ALPA and depth of field

[ChristianRandwijk]

Hey everyone, my first post here in this forum. I am very fond of architecture and landscape photography. And the coming year might even see me getting a couple of assignments that pay although I have an altogether different career as my dayjob. I have been looking long and hard at the beautiful ALPA cameras, and fondlede them a bit at a local store. This would be my first foray into digital MF, and I have some concerns about depth of field and diffraction. How far down do you ALPA users feel comfortable stopping down, and does this yield enough depth of field for landscape photography? I have been looking hard at the Cambo RS as well, especially since they make lensmounts, for some lenses, that tilt/swing. Apparently tilt isn't possible with shorter lenses than 80mm in the ALPA system, but I might be wrong.

[ErikKaffehr]

Hi,

With good lenses stopping down past f/8 will loose some resolution. The better the lens the less can you stop down. On the other hand, diffraction is benign to sharpening.

If you need to stop down, f/16 is quite OK. You are loosing significant sharpness. Past that you start to loose a lot.

This page shows the effects of diffraction and defocus. Left column correctly focused, the other columns are defocused 3, 6 and 9 cm at 3 meters with a 100/2.8 macro lens.

The test was done with an APS-C DSLR, but the same laws of physics apply to any lens and to any sensor format.

Best regards
Erik

Hey everyone, my first post here in this forum. I am very fond of architecture and landscape photography. And the coming year might even see me getting a couple of assignments that pay although I have an altogether different career as my dayjob. I have been looking long and hard at the beautiful ALPA cameras, and fondlede them a bit at a local store. This would be my first foray into digital MF, and I have some concerns about depth of field and diffraction. How far down do you ALPA users feel comfortable stopping down, and does this yield enough depth of field for landscape photography? I have been looking hard at the Cambo RS as well, especially since they make lensmounts, for some lenses, that tilt/swing. Apparently tilt isn't possible with shorter lenses than 80mm in the ALPA system, but I might be wrong.

[theguywitha645d]

The effects of diffraction and the lack of DoF is overemphasized in MFD photography. Most of this comes from viewing at 100% which matches no real-world viewing distance of an image. I constantly read you cannot shoot at f/16 and so I made an image at f/22 and printed it on 36" roll paper. It is in my living room and it is a beautiful image. Yes, you can compare two images at f/11 and f/16 and see the difference in diffraction at 100%, but are your final viewers going to be looking at comparison shoots on a monitor at 100%? I don't know many members of the public who are pixel peepers and judge images solely on technical considerations.

[ErikKaffehr]

Hi,

Quite true, but resolution is one of the primary reason for going to MFDB and definitively the reason for buying high end MF lenses like HR Digitars. Why spend a lot of money on optical excellence if it's thrown away by stopping down?!

The other advantages with MF are also available with lesser lenses and backs.

Best regards
Erik

The effects of diffraction and the lack of DoF is overemphasized in MFD photography. Most of this comes from viewing at 100% which matches no real-world viewing distance of an image. I constantly read you cannot shoot at f/16 and so I made an image at f/22 and printed it on 36" roll paper. It is in my living room and it is a beautiful image. Yes, you can compare two images at f/11 and f/16 and see the difference in diffraction at 100%, but are your final viewers going to be looking at comparison shoots on a monitor at 100%? I don't know many members of the public who are pixel peepers and judge images solely on technical considerations.

[theguywitha645d]

Hi,

Quite true, but resolution is one of the primary reason for going to MFDB and definitively the reason for buying high end MF lenses like HR Digitars. Why spend a lot of money on optical excellence if it's thrown away by stopping down?!

It is a matter of balance. What is the point of minimizing diffraction when you don't have enough DoF for the object? A photograph is more than a technical study in resolving power. Also, the great optics will continue to work better at small apertures than bad optics and so you are really not throwing anything away. And MF sensors sizes and pixel resolutions are really forgiving--just because you see pixel level changes, does not mean it is significant for the image as a whole.

