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Forum: Monthly Photo Contests
08-09-2023, 05:46 AM
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I would like to nominate this photo
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Forum: Pentax K-S1 & K-S2
02-01-2022, 01:48 PM
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Dear Community
I consider that this issue is really resolved for me and it makes no sense to continue collaborating and receiving answers in which the experience that one has lived is underestimated.
It was a pleasure to share with some members of the forum, with others it has been unbearable.
Good luck.
Until never.
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Forum: Pentax K-S1 & K-S2
01-31-2022, 05:34 PM
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Dear Kai-Lucas: a pleasure to greet you.
From the photos you have uploaded it is clear that the solenoid you modified has lost the magnetic retention capacity, which has to be a minimum of 150 gr. according to what I explained in my post # 47.
If the solenoid does not lock, a fact that has to happen by a mechanical blow produced by the Aperture block when lowering the mirror when the photo is finished, it is because Plunguer's legs are very short, or there is some imperfection in the polishing of the surfaces that prevent the blockage.
I suggest a length of Plunguer's legs of 4 mm, but this length must be verified with a caliper, because the armor of the different sets of solenoids can be different dimensionally. You have to ensure that the legs reach the armor and a minimum light is produced between the heads of the coils and the Plunguer of at least 0.2 mm.
After you practiced the slots or reductions that I suggest in post #144, you must verify that the Plunguer is magnetically retained at least with more than 150 gr. You should study the graphics developed in post #91.
If the Plunguer does not lock, it will be permanently unlocked and loses the possibility of electromagnetic unlocking at the exact moment sent by the perforated crown of the Aperture block, which will select the diaphragm aperture determined by the processor. This is the reason of the overexposed photos you have taken. Directly the system stops working.
This modification of the solenoid, is designed to take advantage of a weakened signal of the Aperture block, and has the advantage of being able to be done without welding ability. Now if you have the white solenoid, use it and that's all, otherwise try to lower the consumption of green by following these tips.
My Ks2 camera, works with the original and reduced Plunguer without any problem. I have already sent many photos of it where it is shown to produce consistent exposures.
I hope this helps you.
Attentive greetings
---------- Post added 01-31-22 at 10:02 PM ----------
Dear Swanlefitte:
A pleasure to greet you in this 2022
Thank you for following this thread and your confidence in everything published.
I understand that intervening the Aperture block is a very complex operation and requires maximum qualification in welding and understanding the disassembly and assembly using equipment and measurement procedures that not everyone has or understands.
I have tried to explain as well and as clearly as possible all the procedures, but it is so complex that even having videos of the whole operation it would be very difficult to explain it.
Readers should also understand that my Ks2 is the only camera I have, and when intervening, use freehand graphics and reference photographs to then reconstruct the wiring.
Thank God, I did not have any accidents during the intervention, which allowed me to continue enjoying my Ks2.
Best Regards!
---------- Post added 01-31-22 at 10:05 PM ----------
Dear Swanlefitte:
A pleasure to greet you in this 2022
Thank you for following this thread and your confidence in everything published.
I understand that intervening the Aperture block is a very complex operation and requires maximum qualification in welding and understanding the disassembly and assembly using equipment and measurement procedures that not everyone has or understands.
I have tried to explain as well and as clearly as possible all the procedures, but it is so complex that even having videos of the whole operation it would be very difficult to explain it.
Readers should also understand that my Ks2 is the only camera I have, and when intervening, use freehand graphics and reference photographs to then reconstruct the wiring.
Thank God, I did not have any accidents during the intervention, which allowed me to continue enjoying my Ks2.
Best Regards!
Read more at: Dark frames or dark expositure problems in KS2, K30, K50, etc. - Page 11 - PentaxForums.com |
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Forum: Pentax K-S1 & K-S2
01-25-2022, 05:02 PM
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Dear user community of Ks2.
Happy 2022 with a lot of health and many good photographs.
I want to tell you that my Ks 2 has already reached 15200 shots and I no longer experience the dreaded ABF.
