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Forum: Pentax Camera and Field Accessories 12-19-2014, 06:26 PM  
Rear Curtain Sync Off Camera
Posted By sandilands
Replies: 22
Views: 5,002
The Metz overcomes a problem with the camera, much like the digi-adapt. The trouble with that is from there on you are triggering optically. A radio trigger works fine on the digi-adapt but only after the digi-adapt "sees" the series of flashes from the popup. I don't have a high end radio trigger like a pocket wizard, but maybe they have some smarts similar to the Metz. I use Elinchrom Skyports which have pretty basic functionality. The camera doesn't recognize the Skyport so no direct rear curtain.

From what I have found, the K5 will only send a rear curtain "signal" to the pop-up flash, or when if finds or think it finds a Pentax 360 / 540 mounted on the camera or via a PTTL cable.

The cactus v6 looks interesting but I couldn't find anything in the literature that would suggest it will solve the problem. It does claim to have Pentax profiles which hopefully means the K5 will think it is a Pentax flash.

Let us know if the V6 works.
Forum: Pentax DSLR Discussion 09-26-2014, 07:16 AM  
Noise and other noise
Posted By sandilands
Replies: 20
Views: 2,220
Don't forget my "test" was not a typical shooting situation. Even the "analysis" technique was meant to find noise. In most cases we optimize the shooting situation as best we can to avoid noise. The values on the graph can be a bit frightening when you notice that the RGB values of a pure black space are nearly white (200,200,200) at ISO 51200. This would imply that an image at 51200 would have nearly zero contrast
but we know from experience that even at 51200 although grainy, we can make an image with a recognizable subject. I think the problem with the test technique is that I cannot select a threshold level of less than 1. That means the slightest non black pixel (even if its RGB value is 1, 1, 1) is going to be forced to white (255, 255, 255). In reality the fact that there are still some purely black pixels at 51,200 is remarkable.

So don't get too concerned how the slope increases so severely at ISO 3200 As others have posted, real life photographs can be excellent even at high ISO.

---------- Post added 09-26-2014 at 07:55 AM ----------

And after seeing Dave's car photos (my K-7 experience was similar), I want to design some simple controlled environment test for dynamic range.
I did a luminosity studio test with a friend who has a Canon 5D MKIII. I need to study up on the meaning of dynamic range vs. what I think we tested which I will call static' range.

Basically a continuous light setup and a photovision 3 bar calibration target with pieces of white and black lace stretched over the target to provide some texture. We balanced the lights (Videolux 5600K) as evenly as possible and used the target to get perfect exposures which we both set at f/5.6 ISO 100 for 2 seconds. Then we made shots from 30 seconds to 1/8000 sec. Then we imported all the images into Photoshop, zoomed in, and looked for details in the white and the black lace. Bottom line was the K-5 shots showed details in the black lace over the dark section of the target 3 stops stops faster (darker) than did the 5D. On the other hand, we could detect details in the white lace over the light section of the target 1/3 stop slower (brighter) from the 5D than we did the K-5 .
Conclusion: The K5 has a static range 2.7 stops larger than the Canon 5D MKIII, therefore is a better choice of camera when shooting in caves ... I guess.

I like doing simple repeatable experiments like this. I know the reviewers have all kinds of fancy measurement gear, but these tests can be done in my basement with gear that is commonly available. I would be very interested in anybody else's results doing similar experiments.

Oh and I'll post the graph when I get the chance.
Forum: Pentax DSLR Discussion 09-11-2014, 08:21 PM  
Noise and other noise
Posted By sandilands
Replies: 20
Views: 2,220
I think you are pretty safe up to ISO 800 for most lighting situations. The average amount of white in the samples is only 25. You could probably see an RGB value of 25, 25, 25 on a pure black background, but since this is just an average of 101x101 pixels the actual noise would be distributed and not clustered in any one place. If you are shooting a fairly bright scene you wouldn't see it at all. Based on what kh mentioned though I'd keep even bright shots to a max of 1600. The last thing I want to sacrifice is dynamic range.
Forum: Pentax DSLR Discussion 09-10-2014, 06:00 AM  
Noise and other noise
Posted By sandilands
Replies: 20
Views: 2,220
Ahha. That makes sense. I was wondering if it was truly an anomaly. It did that quite consistently from trial to trial. Thank you.
Forum: Pentax DSLR Discussion 09-09-2014, 09:21 PM  
Noise and other noise
Posted By sandilands
Replies: 20
Views: 2,220
Musings on a few topics ...

