Forum: Photographic Technique
2 Days Ago
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Presumably one of them has more shutter shock than the other.;)
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Forum: Photographic Technique
3 Days Ago
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Back in the days of film, I found that hand-holding the camera with the tripod attached helped stabilize it. The dangling mass helped hold the camera level and the tripod added a lot of inertia against pitch and roll rotations.
(You might well ask why I did not just put the camera and tripod down for even better stabilization. Sometimes it takes too long to extend the legs, find solid flat ground, and loosen the tripod head for composition.)
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Forum: Pentax SLR Lens Discussion
3 Days Ago
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First, a 95% eclipse is nothing compared to a 100% eclipse. At 95%, all you'll get is a bright featureless crescent on a dark background. A total eclipse is totally different and creates totally different images with the wispy corona and prominences showing. You might consider a road trip to totality. You might be able to decide the morning of the eclipse but be prepared for insane traffic if your route involves any roads that connect the zone of totality to any major metro area.
As for lenses, the longer, the better!. On APS-C and with a 300mm lens, the sun will only be 1/9 the height of the frame and cover less than 1% of the pixels of the sensor. Even with 600mm, the cover less than 2.6% of the pixels of the sensor.
A "good" lens with a matched "good" teleconvertor will be somewhat better than cropping. But it's hard to know which of your lenses are good and which teleconvertor best matches them. You'll have to try it yourself on the sun just as you did with your 500mm. You might even trying stacking the teleconvertors (Tak 300 + M42 2x + M42-to-K adaptor + K mount 2X) and downsampling the image a bit -- it's a long shot but it will only take a few minutes to try it.
Good luck & have fun!
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Forum: Pentax News and Rumors
4 Days Ago
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The role of sharpness or softness varies with the intentions of each artist and each artistic movement.
For Group f/64 - Wikipedia , edge-to-edge and front-to-back sharpness was a key quality of creating images that revelled in the details of everything from landscapes to farm implements. For Henri Cartier-Bresson, sharpness was irrelevant and, in fact, blur and softness helped convey that the image captured some fleeting moment in which the photographer had no time to carefully control and dial-in the settings for perfect sharpness. It's not unlike the difference between the intensely detailed pin-sharp brushwork of a Vermeer compared to the dreamier brushwork of Impressionism. (And then there is Salvador Dalí who synthesized dream-like surreal subjects often executed in Vermeer-like detail!)
Beauty is in the eye of the beholder. And control of the creation of whatever standard of beauty is in the hands of the camera holder.
Some people simply love a large, intensely detailed landscape, cityscape, architecture, or astro images that they feel they can walk into and lose themselves. And some feel that too much detail (every pore on the subject's face) distracts and detracts from conveying the essence of the subject. Other's love motion blur, limited sharpness, and some delineation of a relative sharp subject with blurring of the contextual objects of the corners, edges, and background. And there is also the ethos of creating art under constraints -- using a simple camera and simple lens and proving that it is the skill of the photographer that made the beautiful image, not the size and cost of the equipment that mattered. (How many photographers cringe when they hear someone tell them "you must have a good camera"?!?!)
Interchangeable lens cameras offer control of lens choice, lens filter choice, focus point, aperture, and shutter speed. Those controls mean that the photographer can intentionally create sharpness or softness (across the plane of the image and into the depth of the subject) through the intentional choice of lens, filter, aperture, shutter speed, and how the camera is held during exposure. If a photographer wants to create images across the span of sharpness-to-softness sensibilities, then those large, bright-aperture, highly-corrected lenses are essential. That said, many photographers simply don't seek insane detail on large prints so these large lenses aren't that useful.
Each person has their own sensibilities and photographic preferences. Although we might not always agree with another photographer's choices of camera, lens, sharpness, blur, subject matter, etc., I do believe we can always learn from other people's choices. We can at least be aware that other styles/options/techniques exist and one never knows when another style might be useful.
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Forum: Pentax Medium Format
4 Days Ago
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The mask is probably centered to make the most of the sharper and less distorted center of the lens. The mod is almost certainly a rectangle of some thin material with a centered rectangular hole. That rectangle was then set into the film gate area. You can actually tell that the mask is slightly warped (it might be a tiny bit too long to fit flat) which makes the left and right sides of the image slightly taller and the middle slightly narrower.
