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Forum: Pentax DSLR Discussion 09-27-2016, 01:13 AM  
Sigma 50 1.4 EX DG HSM
Posted By Ratcheteer
Replies: 4
Views: 659
i think sigma is to invested in making super35 cine lenses its only a matter of time before they drop support for other dslrs
Forum: Pentax Q 09-23-2016, 03:53 AM  
Lens Distortion?
Posted By Ratcheteer
Replies: 19
Views: 1,283
does a window will appear where you can choose "Native size only" as one of the options
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 09-23-2016, 03:27 AM  
Impressive new specs of canon mirrorless camera leak - eos m5
Posted By Ratcheteer
Replies: 49
Views: 2,901
not really surprising to me, fuji has been making lenses for hasselbad for years and the hasselbad xpan is manfactured by fujifilm, with the increase in tethered shooting the mirror was slowly becoming obsolete to the actual shooters that use these systems as the typical SLR viewfinder would be to hard to see in some situations.
Forum: General Talk 09-22-2016, 02:37 AM  
What happened to Rupert?
Posted By Ratcheteer
Replies: 5
Views: 805
you can be super nice and still break the forum rules, i enjoyed his input.
Forum: Pentax Q 09-21-2016, 07:04 PM  
Lens Distortion?
Posted By Ratcheteer
Replies: 19
Views: 1,283
its normal, the 02 lens has appox 4.75% barrel distortion at the wide end
when shooting jpeg its corrected by the cameras image processor before its output to a file
when shot in raw no correction is applied.
Forum: Troubleshooting and Beginner Help 09-21-2016, 09:55 AM  
My pics are garbage! Why?
Posted By Ratcheteer
Replies: 103
Views: 7,558
watch a few videos on framing and composition, the very things camera's cant do for you
Forum: General Photography 09-20-2016, 08:14 AM  
curved sensor?
Posted By Ratcheteer
Replies: 33
Views: 1,730
forget field curvature for a minute, the reality is lens designers consider this a good trade off for lens sharpness since its not all that visible if your not looking for it in the first place and in fact zoom lenses often trade one or more aberrations for higher image sharpness.

light also disperses, even a focused beam will lose intensity as the beam will get wider over distance, you might not think this is a big deal but that is only one of many factors that is causing peripheral fall off and drop in contrast at the edges of the frame

the one i believe that causes the most problems is angle of light and is also why i think your argument for curved sensors only benefiting fixed focal length cameras is a bit closed minded.

take a torchlight shine it on a flat piece of paper from 4 inches away at a dead on angle you just a nice round patch illuminating the paper evenly, the moment you angle the light the patch is no longer round now nor evenly illuminated, repeat the same test from different distances 2 inches away and 6 inches away (this is like zooming in and out) the results will be the same (this test is actually how you demonstrate the effect of a aberration known as coma)

now repeat the test with a empty fruit bowl and right away you will see the benifit the moment you change the angle, of course one distance will work better than the other but they all are receiving the benefit of illuminating a curved surface (the size/shape of the patch is better controlled and there is less fall off from one edge of the patch to the other vs the paper test.

now back to field curvature, yes zoom lens has varying curvature but its far away from being flat, but the fruit bowl results should show you that a curve surface can in fact benefit zooms, it might be only a little but any thing that helps flatten the curvature has a list of other beneficial effects on image quality (coma resistance, lower peripheral fall off (vignetting), reduce edge astigmatism) those very benefits would allow for future lens to require far less elements, most existing zoom lenses do not correct for the benefits a curved sensor could offer anyway, the only incompatible lenses would be high quality primes :P
Forum: General Photography 09-19-2016, 11:27 AM  
curved sensor?
Posted By Ratcheteer
Replies: 33
Views: 1,730
first off bending light always leads to an aberration of some sort we are dealing with multiple wavelengths not all will end at the same point hence why i brought up the spectrum,

second, bending light to hit the edges of a flat plane means that it hits at an angle, not straight on (this is what causes the most visible aberrations - vignetting and color shifts, coma, chromatic aberration.)

