wow loads of stars there... The little Jpeg has loads of compression artifacts, the larger image is well worth it. Excellent image Bert. How do you combat the light pollution? How bad is it from your observatory?
Amazing deep exposure. I liked the colors too, we frequently see other images full with bluish small stars in the core, which is not right to me. Great shot!
Amazing deep exposure. I liked the colors too, we frequently see other images full with bluish small stars in the core, which is not right to me. Great shot!
I'm not referring to these. Blue stragglers constitute only a minority of the stars there, and they aren't enough to make blue as the predominant color.
Here is an animated gif of the same region from my image and an image taken with an AP175 @ F8.3. This is at the full resolution of the Astro Physics refractor image.
AP175: FL 1400mm F8 with PL29050 5.5 micron pixels
Both with Astrodon filters. Both images from southern hemisphere on top quality mounts. His sky would have been far darker.
The RH200 is about six times faster than the AP175 at F8.3. The equivalent sub exposure on the RH200 would be 20 sec for the 2 minute exposures of the AP175.
wow, I looked at your large images for the first time, amazing, so many galaxies. Either one looks great, though I think the second one just feels better?? One of my faves from you
A 200mm aperture scope is not 6X faster than a 175mm scope. Its about aperture not F ratio in that regard. See the Fratio myth paper by CCDstack author Moore. F ratio is more about FOV, a wider FOV allows more flux in from a wider part of the sky.
Yes Greg I am well aware of all the myths that astrophotographers are devotees of.
My estimate was based on sound Physics. I do have a degree in Physics.
If you consider a single pixel detecting the flux from a bit of sky.
This pixel is accumulating signal as well as noise.
For a shorter focal length optic at some given aperture this pixel will collect more photons in a given time from the same evenly emitting extended object than a longer focal length optic at the exact same aperture. Both will collect the same amount of noise for the same exposure length.
Assuming perfect diffraction limited optics the longer focal length optic has a larger Airy disc. Let us just neglect this obvious problem for now.
The shorter focal length optic has higher signal to noise for any exposure length. That is why very faint stuff is recorded above the noise.
The focal ratio myth is a combination of scaling down optics AND pixels.
Reciprocity failure with film also helped this 'intuitive' myth.
Most of real science is counter intuitive. It takes a depth and breadth of knowledge to navigate it.
just imagine.....
