ED80 has false colour?

[nightfisher]

Here is a bit of a crop from tonights Luna image, is it just me or do i see a little pale yellow around the edge

[Chris]

Maybe the smallest glint around the bottom, Jules.

I'm not sure ED's are said to be 100% colour free, but just very low levels of CA. I think you need a good triplet to get absolute colour free views, but then you get a longer cool down time with a triplet. The Synta ED's are a very good compromise for the price, think I've had 5 or 6 in varying sizes over the years  

Also the Moon has got to be the toughest test.

Very nice image by the way! 

[Alien 13]

Even a triplet will have false colour, light isn't just RGB. The ED80 is probably as good as it gets for a doublet.

Alan  

[xtreemchaos]

that's normal Jules, you can get rid by turning the saturation down on your camera a touch.  charl.

[nightfisher]

Im not knocking it, and now the focuser has been replaced i really like this scope, i guess im just a little surprised to see this

[Stu]

CA can come from a number of places Jules. Could be atmospheric. Even my Tak is not immune to it if imaging the moon.

Was this with a DSLR or afocal?

[nightfisher]

1000D prime focus Stu,

Like i say im not knocking it and love the scope, sorry i did not get to say cheerio at sgl12

[Stu]

On 05/11/2016 at 22:37, nightfisher said:

1000D prime focus Stu,

Like i say im not knocking it and love the scope, sorry i did not get to say cheerio at sgl12

Likewise Jules. I enjoyed seeing your 'mugshot' of me from the drone  

[chiltonstar]

Do we get to see the mugshot?

For comparison, Moon with another ED80 (mine) just now. There is some CA, but it was only 14 degrees above the horizon, and as Stu says....

The original raw file (large) is much sharper.

Chris

[ronin]

There have been a few mentions of minor, very minor, CA on the ED80 over time. So not overly surprised. I think that the general view is that it is present but you have to go looking for it.

[nightfisher]

Funny but its the same hue as i would get with the TAL100, cant help thinking the TAL was slightly better on controlling CA, but very little in it, and the ED80 is more versatile, here is an image from tonight, getting better

[Moonshane]

Not a lot wrong with that Jules. Are you doing single shots?

Do you have a comparable with the Tal?

[wookie1965]

4 minutes ago, Moonshane said:

Not a lot wrong with that Jules. Are you doing single shots?

Do you have a comparable with the Tal?

 I've got his Tal Shane had some great views with it out last night Christmas tree cluster was outstanding. 

[nightfisher]

6 hours ago, Moonshane said:

Not a lot wrong with that Jules. Are you doing single shots?

Do you have a comparable with the Tal?

Yes single shot as not on driven mount, hope to try some stacked from the EQ5 at weekend if weather plays fair, might have a Tal image on other laptop will have a look tonight

[spaceboy]

What was the ISO and shutter speed Jules ? Interesting to see the improvement in the second image. With it only being the bottom portion showing some false colour as apposed to the entire rim I'm wondering if something wasn't properly cooled ??

[Stu]

From my experience the ED80 will have significantly better CA control than a TAL. There can be any number of reasons for it so it's hard to judge unless side by side

[spaceboy]

Not exactly an accurate method but a quick check on stellarium shows the moon on the 5th, at only 16° or so off the horizon when the sun was setting so my guess a lot of the false colour was down to atmospheric diffraction if you were imaging it at a similar altitude.

[nightfisher]

19 hours ago, spaceboy said:

Not exactly an accurate method but a quick check on stellarium shows the moon on the 5th, at only 16° or so off the horizon when the sun was setting so my guess a lot of the false colour was down to atmospheric diffraction if you were imaging it at a similar altitude.

Good post and good point, yes the Moon was low, my location give a bit of a false horizon as the ground drops away sharply past the garden so the moon would appear higher than it really is, as said before i am happy with the ED80 and as time goes by i will get better results from it

[spaceboy]

Seems like a combination of the moon being low and the scope not properly cooled to me Jules. I'm sure you will achieve far better results in the future if you avoid imaging through 2.9 - 12.2 miles of CO2 filled atmosphere.