The K5 has an ISO 80 setting. What does that really mean? Just my opinion but I would think it goes something like this. ISO is an abbreviation for International Standards Organization. In olden days we used to talk about ASA which I think stood for American Standards Association. Now some cameras have sensitivity settings like L1, L2, H1, H2, but the K5 has ISO 80. Perhaps that is because Pentax is able to use the ISO trademark since the K5 does comply with the complete definition of ISO 80. That means, within some tolerance, it is equivalent to an ISO standard for film grain and sensitivity documented as standard number 80. Other manufacturers use things like L1, L2 simply because these sensitivities do not comply with an ISO standard, therefore they are unable to use the ISO trademark.

Noise: Our camera club had a discussion about "native ISO". To me this makes no sense. Now my electronics education was when the vacuum tube was king, but pretty well in any amplification system, the more gain, the more noise. With semi-conductor sensors I expect the least noise occurs when the amplification gain is lowest and in the K5 that is at ISO 80. If that is what is meant by native, OK.
This discussion went on to claim what I think is another misconception; that mid ISO settings are interpolated and it is better to shoot 1/3 stop lower than an integer multiplier of native than it is to shoot 1/3 stop higher. In other words. since the native ISO of the K5 is 80 and the next integer multiplier is 160, it less noisy to shoot at ISO 125 than ISO 100 etc. This rumor may have come from some video/Technicolor issue, but IMO I call it Kazunga when it comes to still shot cameras. So I did a test...

Completely dark room, lens and viewfinder caps on, and the camera covered by a black lightproof blanket. Let's say about -8ev (who knows, it was too dark to see). The process is shoot, increase sensitivity by 1/3 stop, shoot again. Then take all those files (in DNG format) and import them into photoshop as layers. Apply a threshold adjustment layer (set at level 1) at the top of the layer stack, and make 4 101x101 pixel samples around the middle of the frame. Then average the RGB levels from all 4 samples and plot the graph.

This is what I got. A couple of "shelves" in the curve, but nothing other than what I would call a sample anomaly. The results I got, are pretty much what I expected.

Thoughts? Comments? By the way, although I don't have the curve to show, a friend did the same thing with his Nikon D7100. The K5 was less noisy by far.
Forum: Pentax News and Rumors 09-01-2014, 07:43 PM  
Poll: Official Photokina Predictions Thread
Posted By sandilands
Replies: 309
Views: 32,059
Well good news for those who are hoping for a 35mm DSLR. You are more likely to get your wish than am I.

Please a flash and firmware that comes even close to the Nikon SB910. Oh and a new hotshoe adapter that has the cable exiting on the left side instead of across the shutter button. Honestly RIcoh, I promise I will learn to love P-TTL.
Forum: Pentax Full Frame 08-31-2014, 03:27 PM  
How to push the Pentax Full-Frame Idea and get that FF out faster...
Posted By sandilands
Replies: 1,493
Views: 160,924
I haven't jumped into this cat fight for a while, but it would appear that Photokina 2014 will come and go without a 36mm x 24mm sensor in a Pentax camera. Frankly I am glad, because I hope Ricoh R&D dollars are going into solving other problems, notably (for me) is fixing a flash system that is mired in the 1980s (at least). The R&D spent for the K-S1 has me scratching my head however.

But I did want to share this unscientific test conducted with a friend when the subject of low light performance came up.

