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ollypenrice

Beehive, 1st Light FSQ106N/Atik 11000

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I already posted a Lum pic with split stars. Looking at my RGB pics, I also get the same rings around stars. Circular in the center and offset towards the corners, with a line of directionality to the center. I use the Atik 11000 chip with this scope, and Baader filters. Yes they are expensive scopes, but also superb. The contrast, sharpness, and flat field on a large chip are excellent. Its colour correction is super, although not as good as the newer Tak version according to the specs, and the owners. The star rings on bright stars and large orb like glow to very bright stars like Rigel may be the only flaws I can find with this scope. The orb / glow look might be from the chip though. Overspilling light from the pixels. Full well depth etc..

post-4679-0-07307400-1363615811_thumb.jp

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I used to get this effect with the Atik 4000 OSC as well, thinking about it, but not the mono. I dare say it's whatever goes on top of the pixels.

Olly

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The effect looks like the spacer shims ( If the 106 has them ). I have the same thing with the FS78. I'm not aware of anyone having the shims reduced to resolve the issue, though some have suggested it.

The rings round the stars look like a reflection between either the chip face and rear surface of the slip cover or a reflection between the slip cover and the rear of the filter. If the reflection was between the filter and rear of the scope it would be much bigger. There are ways of measuring the size of the ring to determine where it's happening.

Here is an FS78 star to show the effect I got on a bright star. No reflection ring with the Astrodon filter though.

Dave.

post-493-0-29562600-1363621736_thumb.jpg

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The effect looks like the spacer shims ( If the 106 has them ). I have the same thing with the FS78. I'm not aware of anyone having the shims reduced to resolve the issue, though some have suggested it.

Might be interesting to test that by making a temporary front aperture stop (cardboard ring?) to reduce the aperture slightly and cover up the outer ring of the objective where the shims are.

Adrian

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Re stars with a weird defraction - I get these on the pentax+383L too. Badder par-focal 2" LRGB filters

I forsee Olly talking to Don..

Edited by NickK

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Might be interesting to test that by making a temporary front aperture stop (cardboard ring?) to reduce the aperture slightly and cover up the outer ring of the objective where the shims are.

Adrian

It's on my To Do list...

Olly

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Great shot. Regarding the image "errors" I wonder if some post-processing could be done, by estimating the point-spread function as a function of position in the image. I had students working on that, but their demo was about detecting problems, and quantifying the degree of the problem, not correcting the problems. In theory at least, it should be possible to correct for systematic errors.

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Isn't it the lens cell spacers that causes the weird diffraction patterns? I've heard it said by other manufacturers when asked about that effect that "Well even Takahashis do that!"

Do all refractors have issues like them? The only ones I have used are a WO72 and a Borg 77ED, so not exactly the best representation. I only ask because a friend wants me to take some images with his large refractor and i'd like to know what to look out for. I'm picking it up tomorrow, I think it is a 6" triplet, does that make sense? I'll be looking for where to adjust the mirrors :D Won't have an 11000 to test it with though :)

On the subject of APODs and spikes, did anybody notice those on the recent Inside Orion pic? :s

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Isn't it the lens cell spacers that causes the weird diffraction patterns? I've heard it said by other manufacturers when asked about that effect that "Well even Takahashis do that!"

Do all refractors have issues like them? The only ones I have used are a WO72 and a Borg 77ED, so not exactly the best representation. I only ask because a friend wants me to take some images with his large refractor and i'd like to know what to look out for. I'm picking it up tomorrow, I think it is a 6" triplet, does that make sense? I'll be looking for where to adjust the mirrors :D Won't have an 11000 to test it with though :)

On the subject of APODs and spikes, did anybody notice those on the recent Inside Orion pic? :s

The FSQ85 used to give these effects with the one shot colour camera but not the mono, usually. So I think that the microlenses/matrices on the chip have something to do with it. I also suspect that a lot depends on the luck of the draw. Will this filter at that separation create reflections on that chip... etc.

I tried processing out the artefacts and you can do it, but how natural it looks is another matter...

Olly

Edited by ollypenrice

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Nice images the tweaks have cetainly helped bring out the cluster in the wider shot which I quite like

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Thanks for sharing the Beehive, nice image! I love the way things come in pairs with this cluster. A hidden bag of gems!!!

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