strange pattern

[Fons Baerken]

Df 35-70mm f/3.5ai, where you look at the right upper corner, the oof area shows a strange line pattern like a ground glass

[Bjørn Rørslett]

Very strange. The pattern is (almost) in focus in the same plane as the flowers then to become gradually more unsharp towards the rear of the frame. This  looks like there was a grid-like object (say a screen) lurking there in the background?

[Fons Baerken]

This is just a snap no pre meditation of any kind, not my style no specific background etc.
To me it appears as if one is looking at the camera's mirror if not the sensor.

[Bjørn Rørslett]

An enigma, then.

Reflections of the sensor(or rather, microlens pattern) tend to be honey-combed and colourful plus only occur with high-contrast light sources. This cannot be caused by the mirror either as the pattern clearly coincides in sharpness with the overall depth-of-field elsewhere and the mirror has to be up before the exposure can be made. Thus something is rendered that is positioned well in front of the lens.

[MFloyd]

... This looks like there was a grid-like object (say a screen) lurking there in the background?

I have the same impression. If not, very strange then. 

[basker]

The lines seem to go through an OOF light green object, so I wondered if it was reflected.

[Roland Vink]

As Bjørn said, it looks like a fine mesh or screen in the background. The lines recede to the back with normal perspective.
Looking at the out of focus stems and leaves at the lower right, you can see the background bokeh has a hard edge. When you get this kind of bokeh on a finely repeating pattern in the background, the blurs can overlap and reinforce each other, giving the impression of detail you wouldn't normally see.

[richardHaw]

i doubt this is optical
may just be a screen.

if it is then theres a chance that an element was replaced the wrong way but even if that was the case the result would not look like this

[basker]

The lines seem to go through an OOF light green object, so I wondered if it was reflected.

By that I meant that it appears to be behind the lines.

[Matthew Currie]

It's kind of hard to tell with this JPG file, but I blew up a little piece and to me it does not appear that the green bud is behind the lines, but what does appear (here nastily over-sharpened to make it more obvious) is a slightly different frequency of diagonal stripes on one of the yellow petals, which seems odd.  I thought it visible only in that one area, but the more I look the more it appears elsewhere.  JPG artifact maybe?

The question arises whether one can return to the subject, and perhaps investigate a little closer.

[basker]

Matthew, the pale green object I was referring to is in an area well below and to the right of the area you enlarged, if that matters. It is just above the dark blue spot near the center of the right edge. Not sure that it could even be recognized as a bud.

[Matthew Currie]

Matthew, the pale green object I was referring to is in an area well below and to the right of the area you enlarged, if that matters. It is just above the dark blue spot near the center of the right edge. Not sure that it could even be recognized as a bud.

Now I see it.  It doesn't look like part of the plant at all.  Could it be flare?

[richardHaw]

not sure if that's moire
doesnt look like it since its brown