GH2 blown highlights

Started Jun 3, 2012 | Discussions thread
Detail Man
Detail Man Forum Pro • Posts: 16,688
Re: GH2 blown highlights - LGV 14-140mm lens characteristics

Elizabeth Klisiewicz wrote:

Hi, First, thanks for all the useful and technical information. I am still reading the manual and it will likely take many days with my current work/home schedule.

I've been in the habit of stopping down my lenses to approximately f5.6 with my SLR and other cameras for many years, unless I want shallow DOF or some other effect. I imagine a smaller sensor such as the GH2 sensor has greater DOF, thus I might not need to stop down as much.

True. For the same camera-subject distance and image viewing-size and viewing distance, the Circle of Confusion scales with image-sensor size, and as long as the camera-subject distance is a fraction of the Hyperfocal Distance in both cases (say, 1/3 of the Hyperfocal Distance, or less, for a maximum error of around 11%), then:

DOF2 / DOF1 = ( F2 / F1 ) x ( H2 / H1 ) x ( L1 / L2 ) ^(2)

where:

DOF are the Depths of Field;
H are active image-sensor heights;
L are the (actual) Focal Lengths.

For the above situation with the same framing (Field of View) the above formula simplifies to:

DOF2 / DOF1 = ( F2 / F1 ) x ( L1 / L2 )

However, most lens reviews I have read for other cameras I've owned talk about a lens's sweet spot for sharpness.

LGV 14-140mm: http://www.slrgear.com/reviews/zproducts/panasonic14-140f4-58g/tloader.htm

In the case of these flowers, I wanted more DOF (not less), but I guess I blew that with the focal length I used.

Well, what I could not understand is why it seems as deep as it is.
How far away from the plane-of-focus was the outer lens surface ?

Please forgive any naivete on my part for these settings. Every camera is unique, and has its quirks, best settings, etc. I am still learning. I've had my best SLR results with flowers using my Tamron 90mm macro lens. I love that lens for many reasons.

Currently, I have my EV set to -1. I might bring that up a bit to -.5.

Ah, so you have manual Exposure Compensation (already) set to -1.0 EV in that shot ? That would help explain the high Shutter Speed of 1000. At that point, using an ISO Gain lower than ISO=400 would have helped you to guard against RAW-channel "clipping".

Talking about ISO gain means nothing to me at this point. But I am going to print out the helpful info provided above so I can look into it.

Give it a read. Being able to truly believe what you see in the GH2 (or any) Live Histogram is important. The GH2's unique (not on the GX1 or the G3) "Constant Preview" function enables that (but only in Manual shooting mode). Much like Aperture Priority mode (you still can specify the F-Number). The manual exposure-adjustment is just accomplished by selecting a reasonably fast Shutter Speed, adjusting ISO Gain to get close on the Live Histogram, then fine-tuning the exposure-adjustment by using the Shutter Speed control in Manual shooting mode. Slightly more involved - but a Live Histogram you can believe . In similar lighting, the ISO Gain remains appropriate

And, when you think about it, you are adjusting ISO Gain when shooting in Aperture Priority, too.

Thanks.

You bet ! ...

PS_Someone asked me to provide more information on my shooting settings and the lens used, and I did mention the 14-140. Someone may have surmised I was using it anyway by noting the focal length in my EXIF.

Yes, that is exactly what happened.

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