I've been going over everything written in this thread, and the post that best describes the ABF problem is post #29. It accurately describes why the solenoid fails as a result of a poor electrical signal from the aperture control.
Doing the maintenance to this control is essential after about 4 years of use of the camera. This in turn allows us to maintain the design of our cameras.
The green solenoid has the electrical, mechanical and magnetic characteristics that the manufacturer has determined for the excellent and consistent operation of the aperture control.
Belittling the Chinese industry at this time I think is too much.
With this criterion we should think that every modern Pentax camera has lowered its quality by having most of its components of that origin.
It is irrefutable that the green solenoid works well in most cameras and also that it does well at least in its first 3 years of use.
This maintenance consists of renewing the lubricants and checking the state and quality of any electrical contact, static or dynamic of the system.
All the details are explained in some post of this thread.
A good guide to lubricants to use in cameras is in this same forum in the following thread uploaded in 2011 by Pacerr. He apart from suggesting lubricants gives applicative criteria in the different parts that can help those who venture to do the maintenance of their camera.
I hope it will be useful.
Lubricants - PentaxForums.com
Attentive greetings
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Forum: Pentax K-S1 & K-S2
09-07-2021, 05:56 PM
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More than 14000 shots with my K-s2, equipped with its original green solenoid!
More than 6000 failless ABF shots of the green solenoid after intervening and repairing the diaphragm control.
This camera had the first 7000 non-fault shots ABF.
1000 shots in the period of investigation and isolation of the fault.
6000 shots from the intervention of the ABF faultless opening aperture block control.
I am very happy with the consistent operation of my K-s2.
I attach one of the last photographs taken in the Sierras of Córdoba, Argentina.
Attentive greetings
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Forum: Pentax K-S1 & K-S2
05-13-2021, 12:53 PM
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Dear Swanlefitte:
I'm so glad your camera has worked with the white solenoid again.
Your data from the retention value for the white solenoid is great for me, as it confirms my observation that it needs less energy to unlock than green.
Also, the values you've measured are lower than the ones I got, but greater than 150 gr which is the logical limit.
The magnet that equips my green solenoid is more powerful (240 gr with original Plunguer and 230 gr with Plunguer modified according to post #144), than the one that equips your camera.
I believe these are the differences between the different sets of solenoids that are mounted on our Pentax.
As for the 29 ohm resistance, this is an important parameter, as it is determined by the diameter of the copper wire used to wind the reels and the number of turns that have been made. This determines the electromagnetic capacity of the solenoid in fact equal in the green and white solenoid, as has been shown in several forums.
Note that you have chosen the correct function in the multimeter normally identified with the Greek letter omega in its selector.
Keep me on top of your experience.
Best regards!
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Forum: Pentax K-S1 & K-S2
05-10-2021, 03:56 PM
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Dear Community:
With the post #144 I have transmitted everything, absolutely everything I could investigate regarding the operation of the Chinese green solenoid.
The main conclusion is that with proper maintenance of the opening block, the ABF problem disappears and the camera returns to function as new.
The improvement explained in the post #144 experience it before the opening block intervention and I was able to determine that it actually works best.
I've even tried it after the intervention and it has a smoother and equally consistent operation which is why it can help someone
There's a character who challenges everything and this situation is unbearable.
It simply says it doesn't work and isn't even able to build a solenoid operating curve it owns.
I own only the original green solenoid of my camera and a modified Plunguer obtained from a solenoid from a CD floppy disk drive. That's all.
There are those who may doubt that my Ks2 does not work.
Attach one of the last photos taken during this month of May on our beautiful Mendocina mountain in autumn, in fully automatic mode that demonstrates the total and correct operation of the camera.
It has been a real pleasure to share everything and also to have received many recognitions from forum members which I sincerely appreciate.
This is my last post in this forum, as I consider the topic to be exhausted.
Best Regards!
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Forum: Pentax K-S1 & K-S2
05-10-2021, 02:48 PM
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Yes. You are right.
The legs are shorter, but to the right extent for the mirrors to make contact.
