Joseph Holmes MF Observations

[richs]

Some in depth comment on backs and optics:

http://www.josephholmes.com/news-medformatprecision.html

and :

http://www.josephholmes.com/news-sharpmediumformat.html

Regards,

Richard

[ErikKaffehr]

Very sobering...

Conclusions:

1) Have a good dealer
2) Take nothing for granted
3) Do comprehensive tests
4) Nice if you have friends with similar equipment so you can compare

Bet regards
Erik

Some in depth comment on backs and optics:

http://www.josephholmes.com/news-medformatprecision.html

and :

http://www.josephholmes.com/news-sharpmediumformat.html

Regards,

Richard

[tho_mas]

Conclusions:
1) Have a good dealer
2) Take nothing for granted
3) Do comprehensive tests
4) Nice if you have friends with similar equipment so you can compare

5) have a screwdriver to adjust your LF lens to infinity
6) have fun

[Wayne Fox]

Interesting read.  for the price one pays I've always assumed the tolerances would be well within acceptable limits.  

I just order my P65+ complete with new PhaseOne camera system ... it appears some testing well be in order.  I may even mention this to my rep ... perhaps Phase should consider some new QC procedures to tighten things up.

[Mort54]

Phase should consider some new QC procedures to tighten things up.

In addition to addressing their QC issues, what Phase backs really need is live view on the back's LCD, with magnification. There is simply no better way to achieve critical focus than live view at 400% pixel-level viewing. It solves most of the problems Joe has toiled with. It gets rid of most focus calibration issues, and it provides the highest quality magnification achievable (aligning the sensor to the optical axis would still be critical, but forward or backward misalignment issues would effectively be eliminated). It's the one enhancement that would get me to upgrade from my current P45+. And oh yeah, a quality screen to go with it would be nice.

Phase One has made some really commendable improvements in image quality with the P65+ back (documented by Michael a few weeks ago). Now if only they would put a similar amount of effort into improving useability. I know budgets are tight, but I'd guess useability is a bigger issue for many current back owners than getting a fractional improvement in resolution via a MP boost.

Michael has his Canon mirror-lock-up pet peeve. I guess you could say this is my Phase One pet peeve.

[Wayne Fox]

In addition to addressing their QC issues, what Phase backs really need is live view on the back's LCD, with magnification. There is simply no better way to achieve critical focus than live view at 400% pixel-level viewing. It solves most of the problems Joe has toiled with. It gets rid of most focus calibration issues, and it provides the highest quality magnification achievable (aligning the sensor to the optical axis would still be critical, but forward or backward misalignment issues would effectively be eliminated). It's the one enhancement that would get me to upgrade from my current P45+. And oh yeah, a quality screen to go with it would be nice.

Phase One has made some really commendable improvements in image quality with the P65+ back (documented by Michael a few weeks ago). Now if only they would put a similar amount of effort into improving useability. I know budgets are tight, but I'd guess useability is a bigger issue for many current back owners than getting a fractional improvement in resolution via a MP boost.

Implementing Live View on the back LCD seems to be a problem with all MF systems ... supposedly something to do with them being CCD, but then why can you Live View when tethered?

Live View focusing would be fantastic for an MF back. The Mamiya magnifier he mentions or one of the other options I've never considered, but I'll probably give them a try.  Of course this only works if you get a back that is within tolerance so the sensor matches the viewfinder.

[Mort54]

Implementing Live View on the back LCD seems to be a problem with all MF systems ... supposedly something to do with them being CCD, but then why can you Live View when tethered?

Hi Wayne. Yes, that's what we've been told. But they handle live view to a laptop over Firewire just fine. So it's not that CCDs can't stream an image, in real time, to a viewer. The difference here would be to cut out the Firewire and the laptop and do it on the back's LCD. Yes, it's more power, and that will be problematic, but the main power drain is the sensor itself, and they seem to do tethered live view just fine, so they must have solved the sensor power problem associated with live view. I simply don't accept people blithely telling me it can't be done. It can be done. Live view with a tethered laptop proves it. Even if they had to come up with a little portable viewer with a Firewire interface. It can be done, and they should be (and hopefully are) working on it.