FF sensors need bigger glass to 'cover' the sensor. An 82mm diameter lens will capture more light than a 62 mm diameter lens. I yield on this point. That 82mm diameter glass is also much heavier and is more likely to be in my bag than on my camera, but that is a different argument. In the end, does it matter? A friend has a Canon 5d MKIII and I have a lowly Pentax K5. We decided to argue our respective cases in the studio (copious amounts of beer and much shouting hadn't seemed to get us anywhere).
We set up a Photovision calibration target and draped one piece of black lace and one piece of white lace over top of it. Then we set up 4 video-lux 5600K CFL lamps to light the set as evenly as possible.
The Canon had a 24-70mm f/2.8 lens. My closest comparable was a Sigma 17-50 f/2.8. We both made a custom white balance and set the ISO to the 'native' 100 of the Canon. (The Pentax is ISO certified at 80 but since the Canon can't do that we gave it a bit of a break and both used 100). Then we metered the light at +4 ev, and set apertures to f/5.6 (theoretical sweet spot 2 stops less than full open). We both got nearly perfect and similar exposure histograms off the Photovision target at 2 seconds. From there we changed shutter speeds up and down in 1/3 stop increments.
The result: We could discern details in the black lace 3 stops darker with the Pentax than we did with the Canon. The Canon was slightly better on the whites where it had a 1/3 stop advantage. So we concluded the K5 has a 2.7 stop wider range at +4 ev than the 5dmkIII. We didn't bother trying lower or higher continuous light setups (maybe too much beer by then) but although there may be some differences, I don't think it would matter very much. But to the subject at hand ...
Capturing detail in the blacks 2.7 stops darker with the crop sensor camera tells me that the idea of FF cameras having better low light performance is a myth or at least a very broad assumption that my friend and I could not prove with the gear we had available.
OK, this may not have been a completely scientific test but it seemed practical to us, and applicable in the real world. I don't see myself making many photographs at +4 ev, but if I do, I am quite comfortable knowing I will get a decent image at 1/15th, f/2.8 and ISO 800. With the Pentax anti-shake on, I might even get away with hand holding it. The test is pretty simple. Try it yourself and post what you learn. I would also be very interested in opinions about the test and if it is flawed in any way.
Forum: Pentax News and Rumors 11-01-2013, 12:51 PM  
Visit to the Quebec city Photo Expo. Discussion with reps, many interesting things!
Posted By sandilands
Replies: 43
Views: 9,647
Well after spending many years in product marketing, the LAST people we would tell about real products in development is our own salesforce. Their job is to sell what we have to sell, not futures. We don't want that guy to say, "pssst, don't buy that K-3. There's a full frame camera coming out in 9 months or so."
Forum: Pentax K-3 10-05-2013, 07:35 PM  
DPR/Pentax K-3 ongoing poll results
Posted By sandilands
Replies: 37
Views: 7,336
My K-5 is good enough ... almost. I will preorder a K-3 if:

1. significantly improved AF
2. tethering
3. workable rear curtain sync and 1/200+ sync
4. did I mention significantly improved AF?
Forum: Pentax K-5 03-26-2013, 06:15 AM  
K5 Cold weather shutter issue
Posted By sandilands
Replies: 20
Views: 2,585
Yeah, even the Pentax grip can be finicky. I can only imagine what a 3rd party grip would be like. I don't think it was the same issue you describe, but I did have some weirdness when I was using the grip, and the camera was set for auto battery selection mode. Decided that the best use of the grip for the battery was storage..
Forum: Pentax Full Frame 03-25-2013, 07:09 AM  
K3 full frame 27th March
Posted By sandilands
Replies: 242
Views: 38,481
Ha!

If history is any indicator, there may also be a new lens cap series with holes in them.

But if I am allowed to let my imagination roam in warm green fields of spring wildflowers for a while, Pentax will announce a radically new lens technology (sans lead) which will cause chins to drop around the world and will be of a hydrid design to be ready for a FF camera later this year. Maybe that could explain the current backorder situation for Pentax lenses.
Forum: Pentax K-5 03-25-2013, 06:54 AM  
K5 Cold weather shutter issue
Posted By sandilands
Replies: 20
Views: 2,585
By any chance are you using a third party battery? Batteries are still the bane of cold weather shooters. Just for an experiment, keep a spare brand named Pentax battery in your shirt pocket. When the problem happens change the cold battery for the warm one (open the camera only in the cold outdoor dry air). I found that even if the battery indicator shows sufficient charge, the voltage may have dropped enough to cause odd behavior. Also switch to manual focus when this happens. Cold weather = sluggish AF motors. Sluggish motors = high current / high battery drain. If the motor is not sucking all the current the battery can deliver, there may be enough to power the less demanding electricals (like shutter).

