Quattro 8" first light

[JimStan]

The Sky 6 does not indicate it to be a double star.

Object name: SAO 88016

Other ID: HIP 98375

Magnitude: 5.6

Equatorial: RA: 19h 59m 43s Dec: +23°08'03"(current)

Equatorial 2000: RA: 19h 59m 11s Dec: +23°06'04"

Horizon: Azim: 76°05'42" Alt: +20°15'08"

Alternate names: HIP 98375 GSC 2141:2712 PPM 110149

Visibility: Rise 19:05, Set 09:55

Transit time: 02:32

Flamsteed-Bayer: 14 Vulpeculae

Name 6: HD 189410

Name 7: B+22 3872

Object type: Star

Source catalog: GSC catalog

Hour angle: -05h 27m 35s

Air mass: 2.88

Screen x,y: 304.00, 410.00

Sidereal time: 14:32

Click distance: 3.0000

Celestial type: 0

Julian date: 2455744.5423

[Revs]

Could be a slight misalignment of subs. Could you post a full res. light?

[Black Knight]

It's not misalignment. The problem is evident in every single sub individually.

[Deneb]

I told you "Don't worry be Happy" !

[Black Knight]

Hehe, I am happy! :D

[ollypenrice]

Tricky. Top left is pretty bad and looks like classic coma. Top right is coma-like as well, though far less severe. The bottom corners are closer but not quite right.

How is orthogonality? Hard to check, I know.

Olly

[Black Knight]

Tricky. Top left is pretty bad and looks like classic coma. Top right is coma-like as well, though far less severe. The bottom corners are closer but not quite right.

How is orthogonality? Hard to check, I know.

Olly

That does indeed look like classic coma to me too. I am using the Skywatcher coma corrector, but maybe it's not rated at F4? I thought I had read somewhere that the SW CC was suitable for the Quattro, but I haven't been able to re-find that info again, so perhaps I imagined it!

[Starblazer]

If your individual subs are showing faint doubling then could it be something to do with your mount stalling and causing the doubles? It does see like it's on most the stars in the image, which to me seems odd, there does look to be a little coma also so this will play a part.

There is definitely something a-miss here, could you post up a single sub? with a crop on stars from various area's?

[Starblazer]

Looking back at the subs you posted, they all seem to show what looks like some sort of vibration smudge, sometimes in a couple of directions (if you look at the crops, can see colour variance and smudge at about 4 o'clock and 1 o'clock) If this is repeated over all the subs then it may well be orthogonality. The vast majority show a fainter version of the stars at 4 o'clock across the field.

[Black Knight]

Could you explain to me what is meant by orthogonal please? Sorry for the noobish question

[ollypenrice]

Sure, and if my previous post seemed abrupt I'm sorry! Long nights here recently...

The chip of the camera needs to be at right angles to the light cone coming from the scope (through the focuser). Droop in the focuser itself and/or flexure in the metal tube can cause the chip to be at a tilt. If the focal depth is very shallow, as it is with a fast scope, then not all the chip can be in focus. While the abberations in your image don't look like focus it is often hard to tell so tilt strikes me as a possibility. On the other hand, if you are not using a coma corrector, then the native field is not at all bad, I'd have said. I don't image with Newtonians so I have precious little to go on. My one attempt met with issues arising from non orthogonality.

Olly

[Black Knight]

Thanks Olly, I did wonder if that was in fact what was meant by the term! And no, I did not think your post was abrupt . I am using a coma corrector, so if I am seeing non-orthogonality, I'm not sure how to address it, other than tightening everything down.

Anyway, many thanks for your input. It is much appreciated