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Forum: Film SLRs and Compact Film Cameras 11-26-2016, 01:44 AM  
Pentax in 1960 movie
Posted By Alex645
Replies: 3
Views: 1,296
Now that you mention it......back in the late 80ʻs I was the Unit Still Photographer in Return of the Killer Tomatoes (sequel to Attack of the KTs). About midway through this golden turkey there is a scene where the producer runs out of money and they stop filming. It is suggested that they shamelessly employ ʻproduct placementʻ to pay for the film to continue. In this scene with George Clooney my right arm and shoulder with my Pentax 645 appears at the 1:25 mark.
















You Tube




No one can say I havenʻt tried to put Pentax on the map! Thanks Steve for the link. Iʻll add some more trivia to the movie thread.
Forum: Photographic Industry and Professionals 05-26-2016, 01:29 PM  
**Pentaxian Who Needs Serious Help**
Posted By Blacknight659
Replies: 32
Views: 3,722
Give me the 50mm f1.4, 24-105 f4, I would be set.
Forum: Photographic Technique 02-11-2016, 02:01 AM  
Image noise in DSLRs and mirrorless cameras...
Posted By Ventzy
Replies: 21
Views: 3,709
According to physics the light has dual nature – like photons and like wave. As consequence of this dual nature, the noise always appear, in every digital image – sometimes it is invisible, sometimes it is annoying and intrusive. Photographers are in constant battle with it from their first shot on.

But now I am going to write about some other noise, the one connected with the camera and the equipment with which we are working. The noises generated by different reasons in the camera are too many and too different and I will analyze their influence over the final result.

In one modern camera of nowadays, no matter what technological scheme it has (mirrorless or DSLR), the light collector is the so called digital sensor, which is composed of millions, placed one by another, light convertors. I am not going to look in details the different constructive realizations, but their common thing is that they are all analogs.

Yes, it is indeed curious, but the fact is that the so called digital cameras are in their nature analog-digital. No matter what is the specific technology of the photo-receiver, after it reaches certain potential, the digital sensor is “read” and the data is sent to Analog digital converter (ADS). This ADS measures the gathered in every single receiver potential and converts the result in digital format, e.g. in a digital number. From that point on we can call the camera “digital”, because all subsequent actions will be only with digital data and within digital environment.

The aim of this article is not to analyze the methods and the ways of the digital processing of the signals. I am going to focus basically on the noise problem and the cause of its appearance in the analog part of the process, that is to say in the sensor – before it is converted into a digital amount.

From where, after all comes that extra noise? The function of the light sensor is to capture a photon and to transform it into an electron. So far, so good - certain amount of photons are coming, they are transformed into certain potential, i.e. into a certain number of electrons. Essentially we can compare this construction on a capacitor with a certain capacity.

But the electrons can occur there at the same place for other reasons determined by the physics. The main factor is the temperature. I suppose that everybody remembers, from the first physics lessons that the temperature in nature is the average kinetic energy of the atoms and molecules in a certain system. The higher the surrounding temperature is, the bigger is the chance of random electrons to be accumulated in our hypothetical capacitor, without having come in like photons. In other words if we heat the sensor, surely the higher the temperature, the more it will increase the number of the accumulated electrons, which have not been photons. And now starts my essential thesis, aimed at cameras.

The temperature of the sensor, of course, is determined by the temperature of the entire camera as well as from the temperature of the surrounding environment. But there is another factor that is particularly important. A serious reason for the temperature rise of the sensor is its working process and that of the electronics around it. The forced movement of the free electric charges, or simply put the conduct of electricity in one chain is accompanied by the release of heat due to losses, unless the chain is made from excess wires, which are still unavailable in the cameras. And these losses, according to the laws of physics are in fact heat.

Or in shorter and in simpler way we can say that if a camera works, it inevitably produces heat and that causes the increase of the noise under the same other conditions. Actually the reason I am dealing with this problem is an analysis whether and how the noise increases and how this in practice affects the final result – the photography.

