Urban E.E.A. session (27/05/2023) (2) : SiOnyx Aurora Pro + Maksutov 100/750. M57 (lyra) (speed X4).

One more small session, focused on the planetary nebula M57 (Lyra constellation), following the last session here: • Nice E.E.A. session on...
Original video length: around 5mn (speed X1).
Acceleration x4.
Comparison between two afocal configurations:
- (left side): 16mm/1.4 + eyepiece 40mm + Maksutov 100/750
= equivalent focal length 300mm
- (right side): 16mm/1.4 + eyepiece 24mm + Maksutov 100/750
= equivalent focal length 500mm
- Sensor size: 1" (12.8mm x 9.6mm).
Used setup described here (24mm instead of 40mm eyepiece):
• Digiscope : camera SiO...
All details are in the current video, and in the video related to the above link.

[@petrsulc5455]

Thanks for trying. Interesting. It's too dark, isn't that EV.=+2 instead of EV.=+0.3? Or what's the problem?

[@thenightvisionlab]

The EV=+2.0 in this last case was required, it allows to stretch the histogram in order to render the image brighter, but with a trade on the contrast. If i would have adjusted the EV parameter at +0.3, like for the left one, it would have been even more darker, without almost any visible signal. For this last session, the point is simply that the f/# of the equivalent system is to high: with the eyepiece 40mm, (supposing that all of the exit and entrance pupils are matched), f/#= 3 roughly. With the eyepiece 24mm, (supposing that all of the exit and entrance pupils are matched), f/#=5 (roughly). Shortly said, it works, but using a 24 mm eyepiece or shorter focal length would render the system more suitable for brighter target, planet, moon... Because again of the too "slow" (high value) of the f/#.

[@petrsulc5455]

Thanks for the explanation
@@thenightvisionlab

[@thenightvisionlab]

@@petrsulc5455 , my pleasure. Good luck for your own experiences, and please share them with us at the occasion! :)