movement/drag at 125th?

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movement/drag at 125th?

Postby NN199479UL » Mon Feb 06, 2012 12:35 pm

hello,
we are on the brink of investing in the aptus II 12 back with DF645 & LS lenses. However, on a few recent shoots we have had intermittent movement/drag when shooting handheld.
On both occasions we were shooting in a flash only studio set up, with a main source light, fill, and back lights. All flash durations were 1/160 or above. The camera was 50ISO, 1/125th, f11, and we were using the 55mm & 110mm LS lenses.
The movement/blur was not soft focus, as I could see actual drag on parts of the image. It was quite random in its occurence, sometimes everything would be pin sharp, and then there would be a few frames with movement, and on & off etc.

Has anyone heard/experienced any kind of drag or shake at 1/125th on these cameras?

Thanks,
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Re: movement/drag at 125th?

Postby Gareth » Mon Feb 06, 2012 10:35 pm

Sounds like flash duration rather than a camera issue and using a faster sync speed would help. This however would probably reduce the effective power output of the strobes if they have a slow duration.

What strobes are you using?
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Re: movement/drag at 125th?

Postby NN199479UL » Tue Feb 07, 2012 1:49 pm

on two different shoots, first one we were using broncolor grafit a4 head, with the flash duration at 1/160
the second shoot was with a briese 140 reflector wired into a pro 8 air pack, about 2 stops under full power so the duration still should have been fast enough
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Re: movement/drag at 125th?

Postby Gareth » Tue Feb 07, 2012 10:18 pm

Not sure what you're shooting and how fast the object is moving but 1/160 is not really short enough to freeze fast moving objects and while the flash duration of the Pro8 is specified as short that will only be their minimum power output.

The only other possibility is if you have a lot of ambient light causing some of that exposure to register on the capture and causing the dragging effect. Did/can you try using a faster shutter speed with the leaf lenses to see if this has any effect?
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Re: movement/drag at 125th?

Postby Aztecaphoto » Thu Feb 09, 2012 9:53 pm

This same thing happened to me with Bowens - Calumet monolights.
That´s because of the short duration of the flash (1/800 or so).
The graphite has this:

Grafit A4
T 0.1= 1/80 – 1/6000 s
T 0.5= 1/240 – 1/10000 s

So that means that at full power you´ll probably have 1/80 or 1/240 (upss!). Too slow.
And Profoto is probably ok with flash duration at 2 stops under full power, but maybe not enought if you are "shaking" your camera shooting hand held, but not steady.

So I changed to other swiss brand (EL) and learned to shoot hand held steady.

But hey, you have a LS. Use a faster speed even if you loose power. You can try using ISO 100 instead

Saludos
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Re: movement/drag at 125th?

Postby NN199479UL » Thu Feb 16, 2012 2:56 pm

thanks all,
we were shooting a model in a studio, who was not moving.
the photographer was handheld, but has a pretty steady hand.
I know the lens sync faster, but this can result in completley relighting a set.

Really what I would like to know is whether 1/125th is a bad starting point for shooting handheld?
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Re: movement/drag at 125th?

Postby Drew » Thu Feb 16, 2012 4:09 pm

NN199479UL wrote:...Really what I would like to know is whether 1/125th is a bad starting point for shooting handheld?

With an 80mp back, yes.
Granted it depends on the conditions but I find motion blur using a 39mp back, handheld at 1/125th. Granted I don't have the steadiest hands due to a severe caffeine addiction but the factors involved would be Focal Length, Resolution and possibly Flash Duration (if used). The higher the resolution, the more detail you will see but with it the faults will be amplified. The slight motion blur that may be present at lower resolutions and not seen, will now be much more noticeable.
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Re: movement/drag at 125th?

Postby NN199479UL » Fri Feb 17, 2012 2:15 pm

thanks Drew,
if so then why is the X mode (for flash sync) set to 1/125th on this camera?
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Re: movement/drag at 125th?

Postby Drew » Fri Feb 17, 2012 3:04 pm

That is for the Focal Plane Shutter . The "X" sync at 1/125th is the limitation of Focal Plane shutters (some cameras are 1/60th and some 35mm are 1/250th or faster). It's not that we have chosen this speed, it is simply that this is the absolute fastest option when using that specific shutter type on a medium format system. (Reference: http://en.wikipedia.org/wiki/Focal-plan ... nc_barrier)
The solution to that issue then is to simply use Leaf Shutter Lenses and higher shutter speeds on your DF as the Leaf Shutter Lens can sync up to 1/1600th of a second (with compatible backs). When using the LS lenses you can use any speed to sync the flash rather than "X" as the mechanics of Leaf Shutter lenses always expose the whole CCD at once.
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Re: movement/drag at 125th?

Postby NN199479UL » Mon Feb 20, 2012 11:48 am

thanks drew, so essentially to avoid camera movement; one cannot use focal plane lenses with flash in hand held scenarios with the higher resolution backs.
limiting...
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Re: movement/drag at 125th?

Postby yaya » Mon Feb 20, 2012 3:56 pm

Not correct....

Short flash duration and low ambient light, plus a steady hand will work most of the time. Of course output size also matters...

Copyrights Igor Sakharov. 120mm/f4 Macro @ f16 and 125th with Aptus-II 12

Image
Image

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Re: movement/drag at 125th?

Postby Drew » Mon Feb 20, 2012 4:35 pm

NN199479UL wrote:thanks drew, so essentially to avoid camera movement; one cannot use focal plane lenses with flash in hand held scenarios with the higher resolution backs.
limiting...


To avoid camera movement one simply needs to be steady :wink:
As Yair has shown, it's completely possible. It all depends on the specifics!
What I have described is simply that 1/125th may not be fast enough for hand holding depending on many different factors. With higher resolution backs, it is that much more critical to be sure everything is nailed down. When you're using a higher resolution back, you're using a much finer instrument so movement which previously existed but went unnoticed might now be present and the readily available solution is to simply use a higher shutter speed with Leaf Shutter lenses.
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Re: movement/drag at 125th?

Postby NN199479UL » Mon Feb 20, 2012 6:14 pm

thanks Drew & Yair,
on both shoots where these issues were experienced we had only one modeling light on. The flash durations were set as fast as they could be on all packs, and yet we still get movement...
it still seems strange.
I take your point that the solution is to use faster sync speeds, but this itself creates a new bundle of compromises: less flash output or use twin heads, light needs to be thrown differently, super fast pocket wizards or a sync cable is needed, etc etc
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Re: movement/drag at 125th?

Postby yaya » Mon Feb 20, 2012 8:19 pm

As Drew suggests, with your setup you'd probably get movement with a lower res back as well, but you won't notice it since you'll be looking at a smaller image on screen

For best results I always pick the best tools, so if absolute sharpness it crucial I'd use fast triggers (or a sync cable), fast lights (most current main brand lights are fast enough) and a tripod if applicable
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Re: movement/drag at 125th?

Postby NN199479UL » Wed Feb 29, 2012 6:09 pm

I am a bit lost with this then, because in both situations we have done as you suggest, short flash durations and low ambient light. I find it hard to believe its the photographers shaky hand...
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