third, most lens made today have a curved field curvature (not flat as some may believe) including the very popular Distagon and the batis loxia touit



i work with digital cine cameras capible of shooting 8k and lately I've been using Zeiss Milvus lenses and they still have some vignetting, you talk of filters, i call that grading which i need a render farm if I'm to spit out (33megapixel) 43,200 rawDNG frames (30mins@24fps) in under 30mins, somehow i dont see this sort of power coming to a cellphone near you anytime soon, where would they put the 16 lens elements and this is without auto focus

the samsung s7 only has 12 actual megapixels but the quality is closer to 4 perceptual megapixels
Forum: General Photography 09-19-2016, 02:13 AM  
What was your first camera EVER.
Posted By Ratcheteer
Replies: 146
Views: 23,093
i still have my first camera, a mamiya c330
Forum: General Photography 09-18-2016, 03:28 AM  
curved sensor?
Posted By Ratcheteer
Replies: 33
Views: 1,730
military and pin hole enthusiasts :)
they have been curving film along the petzval field plane for years



thats if all light were equal, but its not its a spectrum (a condition that is not limited to a specific set of values but can vary infinitely within a continuum)

for every element you add to correct one aberration, that element introduces another aberration, this is why modern prime lenses can have upto 11+ elements and cost more than most camera bodies

*** just been talking to a guy who actually curved a canon 400d sensor, but it was de-Bayered first (he was using the camera for astro and infrared photography before this experiment)

he said it actually improved the wide open performance and edge sharpness on the entire focal range of a 15-85 efs lens, his conclusion was that it will likely work so well that it might cause some companies to pull out of the camera market altogether due to patients and licensing fees.
Forum: General Photography 09-17-2016, 09:51 AM  
curved sensor?
Posted By Ratcheteer
Replies: 33
Views: 1,730
you think that because of what the past tells us, but back then they didn't have computer aided design and nano coating that not only increases light transmittance and removes reflection but repels water/moisture and dust, glass manufacturing has changed by removing the human element glass is now manufactured in higher temps cleaner environments and handled less and made by precision machining to tighter tolerances not possible by the methods of the old.

the best bit is the lens can be made alot thinner and smaller with even shorter back focus, the idea is not to make it better but make things smaller and give us more options - imagine a cellphone that can take distortion free vignette free sharp edge to edge 8k video
Forum: General Photography 09-17-2016, 08:53 AM  
curved sensor?
Posted By Ratcheteer
Replies: 33
Views: 1,730
who cares its the registration distance that dictates the curvature anyways, the thinking process behind mirrorless was shorter back focus distance so why not make the curved sensor register distance variable to cater for fine tuning



sure if your subject is still and you have all the time in the world and there is no chance it will rain, some of us want to travel and leave the tripod and computer at home



its already been proven that it does work and fringes what ever the colour are not a problem cause the curvature ensures that the focused wavelengths or light hits the sensor at the optimum distance/focal point to reduce wavelength separation which normally causes color bleed known as fringing in areas of high contrast.

when you start adding more elements you start reducing the quantity of light, and the sharpness that people did not like from the 4 element tessar design was it had a undesirable effect on out of focus areas/bokeh/highlights it was distracting.
Forum: General Photography 09-17-2016, 05:17 AM  
curved sensor?
Posted By Ratcheteer
Replies: 33
Views: 1,730
forget backwards compatibility, technological advancements always comes from forward thinking. the main purpose of a curved sensor is lower distortion and aberrations at ultra wide angles, think 8mm full frame equivalent field of view with near perfect flat field edge to edge sharpness from a simple meniscus lens. or a interchangeable 4 element prime lens where you only change out the front element to change the focal length, this is why some companies have patented some designs to make sure their competitors do not get the jump on them.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 09-16-2016, 04:26 AM  
Impressive new specs of canon mirrorless camera leak - eos m5
Posted By Ratcheteer
Replies: 49
Views: 2,901
when ever people talk about how much lens a system has, this meme comes to mind
Forum: General Photography 09-16-2016, 04:10 AM  
curved sensor?
Posted By Ratcheteer
Replies: 33
Views: 1,730
the cost benefit is rarely passed on to the consumer otherwise the camera manufactures own brands of lenses would be cheaper than the third party ones
and yes some of us are happy to do some post processing.