P.S. There are even video cameras with CCD sensors. That's as live view as you can get :-) This argument that they can't do it because MFDBs use CCDs doesn't hold any water.

Live View focusing would be fantastic for an MF back. The Mamiya magnifier he mentions or one of the other options I've never considered, but I'll probably give them a try.  Of course this only works if you get a back that is within tolerance so the sensor matches the viewfinder.

Yes, I'll probably try it as well.

[Kumar]

Even if they had to come up with a little portable viewer with a Firewire interface. It can be done, and they should be (and hopefully are) working on it.

If only Sinar had continued developing the CyberKit: http://ceres.informatik.fh-kl.de/pbw/lehre...Sinarback_e.pdf

Or Megavision's approach here: http://www.mega-vision.com/products/1shot/1shot.htm

Cheers,
Kumar

[Carsten W]

P.S. There are even video cameras with CCD sensors. That's as live view as you can get :-) This argument that they can't do it because MFDBs use CCDs doesn't hold any water.

There are different kinds of CCDs. The ones which do video are not suitable for high-end photography:

http://en.wikipedia.org/wiki/Charge-couple...ce#Architecture

[Mort54]

There are different kinds of CCDs. The ones which do video are not suitable for high-end photography:

That may be. I mostly added that PS for a little humor. The main point I made is that Phase One backs already support live view when used with a computer. So clearly the CCD in their backs support live view. They simply don't provide a way to display this view on the back's own LCD.

[Carsten W]

That may be. I mostly added that PS for a little humor. The main point I made is that Phase One backs already support live view when used with a computer. So clearly the CCD in their backs support live view. They simply don't provide a way to display this view on the back's own LCD.

It depends what you mean with live view. None of the MF backs support live view in the manner expected by DSLR users. They simply send an image once in a while, and I don't mean several times per second.

[skywalker_shiva]

Hi,

I guess most people who recommend live view as a method of achieving critical focus
are landscape/still life photographers.

I shoot mainly people and live view isn't gonna change my life much.
I might as well be using a rangefinder.

DB's are not too forgiving when it comes to focus errors.
The depth of field can't mask minor focus errors like film did.

I use a Hasselblad 503 and have had to calibrate many many times initially.

The focus of the hasselblad is checked by the technician using the film back.
It does not match the focal plane of the sensor.
My service guy sets the focus and sends it to me to check.
I revert back with my notes - front focus or back focus.

This process goes on for a couple of times till the fine tuning is complete
and I can sleep in peace.

The 503 being a manual camera is pretty uncomplicated
and is easy to service here in India.

The H1's are a horror story in India.
Lots of failed bodies that are not serviceable here.
The official distributor does not service them only ships them to Hasselblad HQ.
For the fastest method, you gotta fly to HongKong to fix them.

I used to use a Canon before this
and I can appreciate how great the manual focus is with the Hasselblad.
Anyone tried to manual focus with a Canon ... Successfully
I have lots of grey hairs thanks to Canon.  


 

[David Klepacki]

Live view has nothing to do with the issues that Joe Holmes has exposed.  I think you need to read through his article more carefully.

The gist of Joe's findings are that the tolerances for precise digital capture are not being controlled to the degree that is necessary for lenses as well as digital backs.  His findings have nothing to do with the ability to focus, and no amount of live view will resolve the problems he has uncovered.  Due to the smaller pixels and the geometric accuracy that ultra wide angle lenses impose upon the sensor, the degree of precision required in their manufacture is not being controlled with sufficient tolerance.  Joe found that even a miniscule error in the lens construction could lead to terrible image quality.  In fact, Joe only found two lenses out of eleven that seemed to be "good", and these were the latest digital lenses from Rodenstock and Schneider.

