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02-28-2014, 08:27 AM   #1
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MLU or Live View for long exposures with K-3

The other evening I had some time to kill before my train went, so I took some night time shots.

I used my normal approach of mirror lock up and remote release.
I did not have a tripod with me, so used a Gorilla Pod splayed on a wall.
However, it was not particularly easy to check focus this way, and the jury is still out on stability.
Nevertheless it was useful reconnaissance.

I plan to repeat the session using a proper tripod.

The idea of using Live View instead of MLU crossed my mind.
I am assuming that the mirror is up and stays up, so possibly the same as MLU, but able to see what is happening better.
Other than being a drain on batteries, which is not a problem anyway, what are the pros and cons of Line view for long exposure stuff?
Any comments appreciated, in particular any 'gotchas' which aren't immediately obvious

Thanks


Ken

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02-28-2014, 08:49 AM   #2
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Live View to check focus, for sure. But best to use MLU for the actual exposure. Too many moving parts otherwise. And great shot!

Jack
02-28-2014, 08:54 AM   #3
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Hm, are you sure live view doesn't momentarily lower the mirror before taking the exposure? Not sure about the K-3, but I think some older models did this - a mirror action even when taking photos from live view.
Great photo btw
02-28-2014, 09:44 AM   #4
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The K-3 does not move the mirror at all when shooting in live view. The difference from other Pentax DSLRs is that it has separate motors for the shutter, iris and mirror rather than just one to move all those things.

There is still one thing that could induce some vibration - the iris actuation. When using MLU the iris is closed at the same time the mirror is lifted. Whereas in live view the iris will be close immediately before the shutter is opened. However I think the vibration the iris actuator can cause is much less than what the mirror would, possibly even less than the shutter itself, which is inevitable.

As regards focusing if you have enough light then by all means use PDAF. If you are shooting cityscapes, as opposed to starlit landscapes or astrophotography, there will always be enough light for the K3 to acquire perfect focus in PDAF (viewfinder AF). If properly calibrated PDAF can achieve more accurate focus than focusing in live view, whether manually or automatically.

02-28-2014, 10:39 AM   #5
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All depends on how vibration-critical your work is. Live View, MLU and remote are standard for astrophotography where accurate focus is critical and no vibration is a must. The longer the lens, the more this is relevant.

Jack
02-28-2014, 11:17 AM   #6
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QuoteOriginally posted by KenBarley Quote
Other than being a drain on batteries, which is not a problem anyway, what are the pros and cons of Line view for long exposure stuff?
This is my experience with the K5--it may or may not apply to the K3:

I have noticed that using live view for longer than a few minutes at a time results in dust being attracted to/stuck to the sensor. So much so that it's visible on the camera monitor. This has happened to me a couple of times, so now I'm careful to turn live view off when I'm done checking for critical focus. (I often use manual lenses with the camera mounted on a tripod).
02-28-2014, 11:36 AM   #7
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QuoteOriginally posted by johnyates Quote
This is my experience with the K5--it may or may not apply to the K3:

I have noticed that using live view for longer than a few minutes at a time results in dust being attracted to/stuck to the sensor. So much so that it's visible on the camera monitor. This has happened to me a couple of times, so now I'm careful to turn live view off when I'm done checking for critical focus. (I often use manual lenses with the camera mounted on a tripod).
I've never noticed that happen with K-r, K-30 or K-3 but it may well be that I have not looked carefully enough to notice, especially since the photos I shoot in live view tend to be the sort on which dust is not conspicuous (wide aperture and/or stacking)

Would the dust remain on the sensor or would photos taken later be OK, perhaps being removed by the dust removal mechanism? Put differently, does it affect only the photos taken in live view or do you have to clean the sensor manually to get rid of the dust?
02-28-2014, 11:57 AM   #8
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The first time, I had to manually clean the sensor. The second time, it went away after running the sensor cleaning utility a couple of times.

I've had the K5 for about a year and a half and I've only had to clean the sensor the once--the sensor cleaning on the K5 is pretty darn good, leaps and bounds better than the K20 which is my previous camera.

I should state that 99.9% of the time I shoot with manual primes and I frequently change lenses in the field, so it could very well be that my mirror box contains an above average amount of dust. YMMV.

---------- Post added 28th Feb 2014 at 01:09 PM ----------

Here's a shot to show the dust. Operating the sensor clean utility just shifted it around.



It was especially noticeable as it was against the sky. As I mentioned, I could see it on the monitor when shooting.

02-28-2014, 03:05 PM   #9
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QuoteOriginally posted by KenBarley Quote
The other evening I had some time to kill before my train went, so I took some night time shots.

I used my normal approach of mirror lock up and remote release.
I did not have a tripod with me, so used a Gorilla Pod splayed on a wall.
However, it was not particularly easy to check focus this way, and the jury is still out on stability.
Nevertheless it was useful reconnaissance.

I plan to repeat the session using a proper tripod.

The idea of using Live View instead of MLU crossed my mind.
I am assuming that the mirror is up and stays up, so possibly the same as MLU, but able to see what is happening better.
Other than being a drain on batteries, which is not a problem anyway, what are the pros and cons of Line view for long exposure stuff?
Any comments appreciated, in particular any 'gotchas' which aren't immediately obvious

Thanks


Ken
I suppose you can say the exposure period is Live View regardless of what type of focusing system you use. If you go to a 2 sec delay on the shutter actuation, it won't matter whether you use PDAF or Live View for the focusing step (with regard to vibration).
03-01-2014, 04:07 AM   #10
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Thanks for comments

Thanks for all the comments.
The general impression I'm getting is that Live View is fine for set up / focus.
BUT use MLU / delay for actual shot.

Thanks

Ken
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