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Forum: Pentax K-3 & K-3 II
11-21-2015, 04:18 PM
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Forum: Pentax K-3 & K-3 II
05-18-2015, 11:34 AM
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Forum: Pentax K-3 & K-3 II
05-18-2015, 11:20 AM
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Buscot Weir, same settings
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Forum: Pentax K-3 & K-3 II
05-18-2015, 10:52 AM
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Buscot Weir, 13th May 15, Sigma 18-250 Macro, 18mm, f/3.5
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Forum: Pentax K-3 & K-3 II
04-11-2015, 12:51 AM
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Forum: Pentax SLR Lens Discussion
03-24-2015, 04:16 PM
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Forum: Pentax SLR Lens Discussion
03-22-2015, 07:23 AM
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I recently asked Sigma whether there was a technical reason why the 24-105 F/4 (a full frame lens) couldn't be sold for Pentax? (I currently have the 18-250 Macro on my K-3)
The answer was that there's a shortage due to worldwide demand, but once they are able to fulfill the demand for the current mounts, releasing for Pentax would be contemplated, but not guaranteed.
Usefully, dpreview have reviews for both the 24-105 and the 18-250 Macro on an EOS 7D:
Lens reviews update: test data for the Sigma 24-105mm f/4 DG OS HSM: Digital Photography Review
Sigma 18-250mm f/3.5-6.3 DC Macro OS HSM review: Digital Photography Review
MTF-50 sharpness at 24mm (24-105) and 28mm (18-250):
Approx 1875 (centre) to 1530 (corner) for the 24-105 at f/5.6
Approx 1500 (centre) to 1300 (corner) for the 18-250 Macro at f/8.
Approx 25% centre improvement, 18% corner improvement.
MTF-50 sharpness at 35mm:
Approx 1800 (centre) to 1550 (corner) for the 24-105 at f/5.6
Approx 1500 (centre) to 1300 (corner) for the 18-250 Macro at f/8.
Approx 20% centre improvement, 19% corner improvement.
MTF-50 sharpness at 80mm:
Approx 1700 (centre) to 1375 (corner) for the 24-105 at f/5.6
Approx 1500 (centre) to 1130 (corner) for the 18-250 Macro at f/8.
Approx 13% centre improvement, 22% corner improvement.
MTF-50 sharpness at 105mm: (interpolated approx between 80 and 135 results for the 18-250)
Approx 1600 (centre) to 1375 (corner) for the 24-105 at f/5.6
Approx 1440 (centre) to 1070 (corner) for the 18-250 Macro at f/8.
Approx 11% centre improvement, 29% corner improvement.
The EOS 7D is 18 Megapixel, rather than approx 24 Megapixel for the K-3, but hopefully the sharpness improvement scales between the two cameras?
If so, I'd say it's worth the upgrade to buy the 24-105 for my K-3, if or when they make it. (Ok, it heavy, equivalent to approx 36 to 158mm on the 1.5x crop factor K-3, and needs 82mm filters, but it's impressive!)
And it might perform even better on a full frame camera? (The 22.3 Megapixel full-frame 5D mk3 alternative is selectable in the review, with an MTF-50 up to 2500)
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Forum: Canon, Nikon, Sony, and Other Camera Brands
03-22-2015, 07:14 AM
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I recently asked Sigma whether there was a technical reason why the 24-105 F/4 (a full frame lens) couldn't be sold for Pentax? (I currently have the 18-250 Macro on my K-3)
The answer was that there's a shortage due to worldwide demand, but once they are able to fulfill the demand for the current mounts, releasing for Pentax would be contemplated, but not guaranteed.
Usefully, dpreview have reviews for both the 24-105 and the 18-250 Macro on an EOS 7D:
Lens reviews update: test data for the Sigma 24-105mm f/4 DG OS HSM: Digital Photography Review
Sigma 18-250mm f/3.5-6.3 DC Macro OS HSM review: Digital Photography Review
MTF-50 sharpness at 24mm (24-105) and 28mm (18-250):
Approx 1875 (centre) to 1530 (corner) for the 24-105 at f/5.6
Approx 1500 (centre) to 1300 (corner) for the 18-250 Macro at f/8.
Approx 25% centre improvement, 18% corner improvement.
MTF-50 sharpness at 35mm:
Approx 1800 (centre) to 1550 (corner) for the 24-105 at f/5.6
Approx 1500 (centre) to 1300 (corner) for the 18-250 Macro at f/8.
Approx 20% centre improvement, 19% corner improvement.
MTF-50 sharpness at 80mm:
Approx 1700 (centre) to 1375 (corner) for the 24-105 at f/5.6
Approx 1500 (centre) to 1130 (corner) for the 18-250 Macro at f/8.
Approx 13% centre improvement, 22% corner improvement.
