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Fixing front focusing issues with a leaf back (AFDIII)

Chris Giles

New member
I've not been too impressed with the focusing ability of the AFDIII, and looked into it a bit more now that I've got time and it appears I have a body that front focuses (kind of ruled out the lenses).

I tested the camera with a football and my dog, white dog, black eyes, white distressed football on grass. I repeated this numerous times, my boy tends to pose quite nicely.

Exhibit a: Focus point on the dogs head (red line is where the sharpest focus is).



Then, on the football:



Then onto a static tuft of grass:



Is this something to do with the gap between the back and the body? Or something more?

Thanks!
Chris
 

Steve Hendrix

Well-known member
I've not been too impressed with the focusing ability of the AFDIII, and looked into it a bit more now that I've got time and it appears I have a body that front focuses (kind of ruled out the lenses).

I tested the camera with a football and my dog, white dog, black eyes, white distressed football on grass. I repeated this numerous times, my boy tends to pose quite nicely.

Exhibit a: Focus point on the dogs head (red line is where the sharpest focus is).



Then, on the football:



Then onto a static tuft of grass:



Is this something to do with the gap between the back and the body? Or something more?

Thanks!
Chris

Chris -

Were both the ball and the dog in the focus circle when you captured? In that case, generally, whatever subject in the circle that is closest to the camera will in most cases be the area that the camera will focus on. I've found that setting the bias to the left or right triangle can narrow this to a degree, though it tends to hunt a bit more. On a DF body, you also have the option below, but unfortunately not on an AFDIII.

DF Body AF Accuracy vs Speed :: Capture Integration – Medium Format Digital Back Sales & Rental and Other Professional Photographic Equipment

In the example of your doggie photo, you might have tried to position the dog in the circle without the ball, and then recomposed. That may have provided a better result.


Steve Hendrix
 

Chris Giles

New member
Hi Steve,
Yep, in both cases I made absolutely sure that the central focus point was dead centre. I only used the central one too, turning off the supporting ones either side.

I cropped the images down to fit the web better. But, in all cases, I focused, waited for confirmation and fired the shutter. I didn't focus and recompose. The boys head and the footballl pretty much filled the focus circle and I felt there was enough contrast there to secure a decent lock. In the case of the football it filled the exact diameter of the central AF circle.

Original frames:



 

Steve Hendrix

Well-known member
Hi Steve,
Yep, in both cases I made absolutely sure that the central focus point was dead centre. I only used the central one too, turning off the supporting ones either side.

I cropped the images down to fit the web better. But, in all cases, I focused, waited for confirmation and fired the shutter. I didn't focus and recompose. The boys head and the footballl pretty much filled the focus circle and I felt there was enough contrast there to secure a decent lock. In the case of the football it filled the exact diameter of the central AF circle.
Chris - What I meant was that if both the ball (or the grass parallel to the ball in front of the dog) and the dog were within the circle, then the ball/grass would likely be the point of focus. If you are saying the ball was not in the circle (nor the grass at the spot in front of the dog), then probably it does appear to be a front focus situation, though some duplication in different scenes and tests can confirm this.


Steve Hendrix
 

Chris Giles

New member
Ah I see, yes Steve, I totally made sure the individual objects filled the frame.

So with Harvey (the dog) his head filled the focus circle absolute. The football filled the circle and if anything, was larger than the focus circle.

In a way I'm relieved because I couldn't believe how bad the focus was compared to my H1.

How is something like this usually addressed?
 

FredBGG

Not Available
I have a Phase One AF and a Phase One DF. Both are very accurate both auto focus and manual focus with focus confirmation.

Looks like your camera could use a fine tuning.

It would be nice to have focus calibration in the firmware.
 

Steve Hendrix

Well-known member
Ah I see, yes Steve, I totally made sure the individual objects filled the frame.

So with Harvey (the dog) his head filled the focus circle absolute. The football filled the circle and if anything, was larger than the focus circle.

How is something like this usually addressed?
Chris - notify your dealer and they should be able to arrange for Mamiya/Phase to make an adjustment. Make sure it's done right! Don't accept the situation if it is not properly resolved.