Personally, I went to MFD for the sensor size, not the pixel density. When I put prints from my 22MP Phase images next to my 40MP Pentax images, the extra pixels of the Pentax is really not adding a great deal. The magic of MFD goes beyond the number of pixels. And when you think diffraction at f/16 is not a problem in the 22MP Phase, just because you can see it in the 40MP Pentax at 100%, it does not make any difference when it gets printed--the human eye can only resolve so much. This is really a relative problem related to format rather than an absolute one measured in pixels.

Now, I am like every one that shoots MFD, I love viewing the files at 100% to see the fine details--just look at the hairs on those flies! But in practical terms, the detail is not going to be seen under normal viewing conditions. That does not mean I don't think over sampling is meaningless. Things are smoother. Details have a nice crispness to them. There are real benefits. But this fixation of diffraction and a compulsion to squeeze out every piece of resolution at the focus planes so it can be viewed at 100% on my monitor at the expense of the content of the photograph is something I don't understand.

[Doug Peterson]

If you wanted the sexiness of an Alpa but with the functionality of the RS tilt-swing for wider lenses I personally think (highly biased - see signature) the Cambo RS AE is very sexy while still being very functional.

For anyone on the forum to provide you guidance on diffraction you have to tell us what digital back you have as the resolution and pixel size of the back are a huge factor in which aperture will be noticeably soft but recoverable with proper sharpening and which aperture will result in major loss of sharpness.

Also it would be helpful to know what focal lengths you find you use most often with your current system, as focal length also plays a big role here. If you're an ultra-wide lens kinda guy then DOF will not be a challenge even with the highest resolution backs. If you like semi-wides the story will be a bit different. Compositional tendencies also matter a LOT (do you compose more sweeping landscapes lacking foreground or do you like to often feature foreground elements). Links to your current body of work are a great way to start to answer these questions.

Disclaimer: my company (Capture Integration) has opted to sell Cambo (and Arca) but not Alpa. So we must be considered biased.

Doug Peterson (e-mail Me)
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[ChristianRandwijk]

Thanks for the good replies so far. Well, my current equipment is a 5D2 with an assortment of nice lenses. I had been looking at getting the 24mm TS-E for the Canon. But the expense of eventually getting the three tilt-shift lenses for the Canon put me close to MF territory, as far as a body and lens goes (depending on the make ofcourse). I could start off renting a Digital back. That got me thinking. Also, I've played around a bit with an old 4x5 camera, and really like the slow, contemplative workflow (although I found focusing somewhat of a challenge, but then, challenges aren't a bad thing). The cost of buying, developing and scanning 4x5 slides here in Denmark is ridiculously high, so in the long run a digital investment makes more sense.
As for shooting style, I'm not really an ultrawide person, I like 28mm (on 5D) better than 24mm, but a hypothetical 26mm would probably be my perfect wide lens. I really like the look of dramatic landscapes with foreground interest and a nice sweep towards the horizon; I am a very big fan of Joe Cornish.
The reason for looking at ALPA first is, well, sexiness, but also, I don't think anyone in Denmark is stocking the Cambo, so I have had no possibility of "seeing" it, with my hands. I don't think I'm a brand snob, so if Cambo would be the most sensible solution, price-wise, then I'd go with that. But, I think, no possibility of trying it out in Denmark, nor the Arca Swiss or Sinar technical cameras.
As for diffraction, DOF a.s.o., I'm not so worried about how it looks at 100% on my computer, prints are the thing. But, MF digital is a huge investment, so I just want to make sure I use my money wisely. I think the newer digital lenses are optimised for shooting at around f/8 (I might be mistaken), which wouldn't yield that much DOF on a 35mm or a 43/47mm lens. Hence the wish for being able to use tilt to increase DOF.

[ErikKaffehr]

Hi!

This is from a comparison done with P45 back on a Hasselblad in the "Great 2006 MFDB shootout" by Michael Reichmann, Bill Atkinson and Charlie Cramer.

Left one is f/8 and right one is f/16, you may need to click a few times to see full size image.

