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12-23-2014, 05:43 AM   #16
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QuoteOriginally posted by maxxxx Quote
I wish they would an extended exposure mode like they sometimes do with ISO

---------- Post added 12-22-14 at 11:48 AM ----------



I can see how metering would be a problem but the restriction is there in Manual too.
But metering is still active in M mode so perhaps the programmers felt it would give improper guidance in exposures beyond 30 seconds.

12-23-2014, 08:13 AM   #17
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QuoteOriginally posted by awaldram Quote
so sensor linearity is still a concern for manufacturers
????

Now that is a new one.


Steve
12-23-2014, 08:34 AM   #18
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QuoteOriginally posted by IchabodCrane Quote
But metering is still active in M mode so perhaps the programmers felt it would give improper guidance in exposures beyond 30 seconds.
Ummm...I don't want to sound like a broken record, but has any noticed that the Nikon D7100 (same Copal shutter and same Sony sensor) has the same 30s maximum? This is not a product fault and has nothing to do with pro vs. consumer. 30 seconds maximum timed exposure has been sort of an industry standard dating back at least 20 years. I think the number (30s) is likely arbitrary and imposed by Copal as part of the shutter specification. (The shutter timing, as with all quality time pieces, is determined by the manufacturer of the clock...duh.)

I would suggest that in practical terms, precision exposure timing beyond about 10 seconds is sort of silly. After all, there is only one stop difference between 30s and 60s. For exposures of that length, counting or using the second hand on a watch is probably quite adequate. If that is not satisfying, an external trigger with timer is cheap and works well.


Steve

(...my decidedly "pro" view camera has a maximum timed exposure of 1s and that is not particularly accurate...most exposures with that camera are done using "B" or "T" and a wristwatch...)
12-23-2014, 09:54 AM   #19
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QuoteOriginally posted by stevebrot Quote
Ummm...I don't want to sound like a broken record, but has any noticed that the Nikon D7100 (same Copal shutter and same Sony sensor) has the same 30s maximum? This is not a product fault and has nothing to do with pro vs. consumer. 30 seconds maximum timed exposure has been sort of an industry standard dating back at least 20 years. I think the number (30s) is likely arbitrary and imposed by Copal as part of the shutter specification. (The shutter timing, as with all quality time pieces, is determined by the manufacturer of the clock...duh.)

I would suggest that in practical terms, precision exposure timing beyond about 10 seconds is sort of silly. After all, there is only one stop difference between 30s and 60s. For exposures of that length, counting or using the second hand on a watch is probably quite adequate. If that is not satisfying, an external trigger with timer is cheap and works well.


Steve

(...my decidedly "pro" view camera has a maximum timed exposure of 1s and that is not particularly accurate...most exposures with that camera are done using "B" or "T" and a wristwatch...)
If they have the same shutter, would this mean Pentax is arbitrarily limiting flash sync speed to 1/180 instead of 1/250?

12-23-2014, 11:31 AM   #20
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QuoteOriginally posted by IchabodCrane Quote
If they have the same shutter, would this mean Pentax is arbitrarily limiting flash sync speed to 1/180 instead of 1/250?
I understand what you are saying. How Nikon leverages the shutter's interface does not change the basic interface presented. Pentax likely made a decision to sync at 1/180s, but I don't think it makes sense to call that decision arbitrary. The X sync is based on the maximum speed at which the full frame is exposed (the highest of the "slow" speeds). If Nikon chooses to run the curtains at a faster speed, I would expect there are trade-offs.

I personally don't see the big deal here. To expand a little:
  • Early focal plane shutters: 1/15s ~ 1/30s
  • Pentax SV: 1/45s
  • Pentax Spotmatic: 1/60s
  • Ricoh Singlex and Nikormat (both contemporary with Spotmatic and both having the vertical Copal shutter): 1/125s
  • Almost all electronic shutter film SLR: 1/125s
  • Pentax dSLR (all): 1/180s
  • Nikon D5300 and lower: 1/200s
  • Nikon D7100, D810, D3X: 1/250s
Notice the steps were about one full stop (1/60s, 1/125s, 1/250s). Pentax is 1/3 stop slower than the high-end Nikon. Yes, 1/3 stop. You would be doing well to see that difference with most scenes and the difference in motion stopping capabilities is nil as well.


