December 12th, 2011, 01:58 PM
GRD3 and X10 DOF scales - DON'T BELIEVE THEM!!!!
For those of you who like to use zone/snap focussing for street shooting or whatever, I just did some calculations on the actual depth of field vs the information the electronic DOF scales in these camera produce. And the bottom line is:
IGNORE THE ELECTRONIC DOF SCALES!!
They're so far off its not even funny. They both show FAR LESS depth of field than you're actually working with, and if you believe them, you'll be a real pussy about the lighting conditions you can reasonably use zone/snap focus in.
I've checked the LX5 and X100 in the past, and both of these were off, but by fractions, not multiples. They're useable for zone focussing (just a bit conservative, which isn't a bad thing), although they'll throw you off pretty badly if you try to use them to find the hyperfocal distance. According to some numbers Don (shooter) provided me, the Ricoh GXR has a DOF scale that appears to be just about dead-accurate, so it IS POSSIBLE!
I built a little DOF cheat sheet, rounding the near distances up and the far distances down to be conservative (and to be able to read it easily without all of the decimals). Based on my already conservatively rounded numbers, here are some examples of just how out of whack the X10 is: at the 28mm equivalent 7.1mm lens setting:
5 foot focal point, f2.8 - actual 3-15 feet, DOF scale about 4-7 feet
10 foot focal point, f2.0 - actual 5-287 feet, DOF scale about 7-15 feet
7 foot focal point, f4.0 - actual 2.5-infinity, DOF scale about 5-15 feet
Actual hyperfocal distance at f2.0 - 10.4 feet, DOF scale about 15 feet.
The Ricoh's numbers are every bit as bad and misleading. This is no opportunity for Ricoh of Fuji fanboys to trash the other company's products - they BOTH suck in this regard!
If you believe the DOF scale, you will not trust the camera to do nearly what its capable of and you will crank down the aperture beyond where you can get a reasonable shutter speed in fading light. These cameras have a LOT more DOF latitude than their own scales would lead you to believe. So I urge anyone using zone focus to build a little cheat sheet and get to know your camera's actual behavior out in the field. Jeez, I'd turn that DOF scale off if I could, and just leave the focus point intact, but this isn't an option on either camera.
This is really discouraging. These cameras are amazingly capable street cameras, but one of the most potentially useful tools on both cameras is useless to the point of being counter-productive. This really shouldn't be this hard to get right.
So, now you've been warned!
Last edited by Ray Sachs; December 12th, 2011 at 02:02 PM.
December 12th, 2011, 02:39 PM
very subtle warning, particularly the title
Is it possible that you and the official scales used different circles of confusion?
December 12th, 2011, 03:00 PM
I just used the DOF calculator on DOFmaster. They don't have the X10 in their database yet, so I checked two other cameras with the same sensor size and they were identical, so I used those results for the X10. The GRD3 is in the database so it produced results directly for that camera.
December 12th, 2011, 03:07 PM
Hey Ray I feel your frustration mate. But I'd take some solace in the fact that the purported values are within range....just very conservative measures.
Back when I toted the X100 I was peeved that it didn't have DoF scales at all. But DoF Master to the rescue! Actually I kept a little print-out table taped to the bottom of the body. Was unobtrusive and very handy. You learned it by rote after a time, but it was a great way to get your bearings.
December 12th, 2011, 03:13 PM
Ray, I fully understand your feelings. When I discovered this on the X100, I went on a similar rant all over the net. A Fuji engineer admitted they used 35mm for the calculations and not 23mm.
I have since sold the camera and put it out of my mind. The only camera I have ever found that is close to accurate us the GXR. I can live with its slight offness.
Don't let this disturb you. Just figure out how to work the scale to your advantage and shooting methods. With the X100 I couldn't get past this issue because of the 35mm FOV and shorter DOF.
The X100 is 50% off in the near end.
The GXR is much closer. The key issue is focus by wire and not really being able to set an exact focus distance. The GXR gets around that with the snap focus distance being adjustable.
With a zoom lens like the X10... Drink some Kona and give up on any kind of accurate zone focusing. It would make you crazy.
There are those amongst us that will argue about the scales being conservative.
December 12th, 2011, 03:40 PM
Don, I already did a good bit of zone fucus street shooting with the X10. I just kept it at the 28mm equivalent (7.1mm actual), trusted the insanely conservative numbers on the DOF scale, and did fine. Sort of like when using the GRD3 with the scale showing the actuals or the larger sensor GXR. I've gotten good results out of both, just haven't used either to their potential - not even close. So the inability of these companies to come up with an accurate DOF scale ticks me off, but I'm also feeling liberating knowing how much more capable both of these cameras are than I'd been giving them credit for. So, I'll just use 'em without looking at the useless scales.
Mark, the X100 does have a DOF scale. It shows up in manual focus and I think it can be configured to show in AF too, but I'm not sure off the top of my head. And its a good deal closer to accurate than either of these. That one didn't bother me as much because I pretty much never use that camera in zone focus anyway. Its an OVF camera and I always use it with AF, so the relatively smaller flaw on that never bugged me as much as the HUGE flaws on these two cameras. But it won't take me long to learn to ignore them and just use the cameras' actual capabilities.
December 12th, 2011, 04:00 PM
Ray, your good at what you do and it's obvious that you'll make something work.
It's a stupid thing about the scales. It's like... well, maybe 5.6 or maybe 1/250 sec..give or take...
By the way...the X100 is off 50% on the close range. So if it reads 10', it's really 5'.
December 12th, 2011, 04:34 PM
Ray, another question and finding. You are aware that in snap focus mode, the distance you set is not the minimum distance of the DOF.
For example.... The 28 on the GXR, snap at 2.5 meters and at f5.6 shows exactly the proper DOF. I get about 4.7' to infinity at 5.6. Not bad and the GXR scale is very accurate. Any mistake is due to the conversion from meters to feet..... If we change the snap distance, that will also change the DOF. I know you know this but I'm just trying to eliminate any error you could be thinking about.
Funny thing...at every forum I explained about the X100 scale.... very few people even cared. That amazes me....
December 12th, 2011, 04:55 PM
Not to worry - I get that the snap distance is the focus point, not the near end of the DOF. DOF master makes it pretty easy from there, but the input is the focus point and then THEY tell you the near focus distance and the far focus distance for that combination of focus distance, focal length, and aperture. They'll even build you a table automatically, which I just moved into Excel and rounded off, and then boiled down to a few key columns so as to not be overwhelmed by too much data. A nice little cheat sheet that I'll probably use for a little while and then internalize well enough to trash. As for people not caring, how many people do you think actually use zone focus in this day and age? Not many, that's how many. If I wasn't shooting on the street and often from the hip, and if I hadn't used it with film cameras in my yooot', I probably wouldn't use it either. It used to make sense for lots of shooting in the manual focus, crank the lever for the next shot days, but today its a highly specialized technique I think.
Originally Posted by Streetshooter
December 12th, 2011, 04:56 PM
Sorry but I am one of those that rarely if ever looks at my DOF scales anymore, but back in the day it was the only way one could shoot with a rollei 35 or minox 35, I even remember being mad at the loss of DOF buttons on DSLRs.
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