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Forum: Flashes, Lighting, and Studio 09-01-2017, 09:28 AM  
Photonicz LED Strobe on Kickstarter claims Pentax Support
Posted By maltfalc
Replies: 19
Views: 799
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.
Forum: Flashes, Lighting, and Studio 08-31-2017, 06:52 PM  
Photonicz LED Strobe on Kickstarter claims Pentax Support
Posted By maltfalc
Replies: 19
Views: 799
actually watts is the correct term to be using in this case because we're discussing things like how much power you can push through an led the size of photonicz's prototype, how many watts the heatsink can handle, how many watts the battery would need to put out, etc.. and when comparing a strobe to flash leds, you're looking at <50% additional lumen output from flash leds, so they could maybe get away with 500 w/s to match a 700w/s strobe, not a significant difference in this context. and since their prototype seems to use a standard cob led, i'm actually being extremely generous.

---------- Post added 08-31-17 at 09:22 PM ----------

my main goals with my design are to make it as small as possible at a ridiculous wattage and for as cheap as possible. i'm using 20 100w cobs (cheap generics for now), 4 per side on 5 sides of a cube with mounting bracket,water cooling and electrical connections on the 6th side. that's 4 separate strings of 5 cobs which run at just over 30v per cob so i can run them directly off of rectified and filtered a/c with no driver, varying the output by switching on 1-4 strings.
Forum: Flashes, Lighting, and Studio 08-30-2017, 11:53 PM  
Photonicz LED Strobe on Kickstarter claims Pentax Support
Posted By maltfalc
Replies: 19
Views: 799
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.
Forum: Flashes, Lighting, and Studio 08-30-2017, 07:57 PM  
Photonicz LED Strobe on Kickstarter claims Pentax Support
Posted By maltfalc
Replies: 19
Views: 799
i know what a watt is, i know how efficient leds and strobes are and how to compare their output (total l/s output per pulse, not constant lumen output btw). i've been designing, building and repairing these things for years. given the relative efficiency of leds and strobes we're looking at somewhere over 100,000w at a minimum and possibly several hundred thousand watts given the reduced efficiency of leds when pulsed at high amps. and your entire second paragraph has absolutely nothing to back it up.
Forum: Flashes, Lighting, and Studio 08-29-2017, 08:28 PM  
Photonicz LED Strobe on Kickstarter claims Pentax Support
Posted By maltfalc
Replies: 19
Views: 799
w/s is a measurement of total power used. flash duration makes no difference. the minimum an led needs to run at to reach 700w/s at 1/250 is 175,000 watts.
Forum: Flashes, Lighting, and Studio 08-29-2017, 05:48 AM  
Photonicz LED Strobe on Kickstarter claims Pentax Support
Posted By maltfalc
Replies: 19
Views: 799
going by the numbers in the article, they would have to be running that led at somewhere around 175,000 watts. the one in the prototype looks like a standard 200-500 watt led at best. 100% BS.
Forum: Pentax DSLR Discussion 07-31-2017, 12:00 PM  
Why has no camera maker done this..?
Posted By maltfalc
Replies: 40
Views: 2,435
4 slots each only recording every fourth photo would quadruple write speed with no need for any additional software, and if space becomes an issue, micro sd.
Forum: Pentax DSLR Discussion 07-30-2017, 12:20 AM  
Why has no camera maker done this..?
Posted By maltfalc
Replies: 40
Views: 2,435
better idea, give the camera 4 sd card slots that can run simultaneously and let the user choose from different raid configurations depending on whether they want redundant copies or 4X normal write speed or whatever.
Forum: Pentax Medium Format 07-26-2017, 11:17 AM  
no screen with cable release
Posted By maltfalc
Replies: 2
Views: 390
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.
Forum: General Photography 07-26-2017, 02:20 AM  
Question about manners
Posted By maltfalc
Replies: 39
Views: 1,460
define "commercial venture".
Forum: General Photography 07-25-2017, 12:23 PM  
Question about manners
Posted By maltfalc
Replies: 39
Views: 1,460
we need to clarify the term "sell". the photographer can sell copies of the photo in the form of prints, photobooks, paid access to an online gallery,
etc. without the model's permission, at least here in north america. if we're talking about selling or licencing the photographer's rights to the photo,
the photographer doesn't need the model's permission for that either. the only way the photographer could get themselves in trouble is if they falsely claim to own the rights for commercial use and include those in the sale.i assume you mean this model? https://thenypost.files.wordpress.com/2013/09/hivad.jpg?quality=90&strip=all&w=1200 she sued getty, not the photographer.
sounds like the issue in all these cases is how the photos were used, not just the sale of the photos.
Forum: General Photography 07-25-2017, 02:26 AM  
Question about manners
Posted By maltfalc
Replies: 39
Views: 1,460
agreed, so what's your problem? tfp is common for models looking to add to their port or photographers not wanting to pay cash for models, but there's no expectation that photographers won't be selling photos from a tfp shoot. even your wikipedia link doesn't support your claim.sometimes, but it's not a requirement a great deal of the time, at least for photographers.why wouldn't they be? happens all the time.ok. agencies are another matter entirely.why are you bringing wedding photography into this?

