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Forum: Pentax K-1 & K-1 II
04-04-2024, 01:34 PM
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Adhesive has set down and I've gained some front focus. Replaced it with 24 layers of tin foil (0.24mm).
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Forum: Pentax Camera and Field Accessories
04-02-2024, 12:57 PM
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Are there any donsides to precision matte screens if I won't use anything darker than F5.6?
Does K-1 also do metering through the FS? I thought it has RGB scene sensor for that.
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Forum: Pentax K-1 & K-1 II
03-31-2024, 03:55 PM
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Solution: move the lens around to produce jitter with micro raster. Spot on focusing at F1.4 is easy if the contrast of the object is good. However, I can't easily focus using fine details like pine needles, they do not allow to see the raster jitter well.
I ordered another spare screen from Bresson but it's slightly dirty again (some outer rings are dirty). Should I try cleaning it? I know I should use distilled water to rinse it in the end. Should I soap it up and brush it?
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Forum: Pentax DSLR Discussion
03-26-2024, 08:26 AM
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Forum: Pentax K-1 & K-1 II
03-26-2024, 03:10 AM
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What's the lowest lens speed K-1 can focus at? I tried to find any spec but could not. Quick test of non-electric lens tells me F11 is a hard limit on K-1 but I remember it's typically said to be F8. I'm asking because I'd like a TC which will result in slightly worse than F8.
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Forum: Pentax K-1 & K-1 II
03-24-2024, 12:26 AM
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It sounds to me like you are mixing multiple clock domain operation and asynchronous device access. Those are hardly related.
Speaking of device access: it's called interrupts and it's widely used. Interaction with device happens through special address regions. There is nothing complicated about it as you describe it. There is no need to synchronise SD controller clock to the CPU in any way because latency of the device much higher anyways. Instead, the data can be buffered.
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Forum: Pentax K-1 & K-1 II
03-23-2024, 09:42 AM
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Of course I do. Thanks for detailed response but I cannot see how it brings any practical conclusions to the table. It was not my idea to discuss sequential operations.
Specifically talking about device access: I'd imagine it would be horrendous if it was avoided. I genuinely surprised by your claim.
That's why all advanced cameras use some generic (to a varying degree) kernel which has those generic functions implemented.
All high efficiency high throughput processors are hyperscalar today and that includes cameras. Any CPU having a pipeline means it's doing more than just one instruction at a time.
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Forum: Pentax K-1 & K-1 II
03-23-2024, 03:08 AM
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Bob did not say that much at all except that computers are sequential.
Duh.
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Forum: Pentax K-1 & K-1 II
03-22-2024, 10:29 PM
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Wrong. They can if it's a read call and all modern architectures also feature a handful of synchronization primitives to facilitate faster writes to same memory correctly.
If a storage controller could not do operations asynchronously (without blocking a core of the CPU or MCU) it would be horrendous. For every modern CPU and MCU architecture it's essential that any device (let alone low speed device like SD controller) access can be done asynchronously and it has been this way for decades. I have no idea what's the "support" you are talking about.
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Forum: Pentax K-1 & K-1 II
03-22-2024, 07:12 AM
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If you cared about the topic you would know that all high performance cameras have multicore processors. All high performance cameras run on a small OS which totally has multiprocess support (i.e. context switching). Writing to two cards is trivial programming task and will improve performance if bandwidth is not limited by a single card.
Implying that K-1 does only one thing at any time is laughable.
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Forum: General Photography
03-21-2024, 01:18 PM
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Don't know about 10mm but 20mm T1.9 cannot be easily used on K-1 for photos.
1) Camera won't stop down aperture ever.
2) Camera does not have lens speed information because the necessary pin while present is retracted in the mount.
The modification is simple (leaf spring must be partially bent so that the pin is protracting and aperture ring must be fixed at F22 to allow full adjustment from camera) but if you have doubts you should not do it. Plus the focus scale is facing to the side and the gears are uncomfortable to use unless you wrap them.
