Something

            Observable
                .Start(() => _channelFactory.CreateChannel())
                .SelectMany(channel => Observable
                    .Timer(TimeSpan.FromSeconds(1), Scheduler.Immediate)
                    .Select(channel))
                .SelectMany(channel => Observable
                    .FromAsyncPattern<string, Stream>(
                        channel.BeginGetImage,
                        channel.EndGetImage)(imageUri))
                .Retry()
                .Repeat()
                .Subscribe(stream => UpdateImageStream(imageUri, stream));