The mask would have no effect on focal plane shutter speeds unless the mask touches the shutter and then the effects would be BAD!
In theory the half-size frame might enable a faster flash sync (the first curtain clears the second edge of the half frame sooner than on a stock 645 and the second curtain takes longer to get to the first edge of the half frame than on a stock 645). If (and big if) the clever modder could advance the flash trigger by 2 milliseconds, they could probably get successful flash sync at 1/125 sec instead of 1/60 sec on the full frame 645.
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Forum: Pentax Medium Format
5 Days Ago
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Doing the math, that makes this camera a 622.5n. ;)
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Forum: Pentax News and Rumors
5 Days Ago
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I voted both!
I don't mind lugging around big lenses and certainly like the big apertures, performance, and other features (e.g., tilt & shift lenses).
But I also enjoy throwing a small lens on the camera or a small lens group in the bag and making the most of these lenses. I especially like using a compact set of M42 lenses -- a 28, 55, and 135mm set -- that are extremely portable in the bulk department and very competent in the IQ department.
Every lens deserves a little time on the camera.
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Forum: Troubleshooting and Beginner Help
03-11-2024, 10:18 AM
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The best advice is to try it and see but to watch out from some common problems with using lighting that is not explicitly (and carefully) designed for photography:
First, As @pschulte says, LED lights tend use a pulsed power supply and flicker at some unknown high frequency. High shutter speeds or using an electronic shutter can lead to banding, inconsistent exposures, and weird color shifts. Slower shutter speeds might be OK but that seems to defeat the purpose of using a bright light.
Second, the light's color accuracy might be poor. Although the LED light might look "white," LEDs tend to have a lumpy light spectrum. They are not as bad as fluorescent lights but the lumpy colors can cause objects to have slightly off colors compared to images take in full sun or with a good photographic flash. The Amazon page does not give the light's CRI -- the Color Rendering Index -- which is an industry standard way of measuring color accuracy.
Third, the light might have an unstable white balance. That is, the light's white balance might shift with the power level setting, ambient temperature, internal operating temperature, and over the life of the bulb. This is only a problem if you shoot a lot of shots with this LED light and expect to be able to apply the same white balance correction in post.
Fourth: the color of the LED's beam might be non-uniform. The center of the beam might have a slightly different color than the edges of the beam. A picture of a white wall might have a different white balance in the center compared to the edges.
But, all that said, you may be willing to live with or work around these downsides. These lights are perfect for your purposes. The only reason to be wary is if you are persnickety about color and get upset when images do not look quite right.
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Forum: Troubleshooting and Beginner Help
03-10-2024, 10:35 AM
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Indeed!
Frame transfer CCDs quickly moved the signals stored in all the pixels to a second covered copy of the sensor. Alas the transfer was never truly instantaneous and scenes with very bright lights (e.g., the Sun) tended to have streaks.
Interline transfer CCDs had an array of small uncovered photodiodes with each photodiode being connected to a covered line of CCD wells. This avoided the streaking problem of frame transfer but the image quality wasn't that great because the only a tiny fraction (about 20-30% fill-factor) of the light falling of the pixel got measured and the design also created problems with aliasing and moire. If you read more about the Sony A9 III, you'll find that Sony has resurrected the interline transfer concept with a small light-sensitive part of the each pixel connecting to another small covered part of the pixel.
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Forum: Troubleshooting and Beginner Help
03-10-2024, 08:19 AM
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The best way to think about it is that BOTH mechanical and electronic shutters depend on two traveling curtains:
The first curtain starts the exposure (traveling from one edge of the sensor to the other). The second curtain ends the exposure (following the first curtain from one side of the sensor to the other). These curtains have a maximum speed imposed by design limits.
For "very short" shutter times (faster than the travel time needed by each curtain), the second curtain must start moving before the first curtain has completed its travel -- creating a traveling slit. The result of having a traveling slit is that side of the sensor is exposed a relatively long time before the other sider is exposed. That means that anything that happens while the slit is moving (e.g., flickering of the light, motion of the subjects, motion of the camera) will create artifacts in the image.