At the moment I have available the ideal composition to determine the influence of the temperature – Pentax K3II. The camera is perfect for that purpose, because it is DSLR and I can test it either in a short time working mode of the sensor or in continuous mode - the so called live view, so that to be able to see the difference.

Of course, I will surely check, how the camera behaves at temperatures below zero of the body, at normal room temperature and also at that around the maximum levels to which the manufacturer guarantees normal functioning of the camera.

It is winter outside and it is the right time for testing the camera in real freezing conditions.



The room temperature of 20 degrees Celsius is easy to provide, so I give more attention to the upper limit of 40 degree Celsius, which according to Ricoh is permissible.


I supervise the process and do not rely much on the stove thermostat, because its tolerance is too big, so I am controlling the temperature by checking it with a digital thermometer. And of course I’m waiting for 30 minutes at that temperature, to make sure that the camera is heated evenly inside.

What follows is a photo material that can visualize the results. They are obvious and notable, but I did not intend them to be in exact numbers. This will probably be the subject of a future analysis, for the moment what I see is more than enough to prove my thesis. In order to have good consistency, all images, that I compare with one another and quote here, are treated in a same RAW->JPG convertor with the same settings, such as exposure corrections and so on.

In order to avoid possible problems such as light entering around the lens cap, every tested camera was with its front cap on, at maximum closed aperture and before taking the photo was placed in well closed 100% opaque box.

At approximately-5 ° body temperature, exposure 30 sec./ISO 100/~ + 4stops

At approximately + 40 degrees, 30 seconds exponation/ISO 100/+ 4stops


At room temperature of 20 degrees Celsius.
Fully tempered camera, which was not switched on at least one hour.

Exposure 30 sec,/ISO/100 + 4stops

The quoted image was shot immediately after the camera was working almost 50 minutes in live view mode.

Exposure 30 sec,/ISO/100 + 4stops


And a little more on this subject, I did four consecutive photos with Pentax K-3II at equal conditions ISO 100, closed front caps and in a dark. The only difference is that the exposure times are respectively 1/1 100sek sec, 15 sec, 30 sec. The camera is at the room temperature of about 20 degrees Celsius and has not worked at least one hour before the shot. Adjustment of the shutter stops 5 + (the same for all frames).





In the last shot you can clearly see how exactly the sensor starts to heat up, more at the edges and in the middle...

Up till now everything was connected with a single camera Pentax K3-II. Is it possible that all that is not valid for the other cameras?

Hardly. Physics is the same for all, at least for now, but the good practice requires a check.

I asked a friend of mine (Sabin Kolarov) with Fuji X-T1 to do the same tests, as the one above. The tests were made at the same exposure time and other conditions as those made with the Pentax K3-II. We did not made the whole range of tests at all temperatures (-5C….+40C), but we focused on two tests. The one at room temperature and that in the room temperature but after 50 minutes of camera working time.

The results was treated by photograph Sabin Kolarov and for a better visualization they are graphically presented after an analysis with RAW Digger over the RAW files.

Here is the result after 50 minutes working time, in the same other conditions. I have to note that the outside body temperature rises with 6 degree Celsius. Meanwhile, the camera was not held by hand but stood on a table.



Of course, we did a series of tests with a duration of exposure of 1/100, 1 sec., 15sek., up to 30 sec., as each of the exposure is accordingly: at the base ISO, that of ISO 400 and ISO1250. I am not going to bore the audience with quotes of the results, in short, there is a direct connection between the temperature of the sensor and the appearing noise. What is more important, we find that there is a clear connection between the working duration of the camera and the final result as a parasitic noise in the image at the same temperature of the surrounding environment.

That conclusion rises many questions. It is serious reason to put under suspicion all published tests regarding the dynamic range and noise, in which the temperature of the camera and its working duration before the shot, was not taken into account and quoted.

An even bigger question is that about the comparison between the different types of construction. It is natural that one DSLR even in a long hour working regime, if it was not in live view mode, will work in a much better conditions, in comparison of the equivalent of mirrorless camera that in the meantime has heated and its electronics has worked without interruption those same hours. In that case, I ask myself the question where exactly we must measure the dynamic range of the one and of the other camera? And which of the results will be the correct one? Because as you can see, only due to one hour working timeout, the results of the same single camera can be reduced several generations back...