Updated: I made prints from these two images in large size (I don't recall the size but probably around 30x40"). The difference between f/8 and f/22 was definitively obvious at 1-2 meter viewing distance. A photograph of a one dollar bill taken with my Sony Alpha 900 at f/8 is essentially on par with the f/22 image on the H1/P45 combo. So the difference really matters in print. But I used same sharpening for both f/8 and f/22.

Best regards
Erik

Thanks for the good replies so far. Well, my current equipment is a 5D2 with an assortment of nice lenses. I had been looking at getting the 24mm TS-E for the Canon. But the expense of eventually getting the three tilt-shift lenses for the Canon put me close to MF territory, as far as a body and lens goes (depending on the make ofcourse). I could start off renting a Digital back. That got me thinking. Also, I've played around a bit with an old 4x5 camera, and really like the slow, contemplative workflow (although I found focusing somewhat of a challenge, but then, challenges aren't a bad thing). The cost of buying, developing and scanning 4x5 slides here in Denmark is ridiculously high, so in the long run a digital investment makes more sense.
As for shooting style, I'm not really an ultrawide person, I like 28mm (on 5D) better than 24mm, but a hypothetical 26mm would probably be my perfect wide lens. I really like the look of dramatic landscapes with foreground interest and a nice sweep towards the horizon; I am a very big fan of Joe Cornish.
The reason for looking at ALPA first is, well, sexiness, but also, I don't think anyone in Denmark is stocking the Cambo, so I have had no possibility of "seeing" it, with my hands. I don't think I'm a brand snob, so if Cambo would be the most sensible solution, price-wise, then I'd go with that. But, I think, no possibility of trying it out in Denmark, nor the Arca Swiss or Sinar technical cameras.
As for diffraction, DOF a.s.o., I'm not so worried about how it looks at 100% on my computer, prints are the thing. But, MF digital is a huge investment, so I just want to make sure I use my money wisely. I think the newer digital lenses are optimised for shooting at around f/8 (I might be mistaken), which wouldn't yield that much DOF on a 35mm or a 43/47mm lens. Hence the wish for being able to use tilt to increase DOF.

[dchew]

Christian,
If you find a good local dealer the option of renting can be surprisingly viable.  I rented a back from my dealer at great rates because I wanted the back over the weekend, which is when they usually sit idle.  Then as long as no one was in the que for the back I could keep it for extended periods.

My experience with DoF is that both sides of the argument are valid.  At 100% you will see a difference on the screen between f/8 and f/16.  In a print, even a big print, you will struggle to see the difference, and anyone else will not notice unless they are prompted and trained to look for it.  My rule of thumb when in the field is to not worry about diffraction on a ~54x40 sensor up to f/16.  If I need more DoF I will either focus blend or make a "what's most important" focus choice.  That may vary if I know ahead of time what the image will be used for. 

I believe people tend to underestimate the advantage of a larger sensor area when printing.  When we used film no one argued about the benefits of MF over 35mm when printing larger, even though the film was exactly the same emulsion.  Point being when you print a MF file diffraction issues are not magnified as much on the print, which gives you more leeway than the 100% screen view might make you think.

Dave

[theguywitha645d]

But, MF digital is a huge investment, so I just want to make sure I use my money wisely. I think the newer digital lenses are optimised for shooting at around f/8 (I might be mistaken), which wouldn't yield that much DOF on a 35mm or a 43/47mm lens. Hence the wish for being able to use tilt to increase DOF.

I would say the new digital lenses are more optimized for resolving power rather than contrast. Lenses, film or digital, historically have always worked better at f/8 if you are using a simple technical scale. Digital lenses may also show some more improvement wide open, especially view camera lenses like the ones used on the Alpa. As far as small apertures, nothing has really changed. As far as my shooting experience goes, the added DoF field easily trumps any increase in diffraction. But this is also a digital world and you can use focus-stacking software like Helicon focus to shoot multiply images of a scene at different distances and combine them for a sharp image. The technology is not without its downsides as artifacts can be introduced--as you focus, you change image size and edge artifacts can be seen, not always and some are easily fixed in Photoshop, but that is also more work for you.

