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What kind of optical aberration is that??
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PostPosted: Sat Feb 19, 2022 5:47 pm    Post subject: What kind of optical aberration is that?? Reply with quote
Hi Everyone:

As I mentioned in a recent post, I have an old projector lens, actually a hybrid of two lenses. It has numerous artifacts due mostly to spherical aberration, especially around the edges, but that's what gives it its charm. Occasionally, I get a weird sort of fringing. I am just wondering what kind of optical aberration it is to the right cheek of the fellow below? Is there any way to avoid it, as I don't see it in most of my other images with this lens. Although admittedly, I have occasionally seen such fringing in other projection and vintage lenses. Thanks!

-Charles





PostPosted: Sat Feb 19, 2022 5:55 pm    Post subject: Reply with quote
Astigmatism perhaps?


PostPosted: Sat Feb 19, 2022 7:10 pm    Post subject: Reply with quote
Does this fringing occur only on the right side of the image or both?

I ask because I have a Sigma mirror that does something very similar -- this sort of soft doubling of the image, but it is in a vertical direction, and the doubling occurs only at the top of the subject. I have assumed that, with my mirror, the elements are out of collimation in a vertical direction.


PostPosted: Sun Feb 20, 2022 1:23 am    Post subject: Reply with quote
Misalignment?
You said that lens is a hybrid of some sorts.


PostPosted: Sun Feb 20, 2022 3:26 pm    Post subject: Reply with quote
caspert79 wrote:
Astigmatism perhaps?


I am not sure if astigmatism causes such fringing?


PostPosted: Sun Feb 20, 2022 3:32 pm    Post subject: Reply with quote
cooltouch wrote:
Does this fringing occur only on the right side of the image or both?

I ask because I have a Sigma mirror that does something very similar -- this sort of soft doubling of the image, but it is in a vertical direction, and the doubling occurs only at the top of the subject. I have assumed that, with my mirror, the elements are out of collimation in a vertical direction.


It is possible that the lenses are misaligned. I actually checked some other images and it seems like it does happen sometimes, particularly on the right side. Sometimes it is a bright fringe, and sometimes it looks like a double edge.

-Charles


PostPosted: Sun Feb 20, 2022 3:40 pm    Post subject: Reply with quote
Himself wrote:
Misalignment?
You said that lens is a hybrid of some sorts.


Yes, it is possible that it is a misalignment of some sort. It tends to happen on the right side as a kind of double edge, and as a bright fringe on the left side... although not with all the images. I guess I am going to have to live with it and consider it as part of the lens' charm!


PostPosted: Mon Feb 21, 2022 7:15 am    Post subject: Re: What kind of optical aberration is that?? Reply with quote
charley5 wrote:
Hi Everyone:

As I mentioned in a recent post, I have an old projector lens, actually a hybrid of two lenses. It has numerous artifacts due mostly to spherical aberration, especially around the edges, but that's what gives it its charm. Occasionally, I get a weird sort of fringing. I am just wondering what kind of optical aberration it is to the right cheek of the fellow below? Is there any way to avoid it, as I don't see it in most of my other images with this lens. Although admittedly, I have occasionally seen such fringing in other projection and vintage lenses. Thanks!

-Charles


I did manage to correct the issue a bit in post-processing. Thanks everyone for your reflections!



PostPosted: Mon Feb 21, 2022 7:26 am    Post subject: Reply with quote
Like 1 small Like 1 small


PostPosted: Mon Feb 21, 2022 10:38 am    Post subject: Re: What kind of optical aberration is that?? Reply with quote
charley5 wrote:
I did manage to correct the issue a bit in post-processing.


That would have been my solution as well. I found the "Topaz Sharpen AI" very helpful to make the best out of such bad pictures (for whatever reason, even camera shake).


PostPosted: Mon Feb 21, 2022 5:45 pm    Post subject: Re: What kind of optical aberration is that?? Reply with quote
tb_a wrote:
charley5 wrote:
I did manage to correct the issue a bit in post-processing.


That would have been my solution as well. I found the "Topaz Sharpen AI" very helpful to make the best out of such bad pictures (for whatever reason, even camera shake).


Yes, I have the Topaz Sharpen and it is quite helpful, although I wouldn't say this is a bad image. Some people don't like the softness. My issue was the double contour which i think I fixed.


PostPosted: Mon Feb 21, 2022 6:06 pm    Post subject: Re: What kind of optical aberration is that?? Reply with quote
charley5 wrote:
tb_a wrote:
charley5 wrote:
I did manage to correct the issue a bit in post-processing.


That would have been my solution as well. I found the "Topaz Sharpen AI" very helpful to make the best out of such bad pictures (for whatever reason, even camera shake).


Yes, I have the Topaz Sharpen and it is quite helpful, although I wouldn't say this is a bad image. Some people don't like the softness. My issue was the double contour which i think I fixed.


Excuse my incorrect description of the error. The image is of course not bad. I meant the image errors and not the image itself.
At least we had the same idea as to how to fix it.


PostPosted: Mon Feb 21, 2022 10:31 pm    Post subject: Re: What kind of optical aberration is that?? Reply with quote
tb_a wrote:
charley5 wrote:
tb_a wrote:
charley5 wrote:
I did manage to correct the issue a bit in post-processing.


That would have been my solution as well. I found the "Topaz Sharpen AI" very helpful to make the best out of such bad pictures (for whatever reason, even camera shake).


Yes, I have the Topaz Sharpen and it is quite helpful, although I wouldn't say this is a bad image. Some people don't like the softness. My issue was the double contour which i think I fixed.


Excuse my incorrect description of the error. The image is of course not bad. I meant the image errors and not the image itself.
At least we had the same idea as to how to fix it.


Thomas, no problem. That's what I thought you meant!
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