They produce a locking force similar to the original.
For this reason the Plunguer can weigh up to 20% less (that is my case) This Plunguer works as well as the original, and produces a very smooth and less noisy operation of diaphragm control.
I do not include the shortening of the legs because it is very complex and lends itself to the Plunguer being out of square and what you claim to happen.
My KS2 camera wonders with the diaphragm block intervention so I don't need a white solenoid or look for it.
This contribution will surely help many people who understand the problem from their theoretical foundations and want to try to extend the maintenance period of their camera.
Photogem: I appreciate your time, your intervention and great power of observation.
Best regards
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Forum: Pentax K-S1 & K-S2
05-09-2021, 12:45 PM
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Dear Photogem:
I'm so glad you tried the test.
Something's wrong with the solenoid you used.
The section reduction at the top does not mostly affect the retention effort exerted by the magnet, as the magnetic flux density in the magnetic clusters of the mirrors remains virtually constant, because this is a quasi-static phenomenon achieved only by the magnetic power of the magnet.
Either you have the magnet unloaded or you have strange objects in the armor/Plunguer mirrors.
The discharge of material strongly influences the moment the electric pulse appears in the coils. They are different actions at different times.
Considering that the retention force specified in the post #91 charts is 500 gr depending on the manufacturer, 240 grams for my solenoid (approximately the same value with both original and reduced plunguers) and considering that it could drop up to 150 grams, you are left over to have a safe retention even removing more material.
You must do the retention measurement according to the instructions given in the post #47 and by the way you can measure the curve of the white solenoid, which I have tired of asking you.
Waiting for your comments.
Attentionful greetings
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Forum: Pentax K-70 & KF
05-06-2021, 05:09 PM
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Forum: Pentax K-S1 & K-S2
05-06-2021, 05:04 PM
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In this Threar developed throughout 2020, I have reached the following conclusion, hoping to serve many Pentax camera users with aperture control commanded by a solenoid.
After trying to improve the friction by solid lubrication of the solenoid, try to adjust the eggs, check the static and dynamic capabilities of the solenoid, interpret the signals on the oscilloscope, the main conclusion, is obtained from verifying that the opening control system, must be properly clean, properly lubricated and calibrated.
This condition will cause the solenoid to receive the electrical signal with maximum energy in its coils at the precise moment, which will generate a magnetic cluster of high flow density in its mirrors, which will unlock in time the Plunguer producing the appropriate selection of the diaphragm opening selected by the microprocessor, and consistently.
All these conditions exist in a new equipment, which is why the green solenoid works well for a more or less prolonged period, depending on the intensity of use and the storage conditions of the camera.
My camera in particular was able to receive specialized treatment (explained in this thread) which made it possible to recover factory operating conditions. It is working very well with the absolutely original green solenoid and has already added about 13,500 shots.
It is logical that this treatment must be carried out by suitable personnel, with a high qualification in the welding soldering process, because at least 100 welds must be made and specialized instruments and tooling available.
Now it remains to explain why a white solenoid, can work with a decreased electrical signal, allowing with a simple intervention, (two welds and the disassembly of the housings) the correct operation of the camera.
As we said above it is necessary to generate a high intensity magnetic cluster in the solenoid mirrors. This is achieved in the White solenoid by the presence of a slot (see Fig 2) practiced in the armor by machining (all white solenoid has it).
The explanation of the model is complex, as it is necessary to have clear concepts of flow density, magnetic reluctance, dispersed flows generated by the magnet, and dispersed flows generated by the coils, with interaction of both phenomena simultaneously.
Making this slot in the armor of a green solenoid is not impossible, but complex.
That is why I decided to practice a decrease in material in a Plunguer of another solenoid, according to Fig. 1.
The decrease in material in Plunguer increases the reluctance of the magnetic circuit in the same way as the white solenoid armor slot does, increasing the flow density generated by the coils in the mirror clusters.