you still haven't answered my question. what is it models are supposed to "be careful" about? how does a photographer negatively impact a model by selling photos from a shoot she was paid for in photos???
Forum: General Photography 07-24-2017, 09:05 PM  
Question about manners
Posted By maltfalc
Replies: 39
Views: 1,460
why? what does the model being paid in photos rather than cash have to do with what the photographer does with the photos afterwards? why should models "be careful" when a photographer plans to sell photos he has every right to sell?
Forum: General Photography 07-20-2017, 11:29 PM  
Question about manners
Posted By maltfalc
Replies: 39
Views: 1,460
unless you (or any other photographer in this sort of situation) have signed over rights to the photos in a legally binding agreement, she can't do anything with them without your express permission. doesn't matter if you gave her prints or digital files. she can't take them to a print shop, post them on facebook with bad edits and missing watermarks, tell the photographer to take them down, any of that nonsense. if you're fine with her behaviour, that's entirely your call to make, but it's just going to encourage her to mistreat other photographers.
Forum: Pentax K-1 06-15-2017, 08:49 AM  
Travelling with K-1, but forgot charger. Advice?
Posted By maltfalc
Replies: 22
Views: 1,762
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.
Forum: Pentax DSLR Discussion 06-10-2017, 11:07 AM  
Using iphone as a field monitor on K-3
Posted By maltfalc
Replies: 6
Views: 760
you're going to need an hdmi capture device or an hdmi to rca converter and rca capture device, and i'm not aware of any compatible with iphones. even if you found one, you'd be better off just getting a cheap lcd viewfinder.
Forum: Photographic Technique 06-02-2017, 11:00 AM  
Macro Auto aperture control for reversed lenses; any tinkerers out there doing this?
Posted By maltfalc
Replies: 12
Views: 487
both the actuator and lever are spring loaded and the actuator has plenty of torque. polished steel or chrome plating or a bit of teflon would keep friction to a minimum. as long as one end of the cable has the same sort of length adjusting nut as a cable release to eliminate slack, there shouldn't be any issues.
Forum: Photographic Technique 06-01-2017, 09:44 PM  
Macro Auto aperture control for reversed lenses; any tinkerers out there doing this?
Posted By maltfalc
Replies: 12
Views: 487
none of that would be required (unless you wanted af for some reason). all you would need is to link the lever to the actuator mechanically with a flexible cable, just like an old shutter release cable.
Forum: Pentax SLR Lens Discussion 05-22-2017, 03:32 AM  
Counterfeit old Pentax lenses? SMC 18/f2.8
Posted By maltfalc
Replies: 30
Views: 2,154
looks like a 40mm, except for slightly different markings.
Forum: Pentax Film SLR Discussion 05-05-2017, 04:10 PM  
Pentax NEd
Posted By maltfalc
Replies: 18
Views: 1,431
does it come with one of these 50mm "f/1.2" lenses i always see on ebay? :P

Forum: Sold Items 05-04-2017, 03:36 AM  
For Sale - Sold: Pentax MZ-S
Posted By maltfalc
Replies: 3
Views: 793
pm sent.
Forum: Sold Items 04-30-2017, 02:49 AM  
For Sale - Sold: SMC Pentax-DA 35mm F2.4 AL
Posted By maltfalc
Replies: 6
Views: 1,022
pm sent.
Forum: Pentax SLR Lens Discussion 04-27-2017, 03:16 PM  
Alternatives to the Pentax M 28mm f2?
Posted By maltfalc
Replies: 21
Views: 1,182
vivitar 28mm 1:2 mc, if you're lucky enough to find one at a thrift store for a few bucks like i did.
Forum: Pentax SLR Lens Discussion 12-24-2016, 03:08 AM  
What lenses "Swirl"
Posted By maltfalc
Replies: 82
Views: 5,448
*sigh* i'm tired of repeating myself over and over again in this thread. a deeply recessed front element is not required, it's just one of the factors that can contribute to swirl.
Forum: Pentax SLR Lens Discussion 11-30-2016, 02:50 AM  
What lenses "Swirl"
Posted By maltfalc
Replies: 82
Views: 5,448
i mentioned at least three times that it wasn't specific to the front element. you just need at least two edges somewhere on the lens to clip the sides of the cat's eye shape. one on the way in and one on the way out. could be the filter ring, the edge of any of the glass elements, an internal baffle, the iris or the inner edge of the lens mount.
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