton, Ektar 100 hyp

Processing of the pictures is done on a computer after digitalization with Photo CDs. A modified version of the XV programm is used for processing.

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