Bright stars seem to have some kind of flare happening

andrea tasselli:
What was used to take the frames? Reflector or refractor?

A refractor was used to take the images. I have a William Optics GT71 with the flattener/reducer.

andrea tasselli:
Then those are the effects of the clips used to hold the lens in place. I'd assume you can mask the lens down to remove them but I won't advise it.

Is this what pinched optics are? As soon as you asked what type of scope I had, a lightbulb went off in my head and I remembered seeing something about pinched optics before. I will definitely be contacting William Optics to see what they say. Thanks for your help.

Pinched optics is different - results usually from cold temperatures causing the retaining ring to contract and put pressure on the lens. Tell tale sign is triangular stars. This is simply the blocking effect of the clips causing the aperture of the lens to be non circular. As Andrea said, it may be possible to put a mask that covers these clips and also covers the spaces in between. This will result in a circular aperture but will reduce the amount of light the lens gathers.

Thank you very much for your help

Lynn K:
I agree with the above comments. I have had pinched optics in a TMB130SS and it will usually create a diamond shaped star. It may only happen in extream cold conditions.

I have had simular spicks/flares fron refractors. And they were caused by the spacers between the lens elements. Sometimes there are three and as yours four.

Lynn K.

Thank you very much!

I have a similar situation with my William optics GT81IV with 6AIII reducer flattener. This attached photo was taken back when it was freezing outside, but I don't notice it anymore with the warmer weather which makes me believe it is pinched optics. I did unscrew the dew shield and saw 3 sets of 4 screws but I haven't tried to adjust anything. The middle set of screws appears to have some sort of lacquer on them while the front and rear sets of screws have nothing.

This attached photo was taken back when it was freezing outside, but I don't notice it anymore with the warmer weather which makes me believe it is pinched optics

I have used mine in weather as cold as 28 degrees and then just last week when it was in the 50's so the cold weather is not really the problem I don't think. I have also read that some people have received their William Optics scopes from the factory in this condition and yes they had to adjust those screws. I will wait for a reply from William Optics before I do anything but that may be my first move is to adjust the screws and see what happens. Fingers crossed

Dale Penkala:
Yup I agree with everyone above, I don’t believe its pinched optics. Its the tab’s in the lens.

Dale

Good to know, thanks a lot Dale

Us reflector folks learn very early that anything blocking your optical path affects the shapes of your stars.  One of the obvious ones you'll see in 90% of reflector images is the mirror clips, which produce a star that looks very similar to yours, only we have 3 clips, and you clearly have 4.   Imagine shining a flashlight directly through a paper towel tube and projecting it on a wall.   You will see the outline of a tube.   Now use your finger or something to block that light…  you'll see that 'obstruction' as we call it.      The stars are like your flashlight, bright ones will easily show any  obstructions down your optical tube.   Reflectors will show the clips, refractors will show the clips (if they're not masked) and even camera lenses will end up showing interesting patterns due to the iris mechanism.

What you see is exactly that.  It's not pinched optics.   Pinched optics will misshape stars.   Yours are still round.  There is nothing wrong with your scope.        Can it be fixed?  Sure, (maybe?) but it will probably be much more effort than its worth.   In the end you'll only end up reducing the amount of light that comes into your scope.     You'd be better off just living with it and upgrading your scope down the line.

edit: Jeez I just realized this was an old post lol.

I keep on-hand a set of filter size step-down rings that thread into one another so can be stacked as desired and then mounted to the front of camera lenses or smaller diameter refractors. I got these originally to avoid strong star diffraction flares from using camera lenses' internal diaphragms to stop down the f-ratios. 

The ring set is handy as a testing tool, however, to reduce aperture by one or a few millimeters to test if internal clips are shadowing the light path, or to use anytime one prefers to image at a higher, albeit slower, effective f-ratio to obtain better optical performance from the optic.

In the context of the topical discussion here, my point was that if there is any suspicion that some internal small edge clips holding a lens are shading the optical path and introducing diffraction effects, one can rule that theory in or out pretty directly by restricting the objective's diameter with a known circular aperture a millimeter (or more as may be needed, by simple stacking the rings) to block light from reaching such clips. 

—

To diverge briefly off topic into your experience with vignetting for just a moment, I am not an optical designer, nor do I get very theoretical about all this. I'm an hobbyist and experimentalist: I try lens, f ratio, camera (sensor size) and filter combinations and just remember what has worked better or worse or not at all.

Front mounted rings on my Rokinon 135mm f/2 ED UMC to operate at effectively f/2.4 to f/2.8 produce a better quality image than no rings at f/2 or by using the internal diaphragm at those ratios, whether I am using full frame sensors or my older, smaller ASI1600MM. Flats compensate any vignetting in these combinations, but I can't speak for f/8 for example, as I never performed that experiment. The image quality and shorter exposure times have proven a good tradeoff. I have not seen vignetting I'd call crippling, i.e., beyond the ability to compensate with flats, in the combinations I've tried.

I also know that I can use a Baader UFC-series filter drawer mount adapter on the front of that lens and insert my 2x2" filters which happen to produce better halo behavior than any other filters I own: smaller filters that could fit between the lens and camera in the conventional position. Sure, it's a square aperture but creates a more pleasing result on star appearance, to me anyway, than the diaphragm petals do, and the haloes are better. 

When a quality very dark sky night comes along, I stick to setups I already know work, and don't waste any time experimenting on a fine night.

I try not to assume any generalized answer or rule or very strongly held opinion, but indeed have formed a couple opinions that are pretty well cast in stone at this point, not worth further time to experiment with. I'll never again try a zoom lens for astrophotography!  I've also not found much success with any DX lens (for the 1600MM; of course I would not expect DX to work full frame), so I no longer try those (n.b., in both cases for reasons other than vignetting).

Now others on AB will likely share contrasting opinions…but we are off topic.

I think I have reached the end of my testing regarding star-flaring.

It evolved into mitigation methods, using various aperture masks.
My thinking was that if I could not remove the asymmetric flare patterns, I could superimpose, or perhaps even substitute a more symmetric and pleasing flare pattern, hopefully without losing any significant light gathering area.  That, by itself, had interesting results.

A full photo summary is here:

https://www.flickr.com/photos/125134422@N06/albums/72177720308616569

It is also interesting how much more prominent the diffraction spikes are for the Newtonian.  I had expected the diffraction spikes from the four segment aperture mask to be similar.  Note that the four segments, placed on the outside edge of the aperture, obscure 2.2% of the total area.
If you only consider the 0.5mm thick secondary vanes in the 114mm Newtonian, (not the secondary itself) they obscure approximately 1.1% of the area.
Yet those spikes are much more visible.  But perhaps the open aperture on the GT-71 is not actually 71mm, making the segments a smaller percentage than calculated, which would explain it.

edited:  This is most likely due to the fact that the diffracting "edge' is so much shorter on the mask than the full-aperture length vane..

Steve