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12-23-2014, 11:57 AM   #21
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I was told that reciprocity failure was what you told your clients went wrong, if something went wrong on a shoot, because it made you sound really smart. After all, only a fool would argue with some one who knows words like "reciprocity."

I get impatient with these things, if I go over 30 seconds, I go to 200 ISO.

I hate it when my exposure goes over 15 seconds... short attention span...

I start to worry if the camera is broken...

I panic and turn the camera off and on just to make sure everything is all right..

Then "OK, take a deep breath, press the button again, this time go read a book" ...
12-23-2014, 11:57 AM   #22
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Panasonic GH4 and GX7: i checked their specs and they both have 60 second minimum shutter. If its no big deal, than why can't Pentax provide it as well. A year ago, i used to bring up the fact that tilting LCD monitors on the back were useful. All the apologists said that they aren't useful and would break anyways. So i bought 2 Sony Nex/s and loved the tilting LCD screens. Now, Nikon and Pentax have finally started to catch up with tilting screens and providing them as new models come out. Life is short, if Pentax doesn't have the features you want, buy a different brand is my advice.
12-23-2014, 12:44 PM   #23
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QuoteOriginally posted by normhead Quote
I panic and turn the camera off and on just to make sure everything is all right..
Don't forget to reset to factory settings and clean the contacts too, just be thorough.


Steve

12-23-2014, 12:55 PM   #24
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QuoteOriginally posted by stevebrot Quote
Don't forget to reset to factory settings and clean the contacts too, just be thorough.


Steve
You're not helping....
12-24-2014, 02:35 AM   #25
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QuoteOriginally posted by stevebrot Quote
????

Now that is a new one.


Steve
Not really its (i thought) common knowledge that sensors/amps have a linear part of their response, this linear portion is utilized for each offered ISO step within the cameras exposure solution range.

Once off the linear portion the sensor will behave unique to the light falling on it making exposure prediction impossible in a manufactured environment.

With the K5 Pentax took advantage of the sensors response staying linear (within production averages) outside Sony's specification for the sensor and so offered ISO 80.

I'm not saying this is why 30sec is standard but why a limit is required , I suspect 30 secs is chosen as a safe limit historically.

Pentax has also shown if they have any leeway they will extend ISO not Tv so do expect that 30 sec to alter any time soon.

---------- Post added 24-12-14 at 09:56 AM ----------

QuoteOriginally posted by philbaum Quote
Panasonic GH4 and GX7: i checked their specs and they both have 60 second minimum shutter. If its no big deal, than why can't Pentax provide it as well. A year ago, i used to bring up the fact that tilting LCD monitors on the back were useful. All the apologists said that they aren't useful and would break anyways. So i bought 2 Sony Nex/s and loved the tilting LCD screens. Now, Nikon and Pentax have finally started to catch up with tilting screens and providing them as new models come out. Life is short, if Pentax doesn't have the features you want, buy a different brand is my advice.
A cameras exposure flexibility is made up of ISO, TV and Av to create an exposure solution this is merged into 1 specification known as sensitivity or metering range

The Gx7 has a range of 0 to18 Ev (f2) the k3 -3 to 20 Ev (f1.4)

It is good to buy the camera with the features you desire but perhaps more important to know what those features mean and how they effect the cameras ability to take a picture ?

Given the k3 is able to meter over a greater range than most light meters it woudl appear you woudl be able to take an image with the k3 in lower lighting conditions than any other camera on the market today despite its 30 sec limit.

of cause with a modicum of photography knowledge it is easy to convert a metered 30sec / f2 / iso 400 into a used 2min / f2 /iso100 problem being if you've dropped out the linear portion of the sensor the exposure may be incorrect and some trial and error required (something the cameras processor can't do)

Of cause as the Bayer filter causes variance in light in the RGB pixels and they're non-linear then colour shifts will also occur

If you have a need for long exposure regularly then an external timer would be the appropriate tool my timer cost 3.99 and give many options including 9hour+ exposures !

To the OP yes 30 secs is an arbitrary value that someone thought was a reasonable end point before BulB , It could be 1min 2min or 5min and the same questions and complaints woudl be in this thread for whatever end point was chosen.

Its just a 3rd of the options in an exposure solution and I guess Pentax thought exposures requiring greater than 30sec are better left to hand timing or external timers due to the specialist nature of there use.

Last edited by awaldram; 12-24-2014 at 03:12 AM.
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