These LF lenses consist of two components that must be attached to a (usually Copal) shutter.  Even a slight tightening or loosening of this interface that holds the lens pieces together will cause significant out of focus issues for a digital sensor.  Furthermore, I would guess that the tolerances of the Copal shutter thickness itself are not controlled very well either, which makes it almost impossible for Rodenstock and Schneider to consistently produce lenses with their intended performance.

In my opinion, this is a serious crisis in LF lens use for digital imaging (at least for wide angle).  The only solution is for each and every lens to be individually calibrated (as well as the camera/back), which apparently is not happening.  This is the critical message from Joe, who has done a fantastic job in bringing this to light.  

David

[Wayne Fox]

Live view has nothing to do with the issues that Joe Holmes has exposed.  I think you need to read through his article more carefully.

The gist of Joe's findings are that the tolerances for precise digital capture are not being controlled to the degree that is necessary for lenses as well as digital backs.  His findings have nothing to do with the ability to focus, and no amount of live view will resolve the problems he has uncovered.  Due to the smaller pixels and the geometric accuracy that ultra wide angle lenses impose upon the sensor, the degree of precision required in their manufacture is not being controlled with sufficient tolerance.  Joe found that even a miniscule error in the lens construction could lead to terrible image quality.  In fact, Joe only found two lenses out of eleven that seemed to be "good", and these were the latest digital lenses from Rodenstock and Schneider.

These LF lenses consist of two components that must be attached to a (usually Copal) shutter.  Even a slight tightening or loosening of this interface that holds the lens pieces together will cause significant out of focus issues for a digital sensor.  Furthermore, I would guess that the tolerances of the Copal shutter thickness itself are not controlled very well either, which makes it almost impossible for Rodenstock and Schneider to consistently produce lenses with their intended performance.

In my opinion, this is a serious crisis in LF lens use for digital imaging (at least for wide angle).  The only solution is for each and every lens to be individually calibrated (as well as the camera/back), which apparently is not happening.  This is the critical message from Joe, who has done a fantastic job in bringing this to light.  

David

While the issues you bring up are in his article, he talked about more than just LF cameras.  In his discussion of Phase cameras he talks of misaligned sensors, as well as difference between the sensor plane and the focus plane for the prism.  He goes into great length to talk about loupes so you can manually focus using the prism and ground glass, then discusses how many sensors are out of alignment ... meaning use of a loupe to focus wouldn't help.

Live View focusing would resolve many of these problems ... even if the sensor was off, you would easily be able to adjust focus to compensate.  Since you are no longer relying on the ground glass and prism to focus, any misalignment there would also be compensated for by Live View.  

Granted that Live View Focusing wouldn't resolve every issue he describes, but many of those issues aren't related to Live View or focusing ... they are just issues.  Bad lenses are bad lenses ... obviously nothing Live View could do about that.

However, Live View focusing would most likely help achieve the absolute maximum possible focus with what ever is in front of the sensor ... be it bad lens, misadjusted shutter, out of alignment focus screen, etc.  To me if using a LF camera, my chances of accurate focus using Live View would be better than using a ground glass and loupe ... after all you are seeing the data the sensor is seeing.

[ErikKaffehr]

Hi,

In addition to all Wayne's wise words, live view would allow you keep the sensor mounted all the time and probable allows for better enlargement and more comfortable viewing and better magnification. A sliding adapter adds a lot of bulk and is also something that may need adjustment. I really find Mr. Holmes findings disturbing. The equipment vendors have advanced equipment to measure and calibrate what they sell, photographers just have their monitors and eyeballs, so it reasonable that vendors would be doing QC, not shipping out bad stuff to customers.

Best regards
Erik

While the issues you bring up are in his article, he talked about more than just LF cameras.  In his discussion of Phase cameras he talks of misaligned sensors, as well as difference between the sensor plane and the focus plane for the prism.  He goes into great length to talk about loupes so you can manually focus using the prism and ground glass, then discusses how many sensors are out of alignment ... meaning use of a loupe to focus wouldn't help.

