[kernos]

Just a note for the fixers vs replacers - my K50 failed after warranty repair. I got it back with (the possibly damaging) blast of shots, but there is no guarantee that even a fix is a fix.

[LensBeginner]

Just a note for the fixers vs replacers - my K50 failed after warranty repair. I got it back with (the possibly damaging) blast of shots, but there is no guarantee that even a fix is a fix.

You're not the first one I hear of...

[reh321]

Yeah, this has got to be cheaper than getting Ricoh to replace the whole aperture block, and more lasting than filing or using AA batteries or whatever.

My K-30 needs to last twelve months without costing me anything - I expect to purchase a KP then, and I'll have enough put away if I don't spend any more on the K-30 - so I'm carrying AF lenses with aperture ring around with me. My K-30 has gotten to the point where the first photograph of the day is bad, but everything after that is OK.

[reh321]

Just a note for the fixers vs replacers - my K50 failed after warranty repair. I got it back with (the possibly damaging) blast of shots, but there is no guarantee that even a fix is a fix.

How long ago was the warranty repair? There is evidence that the aperture control units used by Pentax in to "repair" have the same kind of solenoid as is in the original unit, so they are just as likely to fail.

[clackers]

My K-30 needs to last twelve months without costing me anything .

Not even $20 for a replacement solenoid, Reh?

You'll be able to sell the K-30 towards the cost of your KP, but not if it isn't repaired!

[reh321]

Not even $20 for a replacement solenoid, Reh?

You'll be able to sell the K-30 towards the cost of your KP, but not if it isn't repaired!

I'm not brave/dumb enough to do surgery on it.
I have never sold a camera.
If I can get it to last that long, I will pack it away with several manual lenses to serve as my backup.

[bhbrake]

Bought by K-50 brand new and had the block failure at 16k. It is still usable as my backup, but super annoying.

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Last edited by bhbrake; 06-17-2018 at 09:34 PM.

[reh321]

What happens if I try to use modern lenses at f/22 only?

I know that diffraction would be a factor, but how much?

Has anyone looked at DNG files? Is there actually something there if I process them enough??

[LensBeginner]

What happens if I try to use modern lenses at f/22 only?

I know that diffraction would be a factor, but how much?

Has anyone looked at DNG files? Is there actually something there if I process them enough??

On a 16MP sensor I start seeing a difference from f/9.5-11 onwards. f/16 is noticeably softer.
The K-30/50 sensor is quite ISO-invariant, so if you shoot at base ISO you can count the stops and it will be like shooting at that ISO (e.g. 2-stops push = ISO400), but you are losing quite a bit of data in the process.
The best thing you can do is probably to expose properly at f/22, with ISO as low as you can get away with, so you only get the damage from the diffraction.

BTW, I'm reporting this without any guarantee of success, but I've heard a member of the Italian forum saying his camera got (temporarily) better when he rubbed a magnet on the camera body where the ACB is (between the lens and the grip, above the lens release button).
I wouldn't try that, but I'm saying just in case you're desperate to get one particular shot and what to try everything before giving up.

[Brathahn]

Camera PENTAX K-50
Shutter Count 40,613

Aperture Block Failure

Well considering that I bought it on discount for only 250€ (including 50€ payback) and the abuse it took I'm not sad at all. Still works with old lenses so its not even a total loss!
For all the convenience I got me a used K-5 (with all the bells and whistles) how ever really wonder why this thing is so cheap, not complaining tho since the two had cost me what my k-50 would have been new I doubt that i would have replaced it anytime :/

What happens if I try to use modern lenses at f/22 only?

I know that diffraction would be a factor, but how much?

Has anyone looked at DNG files? Is there actually something there if I process them enough??

you will need a tripod where you normaly wouldn't even think about it and you would need to raise ISO to an level where IQ will turn to noise + you will see all the dirt that your sensor might have collected in almost every shot (see my picture). I think you would gain more with an oldr lense that still hase the aperture ring.

[reh321]

On a 16MP sensor I start seeing a difference from f/9.5-11 onwards. f/16 is noticeably softer.
The K-30/50 sensor is quite ISO-invariant, so if you shoot at base ISO you can count the stops and it will be like shooting at that ISO (e.g. 2-stops push = ISO400), but you are losing quite a bit of data in the process.
The best thing you can do is probably to expose properly at f/22, with ISO as low as you can get away with, so you only get the damage from the diffraction.

BTW, I'm reporting this without any guarantee of success, but I've heard a member of the Italian forum saying his camera got (temporarily) better when he rubbed a magnet on the camera body where the ACB is (between the lens and the grip, above the lens release button).
I wouldn't try that, but I'm saying just in case you're desperate to get one particular shot and what to try everything before giving up.

I posted this last night because of our conversation elsewhere about the Sigma 10-20mm.

I carry a FA 28-105 in my bag as a backup for my DA 18-135 - if I need an aperture ring AF I'm set. Back at home I have a Sigma 70-300mm, again AF with aperture ring, so if my aperture control totally fails, I can cover 28mm - 300mm with aperture ring equipped lenses, but I lose everything below that, and the 10-20mm has become more important to me over time. Thus, my thinking of whether there is any way to get a useable photo from a lens that is effectively a f/22 only lens {playing around with the Sigma 10-20mm, I discovered that at some focal lengths it actually goes to f/32!

[LensBeginner]

I posted this last night because of our conversation elsewhere about the Sigma 10-20mm.

I carry a FA 28-105 in my bag as a backup for my DA 18-135 - if I need an aperture ring AF I'm set. Back at home I have a Sigma 70-300mm, again AF with aperture ring, so if my aperture control totally fails, I can cover 28mm - 300mm with aperture ring equipped lenses, but I lose everything below that, and the 10-20mm has become more important to me over time. Thus, my thinking of whether there is any way to get a useable photo from a lens that is effectively a f/22 only lens {playing around with the Sigma 10-20mm, I discovered that at some focal lengths it actually goes to f/32!

Yes, I read it on the other thread... f/32 is not exactly an aperture I'd use often... in fact I don't think I ever used it!

[reh321]

I always tell people to avoid deleting images in the field - to at least make a backup and view it on a computer before deleting it, but I've been breaking that rule with so-called "black images". However, I did find one I retained, and it was taken with the Sigma 10-20mm, so it is especially relevant. Seen on the computer, it is not completely black. My current desktop computer is a "new" Linux box, so right now I don't have any way of looking at DNG files, but I used gimp to open the JPEG. The histogram shows an image there - it is squeezed into the darkest 1/8-th of the histogram, but it is there. That fact is what ultimately led me to ask these questions.

[iheiramo]

What happens if I try to use modern lenses at f/22 only?

I know that diffraction would be a factor, but how much?

Has anyone looked at DNG files? Is there actually something there if I process them enough??

I've taken one shot on purpose with DA18-135 and K30 after ABF to test how it works and if I could use it to shoot against the sun. It didn't work quite as well as I hoped.

[LensBeginner]

*snip*

The histogram shows an image there - it is squeezed into the darkest 1/8-th of the histogram, but it is there. That fact is what ultimately led me to ask these questions.

Of course it's there, and it'll be even "more there" in the DNG file.
The problem is that, when you push it, what you will get will probably range from "ok-ish" to "confetti mess".
With digital you always get information in the blacks, but the best SNR will be in the highlights, until clipping (noise will be stronger, but signal will be much stronger, hence the better ratio).