This article, I hope, could serve to my colleagues for specific conclusions.

Knowing the problem, every one of my colleagues can do the comparisons I quoted above on his own and specifically for the equipment he/she is working with.

The conceptual basis of this analysis are the principals by which are made the astro shots in the big telescopes, where the sensor is obligatory cooled to a very low temperatures, which brought me to the idea of the same problems into the photo equipment.

I am sure that the sceptics who read the article up to here are already smiling and asking themselves, well, has no one until now thought about the problem and how the video cameras work then? In them the sensor is permanently activated and the same is the electronics. This is a serious argument and I made a research on that question myself as I consulted a colleagues from an official video technical service of one of the world’s leading video companies. I received a very clear respond from there – yes, the problem is well known from long time and it is very serious in the video cameras. To solve the problem in all serious video camcorders, the sensor MUST BE COOLED VERY INTENSIVELY. They even send me an image showing, how the radiator on which the camera must be mounted, looks like, for a certain model of professional video cameras. Here it is:



Probably similar solutions can be applied to the photo cameras, but considering the size of the sensors, it will be impossible, because it will cause a general increase in the camera size, energy consumption, etc. In this connection, the advantage of the DSLRs for some specific tasks is obvious (when they are not in live view mode) and the owners of mirrorless cameras must consider some strategies when making photos requiring long time working of the sensor. This, of course, concerns mostly for those cameras that have bigger sensor. It is of great importance what kind is the body of the camera, from what material, what size, and also whether it could and how well to dissipate the heat.

At the time of the survey I and my colleague noticed some signs, that suggest us that there are some manufacturers who adjust noise reduction according to the sensor temperature. This article does not aim to analyze this phenomenon, but surely in the future we will pay attention on that problem, all the more it was visible in the RAW files – something that cannot be easily avoided.

And after all, are the damages, from the published in that article effects, on the photos, so serious?

It depends a lot on the specific situation but even at 1/100 sec. are completely capable, in my opinion, to ruin one otherwise successful shot. And as a whole, the added noise and the reduced dynamic according to the temperature conditions, are more then what have been achieved from generations of technology development.

(Sorry for my English, it is not my mother language)

VPetrov-photography.com
Forum: Pentax DSLR Discussion 06-13-2015, 03:26 PM  
K-3 or K-3II or wait?
Posted By stevebrot
Replies: 8
Views: 1,837
Well, there is your answer! You have been actively using your K-5II for two years and it does what you want. If you are not frustrated by things that the K-3 is reputably better at, then there is no need to upgrade.


Steve

(...waited seven years to upgrade from K10D to K-3...)
Forum: Pentax Lens Articles 08-12-2010, 04:24 AM  
Sticky: How to use/meter Manual & M42 Lenses on all Pentax DSLRs (K-1, K-3, K-5, K-30, etc)
Posted By Adam
Replies: 358
Views: 415,771
Many Pentax DSLR owners want to use M42 screwmount (Takumar) lenses, or M or K manual lenses, on their cameras because of the low cost and relatively high image quality of these lenses.


If you're wondering whether or not these lenses can be used with Pentax DSLRs (or the K-01), then the answer is yes! Pentax as well as third-party manual and screwmount lenses can easily be mounted on any Pentax DSLR (such as the K-1 series, KP, K-3 series, K-70, K-S2, K-S1, K-50, K-500, K-30, K-5 series, K-r, K-x, K-7, K10D, K100D, K200D, *ist D, etc.) Just follow this guide!



Modern Pentax DSLRs use the Pentax "K-mount", which employs a bayonet and therefore differs significantly from the M42 screw mount. The older manual M and K (SMC Pentax-M, SMC Pentax) lenses actually use the bayonet, so they will not need an adapter - you can skip straight to the lower portion of this article (starting at "Important!") for information on how to meter with those lenses. Screwmount lenses usually have "Takumar" in their names, and in order to mount screwmount lenses on your k-mount body, you'll need a Pentax k to m42 adapter. Pictured above is the genuine Pentax adapter, which is ideally the one you want to get. Similar third-party adapters are also available. Caution: Many third-party adapters, such as this one, have a protruding flange which will prevent you from focusing all the way to infinity. If you want to buy a third-party adapter (they're generally cheaper), make sure that they don't have this flange. Here's an example of a good third-party adapter.