Yes about the cold to warm transition. WR or not, keep a "Space Bag" with your gear. These are big enough to hold the camera and lenses you have been using in the cold and will keep warm most air away from the camera until it has warmed up. Another option: warm up your vehicle with defroster on full until you can't stand it anymore and your gear is warm to the touch before bringin it into a warm humid environment. I would suggest not breathing while waiting in the vehicle, but that would be poor advise.
Forum: Pentax DSLR Discussion 02-09-2013, 02:51 PM  
dual/twin tethering
Posted By sandilands
Replies: 12
Views: 1,629
Obviously this project is more involved than I appreciate. After all scanners are made for scanning books and that would be my first choice. In any event, how about a different tactic. Set Live View on the cameras and use video capture software on the pc to grab the images.
Forum: Pentax Full Frame 02-06-2013, 07:08 AM  
Pentax Confirms Full-Frame Plans at CP+ Inteview
Posted By sandilands
Replies: 810
Views: 104,725
Nope. Just too much experience in business and seeing what happens to rudderless ships.
- hp retiree
Forum: Pentax Full Frame 02-05-2013, 09:43 AM  
Pentax Confirms Full-Frame Plans at CP+ Inteview
Posted By sandilands
Replies: 810
Views: 104,725
I think I mostly agree with you, although I'm not crazy about 29 minute video cameras in an DSLR package.

The Apple comparison is interesting, however Apple is about to go swirling down a sinkhole. It had one asset - an arrogant despotic visionary genius. That is gone,
Forum: Pentax Full Frame 02-05-2013, 09:30 AM  
Pentax Confirms Full-Frame Plans at CP+ Inteview
Posted By sandilands
Replies: 810
Views: 104,725
I had to check the signature line under your post to make sure I hadn't posted it. Alas, my version would not have been so eloquent. My instructor's words were, "The camera is just a light proof box that holds film - first, find that lens that brings your vision to life."
Forum: Pentax Full Frame 02-05-2013, 08:49 AM  
Pentax Confirms Full-Frame Plans at CP+ Inteview
Posted By sandilands
Replies: 810
Views: 104,725
Mine too.
Forum: Pentax Full Frame 02-05-2013, 08:46 AM  
Pentax Confirms Full-Frame Plans at CP+ Inteview
Posted By sandilands
Replies: 810
Views: 104,725
+1. For that matter +1,000. When leaders of this forum claim to speak for members of this forum and imply its members are demanding FF, that is untrue.

As a devotee to the concept of continuous improvement, leapfrog jumps are seldom a good idea. They should continue to 'Pareto' the line's technical, marketing, and sales barriers, and starting at the top, address them. I doubt if lack of a full frame system is anywhere near the top 5 on that list.

The example of the Honda Civic comes to mind. Some of you might remember the 1970s something version - a rust bucket glorified motorcycle. But one step at a time Honda knocked off the Civic's issues to become one of the most highly demanded cars available today.

