Abecedarian avatar
I am very new to astrophotography ( hence the name)and have just purchased a Redcat 71. While looking through the pictures I noticed something odd.
Pictures credited to the Redcat 71 that have clear and very prominent diffraction spikes Are they by poseurs ? A mistake ? Or is there something I need to learn?
Oscar avatar
No no. Stars may show halos (which is unusual for a Redcat, but may be caused by narrowband filters with poor anti reflective coatings), but not diffraction spikes, for a refractor. 

You can make diffraction spikes by adding with tape 2 intersecting strings at the end of the refractor to make a cross, which will appear as cross diffraction spikes in the astroimages.

Why the spikes occur when something is in the way of the lightpath is unknown to me smile

If a professional notices an inaccuracy in my post, plz correct me.
Abecedarian avatar
Thanks. I am so new that I don't  know much more than the most basics things in astrophotography.
Well Written
Bill McLaughlin avatar
Star spikes can also be added using a Photoshop plugin called "Star Spikes Pro".  I have it, although don't use it much. I will say it offers a lot of control and works very well and can make some images have a bit more impact. As with the strings method, you should always disclose it's use, of course. The only possible exception is when it is used only to clean up existing star spikes.
Well Written Concise
Brian Puhl avatar
Bill McLaughlin:
Star spikes can also be added using a Photoshop plugin called "Star Spikes Pro".  I have it, although don't use it much. I will say it offers a lot of control and works very well and can make some images have a bit more impact. As with the strings method, you should always disclose it's use, of course. The only possible exception is when it is used only to clean up existing star spikes.



This plugin needs to die... lol
Bill McLaughlin avatar
Brian Puhl:
Bill McLaughlin:
Star spikes can also be added using a Photoshop plugin called "Star Spikes Pro".  I have it, although don't use it much. I will say it offers a lot of control and works very well and can make some images have a bit more impact. As with the strings method, you should always disclose it's use, of course. The only possible exception is when it is used only to clean up existing star spikes.



This plugin needs to die... lol

Many people would say the same about anything that is "unscientific" (whatever that is, and there is no clear definition). We heard the same thing about BlurX and yet it yields more true to life (as defined by comparison to professional high res images) results than the older so-called "scientific" deconvolution.

The bottom line is that esthetic imaging is, by any reasonable definition, not science. As long as one discloses any significant modification to the image, then I cannot see how it is a problem.

It is up to the imager as to what is "significant" but for me and for star spikes, "significant" is putting them in where they were not originally present or making them easily noticeable as different than they were natively.

But then one could also argue that removing star spikes entirely is actually what should be done - they themselves are merely an artifact of telescope construction and not really there in any real sense whatever!

It is all about integrity and disclosure and standards differ.
Engaging
Oscar avatar
Bill McLaughlin:
But then one could also argue that removing star spikes entirely is actually what should be done - they themselves are merely an artifact of telescope construction and not really there in any real sense whatever!


But I think we all know that it's man-made and only for aesthetics and it's not actual rays from the stars.

Well, if there any newbies who believe that they are actually coming from the star, there you go. In real-life, the rays coming from a star is not any different than the rays we see from the sun or a streetlamp at night.
Bill McLaughlin avatar
Bill McLaughlin:
But then one could also argue that removing star spikes entirely is actually what should be done - they themselves are merely an artifact of telescope construction and not really there in any real sense whatever!


But I think we all know that it's man-made and only for aesthetics and it's not actual rays from the stars.

Well, if there any newbies who believe that they are actually coming from the star, there you go. In real-life, the rays coming from a star is not any different than the rays we see from the sun or a streetlamp at night.

I guess my point was is that one can define what is real or not and the resulting "what should or should not be displayed in an image" in many ways and the "rules" are pretty arbitrary. 

At the end of the day, it is all about disclosure and what the imager thinks is valid and appropriate.

I have been doing  astro imaging since the early 90s and I can remember this discussion from those days. In fact, I suspect this discussion started the same day the first photo was developed.