In addition, the Plunguer's mass reduction (may be 20% less) makes it possible to have less inertia to get the Plunguer moving, resulting in the crossbow spring (#75) being able to remove and accelerate the Plunguer more easily and faster achieving greater precision and safety in the selection of diagram opening. This gives great safety and consistency in operation. This improvement is very important and gives us a great benefit.
This modification will require only the ability to disassemble camera housings (widely developed), a mini lathe with mini grinding disc to produce Plunguer discharges according to Figure 1 and reassembly.
You won't need to weld or look for a white surrogate solenoid. At most if you wish you are looking for another Plunguer and keep the original in shape.
I hope you can verify this improvement in your’s cameras with ABF problems.
Best regards
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Forum: Pentax K-S1 & K-S2
12-10-2020, 07:30 AM
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Hello Penwiew52
Your camera works properly. If the diaphragm was close in f22/32, which is the situation where the solenoid fails, the two photos would be identical and only the window would come out very dark.
You are photographing a backlight, the lighting differences are very large.
If you are working in auto mode, you must set the exposure operating method in menu 1 (AE Measurement). I suggest the midpoint that mostly uses the central part of the sensor (p. 55 of the user manual)
You can make an interesting combination, which is to combine the exposure measurement with the focus point. You'll find that in menu C1, item 5. See also page 55 of the user manual.
If you select this combination, the camera evaluates the light at the place in the focus where the red index of your viewfinder is turned on.
You'll get a well-lit photo at the focus site, but places that have too much light will come out overexposed.
Don't forget that you can also use Flash with different intensities as fill light. That's a powerful weapon for these circumstances.
You have to train with these situations and see what the best compromise is.
I hope this helps.
Best Regards
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Forum: Pentax K-S1 & K-S2
12-08-2020, 07:07 AM
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A Pentax is a Pentax.
Anyone who has enjoyed this technology since the 1970s knows what's on their hands.
It is a perhaps old technology, but it gives the possibility to learn how to use a state-of-the-art electronic sensor with the electromechanical resources of that time.
It teaches you how to handle optics and create amazing situations.
With an Android you will only experience the thrill of pressing a button and seeing the photo. There's an audience for that and it's respectable.
As for my Ks-2 it still walks great with all its original components.
You simply have to do regular maintenance with proven services and I can assure you that you shoot your photos for many years to come.
Attached a couple of photos of the Beautiful Valley of Mendoza Argentina, taken this weekend in AUTO viewer mode, where it is shown that the whole system works properly.
I take this opportunity to wish all the enthusiasts (as Mark says) a very happy Christmas and prosperous 2021.
Best Regards
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Forum: Pentax K-S1 & K-S2
10-02-2020, 09:59 AM
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You're very kind and polite.
Best regards
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Forum: Pentax K-S1 & K-S2
10-02-2020, 08:46 AM
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I think you're starting to understand the problem.
If you have a good negative reference, which is given by the diaphragm control switch, you will no longer have a problem with the solenoid.
My Pentax is doing very well with green, more than 5 months ago.
Thank you Photogem for all the information you provide us, which gives good orderly results.
Strong hug.
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Forum: Pentax K-S1 & K-S2
10-01-2020, 04:37 PM
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Dear Swanlefitte:
I've been left thinking about the flaw in your KS2, and I think you should check the off/on/video selector brushes, which work concentrically with the shutter switch. These brushes have a direct influence on the logic of photography mode.
Getting to these brushes is not complicated at all and you don't need to keep skinning any wires.
Any of the threads photogem has written will help you get to the brushes of this switch smoothly.
Check that the brushes are aligned, have coherent radio, are on the same plane so that they discharge the same pressure at any angle, and essentially that they are clean.
Once the physical condition has been checked, check the rubbing surface of the same on the contact plate. After carefully cleaning everything with isopropyl alcohol, proceed to lubricate the contact plate with some good lubricant cleans good quality contacts.
Another element that may be interfering is the same shutter switch, which gives two effects, the half-race and the race background that shoots the photo. Perhaps this switch, presents some crack in your contact saucers that may be interfering. If you could inspect it and try it off the equipment it would be good, but here you would need to have a lot of experience.
