Bubble Nabula HaSHO

[MarsG76]

1 minute ago, MarsG76 said:

The problem that arises is when you crop, if you don't downsample at the same time (or immediately after or before), then the image gets a bit too large for the forum post.

The lower the focal length the sharper the image will look when you zoom in... but I'm not saying to rescale the image, just simply crop the final processed image.... a 4000x3000 image might become 3300x2200, so still should look great.

[Rodd]

For me the RMS is not an easy thing to figure in your head--my guide cam has a different pixel size than my imaging cam--so the RMS values are for the lodestar--not the main camera.  The best way for me to judge guiding in the field (I use Maxim) is to measure the FWHM of the stars.  That tells me 2 things--guiding and focus.  I think my guiding could be improved--for one I am using a guidescope and guide cam with a much larger pixel than my main cam--I am right on the edge of what is considered appropriate--not appropriate in some eyes for 1,000mm.  I really should get an OAG for the TOA--or use the STT-8300 that has one built in (but I got tired of the filter wheel jamming).   After I finish the Iris I am going to switch to 318 mm, so my guiding should be fine.

Rodd 

[Rodd]

26 minutes ago, MarsG76 said:

The lower the focal length the sharper the image will look when you zoom in.

Hmm......are you sure? 

Anyway--what I mean is, when you crop an image, the forum will display the image at a larger screen size that can be too much for the data.  Even without a resample.  So when I crop to make image smaller, which will result in it being displayed at the same size as normal resulting in the target looking bigger (smaller FOV same screen size), I often resample downward so the target looks the same size as it would without the crop-smaller FOV, same screen size, same target size. 

Rodd

[MarsG76]

2 minutes ago, Rodd said:

Hmm......are you sure? 

Yes, as in that the contours look sharper comparing, say, 500mm focal length and 2000mm focal length.. the 2000mm FL images do seem to have a soft focus filter effect through them... I guess that is the fact that I'm magnifying more through the atmospheric distortion.... It's got to be since my tracking is at or below the arcsec/pixel resolution.

[MarsG76]

4 minutes ago, Rodd said:

Anyway--what I mean is, when you crop an image, the forum will display the image at a larger screen size that can be too much for the data.  Even without a resample.  So when I crop to make image smaller, which will result in it being displayed at the same size as normal resulting in the target looking bigger (smaller FOV same screen size), I often resample downward so the target looks the same size as it would without the crop-smaller FOV, same screen size, same target size. 

It shouldn't make a difference if your original image resolution is high enough. Lets say you lose 10 or 15% from the edges from a 12 or 15 megapixel photo... no matter what, the website will still downscale the image to display on a screen..... effectively downscaling it to 1-2 megapixels... Unless I'm missing something with what astrobin does with the images.

 

[Rodd]

27 minutes ago, MarsG76 said:

Yes, as in that the contours look sharper comparing, say, 500mm focal length and 2000mm focal length.. the 2000mm FL images do seem to have a soft focus filter effect through them... I guess that is the fact that I'm magnifying more through the atmospheric distortion.... It's got to be since my tracking is at or below the arcsec/pixel resolution.

I think it depends on pixel size.   When you zoom on a wide field image that has a resolution of 3.5-4 arcsec/pix, it does not hold up well.  But if you use smaller pixels and that same widefield image has a resolution of 2.4 arcsec/pix, it will hold up better. 

 

25 minutes ago, MarsG76 said:

It shouldn't make a difference if your original image resolution is high enough. Lets say you lose 10 or 15% from the edges from a 12 or 15 megapixel photo... no matter what, the website will still downscale the image to display on a screen..... effectively downscaling it to 1-2 megapixels... Unless I'm missing something with what astrobin does with the images.

 

No--the forum (SGL) will portray the image the same in the discussion mode--but if you click on it (not full resolution but isolate it by selecting it) it will be displayed larger depending on the crop.  That's my experience anyway.  Here, an example.  First image is normal (it is one of my bubble versions--don't know which one but its not important.  It was slightly cropped from the full image but that should matter for this demonstration).

 

Rodd

Full size

 

crop

 

Edited August 2, 2019 by Rodd

[MarsG76]

7 minutes ago, Rodd said:

I think it depends on pixel size.   When you zoom on a wide field image that has a resolution of 3.5-4 arcsec/pix, it does not hold up well.  But if you use smaller pixels and that same widefield image has a resolution of 2.4 arcsec/pix, it will hold up better. 

 

No--the forum (SGL) will portray the image the same in the discussion mode--but if you click on it (not full resolution but isolate it by selecting it) it will be displayed larger depending on the crop.  That's my experience anyway.  Here, an example.  First image is normal (it is one of my bubble versions--don't know which one but its not important.  It was slightly cropped from the full image but that should matter for this demonstration).

 

Rodd

Full size

 

crop

 

Yes, but thats a very heavy crop, you're only keeping 25% of the frame and stretching it to the original size, in this case yes, it would be softer but I'm talking about only cropping maybe 10% from the edges...

I attached the crop I'm was trying to explain.... losing some of the data isn't that bad.

 

[Rodd]

11 minutes ago, MarsG76 said:

es, but thats a very heavy crop, you're only keeping 25% of the frame and stretching it to the original size, in this case yes, it would be softer but I'm talking about only cropping maybe 10% from the edges...

I did not mean to suggest that this would be OK--I only posted this to make my point that the forum posts images differently when you crop them.  This was an extreme example.  But when I posted the image originally, it took me a while to figure out if I wanted to crop at all and by how much for the best portrayal of the image.  Then again, I am hyper nit picky when posting my images.  As time passes, my preference in which version I like better blurs and I often ridicule myself for being so picky

Rodd

[MarsG76]

4 minutes ago, Rodd said:

I did not mean to suggest that this would be OK--I only posted this to make my point that the forum posts images differently when you crop them.  This was an extreme example.  But when I posted the image originally, it took me a while to figure out if I wanted to crop at all and by how much for the best portrayal of the image.  Then again, I am hyper nit picky when posting my images.  As time passes, my preference in which version I like better blurs and I often ridicule myself for being so picky

Rodd

I think we're all picky about our work.. simply we are comparing our images to the Hubble (whether consciously of subconsciously) and are always critical about our pics, but ultimately there is hardly any difference and the differences that are there are only visible because of the side by side comparison.. individually they look the same..

Compare your photos from astrophotos published in books mid 1990s, pre hubble era, and you'll realize just how good amateur astrophotography has become.

 

 

[Rodd]

14 minutes ago, MarsG76 said:

Compare your photos from astrophotos published in books mid 1990s, pre hubble era, and you'll realize just how good amateur astrophotography has become.

I know--its rather amazing really

Rodd

[MarsG76]

6 minutes ago, Rodd said:

I know--its rather amazing really

Rodd

Definitely. Some amateur images today a way, WAY better than the pros upto the end of 20th century....

 

Edited August 2, 2019 by MarsG76