The mechanical shutter is limited by how fast the mechanism can accelerate the curtain blades. Literal decades of engineering have made some relatively faster mechanical shutters. For the mechanical shutter, the flash sync speed tells you it's speed limit. In the case of the Pentax K-3 III, the flash sync is 1/200 sec which is 5 milliseconds. But the shutter must move a bit faster than that to give time for the flash to operate. That means the first curtain probably travels across the sensor in under 4 milliseconds, leaving the sensor fully exposed of at least a millisecond (the typical duration of photoflash), before the second curtain must start moving.
The electronic shutter curtains are limited by the speed of the read-out and digitizing circuits. For the electronic shutter, the maximum frame rate probably indicates the electronic curtain speed limit. In the case of the Pentax K-3 III, the max frame rate is 12 frames per second which means the exposure of the sensor on one side is about 83 milliseconds after the exposure on the other side.
P.S. There are ways to design a so-called "global shutter" where the entire sensor is simultaneously exposed but the technology creates notably worse images and adds a lot of cost.(see the Sony A9 III Sony a9 III: Global shutter comes with an image quality cost: Digital Photography Review) The fundamental sensor design problem is in the physics of semiconductor sensors. There is no way to "turn off" a silicon sensor. If any light is hitting the chip, the exposure continues to happen. The only solution is to carefully move the collected pixel signal somewhere else.
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Forum: Troubleshooting and Beginner Help
03-09-2024, 12:00 PM
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Yes, that looks like classic banding from using Electronic Shutter with LED (and some CFL) lighting.
in future, the solutions are:
1) Don't use the electronic shutter. (This also avoids motion artifacts in shots of moving subjects even if you use a fast shutter speed.)
2) If you do use ES, do some pre-event test shots with different shutter speeds to find one that works. Slower is better. A setting of 1/60 or 1/50 sec (depending on your country's AC power grid frequency) should work. If you need want faster shutter speeds, the trick is the find a shutter time that is an exact multiple of the LED's pulse width. Then use Tv or TAv mode to stick with the band-free shutter time.
(P.S., anti-flicker settings of some high-end cameras might work with stadium lighting and room lighting but I'd bet that the mixed lighting of theatre and music venue lights (different brands of lights for different purposes) often have different flicker frequencies which makes these settings much less likely to work.)
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Forum: Pentax SLR Lens Discussion
03-08-2024, 04:34 PM
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Extension tubes with the Pentax-M 100 F4 Macro would be sharper than using a Rear Converter-A 2X-S. I'd expect the 100mm F2.8 ED AW Macro to be sharpest solution based on its more sophisticated optical design (10 elements in 8 groups vs 5 element in 3 groups) but that's a prediction, not from experience.
The AF on the 100mm F2.8 ED AW Macro might be nice if some negatives curl more than others in the holder.
Good luck!
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Forum: Pentax SLR Lens Discussion
03-06-2024, 11:22 AM
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"AF integration time" is essentially the "shutter speed" for the AF sensor.
In low light, the sensor needs to take more time accumulating photons to get a clear signal of the patterns in the scene for the AF calculation. A longer integration time in dim light or with very dark subjects is a major contributor to poorer AF performance under those conditions.
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Forum: Photographic Technique
02-24-2024, 07:09 AM
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Fantastic work, AstroDave!
Now you need a large prism to put in front of your camera and a point or line light source so you can characterize the response curve of your cameras on one of your light sources.
The scanner light source is interesting because a 3-peak light source would improve the scanner's ability to get a clean color separation when scanning the 3 colors of dyes in negatives or slides. But such a light source would be inferior when trying to use the scanner on art work because art uses a much wider palette of pigments with more complex spectra.
P.S. I've got an astronomer friend who bought a large prism, mounted it front of a astrograph lens to take images of planetary nebulae. Because the nebulae mostly emit in a series of sharp spectral lines, the result is an image with little copies of the nebulae in each spectral line.
