mrbacco Loc: dublin

Thanks gentlemen for all the suggestions. This has been a great learning lesson today, I will revisit again the user manual, and I will try to take some more shots... thanks

PHRubin Loc: Nashville TN USA

FWIW - It seems the camera is malfunctioning. If you bought it from a responsible vendor you should be able to return it for full refund. If you believe the camera has a built in flaw, you might check with the manufacturer to see if they have a remedy. If not, I might consider another brand as a replacement.

Grahame Loc: Fiji

Here's a test you can do.

Outside during good daylight ....................................

Set your camera to full 'Manual'
Set you 'Aperture' to f/16
Set your 'Speed' to 1/125s (or nearest possible)
Set your 'ISO' to 100
Ensure you have no 'EC' (exposure compensation) set

This is what is known as the simple 'Sunny 16' rule.

These settings should give you a 'good' exposure, post the result for diagnosis.

If the picture is 'dark' adjust only your Aperture to wide open and take again. If there is no difference with the result it would indicate an aperture problem.

Riggson Loc: Tucson, Az

Read up about 'aperture block failure'. Some models the solenoid that controls the lens aperture fails, causing darks photos. K-S2, K-30 & K-50 are known to have this issue as they age. An early symptom is to have a few dark (or black) photos to start then the camera will seem to correct itself. Eventually the solenoid fails completely so all you get is dark photos.
Doesn't affect manual lenses of course.

Grahame Loc: Fiji

It could be one of these;

a) Is there a 'minimum' speed of 1/125 selected in the Auto ISO mode, or

b) Is this one of those cameras that can determine a minimum speed based upon lens FL being used when the function is selected?

krmitchell55 Loc: Springdale, Arkansas

You may have an aperture block failure. Check the posts on Pentax forums

TSHDGTL

Someone correct me if I'm wrong, but I thought aperture problems usually result in over exposure when small apertures are selected. Read they're may be some shutter problems with those models.

TSHDGTL

Also, sticky aperture blades can cause similar problems. Have you tried setting a small aperture and hit aperture preview but while looking in the lens to se if the aperture closes quickly?

jeep_daddy Loc: Prescott AZ

Read your book. I can guarantee it's user error. You can also watch Youtube videos on use of your camera if that's easier for you.

After looking at the EXIF data, I can affirm that it is user error. You don't know what you are doing and have the camera in M or manual mode with your settings so messed up that you aren't going to get what's expected.

I don't mean to be so blunt, but you don't know about the 3 things that are needed for a proper exposure. Your ISO is way too high, the f/stop is stopped way down on the second really bright photo, and you don't have a shutter speed that will net a proper exposure.

I suggest you read the Bryan Peterson book on exposure so that you can get a grasp of how exposure works. Then put your camera back in Auto and take some pictures. Study the EXIF data and note what camera settings your camera chooses for you. This is a good way to get you in the ball park of what a normal exposure setting would be.

One thing you should take note of and study is the exposure meter that EVERY camera has built into the viewfinder and or the LCD when shooting in LiveView. The exposure meter will tell you if you are going to get a properly exposed picture. Whether you are in M,A, or S mode, the meter tells you if the camera is exposed properly.
If you are going to play with the camera in M mode (manual) start with a much lower ISO like 400. Just leave it at 400 and then play with your f/stop and shutter speed. You almost never need to put a camera at f/29. So put the f/stop at f/8 to start and then just play with the shutter speed while looking at the exposure meter. So put it at ISO 400; F/8 and then use the shutter speed adjustments while watching your meter. Keep another thing in mind. You might need to keep your camera "awake" as in a half press of the shutter because most cameras will not let you see the changes in the exposure meter if the camera is "sleeping". Most modern cameras sleep in as little as 10 seconds of not pressing any buttons.

Oh, I almost forgot to say, Those other photos might all be exposed differently because you might have the "bracketing" feature set in your camera. Read about bracketing in your manual and if it's on, make sure you turn it off before your next set of pictures. After you have a grasp of how exposure works, then you might want to learn more about bracketing. But many people play with settings that they don't understand, and then don't realize that it needs to be turned off or it will drive you nuts.

PhotogHobbyist Loc: Bradford, PA

I disagree with using a blower as I've always understood that using a blower to remove dust from the sensor is not a good idea as it can, and often does, move the dust to another place in the camera, usually that other place is back onto the sensor. I have had very good results using the VSGO wet swab sensor cleaning kit. Just follow the directions carefully. It is available from Amazon and is reasonably priced. Just be sure to get the proper size for your camera. It comes in two sizes, full frame, and APSC for cropped sensors. I bought a kit a few years ago to clean the sensors on my two Kx cameras and recently had to use it on my recently purchased K70. The cleaning fluid has a great stopper to prevent evaporation when not in use, also. Well worth the few dollars to buy it.

OldJeff

Looks like both of our ships have sunk.I had a Canon T2i that serves me well and just decided to upgrade a little to a Canon 90d.
I am having the same issues. I'm using a Tamron 18-270 lens that I used on the T2i. I'm beginning to think the lens may not be compatible with the 90d.
I have resorted to using Manual mode and a light meter. That seems to work ok.
I need to play some more. When I use my Canon 50mm lens, it seems to work ok.
I sent the camera back to Canon, and they returned it saying everything was ok. They did say it uses two different types of metering between Live View and Viewfinder.
Good Luck. I'm planning on taking the camera and lens into a local camera dealer, and maybe trying a new Tamron lens to see it that helps. Again, as old as my Tamron lens it, it may not be compatible.

Grahame Loc: Fiji

The image brightness difference with the set of 5 images according to the Exif is due to the change in EC (which the post advised), which adjusted the ISO in each only . EC settings were +0.7, +0.7, +1.7, +3.0, +3.3.

The final image f/8, 1/125, ISO6400 that shows a good exposure may very well be correct if it was a dull Dublin day at 5.17pm

rehess Loc: South Bend, Indiana, USA

Actually it can. The Optical Viewfinder uses a sensor in the prism hump, while Live View uses the main sensor - they have been known to give different answers, perhaps related to the known issue with the solenoid {the last time I looked, the Pentax community was arguing about that}, but the solenoid issue results in dark images, because it causes the lens to use its smallest aperture regardless of what is called for.

Grahame Loc: Fiji

Correction to above post.



The last para was incorrectly based upon the time of day where I am, the opposite side of the world from Dublin

Further pondering;

Taking the last shed image, (histogram showing decent coverage), taken at 5.17 in the afternoon 4 hours before sunset and obviously in shade could we expect a scene Light Value of around 12EV? If so, that would be equivalent to f/5.6, 1/125, ISO100.

The settings 'indicated' used for the last shot were f/8, 1/125, ISO6400 equivalent to a Light Value of 7 EV.

If the aperture was faulty and going to minimum of that lens the 'actual' shooting parameters would have been, f/32, 1/125, ISO6400 which is equivalent to a scene Light Value of 11 EV. Not far off from what would be expected.

A similar assumption can be made with the first image posted in that if the aperture went to 'minimum' f/32 the result would have been 2.33 underexposed of which that image is roughly.

Perhaps I'm bored ...................

mrbacco Loc: dublin

Hi All. I read few posts on the pentax forum and tested the camera according to the following suggestions I found in the forum. According to the post, seems the issue is related to solenoid not managing the aperture properly. That might also explain the dark photos when in AUTO mode.

https://www.pentaxforums.com/forums/184-pentax-k-s1-k-s2/402051-how-detect-aperture-block-failure-pentax-k-s1-k-s2.html

I might send the ca,era back to the seller ... :-(

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