When I was researching MFD, I kept reading how difficult is was and such. Now, I have used many formats over my career from 35mm to 8x10, so when I finally got my first MFD, a P25+ on a Linhof M679, I really did not find it hard at all. Except for remembering to wake up the back, some bugs with tethering, and shooting LCC to correct color casts introduced by the optics, there was nothing really unique about the shooting process. I think if you are a skilled photographer, you will be fine with the systems. Of course when I started with these larger files, suddenly I also had to address storage and computer power. My Pentax is as easy to use as any DSLR.

As a business decision, that is something only you can answer. There will be an increase in quality that you will see, it may not be significant for your clients. Could shooting MFD be a selling point to get more clients and move your career along, possibly. You could also start by renting the equipment for a few shoots to see how it works and how your clients react--you bill the rental costs to them as well.

[theguywitha645d]

Double posting. What Dave said.

[Doug Peterson]

The reason for looking at ALPA first is, well, sexiness, but also, I don't think anyone in Denmark is stocking the Cambo, so I have had no possibility of "seeing" it, with my hands. I don't think I'm a brand snob, so if Cambo would be the most sensible solution, price-wise, then I'd go with that. But, I think, no possibility of trying it out in Denmark, nor the Arca Swiss or Sinar technical cameras.

If seeing it is the only obstacle I'm sure many dealers (I can only directly speak for us) would be happy to do a video chat conference with you with the gear. And if you want to get your hands on one a paid rental which is counted towards your purchase (if you do purchase) is a great option.

[siebel]

As an ALPA user and an architectural/industrial shooter I would suggest to you that the whole DOF discussion online has been hijacked by "measurers" (I call them something else, but I can't use that word here). Technically, diffraction becomes more of an issue as pixels get smaller. Hence, in theory, the all singing, all dancing IQ180 and Aptus12 backs (I own both of these backs), with a pixel pitch of 5.2 microns are the worst performers in this regard. This is correct in both theory and in fact. Yet somehow, they are producing the best quality files I've ever shot.
Modern digital lenses are optimised for the larger apertures. As an example, my 23HRS is at its best between f5.6-f8. My 35XL is best around f8. However, these lenses are so ridiculously sharp to start with, that it takes the most ardent pixel peeper to spot any observable image degradation even at f16. Keep in mind that at f16 I have more DOF than I know what to do with and prints look pin sharp even at sizes over 1.5m. If someone is evaluating my work based on absolute resolution, then I've clearly not done my job, which is to create engaging memorable images. It's about the images, not the sharpness of that line on the edge of the frame.
I think it is important that you get your head around the subject of DOF and diffraction, but in the final washup, it's a minor issue when you are dealing with this level of gear.
What IS important, is that cameras like the Alpa are rigid and precise as depth of focus (as opposed to depth of field) is miniscule with wide lenses. This is why Alpa go to the trouble of shimming mounting adapters. This simple step contributes more to image quality than any amount of worrying about DOF.
My Alpa STC and the lenses from Rodenstock and Schneider that mount on it are purely and simply the most precise, finest quality photographic devices I have ever had the pleasure of working with. The sheer simplicity of the camera makes it a joy to work with.

Cheers

[BJL]

The good news, sort of, is that the trade-offs between DOF (judged at a certain print size and viewing distance, so it gets a bit harder when your aim is high res. images for "printing large and viewing close") do not depend much if at all on the camera or format. So if the combination of detail/resolution and FOV and subject distances and DOF you want is optically possible, then the gear you use can achieve that so long as it can give the FOV and resolution you need.

[Graham Welland]

DoF with medium format digital is certainly different to what you may become used to when shooting with either film or 35mm digital. However, I agree with the other posts here in that it's not as big of an issue in reality as some people would have you believe. In particular, the current trend amongst folks shooting with technical cameras is to believe that the sky is falling if they don't have tilt and scheimpflug ... don't believe a word of it! I don't see the whole fraternity of MF DSLR shooters dumping their gear because of this and, as Bryan Siebel notes, neither he nor his clients have any issues with the quality of his work due to the perceived DoF problem.

