What's the use of snapfocus with an APS-C sensor?

[wimvangrinsven]

Ricoh gave us a GR with an APS-C sensor and a razorsharp lens.

But there is a counterside.
The APS-C sensor gives the GR a shallow DOF. According to DOF-master, I have to use f-11, if my subject is between 1.4 en 3.3 meters with snapfocus set at at 2 meters.
I've got a lot of thinking to do before I shoot. Is there enough light or do I have to use a higher ISO? Is my subject in range?

I think I would rather use AF and recompose.
What do you think?

 

[Tom Caldwell]

Wim,

Set Fn2 to AF/MF then you can use AF to get focus and switch to MF which is effectively focus lock.
The GR is not a great camera for MF. Note also that in Snap Focus mode you can hold the up arrow and rotate the wheel to change snap focus distance setting very quickly.

Tom

 

[wimvangrinsven]

Thanks Tom, but my point is that the snapfocus-function, compared to the compact-GR's, is far less usable on the GR (APS-C).

The snapfocus-function is a major selling-point for the GR-series.
Have a look at the presentation video:
http://www.youtube.com/watch?v=88LiM3RSVVo "Best snapshot camera" at 0.21 and "the only thing that can beat a GR is another GR".
But it isn't the best snapshot camera! The GR Digital IV is, because it has a hyperfocal distance of 1.5m at f/4.

Although I love my GR for other reasons I think Ricoh shoots in its own foot.

Wim

PS Instead of changing to MF I prefer to use the AFbutton to get focus lock.

 

[riccadonna]

May I be to a little help wimvangrinsven. You write that "The APS-C sensor gives the GR a shallow DOF. According to DOF-master, I have to use f-11, if my subject is between 1.4 en 3.3 meters with snapfocus set at at 2 meters". I checked DOFmaster table and discovered that DOF for my GXR 28 at f:11 set at 2meters is 0.86 to inf ! What about that? Well, I investigatet further and indeed for Ricoh GR your numbers fit. I looked closer and saw that somehow they used COF ( cicrcle of confusion) of 0.006mm while COF for GXR 28 is 0.02. What`s the hell then.?
It seems that somebody used COF of GR Digital IV which is 0.006 because of much smaller sensor for which 18,3mm corresponds to ca 85mm on full frame.
By the way I checked DOF on my 19mm FF canon and it goes from ca 0.7 to beyond infinity due to bigger COF and finally I checked the visual DOF bar indicator on my GXR A28 and it confirmed DOFmaster read out, from somewhere below 1m to infinity, I hope that solves your problem. Set the snap at 1.5m and everything between 0.75m and infinity should be more or less sharp ( at 1.5m very, very, very sharp ). Enjoy. Stanislaw

 

[Tom Caldwell]

Thanks Tom, but my point is that the snapfocus-function, compared to the compact-GR's, is far less usable on the GR (APS-C).

The snapfocus-function is a major selling-point for the GR-series.
Have a look at the presentation video:
http://www.youtube.com/watch?v=88LiM3RSVVo "Best snapshot camera" at 0.21 and "the only thing that can beat a GR is another GR".
But it isn't the best snapshot camera! The GR Digital IV is, because it has a hyperfocal distance of 1.5m at f/4.

Although I love my GR for other reasons I think Ricoh shoots in its own foot.

Wim

PS Instead of changing to MF I prefer to use the AFbutton to get focus lock.

Wim

I think Stanislaw may have answered your query. In any case the larger sensor was bound to reduce the dof capacity and there already has been some talk about the need to be a bit more precise with snap focus distance settings.

As far as I know Ricoh has never provided a focus lock button on any of its cameras. Toggling AF/MF works just as well and MF is available for fine tuning. Of course full press snap does not work when MF is in effect.

Tom

 

[MikePenn]

I have never used snap for hyperfocal, I use it for my target distance as I walk down the street.

 

[thelps]

As far as I know Ricoh has never provided a focus lock button on any of its cameras.

I think the only form of focus lock is the partial shutter press. I use this a lot, old habits from Contax T2/T3 days which had an in viewfinder lock LED.
The GR is very welcome to have a much finer spot focus point now.

An old cry of mine is a center mark either [ ] or a + mark for the OVF so we know where the center is while using an OVF. The LED light lights up next to the eye to indicate partial press lock.

 

[wimvangrinsven]

It seems that somebody used COF of GR Digital IV which is 0.006 because of much smaller sensor for which 18,3mm corresponds to ca 85mm on full frame.

Thanks Stanislaw. That really helped. I contacted DOFmaster.com and asked to change the CoC of the GR.

As far as I know Ricoh has never provided a focus lock button on any of its cameras. Toggling AF/MF works just as well and MF is available for fine tuning. Of course full press snap does not work when MF is in effect.

