What is going on

[Shelster1973]

on two fronts here......I may have an idea as to what is occuriong, but looking for validation really.

1st of the two are the rather nasty looking blobs that are there.  I am guessing that is down to some sort of debris on the sensor?  Have run the sensor cleaning utility a few times but they do not seem to shift at all.  Am guesing am going to have to look at getting the sensor cleaned?  Any ideas on how to do that on a D7100?

2nd is the star shapes, they all appear to be blobby triangle shapes.  I am thinking this may be down to pinched optics?  I did clean and re-spot my primary a few weeks back.  Would it be worth my while backing off on the screws that hold the primary in the cell?  If it aint that, then what do people think it may be?

Have not done anything to it yet in PI other then calibrate, debayer, register, integrate, run a DBE on it and then colour calibrate.  The image above is a quick and ready stretch in PS to show my issues

[wavydavy]

Theres dust motes either on the sensor or the optical glass in front of the sensor, taking flat fields will remove this, its also possible that there may be a slight dew (you may not even be able to see it) in front of the sensor, ive had this appearance on my CCD when the desicant needs to be replaced, ect.....gona look for my thread on here, and link it to your post, then you can see SGL members responses. Its also worth noting that if the particles are sharp in appearance on the frame/image then its v likely its on the chip/sensor itself, but luckily it seems in the glass (?)........

[wavydavy]

the star like objects with "streaks" looks like dew to me.

[wavydavy]

http://stargazerslounge.com/topic/234894-can-anyone-explain-this/

[Shelster1973]

Cheers Wavy....the above image has had flat frames used on it....just going to have a read through the thred you have linked to now...

[Shelster1973]

Read through and am not sure it is dew, but it may be but in a very thin film.....when I brought the scope in from outside had a look see and could not see any obvious dewing on there.

Am going to look at my primary too.  Plan is to slacken off the three holders until i can just turn the mirror in the cell adn then give it 1/4turn on top of that to hold it.  Would be very handy if they supplied info on a torque setting for holding scres.  Would be no issues then of over tightening and distorting anything

[wavydavy]

Unusual that its pinched?? But its possible I guess.

[lensman57]

on two fronts here......I may have an idea as to what is occuriong, but looking for validation really.

1st of the two are the rather nasty looking blobs that are there.  I am guessing that is down to some sort of debris on the sensor?  Have run the sensor cleaning utility a few times but they do not seem to shift at all.  Am guesing am going to have to look at getting the sensor cleaned?  Any ideas on how to do that on a D7100?

2nd is the star shapes, they all appear to be blobby triangle shapes.  I am thinking this may be down to pinched optics?  I did clean and re-spot my primary a few weeks back.  Would it be worth my while backing off on the screws that hold the primary in the cell?  If it aint that, then what do people think it may be?

Sunflowerintegration_DBE.jpg

Have not done anything to it yet in PI other then calibrate, debayer, register, integrate, run a DBE on it and then colour calibrate.  The image above is a quick and ready stretch in PS to show my issues

Check the retaining clips on the primary for being too tight.

A.G

[ollypenrice]

Cheers Wavy....the above image has had flat frames used on it....just going to have a read through the thred you have linked to now...

Did you calibrate the flat frames by dark subtracting them? (You don't need to take 'real' darks for your flats. Just use a master bias.) The first thing I thought was that the bunnies were a very complex shape and nothing like the usual doughnuts. When flats are not dark calibrated they over-correct and that might account for the strange bunnies. There is some evidence that the edges and corners of the image are too light which would confirm the 'over-correcting flat' hypothesis but the effect is too mild to be conclusive.

It could also be dew, or a bit of both.

Triangular stars do suggest pinched optics which are worse in the cold. An EP star test would confirm or refute this.

Olly

[Shelster1973]

Cheers Olly......can't recall if I did the flat with dark subtraction or just image integration.... will bin the master flat I have and redo again.

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