I hope that with the cleaning of the brushes it reaches. Also try adding a drop of clean contacts to the shutter switch.
Good luck.
A big hug.
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Forum: Pentax K-S1 & K-S2
09-09-2020, 06:33 PM
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Yes, you're right, the solenoid is commanded by electronic elements, but the switch enables the negative pole that electronic components receive at different times that build the trigger logic.
If this negative signal is not clear and noise-free, the energy received by the solenoid may be insufficient and is the cause of the dark photos, as the anchors, that selected the diaphragm aperture determined by the processor will not arrive in time and the diaphragm will close to the maximum.
It is important to understand the idea of energy received by the solenoid. That is why the differences found between analyzing the solenoid with an energy produced by direct current (case of the graph explained) and the energy it receives through a pulse in the camera that does not reach 10 msec. (this is the time that the diaphragm control switch makes contact at the time of shooting)
Finally the areas under the curve must be the same and must trigger the solenoid.
It is for all this (quite complex and difficult to understand and explain) that a white solenoid, which is surely of better quality, will also fail if the diaphragm control switch is not in perfect condition.
The white solenoid is surely activated with less energy than green, which is why the cameras will run a while longer, but when the wear, dirty or damage of the brushes of the diaphragm switch no longer send that minimum signal, the fault will appear inexorably.
Thank you for your interest.
Best regards
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Forum: Pentax K-S1 & K-S2
09-04-2020, 07:03 PM
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Dear Solatana.
You should carefully read the post #47 and #91, which will allow you to evaluate only the solenoid.
If you find values similar to those of the manufacturer's curves and the curve I found in my KS2, the solenoid is in good condition.
If the solenoid is in good condition after testing outside the camera, but you have dark photos, the fact that you measured a peak voltage of 7.12 volt is not enough for it to work, as that voltage peak does not last long enough for the solenoid to act efficiently.
In this case you have to intervene the diaphragm control switch that surely does not make good contact.
All this is developed in detail in this block.
I hope it helps.
Best regards
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Forum: Pentax K-S1 & K-S2
09-01-2020, 08:25 PM
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Dear FozzFoster:
With the camera off, disassemble the lens, turn it on, it will offer you the menu select a focal length. Choose anyone. Fire the camera without a lens two or three times.
See if it gets rearm.
Sometimes the diaphragm control cannot be rearm because the lens does not leave it.
If it doesn't get backed up, there's another problem.
I hope it works.
Best Regards
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Forum: Pentax K-S1 & K-S2
09-01-2020, 05:25 PM
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Yes Swanlefitte.
From what you describe, it's a good decision to live with the problem if the shots are good.
In addition to how failures happen, it assumes that it is a problem of false contacts.
The only critical contacts that exist are the diaphragm control switch (which controls the movement of the mirror) and a switch mounted on the curtain control, which sends the flash timing signal, and can probably have an influence on the image recording signal.
When the time comes you have to think about doing lubrication and cleaning maintenance and surely your camera will be reborn.
My camera's really good. It's consistent to function like it was new.
Strong hug
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Forum: Pentax K-S1 & K-S2
09-01-2020, 04:06 PM
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Dear Swanlefitte
It's a rare fault.
How does the camera behave in Live view mode?
Remember that in this mode the camera works in a raised mirror.
When the camera shooting, lower the mirror, measure, lift the mirror taking the exposure, lower it again, and then lift it up to continue in Live View mode.
If you see that the camera add one more mirror move, then there's a problem.
Another test you can do is turn Live View on and then turn it off to switch to normal mode before taking a photo. Then take the picture. He's doing this for a few days.
This will make the mechanisms and contacts preheat a little the old lubrication they have and re-run.
If the camera does not fail to do this practice, then you may think that the diaphragm control and/or curtain control may need maintenance.
So you describe, in the first lift of the mirror, the sensor does not receive the order to record the image.
You would have to get a flowchart where you can determine where the recording order passes and review the electronic stage that participates.