Live View focusing would resolve many of these problems ... even if the sensor was off, you would easily be able to adjust focus to compensate.  Since you are no longer relying on the ground glass and prism to focus, any misalignment there would also be compensated for by Live View.  

Granted that Live View Focusing wouldn't resolve every issue he describes, but many of those issues aren't related to Live View or focusing ... they are just issues.  Bad lenses are bad lenses ... obviously nothing Live View could do about that.

However, Live View focusing would most likely help achieve the absolute maximum possible focus with what ever is in front of the sensor ... be it bad lens, misadjusted shutter, out of alignment focus screen, etc.  To me if using a LF camera, my chances of accurate focus using Live View would be better than using a ground glass and loupe ... after all you are seeing the data the sensor is seeing.

[michael]

Joe's findings need to be taken with a grain of salt. This is not a universal finding.

For example, I have now worked with three different P65+ backs on two different bodies and with 6 different lenses, and my most critical analysis has not shown there to be any misalignment issues.

I'm not saying that Joe's findings aren't actual, I'm sure that they are, but they are not universal.

The reason that I wrote my latest article, published with today's date, is that I found that meticulous technique was as big a factor as anything else in ensuring optimum image quality.

What also needs to be mentioned is that Joe is one of the most critical people that you're likely to find when it comes to image analysis. What many people would accept as "just fine" Joe would reject as substandard.

And finally, it's only when you see what is actually possible, that you become critical of anything less.

Michael

[gwhitf]

The reason that I wrote my latest article, published with today's date, is that I found that meticulous technique was as big a factor as anything else in ensuring optimum image quality.

And finally, it's only when you see what is actually possible, that you become critical of anything less.

Michael

I agree. These are excellent points.

I have been working with this p45+ this week, just playing around with it before a trip next week, and you realize quickly that, if utmost detail is your goal, then forget about shooting handheld. It starts there, then you realize that not only is the tripod required, but then also raising the mirror, but then you realize that you need to let the body calm down even after raising the mirror. (It makes you wonder what else could affect things, even beyond this).

And then, there is also the flipside of every perspective. I know for me, some of the most boring photographs I've ever come across are ones where you could count every leaf on every tree, even out to infinity. You stand there, looking at the print, and you think, "Yep, the detail in that incredibly boring photograph is awesome".

So, I think it's about where you put your energy, and what's important to you. I just think it's also important to not get caught up in this resolution mess so much that the photographs become stale and clinical and unemotional -- just another endless landscape that's clinically perfect but doesn't pose any questions or stir any emotion. Sometimes, TMAX3200 in Rodinal is the way to go. Sometimes, Type55 is the way to go. I'm sure so many people on this forum are good people, but if you read this forum enough, you see enough hair-splitting that you'd think that Resolution is the key to life, when clearly, it's not, in every case. We are photographers -- not opticians, or scientists, or chip designers, or software engineers. This is one main downside to digital -- getting caught up in all this mess, and mistakenly thinking it'll make your pictures much better.

[Guy Mancuso]

Well said. BTW on the AFDIII you can set the Mirror lockup to combine with the self -timer. So mirror goes up than hit the shutter again and depending on the self -timer you set like 3 seconds than it will fire. I use this all the time with nice results

[David Klepacki]

First, I will agree that Live View shooting offers the most precise focusing ability.  I use it all the time, and so there is no argument here.  It just cannot compensate for the out of tolerance issues affecting the flatness of field throughout the focusing range of the lens.

While these lens issues that Joe raises may not affect everybody to the same degree, I  believe this is a real and serious issue. Joe is not addressing those people who shoot mostly hand-held or who are not interested in the highest resolution image quality.  Indeed, his findings are pertinent to the people who do seek the highest possible resolution image quality.  I would think this includes the type of person who would invest in the highest end digital backs like the P65+ and such.  If the highest resolution were not so important, at least to some people, why would such a market even exist?

Off course technique is important.  Joe is a scientist, and I don't think technique was a problem for him.

[Jack Flesher]

Michael,

Glad to see you finally saw the light with the Arca Cube. Makes life easy, doesn't it?  

,