Tamron 24-70 f/2.8 - Safe to buy yet?

Started Dec 10, 2012 | Discussions thread
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dtronvig
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Re: Can you blur the onion rings in post?
In reply to m_appeal, 1 month ago

You can selectively blur the rings with a few quick steps in Photoshop. The saving grace is that the bokeh dots are inherently sharp-edged, so Photoshop sees them as being in sharp focus, and you can select them with the fairly new Focus Area operation. I've been doing this with flat, hard-edged bokeh dots and "rolled-condom" dots from various lenses with pretty good results. Once you select the dots you can blur them and otherwise adjust them in a few helpful ways. I'm happy enough with the results that yeah, I'm gonna buy one of these. Because, VC.

As an example, I opened Manny's picture in Photoshop, went to Select: Focus Area, left default settings except using an In-focus range of 2.3 (YMMV) and feathering by 1 pixel. Then with one quick Lasso I deslected the in-focus areas on the box (which were a fair distance from the bokeh dots) then applied a Gausian Blur with a radius of 2 pixels. For comparison, there's one olive-colored dot near the upper right that evaded the Focus Area selection

Doing this manually, once you're in the groove, it takes about a minute to fix each affected photo. If "in-focus" areas of the foreground butt up against the dots -- which is rare -- then you might have to spend another half a minute deselecting those foreground areas.

Now, you wouldn't want to process a hundred shots at a time like this, but just estimate how many shots you'd get that were keepers except for the onion rings.

Bokeh dots are enough of an issue with any lens that you'd hope somebody has come up with a way to select these readily-identifiable dots (without also selecting in-focus foreground) and either just present the selection or actually apply a blur in batch mode. I haven't tracked anything down like that, but if anybody has heard of one please let me know.

Manny's photo with onion rings blurred out

m_appeal wrote:

Yeah, I know extra work... but if this is a good lens, may be worth it.

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