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01-19-2016, 04:26 AM   #1
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exposure time

This might be a stupid question but...is there a rational reason for limiting the exposure time to 30 sec. in the camera and having no time setting in B-mode?
Just curious..

01-19-2016, 04:41 AM   #2
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Past 30 seconds there'll be the dark frame subtraction routine, yeah?
01-19-2016, 04:50 AM   #3
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QuoteOriginally posted by rednax Quote
This might be a stupid question but...is there a rational reason for limiting the exposure time to 30 sec. in the camera and having no time setting in B-mode?
Just curious..
Nice question which I've asked myself on many occasions. I don't think there is much thought behind this to be honest, more of an adopted standard. My K-5 IIs is indeed limited to 30 second exposures both in M as well as in other modes. As opposed to that, my Ricoh GR is limited to 8 seconds in all modes except for M where it goes up to 300 seconds (5 minutes!) which is perfect for shots using an ND1000 (or "Big Stopper") filter.

B is just that: B(ulb) and has never been anything else on any camera I am aware of past and present.
01-19-2016, 05:27 AM   #4
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QuoteOriginally posted by newmikey Quote
Nice question which I've asked myself on many occasions. I don't think there is much thought behind this to be honest, more of an adopted standard. My K-5 IIs is indeed limited to 30 second exposures both in M as well as in other modes. As opposed to that, my Ricoh GR is limited to 8 seconds in all modes except for M where it goes up to 300 seconds (5 minutes!) which is perfect for shots using an ND1000 (or "Big Stopper") filter.

B is just that: B(ulb) and has never been anything else on any camera I am aware of past and present.
Being a noob I didnīt know about the dark fram subratction thing...hmm doesnīt the noise reduction function deal with that ? Ok the B part of the question might not have been well thought through..but in M...

01-19-2016, 09:55 AM   #5
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QuoteOriginally posted by rednax Quote
This might be a stupid question but...is there a rational reason for limiting the exposure time to 30 sec. in the camera
I don't think so. I guess it could protect the user from themselves if they set it to the maximum by accidentally spinning the dial. 30 seconds (make that 60 if dark frame subtraction isn't disabled) might be Pentax's maximum acceptable time for a user to be confused while they try to figure out why their camera is non responsive during their accidental long exposure.

It would be nice to have a custom setting to override this limit so we can take the personal risk that these long shutter times expose us to. I'd be willing to sign a waiver.

QuoteOriginally posted by rednax Quote
and having no time setting in B-mode?
Just curious..
No reason it couldn't have a B(timer) sub mode that let you enter an exposure time in seconds. Or have a timer displayed on the back or top LCD so you know how long the exposure has been going for.

I know I'd like a built in timer. I don't have a watch or cellphone, so I use a kitchen timer if I remember to bring it with me. Otherwise I use "1 alligator, 2 alligator...", which for me is more reliable than counting off "crocodile"s or even "Mississippi"s.
01-19-2016, 10:13 AM   #6
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QuoteOriginally posted by rednax Quote
This might be a stupid question but...is there a rational reason for limiting the exposure time to 30 sec. in the camera and having no time setting in B-mode?
Just curious..
They need to stop somewhere, right? They've probably figured this is the maximum useful time or perhaps its based on the lowest light levels (say at f/22) the light sensor can reliably detect and measure. It's also a matter of convenience as well: if you're not paying attention, leave the cap on, and it says "infinite exposure time," then you have to turn the camera off or wait the 20 minutes or whatever for the exposure to finish. Turning off the camera with the mirror up is not the best thing to do, I'm sure, so the 30 seconds may have something to do with that.

Plus if you have those long, long exposures, the sensor can overheat. They don't want people who don't know better (lens cap!) messing up their gear. If you switch to bulb mode, you probably know enough.
01-19-2016, 10:20 AM   #7
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But why not an optional timer to put in BULB mode?
In this photo: https://www.pentaxforums.com/forums/12-post-your-photos/312045-night-first-st...l-attempt.html
I was pretty close to my aim of 900 seconds (15 minutes) with 897.33 seconds.
It would still be nice for a timer to get exactly 900 seconds
Another thing I dislike is the default bulb option is holding the shutter down for the exposure.
You have to dive deep into custom menus to change it to one push starts it then the next push stops it.
01-19-2016, 10:26 AM   #8
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It's tradition! Probably tradition comes from limited space on the shutter speed dial. I know on mechanical cameras like a K1000, slow shutter speeds have a separate timer system, which may be complicated to extend beyond 30 seconds.

