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Fun with MF images - ARCHIVED - FOR VIEWING ONLY

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Craig Stocks

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This is a composite image done in three parts. The background shows the three stars of Orion's belt, the two insets are telescope views of the Flame Nebula and the Orion Nebula aligned with the star field.

All done with the IQ4150. The background was done with an XF with Phase One 120 MF macro mounted on a SkyWatcher tacking mount The two telescope views were done with the IQ4150 attached to a Cambo tech camera with a Canon lens mount attached to a SkyWatcher Quattro 200 telescope.

Be sure to zoom in to appreciate the details. This copy is reduced to 2000 pixels on the long side. The original is 35,000 pixels tall.

The IQ4150 has both good and bad points for astrophotography. The live view does not work well to focus and you need to find a very bright star. The bigger issue is that it appears to have an unnatural sensitivity to UV which distorts the colors. (Reflection nebulas should photograph as blue but are rendered as pink by the IQ4150.)
 

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drunkenspyder

drunkenspyder

Well-known member
Wonderful Craig! Hard to complain about pink in nebulae though. Just sayin’. ;)

Craig Stocks said:
This is a composite image done in three parts. The background shows the three stars of Orion's belt, the two insets are telescope views of the Flame Nebula and the Orion Nebula aligned with the star field.

All done with the IQ4150. The background was done with an XF with Phase One 120 MF macro mounted on a SkyWatcher tacking mount The two telescope views were done with the IQ4150 attached to a Cambo tech camera with a Canon lens mount attached to a SkyWatcher Quattro 200 telescope.

Be sure to zoom in to appreciate the details. This copy is reduced to 2000 pixels on the long side. The original is 35,000 pixels tall.

The IQ4150 has both good and bad points for astrophotography. The live view does not work well to focus and you need to find a very bright star. The bigger issue is that it appears to have an unnatural sensitivity to UV which distorts the colors. (Reflection nebulas should photograph as blue but are rendered as pink by the IQ4150.)
Click to expand...
 
C

Craig Stocks

Well-known member
drunkenspyder said:
Wonderful Craig! Hard to complain about pink in nebulae though. Just sayin’. ;)
Click to expand...
It does become a problem with astronomical accuracy. Reflection nebulas are created when bright hot (usually blue) stars reflect from dust clouds and should show up as blue. Emission nebulas are created when gases glow and fluoresce from the radiation given off by stars and normally glow red. When reflection nebulas photograph as red instead of blue it distorts reality.

The IQ4150's sensitivity to UV also distorts colors if you use a black light. Rather than recording as light blue it photographs as hot pink.
 
dave.gt

dave.gt

Well-known member
Craig Stocks said:
It does become a problem with astronomical accuracy. Reflection nebulas are created when bright hot (usually blue) stars reflect from dust clouds and should show up as blue. Emission nebulas are created when gases glow and fluoresce from the radiation given off by stars and normally glow red. When reflection nebulas photograph as red instead of blue it distorts reality.

The IQ4150's sensitivity to UV also distorts colors if you use a black light. Rather than recording as light blue it photographs as hot pink.
Click to expand...
Hmmm... distorted reality has been a problem all my life.:)

Seriously, though, your knowledge of such things is astounding! We appreciate your gracious sharing of these outstanding images.:):):)
 
drunkenspyder

drunkenspyder

Well-known member
Craig Stocks said:
It does become a problem with astronomical accuracy. Reflection nebulas are created when bright hot (usually blue) stars reflect from dust clouds and should show up as blue. Emission nebulas are created when gases glow and fluoresce from the radiation given off by stars and normally glow red. When reflection nebulas photograph as red instead of blue it distorts reality.

The IQ4150's sensitivity to UV also distorts colors if you use a black light. Rather than recording as light blue it photographs as hot pink.
Click to expand...
Totally get it. I saw that when using UV in Africa to watch out for the wrong kind of ground critters. I was just having fun, because the pink in some DSOs can appear so beautiful.
 
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Craig Stocks

Well-known member
Another astrophoto taken with the IQ4150, this time showing the Flame Nebula and the Horsehead Nebula. The bright star in the center is the left-most star in Orion's belt.

I feel like the IQ4150 offers some real advantages for astrophotography. The general astro workflow is to take lots of individual frames and stack them to effectively combine the exposure time. It's not unusual to have multiple hours worth of 4 minute exposures to create a final image.

Sadly, I'm not that motivated. This image is made from around 15 30-second exposures combined in Photoshop. (I generally limit my exposures to 30 seconds because my telescope mount doesn't track all that well and I don't want to add the complexity of computerized autoguiding.) As you might expect the individual frames are quite dark so you need to "stretch" the image through a series of curves and levels adjustments. This is where the IQ data really seems to help, it gives me a lot of latitude to stretch the image to bring out subtle details. The tradeoff is the IQ's apparent heightened sensitivity to UV light which really throws off some of the colors and requires additional processing to correct.

As a point of comparison I've also included one of the frames with minimal processing so you can see how much the image data is stretched.
 

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JoelM

JoelM

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Craig Stocks said:
It does become a problem with astronomical accuracy. Reflection nebulas are created when bright hot (usually blue) stars reflect from dust clouds and should show up as blue. Emission nebulas are created when gases glow and fluoresce from the radiation given off by stars and normally glow red. When reflection nebulas photograph as red instead of blue it distorts reality.

The IQ4150's sensitivity to UV also distorts colors if you use a black light. Rather than recording as light blue it photographs as hot pink.
Click to expand...
Can't you put a UV filter in the optical path?

Joel
 
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Craig Stocks

Well-known member
Here's a comparison between the IQ4150 (hot pink colors) and a Sony a7r2 (blue colors). The target was illuminated on the left side by a roughly daylight balanced LED and on the right by a black light. I positioned a piece of foamcore in the middle to separate the two sides so it could be photographed in one exposure. I set the white balance on the left side (which had very little effect). The cord draped across was included because it is pretty reactive to a black light.

As you can see the IQ4150 red channel is much more sensitive to the UV from a black light. Obviously I can adjust the pink to be blue but that shifts other colors along with it.
 

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baudolino

Well-known member
Inspired by a visit with my wife last week to the Albertina gallery in Vienna, where I saw some hyper-realistic flower paintings by the 19th century Austrian painter Ferdinand Georg Waldmüller. Bought some roses at my local florist a few days later. Had an idle evening today, so unpacked my Mamiya RZ67 ProIID with an IQ280 and two Rotolights, to take this picture. Lens Mamiya APO Sekor Z 250mm f4.5

 
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