As mentioned, the secret is understanding what's important in your images and ensuring that's where you hold critical focus. I find that there's a tremondous difference between pixel peeping sharpness throughout an image and what's usable in print. When I do want to achieve maximum DoF I find that following basic rules about finding the critical focus point & f-stop for your lens/sensor combination goes a long way to making shooting easier. You might find the following useful as a reference, particularly as they apply to the Alpa or any other technical camera:

http://optechsdigital.com/Alpa_and_Hyperfocal.html
http://blog.phaseone.com/2011/03/31/achieve-sharp-images-with-wide-angle-lenses

When all else fails, i'll certainly stop down to f/16 or so or I'll shoot a focus bracket stack at optimal aperture of f/8 or f/11.3 depending upon the lens and combine them either using Helicon Focus or Photoshop. I can do that MUCH faster than I can achieve selecting critical DoF with tilt/swing using even my IQ back and "live view". In most situations a stack of two, three or four images can handle toes to infinity with any wide angles 47mm and below) or even my 90/150mm depending upon the scene.

This is four images stacked with a STC 47 XL APO Digitar on P40+:
http://www.grahamwelland.com/DVSaltCrystals/index.htm

Or a two image stack that tilts wouldn't help with STC/IQ160/35 XL APO Digitar (as-is default C1 Pro sharpening only btw):
http://www.grahamwelland.com/Japanese-Maple-Alpa/index.htm

Now I'm not saying that tilts aren't that important overall (heck I'm testing the Alpa T/S adapter that i have on loan at the moment myself plus I do shoot with a Hartblei 45 super-rotator on my DF too), but even with an IQ back with live view it's not easy to do compared to T/S lenses on a 35mm DSLR with EXCELLENT live view (I used to use Nikon 24/45/85 PC-Es with my D3x), and particularly compared to shooting with a 4x5 on a decent ground glass & loupe. Anyone who can do it using a ground glass with an Alpa, Cambo, Arca, Linhof technical vs LF etc has my respect and admiration because I could hardly even focus mine with a 4x loupe, least of all consider trying to do tilts.

Note to Alpa: you really do need to have a wide angle T/S offering soon because I know from dealers and folks that have swapped systems that it's hurting ...

[Graham Welland]

My experience with DoF is that both sides of the argument are valid.  At 100% you will see a difference on the screen between f/8 and f/16.  In a print, even a big print, you will struggle to see the difference, and anyone else will not notice unless they are prompted and trained to look for it.  My rule of thumb when in the field is to not worry about diffraction on a ~54x40 sensor up to f/16.  If I need more DoF I will either focus blend or make a "what's most important" focus choice.  That may vary if I know ahead of time what the image will be used for. 

I believe people tend to underestimate the advantage of a larger sensor area when printing.  When we used film no one argued about the benefits of MF over 35mm when printing larger, even though the film was exactly the same emulsion.  Point being when you print a MF file diffraction issues are not magnified as much on the print, which gives you more leeway than the 100% screen view might make you think.

Dave

+1 for what Dave articulately said!

[TH_Alpa]

So well said Bryan,

The ultimate precision is required for DBs like the IQ 180 and the Leaf 12, especially when it comes to "depth of focus". Slowly but surely it is recognized that shimming the back makes a difference, and it does. Working with such high-resolution (and small pixels) devices and high-resolution lenses (HRs) is not forgiving.