MTF-50 sharpness at 105mm: (interpolated approx between 80 and 135 results for the 18-250)
Approx 1600 (centre) to 1375 (corner) for the 24-105 at f/5.6
Approx 1440 (centre) to 1070 (corner) for the 18-250 Macro at f/8.
Approx 11% centre improvement, 29% corner improvement.
The EOS 7D is 18 Megapixel, rather than approx 24 Megapixel for the K-3, but hopefully the sharpness improvement scales between the two cameras?
If so, I'd say it's worth the upgrade to buy the 24-105 for my K-3, if or when they make it. (Ok, it heavy, equivalent to approx 36 to 158mm on the 1.5x crop factor K-3, and needs 82mm filters, but it's impressive!)
And it might perform even better on a full frame camera? (The 22.3 Megapixel full-frame 5D mk3 alternative is selectable in the review, with an MTF-50 up to 2500)
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Forum: Pentax K-3 & K-3 II
03-15-2015, 12:10 PM
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If Sigma made the 24-105 without image stabilisation for Pentax... up to 2500 MTF!
They could make it weather sealed as well?
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Forum: Pentax K-3 & K-3 II
03-15-2015, 07:27 AM
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Yes, it has a lot of good reviews. Taking approx 1400 for 'Sharp over', the list should probably be
Zoom - Aperture - MTF centre - Sharp over - MTF corner
18 f/3.5 1800 2/3 1200
28 f/5.6 1700 1/2 900
28 f/8 1500 5/6 1300
35 f/5.6 1650 1/3 to 1/2 1000
35 f/8 1500 2/3 1300
50 f/5.6 1500 1/3 (or 1300 over 1/2) 1000
50 f/8 1500 2/3 1300
80 f/8 1500 1/3 (or 1300 over 1/2) 1150
135 f/6.3 1400 1/6 (or 1300 over 1/3) 950
250 f/8 1400 1/6 (or 1300 over 1/3) 1000
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Forum: Pentax K-3 & K-3 II
03-14-2015, 02:09 AM
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I bought the Sigma 18-250 Macro as my first lens for the K-3. Recently I've wondered whether a different lens might be better?
The results shown at dpreview show the following (albeit on a Canon EOS 7D), which I'll put on a 'boilerplate' to get the best out of this lens (instead of staying at f/8 all the time)
Zoom - Aperture - MTF centre - Sharp over
18 f/3.5 1800 2/3
28 f/5.6 1700 1/2
28 f/8 1500 2/3
35 f/5.6 1650 1/3
35 f/8 1500 2/3
50 f/5.6 1500 1/3
50 f/8 1500 2/3
80 f/8 1500 1/3
135 f/6.3 1400 1/3
250 f/8 1400 1/6
(f/11 is shown to be noticably worse)
It's interesing to compare with other results on dpreview.com/lensreviews, e.g.
Sigma 17-70 f2.8-4 = approx 1800 MTF (best 2000)
Tamron SP 24-70mm f/2.8 = approx 1750 MTF
So at around 1500 MTF, the 18-250 isn't too bad, and can be very good at 18 to 28mm.
Distortion and CA can be taken care of with Lightroom, so not important?
Wouldn't it be cool if the K-3 could automatically adjust the aperture based on a configurable table of aperture vs zoom?
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Forum: Pentax K-3 & K-3 II
12-23-2014, 12:53 PM
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Forum: Pentax K-3 & K-3 II
11-20-2014, 09:00 PM
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"Murphy was an optimist"
Focus peaking in video. But please add this to the K-3 first! -- The higher the visibility of the effect, the better?
Continuous auto focus in video (no button pushing to refocus, and backwards and forwards searching)
Better video stabilisation (like Canon,
You Tube
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src="https://www.youtube.com/embed/66Qsvv4b6M8?controls=1" allowfullscreen>
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, Canon develops Hybrid image stabilization system: Digital Photography Review )
-- I wonder whether the K-3 could stabilise video better with a firmware update to use the sensor shift? (maybe with an add-on gyroscope sensor accessory?)
Video recording duration only limited by the memory and battery available.
Internal GPS and WiFi.
Option to write video to both SD cards? (for a backup, created real-time, or automatically copied after saving to the first card)
Move the Raw/Fx button to somewhere less easily knocked? (I had mine set to turn shake reduction on and off, so I could turn off SR if using a tripod.) I found this summer that I'd accidentally knocked the button without realising it (and I don't use a tripod!) Fortunately there were only a couple of photos which were affected by the SR being turned off.
p.s. my previous camera was a bridge camera. You couldn't crop at all, the pictures were that horrible from the tiny sensor.
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Forum: Pentax K-3 & K-3 II
11-13-2014, 02:28 PM
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Forum: Pentax K-3 & K-3 II
10-05-2014, 01:36 PM
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OK, I know there's a sharpening setting in Develop as well as Export, but haven't experimented with them. I could guess it's best not to use too much sharpening in Develop?