Many were disappointed when the K-5 II was 'big' Pentax announcement. I was overjoyed. It told me that the Ricoh influence was one that supported continuous improvement. They took the top problems with the K-5 and they made significant improvements. More of the same please Pentax.
Forum: Pentax Full Frame 02-03-2013, 03:34 PM  
Pentax Confirms Full-Frame Plans at CP+ Inteview
Posted By sandilands
Replies: 810
Views: 104,725
Frankly I'm tired of hearing about FF vaporware. The K-5 II / S are exactly the kind of incremental improvements Pentax should concentrate on - and there are many more. I won't be jumping on any FF bandwagon (if, not when it happens), however if the speculators on this forum are right that old Pentax glass will become extremely valuable should Pentax release a FF version, well I'll keep my K-5 and make a fortune selling off my 30 year old lenses.
Forum: Pentax Full Frame 02-03-2013, 08:00 AM  
Pentax Confirms Full-Frame Plans at CP+ Inteview
Posted By sandilands
Replies: 810
Views: 104,725
Really? How about getting new tech right in the APS-C body and only after that spend time and money on FF. Let it trickle up instead.
Forum: Pentax Full Frame 10-08-2012, 06:14 PM  
FF Under Development
Posted By sandilands
Replies: 1,291
Views: 156,864
Yawn. So many more things for Pentax to work on than waste R&D on FF... that is if they really are doing any R&D on FF.
Forum: Pentax DSLR Discussion 09-26-2012, 09:14 AM  
Why people complain about Pentax AF and Flash
Posted By sandilands
Replies: 51
Views: 5,878
This has been both the oddest and most informative thread I've read in a while. It has also revealed to me how little I understand about the way AF works in any of my cameras. More to the point this thread is helping me to learn more about how to use the cameras I have instead of bitching that I don't have the camera I think I need.

@JinDesu and @UnknownVT, please elaborate more about how you conducted your tests. First, how do you obtain the interesting diagrams showing the light values recorded by each af sensor?
By trial and error I've been using small LED flashlights for some time as AF assists (giving one to the model to shine on her own face so I can focus), but how have you used them in these experiments?
I have also wrestled with the fact that in extreme low light my eyes can detect a high contrast spot to focus, but they're not good enough to actually manually focus successfully. What have you done to both select the AF point and let the camera achieve focus lock at these light levels?

This shot is typical of some of the work I am doing. The "image" on the model's back is made with essentially a semi transparent GOBO mounted on a fresnel lens and focused with a 2x magnifying glass (think overhead projector but with a speedlight). It alone is a nightmare to achieve focus. To achieve decent contrast most shots like this are made in next to complete darkness. I try to achieve DOF from the spot on her back lit by the projection to the tip of her nose. Not too successful as you can see. My fastest lens (55* f/1.4) not surprisingly is the worst at achieving AF in situations like this - so I am usually more successful with the 18-135.

I think conducting the experiments you have done will be useful as I attempt to perfect this technique.



BTW the image on her back is Aries the Ram, not a buffalo leaving a pile of Ka-Ka.
Forum: Pentax DSLR Discussion 09-23-2012, 07:57 AM  
One disgruntled Pentax owner
Posted By sandilands
Replies: 73
Views: 5,836
Yes, I forgot about the 18-250.

So, it appears a good strategy for Pentax is to go shopping for the best OEM lenses, adapt K mount, add HD coating, badge it PENTAX, and price them competitvely. I can see Tamron, Sigma et. al. be quite happy to sell the guts and let Pentax spend whatever it takes to "K-mount" and market it.

BTW about this thread. Speaking as an amateur (maybe slightly advanced) I can't agree more about mounting one lens and taking a few thousand shots in a few hundred environments. I did this with my 55* and my photographs improved dramatically. I also learned that there is still a lot more to learn - just about the 55. My walkabout lens is the 18-135 and I love it. BUT to really learn, take off the zoom (or stick it on one focal length) and shoot as much as you can in as many different situations as you can. Amateur or pro I think that is a good strategy.
Forum: Pentax DSLR Discussion 09-22-2012, 08:53 PM  
One disgruntled Pentax owner
Posted By sandilands
Replies: 73
Views: 5,836
If the 18-270 is indeed a Pentax badged Tamron:
1. did Tamron not make a Pentax mount version because Pentax requested OR
2. did Pentax go crawling to Tamron to OEM it because Tamron never would.
Forum: Pentax DSLR Discussion 09-22-2012, 08:30 PM  
Why people complain about Pentax AF and Flash
Posted By sandilands
Replies: 51
Views: 5,878
Preeeecisely! 1st choice is always manual focus, but my eyes aren't as good as they used to be. In low light my eyesight is fine for locating a spot to focus on, but not good enough to achieve sharp focus. I need the camera to do that for me. In that case I must use centre point AF - and low light, wide aperture shooting is where the K-5 was weak. My purchase of a K-5II will depend on tests and reviews of LL AF.
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