Observation by Kevin Gurney: Milky way around Deneb

Uploaded by

Kevin Gurney

Observer

Kevin Gurney

Observed

2017 Sep 24 - 00:30

Uploaded

2017 Oct 02 - 08:45

Objects

Deneb
The Milky Way

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Constellation

Cygnus

Field centre

RA: 20^h41^m
Dec: +45°07'
Position angle: -7°14'

Field size

7°32' × 6°01'

Equipment

Tokina 70-200mm lens (MF)
Atik 460EX mono, SX guide cam
Skywatcher AZ-EQ6-GT
Pixinsight
Geoptik EOS CCD adaptor, Fotodiox EOS adaptor

Exposure

5min subs, bin 1x1, 4 subs.

Location

Kelling Heath campsite

Target name

Deneb, surrounding star fields, and nebulosity

Title

Milky way around Deneb

About this image

The weather at Kelling was 'mixed'.... So I decided to try a 'simpler' rig that did not demand as much exposure time (in principle) to get something worth having. This used an old 70-200 zoom Camera lens I inherited from my Dad (he was a keen and technically accomplished film photographer but was always terrestrial in his pursuits). I had bought adaptors to fit my CCD to this lens with a view to doing some wide field imaging. Here was the perfect opportunity...

A first experiment with the lens wide open at f4 showed severe coma around the edges (I had read about this but needed to see it first hand :). I stopped down to f8 and you can see the result. The zoom was set to 70mm to get widest field possible. The effective aperture here is pretty small but there is a relatively large amount of light being recorded.

I would like to use filter sets with this rig (and with different lenses) but the backfocus on camera lenses is limited, making focus impossible with a filter wheel (I did try). The only solution I can see is from Starizona (replace the Geoptik) , or to use the Baader UFC system in front of the lens.

Files associated with this observation

stretch3small.jpg (507.5 kB)

Like this image

Jeremy Shears, Charles Graham Taylor, Dawson, Paul Anthony Brierley, Peter Carson

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