Thierry

As an ALPA user and an architectural/industrial shooter I would suggest to you that the whole DOF discussion online has been hijacked by "measurers" ... ... Keep in mind that at f16 I have more DOF than I know what to do with and prints look pin sharp even at sizes over 1.5m. If someone is evaluating my work based on absolute resolution, then I've clearly not done my job, which is to create engaging memorable images. It's about the images, not the sharpness of that line on the edge of the frame.
I think it is important that you get your head around the subject of DOF and diffraction, but in the final washup, it's a minor issue when you are dealing with this level of gear.
What IS important, is that cameras like the Alpa are rigid and precise as depth of focus (as opposed to depth of field) is miniscule with wide lenses. This is why Alpa go to the trouble of shimming mounting adapters. This simple step contributes more to image quality than any amount of worrying about DOF.
My Alpa STC and the lenses from Rodenstock and Schneider that mount on it are purely and simply the most precise, finest quality photographic devices I have ever had the pleasure of working with. The sheer simplicity of the camera makes it a joy to work with.

[TH_Alpa]

DoF with medium format digital is certainly different to what you may become used to when shooting with either film or 35mm digital. However, I agree with the other posts here in that it's not as big of an issue in reality as some people would have you believe. In particular, the current trend amongst folks shooting with technical cameras is to believe that the sky is falling if they don't have tilt and scheimpflug ... don't believe a word of it! I don't see the whole fraternity of MF DSLR shooters dumping their gear because of this and, as Bryan Siebel notes, neither he nor his clients have any issues with the quality of his work due to the perceived DoF problem.

I can only agree with this.

As mentioned, the secret is understanding what's important in your images and ensuring that's where you hold critical focus. I find that there's a tremondous difference between pixel peeping sharpness throughout an image and what's usable in print. When I do want to achieve maximum DoF I find that following basic rules about finding the critical focus point & f-stop for your lens/sensor combination goes a long way to making shooting easier. You might find the following useful as a reference, particularly as they apply to the Alpa or any other technical camera:

http://optechsdigital.com/Alpa_and_Hyperfocal.html
http://blog.phaseone.com/2011/03/31/achieve-sharp-images-with-wide-angle-lenses

Yes, that's of extreme importance, to understand and to use the hyperfocal of the lens. It is such simple, self-explaining and fast to use, while absolutely precise and reliable, that not using hyperfocal focusing is a mistake.

When all else fails, i'll certainly stop down to f/16 or so or I'll shoot a focus bracket stack at optimal aperture of f/8 or f/11.3 depending upon the lens and combine them either using Helicon Focus or Photoshop. I can do that MUCH faster than I can achieve selecting critical DoF with tilt/swing using even my IQ back and "live view". In most situations a stack of two, three or four images can handle toes to infinity with any wide angles 47mm and below) or even my 90/150mm depending upon the scene.

This is four images stacked with a STC 47 XL APO Digitar on P40+:
http://www.grahamwelland.com/DVSaltCrystals/index.htm

Or a two image stack that tilts wouldn't help with STC/IQ160/35 XL APO Digitar (as-is default C1 Pro sharpening only btw):
http://www.grahamwelland.com/Japanese-Maple-Alpa/index.htm

Wonderful image samples showing the possibilities of focus stacking and the "Helicon Focus", especially the maple tree where tilt and/or swing won't bring anything.

Note to Alpa: you really do need to have a wide angle T/S offering soon because I know from dealers and folks that have swapped systems that it's hurting ...

Well heard and understood, see my announcement about this new T/S possibilities with short focal lenses on any Alpa 12 camera system, here:

New Alpa Tilt Capacity with Wide Lenses

Thierry

[TH_Alpa]

+1 for what Dave articulately said!

+1

Thierry

[theguywitha645d]

And as we are talking about the overemphasis on certain technical matters, Apla does have a long history of overemphasizing precision in their marketing--hey, it helps sell cameras and more power to them. Personally, their marketing turns me off. Alpas are fine cameras and I would certainly recommend them. But the physics of photography is really not that hard to figure out. Shimming has really become overemphasized.

And one small note, depth of focus is a product of the f-number, not the focal length. If you have to shim your wides, you need to shim your normals and telephotos if you are using them at the same apertures. If shimming is required at all. And this always confused me, since you shim the back, what happens when the tolerances in the lens mount requires different shims? And how does all of this work with temperature changes? Personally, Alpas are great cameras and I would not worry about the shim thing.