unlikely, the whole idea of curved sensors is to reduce diffraction when stopped down and vignetting when wide open



the main problem is etching and coating a curved wafer, i imagine yields would be another factor.
Forum: Troubleshooting and Beginner Help 09-11-2016, 01:55 PM  
Focus issues Tamron 70-200 with Pentax k-30 soccer
Posted By Ratcheteer
Replies: 19
Views: 1,414
the depth of field is a matter of preference
but sometimes its needed to get more keepers on older equipment and 3rd party lens
Forum: General Photography 09-11-2016, 11:58 AM  
curved sensor?
Posted By Ratcheteer
Replies: 33
Views: 1,730
probably not today but in the future I'm sure there will be medical uses for such a sensor
Forum: Troubleshooting and Beginner Help 09-11-2016, 11:18 AM  
Focus issues Tamron 70-200 with Pentax k-30 soccer
Posted By Ratcheteer
Replies: 19
Views: 1,414
thanks for that steve, its been a few years since shooting with a dslr and my last pentax dslr was a k200d which lacked the TAv mode
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 09-11-2016, 11:00 AM  
Impressive new specs of canon mirrorless camera leak - eos m5
Posted By Ratcheteer
Replies: 49
Views: 2,901
actually i was using your comment out of context to purposely poke fun at the canon powershot n2
sorry if my failed attempt at humor offended you
Forum: Troubleshooting and Beginner Help 09-11-2016, 10:24 AM  
Focus issues Tamron 70-200 with Pentax k-30 soccer
Posted By Ratcheteer
Replies: 19
Views: 1,414
looks like you had plenty of light so you really do not have to shoot wide open.

I've never shot soccer, but personally i would want greater depth of field.

shoot in manual mode auto iso, expanded af mode with the lower part of the frame selected, set shutter around 1/800 and aperture at least f4
Forum: General Photography 09-11-2016, 09:49 AM  
curved sensor?
Posted By Ratcheteer
Replies: 33
Views: 1,730
something that annoys me about camera manufactures the lens they make for their own bodys are only mildly corrected, the rest of the correction happens in body.
Forum: Pentax Medium Format 09-11-2016, 09:18 AM  
MF film: is there anything it can't do?
Posted By Ratcheteer
Replies: 56
Views: 3,789
the biggest limitation with any format is experience, all the others are minor.... are you sure your not mistaking analog obsession for curiosity and passion?

what you should worry about is gear acquisition syndrome
Forum: General Talk 09-11-2016, 08:32 AM  
Your latest acquisition
Posted By Ratcheteer
Replies: 11,178
Views: 760,493
or a good investment, alot of canon fdn lens got the ssc coating and mirrorless camera's has made them popular again
Forum: General Photography 09-11-2016, 08:14 AM  
curved sensor?
Posted By Ratcheteer
Replies: 33
Views: 1,730
I think you have missed the point, its because the lens image is circular we get vignetting

but a better reason to use a curved sensor would be optics (who needs extreme rectilinear correction when the sensors curvature corrects the image for you)
Forum: General Talk 09-11-2016, 07:27 AM  
Pentax in Schools?
Posted By Ratcheteer
Replies: 11
Views: 784
doesn't help that the modern office environment is trying to go green (paperless)



lack of authorized distributors/dealers of Pentax equipment doesn't help, especially in the south pacific. (schools get goods and sevices tax exemption if they buy from an authorized source)
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