My laptop LCD probably shows about 120 DPI, but with small black bars (I can see the 'pixel grid' at when close to the 17" screen)
Maybe in a print, the inks might merge without any gaps at all, unlike the LCD screen?
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Forum: Pentax K-3 & K-3 II
10-05-2014, 05:19 AM
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Export (Shift Ctrl E) in Lightroom 5.6 is what I've used, while in Library or Develop...
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Forum: Pentax K-3 & K-3 II
10-03-2014, 02:47 PM
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In Lightroom you can export with a different resolution. If you export as 12032 X and 8000 Y, it interpolates between each pixel, and quadruples the resolution to 96 Mpixels, giving an approx 34MB JPEG at 100% quality level. The reduction in blockiness when pixel peeping is very noticeable.
Here's a downloadable full-size approx 96 Mpixel 34MB exported 12032x8000 JPG: https://www.amazon.co.uk/clouddrive/share/oZkLZBEwVJ6vNlJHmFBr9OhTi-pcQexSTMsAq42rVdE
12032 pixels = 40.1 inches wide at 300 dpi.
I've tried exporting to TIFF instead of JPG, but by eye there wasn't a great difference, only in the huge file size.
Unsurprisingly, trying to use Lightroom to quadruple the X to 24064 and the Y to 16000 didn't look good, at least when trying to do so in one step.
But exporting with double X and double Y, then importing this JPG, then exporting again with double X and double Y a second time gives a reasonable result.
Here's a downloadable full-size approx 370 Mpixel 100MB exported 24064x16000 JPG: https://www.amazon.co.uk/clouddrive/share/49F44o9dq5j_jhj1lX3QEHkXsmAIqf_yogBKn5qZ7P8
Shown below is a 'pixel peep' screenshot of the 96MP and 370MP jpg's. I didn't keep the original 24MP from the k-3, so I exported the 96 MP as 24 MP to show how blocky it looks.
Whether the 96MP looks softer overall due to blurred colour transitions than the original 24MP might be a possibility. It is probably better to export to uncompressed dng instead of jpg.
The 370 Mpixel jpg is probably unnecessarily fine :)
Obviously the more you zoom in, the more the noise is noticeable.
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Forum: Pentax K-3 & K-3 II
09-27-2014, 12:52 PM
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East Portlemouth, Sigma 18-250 Macro, DNG raw via Lightroom 5.6
Exposure 0.00
Contrast +10
Tone set manually, to algorithm:
Highlights +20
Shadows -7
Whites +10
Blacks +7
Clarity +5
Vibrance 0
Saturation 0
Lum NR 0
Colour NR 8
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Forum: Pentax K-3 & K-3 II
09-27-2014, 12:34 PM
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DNG raw from Sigma 18-250 Macro, with tone set using my algorithm: LIGHTROOM: Auto Tone - an algorithm that works!
Exposure 0.00
Contrast +10
Highlights +50
Shadows +17
Whites +10
Blacks -17
Clarity +5
Vibrance 0
Saturation 0
Lum NR 0
Colour NR 8
(Compare with the Lightroom Auto version on page 160)
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Forum: Pentax K-3 & K-3 II
09-21-2014, 09:37 AM
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This might be of interest? I've just compared Auto tone on some k-3 photos in Lightroom 5.6 with a slow manual procedure using the ALT (Command) key.
I hope Adobe will take an interest and hopefully update Lightroom with more Auto tone choices?
Algorithm & Pics: Auto Tone - an algorithm that works! |
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Forum: Pentax K-3 & K-3 II
09-20-2014, 07:10 PM
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View of Plymouth Breakwater Plymouth Breakwater - Wikipedia, the free encyclopedia from above Kingsand, 6 PM, 17th Aug 2014
1/250s, f/8, ISO 100, 155mm, Sigma 18-250 Macro, handheld, DNG RAW processed by Lightroom 5.6,
no Luminance noise reduction, small Level 8 Colour noise reduction, Clarity +5, Contrast +10, Auto tone not used to set the black and white levels!
An approx 77 Mpixel jpeg (29 MB) is downloadable from https://www dot amazon.co.uk/clouddrive/share/1jmJCWzZnLHUG7qv1yx6HyfdCTTM21b0bmqG5o4DSAg
(replace dot with . and click the cloud download icon shown below the picture)
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Forum: Pentax K-3 & K-3 II
09-19-2014, 03:54 PM
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Exported with different resolution; double x and double y (11872 x 6678 jpeg, 31MB). Only the small Colour noise reduction (Level 8)
Snapshot of 1:1 Lightroom view of the centre of this jpeg
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Forum: Pentax K-3 & K-3 II
09-19-2014, 03:09 PM
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Forum: Pentax K-3 & K-3 II
09-19-2014, 03:07 PM
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