[troika]

Give me your impressions, please of the exposure of these two shots. I've got something odd going on and would love the input.

I don't want to say to much and bias the result yet.


#1




#2

[enoeske]

I like the brighter one a bit more, personally, though I'd rather see the brighter guitar on the darker wall for some contrast. What other impressions are you looking for?

[othar]

Give me your impressions, please of the exposure of these two shots.

I think the second one is a tad brighter.

[troika]

Both photos have the same shutter speed and ISO. The camera is tripod mounted, I have a 2 second delay on the shutter release. The 2nd photo was spot metered in Tav mode and seems to be more or less appropriately exposed, which seems to match your impressions as well.

The 1st photo was exactly the same, a few seconds later. But the aperture is wider. 1.7 vs 2.0

It should be brighter. If I had left it in Tav, it would have dropped ISO 1/2 stop and it would be noticeably darker. The depth of field is shallower in the 1.7 photo, so I don't think that the photos are exactly the same, but something is off regarding the amount of light coming in.

I can't get my brain around this.

---

Last edited by troika; 08-31-2018 at 04:33 PM.

[othar]

If I had left it in Tav, it would have dropped ISO 1/2 stop and it would be noticably darker.

What mode did you use instead? Between the shots the camera did a new metering and maybe some shadow fell differently onto the guitar in that moment, or when you changed the shooting mode you accidentially moved the camera nearly unnoticable but something changed with the light (are the two pictures excactliy superposable)? The difference is so neglicible I wouldn't bother.

[UncleVanya]

Both photos have the same shutter speed and ISO. The camera is tripod mounted, I have a 2 second delay on the shutter release. The 2nd photo was spot metered in Tav mode and seems to be more or less appropriately exposed, which seems to match your impressions as well.

The 1st photo was exactly the same, a few seconds later. But the aperture is wider. 1.7 vs 2.0

It should be brighter. If I had left it in Tav, it would have dropped ISO 1/2 stop and it would be noticeably darker. The depth of field is shallower in the 1.7 photo, so I don't think that the photos are exactly the same, but something is off regarding the amount of light coming in.

I can't get my brain around this.

Post full exif. Do you use auto shadow or highlight protection? What iso for each? What modes TAv and ?

[photoptimist]

What was the shutter speed and what was the lighting?

Many artificial light sources (especially fluorescent & LED) have significant flicker that is too fast for human eyes to see but will affect cameras. Shutter speeds faster that roughly 1/30 to 1/60 can run into weird random light-level issues. Even the color balance can be slightly different depending on when the shutter fires relative to the flickering light source.

[troika]

1) Thanks guys, I knew that I came to the right place
2) It doesn't matter, because I'm going to win the K1ii tonight!

I'm not sure exactly how to post EXIF or how much is really useful, but shot #2 was Tav mode (spot metered) and I changed it to M mode and moved the aperture to 1.7.

Shutter speed was 1/30th and ISO was 400 on both shots. f1.7 on the first shot / f2 on the second shot.

there was lamp behind the guitar and some overhead LED lighting in the room. The reason I did this is because it was significantly under-exposing wide open. I wanted to see what happened if I properly exposed and then only opened aperture.

Here's full EXIF for the first photo:

• X-Resolution - 240 dpi
• Y-Resolution - 240 dpi
• Software - Adobe Photoshop Lightroom 6.14 (Windows)
• Date and Time (Modified) - 2018:08:31 15:44:30
• ISO Speed - 400
• Exif Version - 0230
• Date and Time (Original) - 2018:08:31 11:57:14
• Date and Time (Digitized) - 2018:08:31 11:57:14
• Exposure Bias - 0 EV
• Metering Mode - Spot
• Color Space - sRGB
• Focal Plane X-Resolution - 2079.219971
• Focal Plane Y-Resolution - 2079.219971
• Focal Plane Resolution Unit - cm
• Sensing Method - One-chip color area
• Custom Rendered - Normal
• Exposure Mode - Manual
• White Balance - Auto
• Focal Length (35mm format) - 75 mm
• Scene Capture Type - Standard
• Contrast - High
• Saturation - Normal
• Sharpness - Hard
• Subject Distance Range - Close
• Lens Info - 50mm f/1.7
• Lens Model - smc PENTAX-F 50mm F1.7
• Compression - JPEG (old-style)
• Thumbnail Offset - 830
• Thumbnail Length - 10144
• Displayed Units X - inches
• Displayed Units Y - inches
• Photoshop Thumbnail - (Binary data 10144 bytes, use -b option to extract)
• IPTCDigest - e9ee0f8db7f316974f058bba03c06993
• Coded Character Set - UTF8
• Application Record Version - 4
• Date Created - 2018:08:31
• Time Created - 11:57:14
• Digital Creation Date - 2018:08:31
• Digital Creation Time - 11:57:14
• Viewing Cond Illuminant - 19.6445 20.3718 16.8089
• Viewing Cond Surround - 3.92889 4.07439 3.36179
• Viewing Conditions Illuminant Type - D50
• Measurement Observer - CIE 1931
• Measurement Backing - 0 0 0
• Measurement Geometry - Unknown (0)
• Measurement Flare - 0.999%
• Measurement Illuminant - D65
• XMPToolkit - Adobe XMP Core 5.6-c128 79.159124, 2016/03/18-14:01:55
• Creator Tool - Adobe Photoshop Lightroom 6.14 (Windows)
• Metadata Date - 2018:08:31 15:44:30-07:00
• Lens ID - 3 33
• Document ID - xmp.did:de872abf-9bd3-2449-a147-9bacb55b8899
• Original Document ID - 2CF83E60B1CEB55BE58C15CA52CAF0CF
• Instance ID - xmp.iid:de872abf-9bd3-2449-a147-9bacb55b8899
• History Action - derived
• History Parameters - converted from image/dng to image/jpeg, saved to new location
• History Instance ID - xmp.iid:de872abf-9bd3-2449-a147-9bacb55b8899
• History When - 2018:08:31 15:44:30-07:00
• History Software Agent - Adobe Photoshop Lightroom 6.14 (Windows)
• History Changed - /
• Derived From Document ID - 2CF83E60B1CEB55BE58C15CA52CAF0CF
• Derived From Original Document ID - 2CF83E60B1CEB55BE58C15CA52CAF0CF
• Format - image/jpeg
• DCTEncode Version - 100
• APP14 Flags0 - [14], Encoded with Blend=1 downsampling
• APP14 Flags1 - (none)
• Color Transform - YCbCr
• Camera ID - 72157631866529417
• Camera Type - Digital SLR

and here it is for the 2nd photo:

• Make - PENTAX
• X-Resolution - 240 dpi
• Y-Resolution - 240 dpi
• Software - Adobe Photoshop Lightroom 6.14 (Windows)
• Date and Time (Modified) - 2018:08:31 15:44:30
• ISO Speed - 400
• Exif Version - 0230
• Date and Time (Original) - 2018:08:31 11:56:55
• Date and Time (Digitized) - 2018:08:31 11:56:55
• Exposure Bias - 0 EV
• Metering Mode - Spot
• Color Space - sRGB
• Focal Plane X-Resolution - 2079.219971
• Focal Plane Y-Resolution - 2079.219971
• Focal Plane Resolution Unit - cm
• Sensing Method - One-chip color area
• Custom Rendered - Normal
• Exposure Mode - Auto
• White Balance - Auto
• Focal Length (35mm format) - 75 mm
• Scene Capture Type - Standard
• Contrast - High
• Saturation - Normal
• Sharpness - Hard
• Subject Distance Range - Close
• Lens Info - 50mm f/1.7
• Lens Model - smc PENTAX-F 50mm F1.7
• Compression - JPEG (old-style)
• Thumbnail Offset - 830
• Thumbnail Length - 10344
• Displayed Units X - inches
• Displayed Units Y - inches
• Photoshop Thumbnail - (Binary data 10344 bytes, use -b option to extract)
• IPTCDigest - 2b2510772ee695c4b163f82b803c31d8
• Coded Character Set - UTF8
• Application Record Version - 4
• Date Created - 2018:08:31
• Time Created - 11:56:55
• Digital Creation Date - 2018:08:31
• Digital Creation Time - 11:56:55
• Viewing Cond Illuminant - 19.6445 20.3718 16.8089
• Viewing Cond Surround - 3.92889 4.07439 3.36179
• Viewing Conditions Illuminant Type - D50
• Measurement Observer - CIE 1931
• Measurement Backing - 0 0 0
• Measurement Geometry - Unknown (0)
• Measurement Flare - 0.999%
• Measurement Illuminant - D65
• XMPToolkit - Adobe XMP Core 5.6-c128 79.159124, 2016/03/18-14:01:55
• Creator Tool - Adobe Photoshop Lightroom 6.14 (Windows)
• Metadata Date - 2018:08:31 15:44:30-07:00
• Lens ID - 3 33
• Document ID - xmp.did:027c547c-4dfe-2c46-b9cb-4fb627843413
• Original Document ID - 11D03E18E0E07E8A5531F980E78FA889
• Instance ID - xmp.iid:027c547c-4dfe-2c46-b9cb-4fb627843413
• History Action - derived
• History Parameters - converted from image/dng to image/jpeg, saved to new location
• History Instance ID - xmp.iid:027c547c-4dfe-2c46-b9cb-4fb627843413
• History When - 2018:08:31 15:44:30-07:00
• History Software Agent - Adobe Photoshop Lightroom 6.14 (Windows)
• History Changed - /
• Derived From Document ID - 11D03E18E0E07E8A5531F980E78FA889
• Derived From Original Document ID - 11D03E18E0E07E8A5531F980E78FA889
• Format - image/jpeg
• DCTEncode Version - 100
• APP14 Flags0 - [14], Encoded with Blend=1 downsampling
• APP14 Flags1 - (none)
• Color Transform - YCbCr
• Camera ID - 72157631866529417
• Camera Type - Digital SLR

[UncleVanya]

I'm thinking the led lighting.

[UncleVanya]

Youtu.be

Youtu.be

the led lighting can have higher frequency also. But for stills the point is exposure may vary a bit. I don't know any solution other than trial and error. But maybe someone with more experience with shooting led lighted scenes can chime in. Of course the small difference is easily fixed in post.

[troika]

I ran a test yesterday in this same spot and the same test outside in decent natural light. All shooting in Tav at each partial apertue stop from f1.7 - 4.

I noticed that the 1.7 shots, indoors and out, were significantly under-exposed. Much more noticeable than these photos. So, what I was trying to do today was keep the ISO steady to just measure the difference in aperture only. I see these photos as being very close to the same. I notice a difference in depth of field that tells me aperture is actually different, but exposure seems almost the same. Histograms are very similar. You guys think that f2 photo is brighter and I think you're right.

I'll try the same test outside and post the results.


Just shot outside at 1.7, 2.0 and 2.8

I did it first in manual mode, adjusting until the meter in the view finder told me I had it right, then I did it again in Av mode.

Much more consistent results. Not worth posting. Minor differences in the histogram, but I don't understand histograms beyond left =under, right = over, middle = generally good.


When I look at outside shots from yesterday, wider apertures were exposing darker than smaller apertures up to about f3.5. I think it's possible in Tav that I was bottoming out ISO, which was causing the under-exposure. Thanks for talking me through it. I'll do some more testing. Getting to know a new-to-me lens, this kept me up a little bit last night, trying to wrap my head around it.

[rogerstg]

I think you need to be comparing raw files, not jpg because the camera's software will make exposure adjustments when creating jpgs.