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Forum: Pentax K-1 & K-1 II
03-21-2024, 08:43 AM
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Does K-1 write to two SD cards simultaneously? It's my understanding that even in dual writing the camera is using only one slot at a time and the time of writing is doubled.
Do all Pentax cameras do the same?
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Forum: Photographic Technique
03-16-2024, 02:12 AM
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I described a specific experiment you can reproduce. You do not need to rub the status quo in my face.
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Forum: Photographic Technique
03-15-2024, 01:49 PM
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In the experiment I described I am combining camera body pitch and yaw so that center of viewfinder makes circles around one spot. I am not tilting camera. Presumably such movement should result in either consistent sharpness or consistent blur but it does not.
I mentioned horizon correction because obviously it might be taking up some of sensor movement range.
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Forum: Photographic Technique
03-15-2024, 11:40 AM
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It directly contradicts what I experience. No it's not in the case I described.
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Forum: Photographic Technique
03-15-2024, 08:26 AM
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Is there any trick for doing longer exposure with shake reduction? It seems to me that the longest exposure SR can do reliably is 1/4s and anything longer than that is hit or miss even if SR is well within sensor movement range. When doing small constant rotation with camera body I get similar smudging at 28 and 105mm with my K-1 at say 1/2s but 1/4s is pretty reliable.
Is there any trick? I tried disabling horizon correction, that did not seem to change anything. The only important thing I noticed is that holding just the camera body helps somewhat.
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Forum: Site Suggestions and Help
03-12-2024, 06:19 AM
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I've certainly seen same issue in some other reviews earlier but I assumed the problem is on my side.
---------- Post added 03-12-24 at 17:22 ----------
Vivitar's F11 image from the mentioned review is not displayed BTW.
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Forum: Site Suggestions and Help
03-11-2024, 09:37 AM
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Forum: Troubleshooting and Beginner Help
03-10-2024, 01:58 AM
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How is it significantly different than mechanic? Is it because mechanical shutter produces diffused shadow on the sensor?
---------- Post added 03-10-24 at 13:02 ----------
This style of defect can be corrected with high quality with Fourier transformation if you need it. Or even simplier method would be creating a stripped layer in any image editor and overlaying it in "divide" mode.
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Forum: Pentax DSLR Discussion
03-07-2024, 09:30 AM
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There is no question about that, I explicitly stated that I am talking about focus ring tolerance of my FA primes. Other than that focusing seems to be spot on.
Nope.
On a side note I am heavily sceptical about that. Whenever my K-1 decides to do a single focus shift from somewhere close to far object with a Sigma 15mm fisheye it always ends up with strong backfocus. Can't imagine this could be possible if Pentax used direct feedback while driving the focus. Also, before I fixed the focal length flex cable of said 135-400 K-1 could barely focus it and often ended with a blinking failure.
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Forum: Pentax K-3 III
03-07-2024, 07:22 AM
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Is there any downside to having big informative top LCD on K-3 III? I like it so much more than what K-1 has. Look like the body has been deepened to accommodate it with a mode switch.
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Forum: Pentax DSLR Discussion
03-07-2024, 04:40 AM
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Okay, that's a bummer but my 135-400 APO gets strong backfocus if I let it down and then shoot a photo of same subject. Totally should shoot anything only after refocusing (I do AF-buttton AF). And it does not rattle when I shake it so it's not malfunctioning I guess.
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Forum: Pentax DSLR Discussion
03-06-2024, 08:33 PM
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Good point but the difference in sharpness is same when I photograph something 50m away.
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Forum: Pentax DSLR Discussion
03-06-2024, 11:42 AM
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My copies have slight focusing stem wobble and slight front element wobble which definitely prevents accurate focusing. The example is from FA 35/2, 100% center crops at F2, K-1 with no AA sim. The only difference between shots is that I moved focus ring as allowed by screw drive tolerance and the image is already soft. Slightly moving the front element in the tolerance range yields same result. I have similar effect with 50/1.4.
Is it a common issue for these models? Is it true that if I want accurate focus I should avoid old screw driven lens?
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