The GetDPI Photography Forum

Great to see you here. Join our insightful photographic forum today and start tapping into a huge wealth of photographic knowledge. Completing our simple registration process will allow you to gain access to exclusive content, add your own topics and posts, share your work and connect with other members through your own private inbox! And don’t forget to say hi!

Diffraction vs DOF for MF wide angle lenses

GrahamWelland

Subscriber & Workshop Member
Well, neither the P25+ nor IQ files fall apart in photoshop at either 22mp or 80mp. If anything it's the colour that is a concern in PS as you pull the files apart. 14bit colour trounces 12bit or less. Resolution, even in big prints, tends to be less of a "real" issue by the time the printer and printer driver have had their way.

I know that you chose to skip my second paragraph but I did relate to the output size which has a direct correlation to perceived DoF & ultimately sharpness perception (influenced also by how close you are too).
 

torger

Active member
Jack & Bob..Thanks very much.
Does it mean that the only ways I can achieve DOF from few feet to infinity for the IQ 180 with insignificant diffraction are T/S (probably from a Tech Camera) and focus stacking?

Tim Fitzharris, an award winning nature & landscape photographer, published a lovely book "National Audubon Society Guide to Landscape Photography" in 2007. He used Mamiya with non-digital (even manual ones) Mamiya lenses and Phase One P25 throughout his book with f/16 and f/22. His pictures looked fantastic. He also claimed they looked great on his big prints.
His approach was quite different from more recent comments concerning diffraction. Does a smaller MP DB (P25) make difference?
I got myself a tech camera and use tilt in I would guess 50% of my images. Tilt often provides you with better options, but it depends a lot on your style. If you have high stuff close (tight forest scenes etc) tilt don't help much, but if you often do open scenery tilt helps a lot. Personally I think focus stacking is a mess, there's always some artifact in there, and I prefer to make one shot images. I go f/32 + some pieces out of focus before I consider focus stacking, but that's my personal decision.

But as discussed above having the sharpest possible picture is not that important for smaller sizes and relaxed viewing conditions, and even if viewing conditions are such that one can see that the image is not tack sharp few cares. Image content is all that matters.

Still as a photographer one may like to make sharp pictures and because one appreciates it oneself. If it weren't for that (and other subtle quality aspects) I think digital medium format would be dead by now.

Concerning tilt vs not having tilt some have a shooting style where you focus at a main subject and you consider that other parts in the picture is a bit less sharp is an advantage, give it a subtle depth. Therefore some landscape shooters can have an IQ180 and never use tilt. Using tilt and shift is for me an integrated part of my photographic process, I simply enjoy using it and it do give me subtle image quality properties I like, but the main reason I use them is simply because I enjoy making pictures "view camera style", it's fun.

There's an interesting aspect about diffraction, which is that it is not a hard limit. This means that if you shoot f/22 with a 80 megapixel back you get slightly more total resolution than f/22 with a 20 megapixel back, but the more diffraction there is diminishing returns. I recently saw an interesting print comparison test, and then a 36 megapixel D800 f/22 carefully deconvolution sharpened and contrast corrected produced as good print result as a 20 megapixel camera at f/8 (also sharpened)! Extremely low noise levels (as the D800 has) improves the possibility to deconvolve as that type of sharpening increases noise.

P25 is only 22 megapixels, the pixels are huge, 9 um. This means that on a pixelpeep level you get less affected of small apertures, so f/16 and even f/22 does look quite sharp at 100% on screen. But as stated above, f/22 on an 80 megapixel IQ180 + sharpening would still make an even sharper print, although it would look fuzzier at the pixelpeep level.

People were happy with 22 megapixels back then, and from an artistic standpoint it is of course enough. But if we have paid tens of thousands of dollars to get an IQ180 rather than a second hand P25 for a couple of grands we surely want to make as sharp images as that IQ180 can do, even if most of our audience would not notice or care.
 

Landscapelover

Senior Subscriber Member
"Tightie-Whities" are slang for men's white underwear briefs ... "in a bunch" or "twisted" refers to uncomfortable and irritating ...making the wearer "cranky" ... which in turn means ill-tempered.

Somehow when you have to explain it, it loses a lot :ROTFL:

-Marc
Thanks for saving me times to look in online dictionary :)
I really appreciate the comments (not only the "Tightie-Whities"). It's hard to get this information anywhere except GetDPI and LUL.
 

Bob

Administrator
Staff member
Jack & Bob..Thanks very much.
Does it mean that the only ways I can achieve DOF from few feet to infinity for the IQ 180 with insignificant diffraction are T/S (probably from a Tech Camera) and focus stacking?

Tim Fitzharris, an award winning nature & landscape photographer, published a lovely book "National Audubon Society Guide to Landscape Photography" in 2007. He used Mamiya with non-digital (even manual ones) Mamiya lenses and Phase One P25 throughout his book with f/16 and f/22. His pictures looked fantastic. He also claimed they looked great on his big prints.
His approach was quite different from more recent comments concerning diffraction. Does a smaller MP DB (P25) make difference?

Pramote
Yes it does, it is all about how much the imager needs to be magnified.

If you print a full 6x4.5 film frame and focus your 55 at 20 feet and f/11 it may appear to have a dof from 10 feet to infinity for an average viewer looking at the print from a distance equal to the diagonal, but it will not look that way if you zoom way in. If you were to be shooting film this is what the calculations would say. Frankly digital is no different, except that we love to pixel peep. Only a few of us nuts would judge film sharpness by looking at it through a microscope and then you would be hard pressed to find any :ROTFL:
If you were to print that same file in a book for example, it would look fine assuming sharpening usual for the printing process.
That is pretty much reality, but for me, as a microscope user, I would use tilts:D
 

dchew

Well-known member
Does a smaller MP DB (P25) make difference?

Pramote
My opinion is different on this question. I know there is a CoC vs. pixel size calculation, but that is relevant to 100% screen pixel peeping, not printing. In my head the lower magnification of prints created with larger sensors and higher MP neutralizes all this.

It's like the common question about diffraction limitations when comparing lenses. A sharper f/4 lens will say the best aperture is f/8, compared to a less-sharp f/5.6 lens that says the best aperture is f/11. So does that mean if I want to shoot at f/11 I would be better off with the f/5.6 lens? Of course not! At f/11 the f/4 lens will still be equal or better than the other lens. It just won't be as sharp as itself at f/8.

There is more depth of field in smaller formats at a given f-stop on screen. But once I print a Micro 4/3 image at the same print size as an IQ180 printed image, the DoF becomes exactly the same (assuming equal subject distance and aperture). Even if it is just an 8x10 inch print. I always thought the core reason MF is still acceptable at higher apertures like f/11 - f/22 vs. the 35mm format is simply because the image magnification is lower.

In other words, at higher aperture you may not gain anything by having a larger format or more MP, but you would be hard pressed to find a situation where you would lose something in a print.

Dave
 
Top