Tom

Hi Tom

It is this button, as explained on page 54 of the manual http://c758710.r10.cf2.rackcdn.com/files/support/manual/1370269958_L7662971_En_web.pdf

With the right settings you can get focuslock even though you halfpress the shutter.

Wim

 

[Tom Caldwell]

It seems that somebody used COF of GR Digital IV which is 0.006 because of much smaller sensor for which 18,3mm corresponds to ca 85mm on full frame.

Thanks Stanislaw. That really helped. I contacted DOFmaster.com and asked to change the CoC of the GR.

As far as I know Ricoh has never provided a focus lock button on any of its cameras. Toggling AF/MF works just as well and MF is available for fine tuning. Of course full press snap does not work when MF is in effect.

Tom

Hi Tom

It is this button, as explained on page 54 of the manual http://c758710.r10.cf2.rackcdn.com/files/support/manual/1370269958_L7662971_En_web.pdf

With the right settings you can get focuslock even though you halfpress the shutter.

Wim

Yes you are right Wim, I read this and forgot about it. I am still trying to find a serious use for the focus peaking. Great tool but of little use on the GR. Much more useful and natural on the GXR-M. So it suited me to resurrect the AF/MF toggle and I quite forgot that the new button can be used as well. Sorry.

Tom

 

[Wouter]

Wim, the snap focus mode makes perfect sense on the GR. F/4.5 to f/8 prefocused at 2, 2.5 or 5 meters provide enough depth of field with the 28mm wide angle lens. Just use it to feel comfortable with it.

 

[MikePenn]

I agree.

 

[sandrini]

the COF should be 0,02m on the GR (not 0,06m as mentioned e.g. on Dofmaster)

Basically:
Subject distance 2 m
Aperture f/3.6
Depth of field
Near limit 1.41 m
Far limit 3.46 m
Total 2.05 m
In front of subject 0.59 m (29%)
Behind subject 1.46 m (71%)
Hyperfocal distance 4.72 m
Circle of confusion 0.02 mm

Subject distance 2 m
Aperture f/8
Depth of field
Near limit 1.03 m
Far limit 37.6 m
Total 36.6 m
In front of subject 1 m (3%)
Behind subject 35.6 m (97%)
Hyperfocal distance 2.11 m
Circle of confusion 0.02 mm

Subject distance 1.5 m
Aperture f/11
Depth of field
Near limit 0.75 m
Far limit Infinity
Total Infinite
In front of subject 0.8 m
Behind subject Infinite
Hyperfocal distance 1.5 m
Circle of confusion 0.02 mm

If you use those adj below you should be really close to hyperfocal distance.
1.0m f/16
1.5m f/11
2.0m f/8
2.5m f/6.3
5.0m f/3.5

cheers

 

[streetshooter]

The thing to remember about Hyperfocal Distance is:
Infinity is the common denominator to any HD equation.
So, changing f/stop and or focus distance changes the near limit. Once you decide on your desired near limit, setting Snap is a cinch.

What I do on the GR is to...use AF and then Full Press Snap.
Here's how I think and work. I'll set snap distance to the desired setting...usually 2 M.
Then I stay in AF mode and is something happens fast, a full press makes it snap at the given f/stop. This is faster then using Snap/AF Fn1 toggle.

I found that DOF Master and Ricoh are slightly off in their calculations. This is due to the camera and not DOF Master. So I trust AF because of a few reasons and use both calculations to find a happy medium.

Gone are the days of the very reliable GRD4. It's taken me a month to just now feel that the GR will work with me. It took 21 1/2 minutes for the GRD 3&4.

 

[Tom Caldwell]

It seems that the GR simply continues the considerable number of choices that Ricoh has always provided (and adds a few of its own):

Snap Focus (various distances - easily changed) Aperture priority to gain extra dof?
Soft press shutter to lock found focus - every camera does this
Assignable to Function button AF/MF toggle to manually lock focus more useful if AEL is used on the custom button
Settable custom lock button on the camera - more generally useful than the above - needs to be set to user preference
Pinpoint Focus (preset focal distance then lock?)
Fixed start up focal length setting in MF - any desired focal length (set in custom modes)
I might have missed something

and "faster" AF with the usual focusing method choices (no phase detect focus unfortunately)

The user is blessed with choices. None of them specifically address the more shallow dof of the aps-c sensor other than perhaps multi-point AF or subject-tracking AF - neither of which would be regarded (possibly) as rapid fire snap focus alternatives.

At least there are choices. And if you are quick there might still be a GRDIV left to buy it has phase detect focus, IS and a greater dof. And is smaller both physically and in sensor.

Tom