I think they don't offer times beyond 30 seconds because it's beyond the range of the camera's meter. At f1.4, a 30 second exposure means -4 Ev. The best current Pentax goes to -3 Ev, and a lot of the other DSLRs go to Ev 0 or worse. If you had another meter, more settings could be useful, but if the camera meter won't work in that range, any automatic mode won't work either.

I have a cheap wired remote that has interval and timed exposure functions. I like using that because I can keep its display away from the camera and not affect the shot. Cameras without the wired remote terminal can't use that unfortunately.

01-19-2016, 10:32 AM   #9
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"Tradition" is probably the best reason so far. A great number of horrible things can be attributed to tradition (fruit cake, eggnog, Tuesday mornings, etc.).

QuoteOriginally posted by bertwert Quote
Another thing I dislike is the default bulb option is holding the shutter down for the exposure.
You have to dive deep into custom menus to change it to one push starts it then the next push stops it.
Just be happy your k50 has the option to make bulb mode 2-clicks. Some of the older models only had the "hold the button down" option and I hear whispers from grey beards of cameras that literally had air filled bulbs for bulb mode. Like a balloon, but not as much fun.
01-19-2016, 06:51 PM   #10
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QuoteOriginally posted by Just1MoreDave Quote
It's tradition! Probably tradition comes from limited space on the shutter speed dial. I know on mechanical cameras like a K1000, slow shutter speeds have a separate timer system, which may be complicated to extend beyond 30 seconds.
In the Pentax lineup, only the original AP, K & S has a separate slow shutter speed control mounted in the front along with shutter control on top.




QuoteQuote:
I think they don't offer times beyond 30 seconds because it's beyond the range of the camera's meter. At f1.4, a 30 second exposure means -4 Ev. The best current Pentax goes to -3 Ev, and a lot of the other DSLRs go to Ev 0 or worse. If you had another meter, more settings could be useful, but if the camera meter won't work in that range, any automatic mode won't work either.
The Pentax LX has the widest unassisted single exposure range of EV -5.5 ~ EV 20 of any camera ever - past or present. In fact, I am unaware of any handheld meter that equals this either - certainly not my Sekonic. Along with this, it is the only camera (past or present, film or digital of any brand) that can aperture priority auto expose a scene for as long as it takes all the while monitoring the scene for light changes and changing exposure time accordingly. I have successfully - and repeatedly, created images with aperture priority autoexposure lasting hours long. With the example below, I started the shutter before 9pm and it closed sometime after 4am. This one taken on Kodak Gold 100.

01-19-2016, 06:52 PM   #11
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QuoteOriginally posted by LesDMess Quote
The Pentax LX has the widest unassisted single exposure range of EV -5.5 ~ EV 20 of any camera ever - past or present. In fact, I am unaware of any handheld meter that equals this either - certainly not my Sekonic. Along with this, it is the only camera (past or present, film or digital of any brand) that can aperture priority auto expose a scene for as long as it takes all the while monitoring the scene for light changes and changing exposure time accordingly. I have successfully - and repeatedly, created images with aperture priority autoexposure lasting hours long. With the example below, I started the shutter before 9pm and it closed sometime after 4am. This one taken on Kodak Gold 100.
Interesting, not something I knew...
01-19-2016, 07:08 PM   #12
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QuoteOriginally posted by bertwert Quote
Interesting, not something I knew...
I used to wonder why aperture priority would just arbitrarily stop at some point until I found the LX.
01-20-2016, 01:27 AM   #13
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Not all cameras are limited to 30 seconds in manual mode. the Hasselblad H5D will do up to 34 minutes.
Admittedly this is a large step up from most digital cameras.

Mostly I think it's a traditional holdover from the film days.
01-20-2016, 08:55 AM   #14
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QuoteOriginally posted by LesDMess Quote
In the Pentax lineup, only the original AP, K & S has a separate slow shutter speed control mounted in the front along with shutter control on top.
Later mechanical cameras like the K1000 had one control, but two internal systems.

Edit: I found my O-GPS1 and checked. If you select Bulb mode and set up a >30 sec. shot in the GPS menu, you can select a time up to 5 minutes. The top display will count down the remaining time. Probably the K-3 II can do that because it has an internal GPS. The GPS features vary slightly between cameras and obviously with no top display, no countdown.

Last edited by Just1MoreDave; 01-20-2016 at 11:15 AM.
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