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Forum: Vintage Cameras and Equipment
02-09-2024, 03:55 PM
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Self Timer = Like "ON' mode but the camera waits some time (maybe 12 second while beeping or blinking) before it takes the picture
OFF = OFF
ON = normal operation of the camera
B.C. = Battery Check: something will light up or blink if the battery has enough juice
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Forum: Canon, Nikon, Sony, and Other Camera Brands
02-07-2024, 03:33 PM
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OVF! The "eye's" have it!
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Forum: Canon, Nikon, Sony, and Other Camera Brands
02-07-2024, 03:32 PM
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Hmm... Haven't Olympus, Hasselblad, and Fuji had pixel-shift super-resolution for a while now?
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Forum: Pentax DSLR Discussion
02-04-2024, 03:48 PM
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Very true!
Form certainly follows function but only within the limits of available materials and manufacturing methods. The "retro" design of old film cameras reflects the limited choices of materials and manufacturing methods of that old era. Those old cameras were made of bits of metal that were machined, cut, and bent. Concerns about both manufacturing costs and product weight contributed to the rectangular slab design of that era's camera. In contrast, the PZ-1 shows the better, more functional forms that are possible with modern materials (high-performance plastics) and modern manufacturing technologies (injection molding). Molded plastic enabled a much more organic/ergonomic shapes for the grip without excessive cost and weight. (it's also worth noting that the front grip of the PZ-1 would not be ergonomically pleasant if the PZ-1 did not contain a motorized film winder.)
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Forum: Pentax DSLR Discussion
02-04-2024, 11:36 AM
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Sometimes the discovered function is a frightening experience!
One time the four-way controller on my K-1 stopped working. I couldn't change the AF points or use the drive, WB, etc. controls. Turning the camera on and off didn't help! Pulling the battery didn't fix it! Had water gotten into the four-way buttons? Was the mainboard on the verge of death?
Nope... it was an undiscovered function. For the first time in 6 years of heavy use, I'd accidentally activated the the "Lock" button on the left side of the lens mount.
I LOL now but at the time I was sweating bullets!
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Forum: Troubleshooting and Beginner Help
02-04-2024, 06:28 AM
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Under a carport is not "natural light." it is light reflected off whatever happens to be visible from the place you put your subject matter.
If the place where you put your subject can see a lot of blue sky from that shady spot, the lighting will be blueish. If a brightly lit cloud flits by, the light will get whiter. If there's lots of sun-lit bushes next to the carport, the light will go green. If one side of the carport has the sunlit beige walls of the house and the other side has shrubbery, then one side of your subject will be tinted beige while the other side is tinted green. The color of you car, if it is parked in the sun next to the carport wil bounce it's color to your subject. AWB will try to correct for these tints but it can't fully color-balance the light if the different sides of the carport have outside objects or sky of different colors.
The washed out images on the veranda probably mean that your location on the veranda is lit by a much wider array of outside objects than in the carport location. Subjects tend to lose definition when lit from all sides.
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Forum: Pentax DSLR Discussion
01-26-2024, 12:34 PM
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First, a monochrome K-1iii, is a great idea. A K-1iii monochrome sensor would certainly beat the K-3iii monochrome sensor on some combination of resolution and image quality. The advantages of a full frame for landscapes would make the K-1iii monochrome a hit with that crowd. (I'd definitely buy one except for the personal fact that SWMBO thinks black-and-white photos are a big waste and would not let me use a monochrome camera on any pictures she wants to see. LOL!)
Second, personally, I think a retro body design is a bad idea because SLRs and DSLRs have very different body designs for a reason: both design constraints and ergonomic requirements
The film SLR body design was driven by the film cartridge system (space required for a spool of film on both sides of the shutter) plus positioning the hand around the end of the body so the thumb can easily reach upward to swipe the top-mounted winding lever. The result is the SLR's long, modest-thickness slab with the lens centered in the slab.
The digital DLR body design does NOT require equal volumes on either side, but needs extra thickness for both the main circuit board and back panel display (plus any articulation of that display), and needs a different positioning of the hand so the thumb can easily reach a wide range of controls on the backside of the camera. The result is the DSLR's thicker slab, off-center lens, and big frontal hand grip (with the fingers curled around the front of the camera, not the side).
