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Color/contrast question


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Hey everyone, I have yet another query....

So, attached are 2 pics I snapped with my phone last night. The first was taken through a zoom ep at about 12mm. The second was through a 25mm plossl.

I see a noticeable color difference, so my question is which one is true? or better yet, which eyepiece yields the truest color? 

I have also seen it mentioned that sct's take away some contrast, but do ep's also have an effect on this? 

Saturn 9Jun17.jpg

Saturn 9Jun17 (2).jpg

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Yes, there is no colour difference it is the brightness that is different as the more you zoom in then the dimmer the object will seem and so will appear a different colour, so the lower the number of eyepiece the more you are magnifying so essentially zooming in on the object... :)

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3 hours ago, LightBucket said:

Yes, there is no colour difference it is the brightness that is different as the more you zoom in then the dimmer the object will seem and so will appear a different colour, so the lower the number of eyepiece the more you are magnifying so essentially zooming in on the object... :)

 

3 hours ago, laudropb said:

Hi. I am not sure that you can say there is a colour difference between these photos.  It may just be a difference in exposures. Any way they are both nice images, especially taken with a phone.

Ok, I was adjusting the exposure and zoom in the camera as I was taking them so that would explain it. 

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1 hour ago, Pondus said:

These are good phone images.

I would say both of them have atmospheric dispersion. If you zoom in on image no 2 you will clearly see the color difference on the rings.

 

Rune

Thanks. I have an adapter that mounts to the ep and holds the phone steady. Lastnight was the first time I tried it and was impressed how well my phone camera captured it.

Yeah I'm in Sicily at sea level (I'm assuming is the issue?) so I get to experience the distortion/dispersion. Looking at the planets they "wobble" 

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Always Nice to see images of Saturn, and I really like the afocal ones.

Unfortunately Saturn is years away from beeing high in the sky for me (59N), and when it finally rises it will be With rings edge on...

 

Rune

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4 hours ago, LightBucket said:

Yes, there is no colour difference it is the brightness that is different as the more you zoom in then the dimmer the object will seem and so will appear a different colour, so the lower the number of eyepiece the more you are magnifying so essentially zooming in on the object... :)

Exactly. The first pic is made with an eyepiece of half the focal length compared to the second pic, thus twice the magnification. Since an image has two dimensions, width and height, each doubled, the larger Saturn has 2x2=4 times the area. Spreading the light on an area four times as large makes it four times dimmer in surface brightness, the brightness relative to the area, a very important concept in observation and imaging.

The color is the same because the light coming from Saturn has not changed, but its concentration has. The effect is the same in visual, and highlights why it matters very much to collect lots of light with an objective as large as is practical. To get a feel for all the levels of surface brightness, aim at a bright star cluster like the Pleiades or the Alpha Persei region, and defocus it.

The stronger stars will remain visible even when the defocus is extreme, but the weaker ones will soon disapppear when their surface brightness becomes less than the sky's surface brightness. This ties in with turbulence blurring, air transparency, natural sky darkness with or without Moon, air glow, quality of focus, and light pollution. A very momentous notion.

Edited by Ben the Ignorant
typo
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As well as the sought-for colour in the bottom image we also see more colour aberration with a top edge looking more greeinsh-blue and a bottom one looking more red. One EP may be better colour corrected than the other.

In processing there are ways of intensifying colour without greatly increasing noise. It's a big subject but in essence you make a copy image and discard the colour from it. This you then process for sharpness, detail and contrast and save it. Then you take the colour version and process that withouht pushing for resolution (sharpness) but instead just for intense colour. By not pushing for resolution you will be able to get strong colour at low noise. The colour layer can also be given a slight blur. The final step is to apply the Luminace to the colour as a luminance layer so getting the best of both layers. You can do all this in Photoshop or, probably, in GIMP which is free or Startools which is inexpensive. I only know Photoshop well.

Olly

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6 hours ago, crcooney said:

Thanks. I have an adapter that mounts to the ep and holds the phone steady. Lastnight was the first time I tried it and was impressed how well my phone camera captured it.

Yeah I'm in Sicily at sea level (I'm assuming is the issue?) so I get to experience the distortion/dispersion. Looking at the planets they "wobble" 

I don`t know about sea level being the cause of distortion / dispersion ... when the planets are low in the sky they tend to be harder to see clearly and if you wait till they are higher they should be clearer ... great pics by the way - what zoom lens do you use ? I have the Seben 8-24 zoom lens and it screws directly onto my DSLR with the T adapter .

Edited by Red Dwarfer
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A simple mount can be found to hold a phone-cam, small digital, and even a web-cam for a reasonable price. Here's one that I've seen 'branded' with many names - this one being 'Celetron.'

 

340x340_template.jpg.5c76b0f40c1805f07b459ad707e490ca.jpg

 

Many people have bought these and reported they were terrible mounts. But the problem is they come without proper lubrication, making necessary adjustments a nightmare. Simply disassemble and use a little grease on all the threads. Voila!

Here's one I was playing with holding a Logitech web-cam.

 

IMG_1082.JPG.85b8f158d9a26c857756c08131d0a1bb.JPG

 

I find the colour of Saturn in your post, crcooney, to be quite accurate to what I see in my eyepieces. Very close indeed!

Thank you for these!

Dave

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1 hour ago, Red Dwarfer said:

I don`t know about sea level being the cause of distortion / dispersion ... when the planets are low in the sky they tend to be harder to see clearly and if you wait till they are higher they should be clearer ... great pics by the way - what zoom lens do you use ? I have the Seben 8-24 zoom lens and it screws directly onto my DSLR with the T adapter .

I have the Celestron model. It was about $60, so a reletively cheap ep to get me started and I have no complaints with it 

 

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30 minutes ago, Dave In Vermont said:

A simple mount can be found to hold a phone-cam, small digital, and even a web-cam for a reasonable price. Here's one that I've seen 'branded' with many names - this one being 'Celetron.'

Many people have bought these and reported they were terrible mounts. But the problem is they come without proper lubrication, making necessary adjustments a nightmare. Simply disassemble and use a little grease on all the threads. Voila!

Here's one I was playing with holding a Logitech web-cam.

I find the colour of Saturn in your post, crcooney, to be quite accurate to what I see in my eyepieces. Very close indeed!

Thank you for these!

Dave

I have this guy. 20 bucks on amazon and well worth it, I believe!

That's good to hear. I immediately jumped to a difference in the ep's before considering the camera.  

From the above posts and re-examing the images, I see that there's not really a difference in color, just a change in the brightness 

616BBCsumFL._SL1300_.jpg

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Saturn has always appeared to me to be a very 'soft' yellow colour. From the first time I saw it (we all remember that view, don't we?), and up to today.

But as us humans only recently in our evolution developed the ability to perceive different colours, others likely would call it something else.

Colours are fascinating -

Dave

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The color (hue) appears to be about the same.  The saturation is less in the more magnified version for reasons stated earlier (spreading out the light over 4x area).  Unless you lock white balance between exposures, you're at the whim of your camera's automatic white balance which can vary greatly between exposures.  You appear to have gotten lucky with fairly consistent white balance between the two exposures.  This becomes crucial when stitching together multiple frames to form a collage as for a large nebula or panoramic image.

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