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Forum: Pentax SLR Lens Discussion
01-27-2012, 12:37 AM
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sounds like the lens got left somewhere hot enough to evaporate off a bit of oil that condensed back out onto the glass.
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Forum: General Talk
01-22-2022, 05:07 PM
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spotted this pic a week ago on facebook marketplace. $50 canadian for everything. seller dropped it off today. here's what i got.
smc pentax-a macro 1:2.8 50mm w/ caps
smc pentax-a 1:2.8 28mm w/ caps
smc pentax-a 1:1.7 50mm w/ caps and case
(all three are absolutely mint)
smc pentax-f zoom 35-70mm w/ caps
smc pentax-a zoom 1:4 70-210mm w/ caps
vivitar 70-210mm 1:4.5
super program w/ case, grip, eyepiece cover, winder me II w/cable release, strap, manual and batteries
sf1 w/ case and strap
af280t flash w/case and manual
case, manual, lens cap and filter set for smc pentax reflex zoom 400-600mm (but no lens sadly)
leather camera bag
3 soft lens cases
assorted filters, caps and other odds and ends
5 rolls of film
everything seems to be in working condition so far. did i get my $50 worth? ;)
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Forum: Flashes, Lighting, and Studio
09-01-2017, 09:28 AM
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colour fidelity's not going to be great with $5 cobs. i may end up using a mix of cool and warm white cobs to fill in the spectrum a bit better, or i may stick with all cool white and use the excess blue to try out another project, gel filters using phosphors instead of dyes. instead of throwing away the extra blue light heating up a normal filter i'd be converting it to red and bluish green to improve colour fidelity or orange to shift the colour temp, etc. i'm going with water cooling because at 2000w it's the easiest, cheapest option to custom build and you don't have to mount the whole thing directly to the back of the leds at the top of a light stand, so you can scale it up as big as you want. if i really wanted to be cheap and lazy i could even just attach a couple of garden hoses to the led cube and it would work just fine.
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Forum: Flashes, Lighting, and Studio
08-30-2017, 11:53 PM
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don't mind me, i'm kinda cranky tonight. :P this whole conversation has gotten way more pedantic than it needs to be. a rough ballpark estimate of the needed led wattage is all that's needed to prove photonicz's claims are false. their prototype would have to be literally hundreds of times larger to get anywhere near what they're claiming, especially air cooled. with that heatsink they're not gonna get much more than 100w averaged output, so even if they had a tiny magic led that could do 700w/s pulses at 1/250s, you'd still have to wait several seconds between shots just to avoid frying it. closest i've gotten is a design i need to get around to prototyping that will run at around 2000w continuously with a 3" 5-sided led cube, but even that's going to need to be tethered to a pretty massive water cooler.
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Forum: Pentax Medium Format
07-26-2017, 11:17 AM
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are you using a cheap shutter release with only a two-segment connector? that would make the camera think you've got the button half pressed to focus and black out the screen, assuming it works the same as other pentax cameras.
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Forum: Pentax K-1 & K-1 II
06-15-2017, 08:49 AM
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you can't treat li-ion batteries like lead-acid batteries. this is horribly irresponsible advice. you should never "guess" when it comes to things that can burst into flames.
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Forum: Pentax SLR Lens Discussion
11-29-2016, 07:04 PM
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the effect is caused by deeply recessed front elements or other design aspects that begin to block the light path as you move away from the center of the image. mounting a step-down ring or too long or narrow hood on your fa 50 will make it swirl.
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Forum: Mini-Challenges, Games, and Photo Stories
12-21-2014, 03:06 PM
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i'm stretching the definition of "re-purpose" a bit with this one, but i built myself a 16", 144w, 5500k, flicker-free, continuous ring light out of an aluminum bike rim, some computer power supply parts and $15 worth of 1w white leds from ebay.
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Forum: Digital Processing, Software, and Printing
05-04-2016, 06:10 PM
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as long as the backup has the same folders as drive a, just replace drive a and copy the files over to it.
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Forum: Pentax SLR Lens Discussion
02-16-2016, 01:15 PM
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vintage lenses can have an advantage in manual focusing because no compromises have been made to accommodate af. the various optical shortcomings of older tech can also add a lot of character to images.
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Forum: Weekly Photo Challenges
09-09-2015, 08:42 PM
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shortly after buying my first pentax dslr, the neighborhood arsonists decided to torch one of the houses across the alley from me.
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Forum: Mini-Challenges, Games, and Photo Stories
11-19-2014, 10:28 AM
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neoprene pencil cases.
music stands, car sun shades and binder clips.
wireless flash slide projector.
frosted clear vinyl umbrella from dollarama. they also have silver ones.
mic stand.
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Forum: Pentax Camera and Field Accessories
02-12-2014, 11:37 PM
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1. motors don't draw "a constant amount of amps" independent of what the voltage and load are.
2. the af motor isn't connected directly to the battery. the power goes through at least one voltage regulator and a digitally controlled driver circuit/speed control before it gets to the motor.
3. you're the one making the claim, it's your responsibility to prove you're right, not mine to prove you're wrong... but i did anyway.
but hey, don't take my word for it, i'm just some guy on the internet who repairs electronics for a living.
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Forum: Photographic Technique
05-28-2014, 07:29 PM
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Forum: Pentax SLR Lens Discussion
04-18-2014, 05:52 PM
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both. autofocus zooms for situations with quickly changing/moving subjects and locations with fog, snow, dust, sea spray, etc.. fast primes for situations where you can take your time and want the best image quality you can get.
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Forum: Pentax K-30 & K-50
04-17-2014, 07:13 PM
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Forum: Pentax SLR Lens Discussion
04-07-2014, 01:10 PM
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Forum: Pentax K-30 & K-50
04-06-2014, 07:31 AM
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why would increased iso heat up the sensor? as far as i know, changing iso just changes how the camera interprets the signal from the sensor. if anything, with long exposures a higher iso should mean less heat because of the shorter exposure.
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Forum: Pentax SLR Lens Discussion
03-16-2014, 08:39 PM
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if you can find one at a decent price, get an "auto revuenon mc 1:1.4 f=50mm". it gives results very similar to the pentax equivalent, but quite a bit sharper and with almost none of the smearing and ca in the corners. it's kind of a one trick pony though because if you stop it down past around f/8 with a dslr you get a noticeable green spot in the center of the image.
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Forum: Pentax K-30 & K-50
01-05-2013, 08:02 PM
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ok, so you had 20c air with 30% relative humidity trapped in your camera when you stepped outside and let it cool down for 10 minutes without doing anything that would have flushed that moisture out of your camera. from 2c to -2c that moisture would have begun condensing out of the air onto the camera's circuitry, some of which is powered up whether or not the camera is turned on. no way to know if that's what caused the glitch, but it's still a good idea to zoom your lens in and out a few times when you first step outside to help flush the warm air out of your camera before it cools down.
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