Steve Hendrix
 

etrump

Well-known member
My DF exhibits the same issue. I'm taking mine to the P1 conference in miami, hopefully they will be able to correct.
 

Chris Giles

New member
Ok so here's an update.

I tried the ruler test with the 85mm wide open and it's fine but anything real world and it's very inconsistent. Life isn't black and white.

Interesting about the DF Ed, I'm more and more swinging back to Hasselblad. I considered the DF as an option, heck even agreed to buy one but it fell through. Can't use the film backs though which is a deal breaker for me, I don't want two cameras for Medium format.
 

Bob

Administrator
Staff member
The necessary diagnostics include determination of where the issue lies.
Lens (if it is one of several and some are ok, back, if the image in the finder is sharp and all lenses are front focusing, camera if AF produces an unsharp image in the finder, or some combination of all the above (take it to an expert)
-bob
 

SergeiR

New member
Question is. Have you shot off tripod?

B/c i personally have issues with recomposing, that i know of - i do tend to lean out when recomposing.. Had to force-train myself to not do that ;) And still do that every now and then
 

Chris Giles

New member
Question is. Have you shot off tripod?

B/c i personally have issues with recomposing, that i know of - i do tend to lean out when recomposing.. Had to force-train myself to not do that ;) And still do that every now and then
Well here's the thing, I used a tripod during a shoot today. Actually had to in order to get ISO50 1/30 sec @ F/3.5.

But despite it getting focus right often there were a lot of shots where the eyes were soft and the cheekbones sharp.....there were no instances of the area behind the eyes being more in focus. Always front focusing.

 

SergeiR

New member
Chris, were you doing any recomposing at all? B/c on this one center would fall on about nose :)

In either case it looks way better than with doggie where focus was way off.

I was on this very boat for a while - my shots with ZD back were dead on, no matter which of AFD bodies i used (i have all 3 versions :)), and with Leaf i kept having focusing issues.. Then i realized that it balances differently when i recompose. ZD is way lighter than Leaf, so for whatever reason i kept overcompensating movement after recomposing. Uppermentioned leaning was part of it.

And then i added RZ to arsenal and all the hell broke loose :)
 

Chris Giles

New member
Well the above shot was on a tripod and the af point I was using was the one just outside the centre so there pretty much wasn't any movement at all.

Things is, and I'm happy to be wrong thinking this way, but the amount of movement (if any) is tiny as it was on a tripod. Focus issues don't seem so troublesome when the subject is close but a few metres away and it all goes a bit wrong.
 

FredBGG

Not Available
When you are this close and using such shallow depth of field you can expect the focus to shift as the subject breaths. Focus going from eyes to cheekbone is within that range.
Shooting with 8x10 I have learned to watch out for subtle movement.

I prefer to manually focus if I'm this close.

Also If you shoot this close I would recommend getting a 210mm for slightly flatter perspective for certain faces. Very nice lens and quite good prices used.
 

FredBGG

Not Available
Well here's the thing, I used a tripod during a shoot today. Actually had to in order to get ISO50 1/30 sec @ F/3.5.

But despite it getting focus right often there were a lot of shots where the eyes were soft and the cheekbones sharp.....there were no instances of the area behind the eyes being more in focus. Always front focusing.

Skin tones look very natural as do the yes. More film like than 35mm DSLR.
 

Chris Giles

New member
Thanks, I took delivery of a 1.9 80mm of which I really like and have a 110mm 2.8 incoming.
Tripod shooting looks the way to go so at least I'll have my hands free for manual focus :D
 

FredBGG

Not Available
Thanks, I took delivery of a 1.9 80mm of which I really like and have a 110mm 2.8 incoming.
Tripod shooting looks the way to go so at least I'll have my hands free for manual focus :D
IF you don't mind shooting stopped down the Hasselblad 110mm f2 is a fantastic lens.

Here is a quick test shot with one.

 

Chris Giles

New member
I've considered the Hassy 110 too. But I'm going to give the Mamiya a try.
Plus it's finding a 110 F2 used, anywhere!
 
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