The point: DSLRs should not be shaped like SLRs were. It's a case of different designs optimized for different imaging technologies.
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Forum: Troubleshooting and Beginner Help
01-25-2024, 10:31 AM
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One fundamental challenge with night photography arises if the scene contains light sources. Light sources such as street lights, headlights, neon signs, the bulbs of holiday lights, the moon, even lit-up windows will be many many stops brighter than the night-time landscape. The landscape might need an exposure of 30 seconds while the light source might need an exposure of 1/30 or even 1/1000 seconds.
If you expose for the landscape, it will look good but the lights will be washed-out blurs. If you expose for the lights, they'll be sharp and colorful but the surrounding landscape will be nearly black.
Such scenes that contain both the light source and the lit scene often need HDR (High Dynamic Range) techniques. HDR methods take more than one image of the exact same scene using different exposure settings to get good image data from both the brightest and darkest parts of the scene. Post-processing merges the multiple frames and compresses the light curve to preserve more details across the entire range from darm to bright.
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Forum: Pentax K-1 & K-1 II
01-22-2024, 08:44 AM
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If you leave the camera "on" and put it in a backpack, there's a decent chance something is bumping/pressing the shutter button as you walk or the backpack rests against something in the car.
I made this mistake once and heard the camera inside the backpack taking a continuous stream of shots when something pressed and held-down the shutter button.
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Forum: General Photography
01-22-2024, 08:37 AM
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The use of a pre-exposure shot certainly suggests that AT3 is analyzing the motion of the stars to estimate the required linear and rotational motion of the sensor that would correct for the motion of the celestial sphere. Note: the camera must take two pre-images (maybe using the electronic shutter between the two) to determine if the camera is pointing N versus S (counterclockwise vs. clockwise trailing), E vs. W (rising vs. setting stars).
Non-star subject matter (foreground terrain, moving headlights, the moon, aircraft, clouds, etc.) could certainly confuse or corrupt the pre-exposure data. Various masking pre-processes and statistical post-processes might be able to avoid or correct much of it but the solution won't be as accurate or reliable as an astro image with just stars.
The documentation for AT3 claims that it does not need GPS or compass calibration. If so, the simplest version of AT3 software would ignore this data. Trying to use any available GPS and compass data would complicate the AT3 software with a bunch of added IF-THEN blocks for various combinations of data availability as well as cases where the image analysis results disagreed with the GPS or compass numbers and the code had to decide which one to trust. Given the limited resources of Ricoh, I'd guess they ignore the GPS and compass data but a bit of careful testing could prove me wrong.
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Forum: General Photography
01-21-2024, 02:47 PM
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From the images I've seen, Astrotracer simply stops tracking (but the exposure continues) if it reaches the limit of travel. The result is images with each star being a nice bright point (light accumulated while Astrotracer could move the sensor) followed by a fainter segment of trailing (star trailing after Astrotracer hit some digital or physical limit.)
Knowing the maximum tracking time is very feasible but requires a lot of careful math involving the geometry of the celestial sphere, the pointing angles of the lens, the orientation of the sensor, and the travel limits of the SR mechanism. Time to call your friendly neighborhood celestial mechanic! ;-)
You can estimate the maximum tracking time empirically: Take one shot with long shutter time and no Astrotracer to see the full length of the uncorrected trail. Take a second shot using Astrotracer with the same long shutter time and look at the length of shorter trails relative to length of the long trail from the no-Astrotracer shot. That relative length will tell how long you went over the max which then tells you what the max time is. (Note: It's also possible that even if you do not high the hard limit of travel, Astrotracer might create slightly elliptical or elongated stars if inaccuracy in the parameters of the tracking creates a slight drift in the trail correction over an excessively long exposure time.)
I don't think the sensor ever bangs into the physical edge - the SR system would make a lot more noise if it did not have some sort of digital soft limit.
Yes, the sensor starts from the center. Starting from the edge would be a nice feature although it poses a challenge in composition because the resulting image could be shifted with respect to what is seen in the eyepiece or in live view. Alas, I also noticed that the K-1 manual says the "Composition Adjustment" cannot be used with Astrotracer :-(
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