Once you have your adapter, the next step is to install it on your camera (it can easily be put on and removed on-the-fly). Check out the m42 to k adapter manual.


After you've installed the adapter, you'll want to mount the lens. This is done by screwing it into the camera until the lens feels firmly attached. The focusing window and lens ring should line up with the camera just like any other lens. Now that your lens is mounted, let's talk about how to take photos with it.

Important! The hard part is to get the camera to actually fire when a manual lens is mounted. In order to accomplish this, enter your camera's custom function menu, select the "Using Aperture Ring" setting (usually at the end of the menu, #21 on the K-7, #27 on the K-5, #27 on the K-3, #26 on the K-1), and set it to 2 (allowed). Once you do this, the shutter will at least fire, as it wouldn't have with this setting disabled (you would simply have seen an F-- indication on the top LCD/info screen). The setting description should read: 'Shutter will release when aperture ring is not set to the "A" position' when "allowed" is selected. Also note that the mount on the lens must be conductive for electrical current so that it shorts the electrical contacts on the camera body. All Pentax manufactured lenses have a conductive mount, but some third party lenses do not in which case the area of the mount touching the contacts must be sanded down.

K-30, K-50, K-500, K-70, K-S1, K-S2 and K-01 users: make sure you also set your green button "action in M/TAv Mode" to Tv SHIFT. This is found under the button customization menu (page 3 of the main menu) on the K-01 or as a custom function on the K-30, K-50 and K-500. On the K-S2 and K-70, look under the e-dial programming sub-menu under button customization in the record menu.

Finally, ensure that auto ISO is disabled.

At startup, if your camera asks you for the focal length, enter the actual focal length as labeled on the lens. This will ensure optimal Shake Reduction performance. For zooms, you can use the lower end of the zoom range (this ensures that there will be no over-compensation), or the focal length that you shoot at most often.

Now, let's discuss metering. Since manual lenses don't feed aperture data to the camera, the only way for the camera to check how much light is being passed through the lens is to measure the light while the lens is stopped down. Follow this procedure to properly meter with a screwmount, M, or K lens:

___0. Ensure that the "Using Aperture Ring" custom function is set to "2 (allowed)" (K-30/50/500/01 users must also ensure that the green button is configured to Tv Shift in M/TAv Mode) as described above
  1. Set your camera to M mode using the mode dial (your camera won't fire in other modes*)

  2. Compose and focus your image.

  3. Using the aperture ring (the ring at the very back of your lens; it will have numbers such as 2.8, 4, 5.6, 8 written on it), select your desired aperture setting. Note that the smaller the aperture number is, the more light passes through the lens, and the blurrier the out of focus areas of your photograph will be (and vice-versa). Note your lens will not stop down until step 5.

  4. [Screwmount lenses only] Switch the diaphragm clutch on your lens to "Manual" (you can leave it on Auto when composing and focusing if you don't want a dark viewfinder).

  5. Measure the light by either pressing the "Green Button" (older bodies may use the Av button), or pushing your power button to DOF preview mode (only available on high-end bodies). Your camera will automatically set the shutter speed for you.

All that's left now is for you to press the shutter release button to take your photo. Congratulations- you've now learned how to use M42 and M & K manual lenses with Pentax DSLRs!

*Screwmount lenses may also be used in Av mode since they are always stopped down to the aperture you will be shooting at (unlike M&K lenses, which are stopped down only when the shutter is released or when you meter as described above).

Note: if your aperture ring has an "A" on it, instead of doing stop-down metering as per this guide, you'll want to set the ring to "A" and use the camera's scrollweel to adjust the aperture via Av mode.

Click here if you found this article helpful!

Video version:















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