[Simon K]

I kindly got the lens for some days to do some testing before buying (or not buying). In general I'm pleased with sharpness and focus speed and accuracy. The thing I do find very strange is how out of focus highlights are rendered. As you can see its a ring with a dot in the middle. The image is sharpened in post which makes it look even more pronounced. In this case its some dropplets but even the far more smooth oof lights in a plastic bottle show the rings and dots.

Picture at 230mm f6.3

Is this the way it just is with this lens or is this faulty behaviour?

Attached Images

View Picture EXIF

File Date

 

[BigMackCam]

I don't have this lens, Simon, but I will say many zoom lenses that cover a wide range of focal lengths have some oddities in highilight / bokeh rendering. I don't own my DA18-270 anymore, but that used to produce mini "Spaghetti Os" / bite-size "donuts" within a certain focal length range...

[UncleVanya]

I've never noticed that but to be fair that's a highly reflective oof highlight. I don't think any of my shots include that level of reflection and oof and that may rule out my seeing this in my own photos.

[Simon K]

I don't own my DA18-270 anymore, but that used to produce mini "Spaghetti Os" / bite-size "donuts" within a certain focal length range...

Now I get hungry

---------- Post added 06-06-23 at 01:29 PM ----------

that's a highly reflective oof highlight.

True, but rings and dots also appear in the much softer highlights in a dimly lit plastic bottle, same shape, just softer.

[mlag]

It is a form of diffraction, some interaction between strong light rays (caused here by a drop of water and I guess strong sun backlight) and sharp edges of in a lens typical the diafragma , which has 6 or more ’corners’ between each of the 6 or more blades....
Light rays have tendency to bend at sharp edges, and the resulting rays cause interference patterns ( bit like the waves when you trow 2 stones in pond and circles are crossing causing patterns..)
There is some impact of lens, rounded diaphragm is less likely causing diffraction than one with angular shapes and less blades, and smaller apertures provoke it quicker....

I guess you can provoke it with (m)any lens(es), I had similar experience with old 55-300 and dew drops:
Flare shaped like a snow crystal...? - PentaxForums.com
Light as a Wave article
Scroll down for hex patterns in article.

[Simon K]

It is a form of diffraction, some interaction between strong light rays (caused here by a drop of water and I guess strong sun backlight) and sharp edges of in a lens typical the diafragma , which has 6 or more ’corners’ between each of the 6 or more blades....Light rays have tendency to bend at sharp edges, and the resulting rays cause interference patterns ( bit like the waves when you trow 2 stones in pond and circles are crossing causing patterns..)There is some impact of lens, rounded diaphragm is less likely causing diffraction than one with angular shapes and less blades, and smaller apertures provoke it quicker....

I know these hexagons well enough since I have a copy of the old smc 55-300 which has six blades, but it never was producing donut rings with a dot in the center.

---------- Post added 06-06-23 at 03:02 PM ----------

Thanks for your replies so far. I think I've found evidence that rendering oof highlights this way is just how the 55-300 PLM do. In this example there clearly are oof highlights shaped as rings with a dot in the centre.

IMGP7688 | acornuser | Flickr

[Des]

Is this the way it just is with this lens or is this faulty behaviour?

I've taken thousands of photos with this lens (two copies), but I don't recall ever seeing this, even in very bright conditions with many specular highlights:


I think it's the particular copy. You need to decide whether it's a deal-breaker for you.

[Simon K]

've taken thousands of photos with this lens (two copies), but I don't recall ever seeing this, even in very bright conditions with many specular highlights:

Thanks for this helpful reply. Actually the vendor has another copy he said, so I will try the other one too. I don't think I want a lens that gives me that kind of frills as an extra.

[mlag]

I've taken thousands of photos with this lens (two copies), but I don't recall ever seeing this, even in very bright conditions with many specular highlights:

Because the highlights are typically outside the sharp, dof zone ? Hence rendered unsharp...?
Check here how highlights in dew on grass evolve front to back, from little dots over donutshapes to complex hexagons.

I had the lens of above picture +10 years before this happened, never seen it before.
It just depends on (im)perfect circumstances...to catch it , blur it, or avoid it.

I think the lens can only be blamed for having ’only’ 6 , non-rounded aperture blades.... hence hexagons with 6 corners.

[Simon K]

I think the lens can only be blamed for having ’only’ 6 , non-rounded aperture blades.... hence hexagons with 6 corners.

The lens I'm testing is the PLM version which has 9 rounded blades.

[ramseybuckeye]

I shoot towards the sun a lot, and from time to time (not often) have seen similar "highlights", Though I can't find any because I priobably cropped that out or discarded the photo. I don't think it's the lens, but the conditions. I would see if you can reproduce it without similar conditions. I think clear plastic and water could create an odd flare.

[Simon K]

I shoot towards the sun a lot, and from time to time (not often) have seen similar "highlights", Though I can't find any because I priobably cropped that out or discarded the photo. I don't think it's the lens, but the conditions. I would see if you can reproduce it without similar conditions. I think clear plastic and water could create an odd flare.

I'm comparing this 55-300 PLM copy with my smc 55-300 which has 3 blades less but never gave me anything like this in all the years of good use. As I do wildIife a lot this is not a rare situation with highlights as harsh for me. I'll test the other copy the vendor has in stock to see if I can reproduce the issue.

[mlag]

The lens I'm testing is the PLM version which has 9 rounded blades.

Sorry, the 6 referred to my picture indeed.
Even if your highlights are less sharp, you can still see some indications of 9 edges, the circle has some vague star-trails, however none is full circle sharp.... it looks consistent with 9 edges.
If you compare all highlights, you see the direction of all (visible) trails is similar arranged... like the one on top right shows also 4 on righthand sideby...

[romay]

It's called an "airy disk" and happens stopped down in high-contrast situations. In astrophotography, you go to great lengths to reproduce this effect since it can be used to gauge the quality of your optics (a pronounced, circular disk with a set number of rings usually means you have good optics).
There may be copies of this lens around that don't produce the effect, but that won't automatically mean they are of higher quality.

Can you easily reproduce the effect even at lower f-numbers? If so, try another copy of the lens.

[ehrwien]

This was shot at 300mm and f/16 and you can see some diffraction effects when you zoom in, but I find them rather pleasing and they don't look like the one in your shot


Four-spotted Chaser / Skimmer