That's what I can think of from a distance.
Greetings
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Forum: Pentax K-S1 & K-S2
09-01-2020, 06:00 AM
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Sorry for the delay Swanlefitte.
If you can clarify that it is ABF?
Thank you!
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Forum: Pentax K-S1 & K-S2
08-31-2020, 05:22 PM
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Dear community.
I would like to share this last concept regarding the solenoids used in our Pentax equipment.
The graph with the static feature of 30 ohms that is that it equips our Ks2, K30 etc. supplied by the company Shinmei E. and that kindly provides us Photogem is very complete and allows quickly to evaluate the solenoid that we have in our hands and make a quick comparison with a specification made by the manufacturer.
As you will see I have added the values obtained in my post #47 and interpolated the intermediate values between 0 and 2.5 volt, which represents the behavior of the solenoid that equips my Pentax Ks2 (green)
You will quickly notice that my solenoid retains only 240 grf against 500 declared by the manufacturer, and releases the Plunguer with 30 grf of charge at 2.5 volt, against 3.5 volt declared by the manufacturer.
I have seen that even with these values my Pentax works well consistently.
This can serve as a tolerance curve for anyone who decides to evaluate the solenoid in this way.
Surely the factory has these tolerance curves.
As for the value of 8.32 volt found by Fotogem in the previous post, I think you should take it carefully.
Measuring with the oscilloscope with the solenoid connected and mounted on the camera can lead to erroneous conclusions if you do not know precisely the interaction between the systems that are interconnected, as there are dynamic phenomena that produce induced shocks and reverse tensions on the same solenoid and in the electronic circuits that completely distort the conclusions.
As you will see if in the static test proposed by the diagram, applied a voltage of 8.32 volt, the magnetic field produced by the coils would not only nullify the field of the magnet, but would overcome it, not letting the Plunger take off from its armor.
This does not happen as Photogem declares.
That is why the manufacturer statically analyzes the solenoid in a range of 0 to 6 volt and 0 to 500 grf, which is the area of interest that represents the operation of the solenoid mounted on the camera.
The research of the measurement with the oscilloscope is interesting, but we would need to have the flowchart to identify the essential events of the camera's synchronism and use at least two simultaneous measurement channels to analyze events in different components of the camera.
Surely the highly specialized repair laboratories have comparison cards of the waves obtained that allow to diagnose quickly and surely the problems that may arise.
Hoping to collaborate
Best regards
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Forum: Pentax K-S1 & K-S2
08-26-2020, 03:53 PM
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Dear Photogem:
You're obsessed with the White Solenoid theme.
You have every right to use it if you prefer. Surely you are right that it is better built, but the fact is that after intervening the diaphragm control on my Pentax, the green solenoid is just like when the camera was new.
I haven't had any more problems.
As for the 8.2 volt you mention, in voltage/force graph does not mention it. Zero is zero in any Cartesian system. The voltage scale (volt) ranges from 0 to 6 volt.
This graph is very well made and clearly states that the solenoid releases a load of approx 102 grams strength at 3 volt.
In any case my green solenoid is better, as it releases 30 grams strength with only 2.5 volts.
It also demonstrates something very important that I also described in my Test: The time of the electrical pulse does not intervene in the evaluation of solenoid.
You can build this same curve for the white solenoid (which is what I always asked you for) and for the green solenoid, and you'll probably prove that the white is better.
The reality that Pentax with solenoid are delivered with green solenoid and work, and my camera, with the maintenance of diaphragm control has worked again.
Let the people on the forum decide what they prefer and that's it.
Thank you very much for sharing this graphic. (it have good information and good specifications)
Best Regards.
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Forum: Pentax K-S1 & K-S2
07-28-2020, 04:00 PM
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Dear MarcusBMG.
I would like to greet you.
Attached an explanatory photograph of itself, where it is clarified where the excess copper washer goes.
It is important to place it, because this will prevent deformations on the lower cover, and will provide proper operation of the battery cover, and a correct seal of all insulating joints.
I hope it's useful.
Greetings
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