Luminous Landscape Forum

Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: bradleygibson on September 15, 2009, 01:58:43 pm

Title: Leica S lens image circles
Post by: bradleygibson on September 15, 2009, 01:58:43 pm
It struck me as curious that the Leica's new S system considers the 70mm lens the normal lens, when the S2's sensor has a 58mm diagonal.

Does anyone know if the S lenses actually have a 70mm image circle, perhaps sufficient to cover 645 (56x42mm) (or since Leica likes 3:2, 58x28mm or 56x37mm, if sensor manufacture is limited to 645 sizes)

Even looking at the MTF graphs Leica published it seems they're easily able to substitue a new value on the X-axis, the way they're written...

Overactive imagination?  Or has Leica left themselves some room for expansion for later generations of the S family?
Title: Leica S lens image circles
Post by: BJL on September 15, 2009, 02:11:29 pm
Quote from: bradleygibson
It struck me as curious that the Leica's new S system considers the 70mm lens the normal lens, when the S2's sensor has a 58mm diagonal.
In 24x36mm format (35mm), the image diagonal is about 43mm, and 50mm is considered a "normal lens". It is rare that the normal lens for a system actually equals the frame diagonal; usually it is longer. For example, 645 (56x42mm) has a 70mm diagonal, but "normal" lenses are often 75mm or 80mm.

Still, 70mm for 30x45mm format is the "narrowest" normal I know of, matching 58mm in 24x36mm format.

Quote from: bradleygibson
... has Leica left themselves some room for expansion for later generations of the S family?
I doubt it: Kodak could easily provide a somewhat larger sensor right now (it makes a 49x37 with the sme 6 micron pixels), and price is no barrier for the Leica S2 it seems, so why would Leica cripple its first model by imposing a "crop" on the new lens system? The S2 needs to succeed in winning over some MF users from alternative like 44x33mm and 48x36mm at similar or lower prices, so I doubt that Leica has the luxury of hobbling the S2 in order to sell a larger sensor upgrade in the next model.
Title: Leica S lens image circles
Post by: EricWHiss on September 15, 2009, 05:10:28 pm
Quote from: bradleygibson
It struck me as curious that the Leica's new S system considers the 70mm lens the normal lens, when the S2's sensor has a 58mm diagonal.

Does anyone know if the S lenses actually have a 70mm image circle, perhaps sufficient to cover 645 (56x42mm) (or since Leica likes 3:2, 58x28mm or 56x37mm, if sensor manufacture is limited to 645 sizes)

Even looking at the MTF graphs Leica published it seems they're easily able to substitue a new value on the X-axis, the way they're written...

Overactive imagination?  Or has Leica left themselves some room for expansion for later generations of the S family?

Hi Brad,
Last year around the announcement of the S2,  I did read something to the effect that the camera system was designed with potential upgrades in the future. Of course this could mean two possible things - higher pixel count or larger footprint.  Both cases  would  probably mean an entirely new camera body as Leica did with the M8 to M9.  
Eric
Title: Leica S lens image circles
Post by: michael on September 15, 2009, 05:21:59 pm
It's in the video interview with lens designer Peter Karbe that i just posted.

Michael
Title: Leica S lens image circles
Post by: ErikKaffehr on September 15, 2009, 05:30:37 pm
Hi!

While your are waiting for that video, you may check this: http://www.imx.nl/photo/leica/leica/page154/page154.html (http://www.imx.nl/photo/leica/leica/page154/page154.html)

Sorry! Its up already, no sleep tonight!

Great video, BTW!

Best regards
Erik


Quote from: michael
It's in the video interview with lens designer Peter Karbe that i just posted.

Michael
Title: Leica S lens image circles
Post by: jackmacd on September 15, 2009, 11:50:23 pm
Michael,
Of all your wonderful videos from Leica, the video of Karbe was most welcome.
I felt that I was in the room with you and Peter, and the information was most encouraging to someone who has this system on order, praying that I am making a smart decision. Put out a video on how to best use this system for landscapes and I will be a buyer. But of course, you need to amortize you video costs across hundreds of buyers, and I'm not sure such a video will be as smart a business move for you as a workshop would be. This will be my first move to DMF so I do not have your challenge of worrying about your legacy lens commitments that you have.  Good to hear these lenses will work well for the S3 and S4. This from a former Pentax 6x7 shooter, so you can see the appeal to me of the S2 form.
Thanks,
Jack
Title: Leica S lens image circles
Post by: bradleygibson on September 16, 2009, 01:32:30 am
Quote from: michael
It's in the video interview with lens designer Peter Karbe that i just posted.

Michael

Unfortunately the iPhone (my only computing device at the moment) is Flash impaired, and even still, I might not get a chance to listen to Peter until the weekend.  But I'll definitely be listening to the whole thing.

If you or anyone can post the short version
of the answer here, I'd appreciate it.

Thanks, (and especially for the interview, Michael--this is great stuff!)
Title: Leica S lens image circles
Post by: tho_mas on September 16, 2009, 09:35:14 am
Quote from: bradleygibson
If you or anyone can post the short version
of the answer here, I'd appreciate it.
in short: the S2 lenses are designed for the sensor size of the S2. But, according to P. Karbe, they outresolve the current pixel pitch so they are designed for future sensors as well (sensors with same size, but smaller pixel pitch).
Title: Leica S lens image circles
Post by: Christopher on September 16, 2009, 10:12:52 am
Quote from: tho_mas
in short: the S2 lenses are designed for the sensor size of the S2. But, according to P. Karbe, they outresolve the current pixel pitch so they are designed for future sensors as well (sensors with same size, but smaller pixel pitch).

If true wrong move. I find it hard to believe that Leica really was dump enough to just design the S2 lenses for their current camera. But hey it's Leica.
Title: Leica S lens image circles
Post by: tho_mas on September 16, 2009, 10:26:13 am
Quote from: Christopher
If true
watch the video at TC 04'20''
Title: Leica S lens image circles
Post by: pcunite on September 16, 2009, 11:04:01 am
Quote from: Christopher
If true wrong move. I find it hard to believe that Leica really was dump enough to just design the S2 lenses for their current camera. But hey it's Leica.

I am not sure. I don't want to look back at this post 5 years from now and feel embarrassed... but 40mp outta be enough for most things. Yes being able to crop out an eye-ball and make an 8x10 print out of it is neat... but how many need to do that? More megapixels than you need means waiting for the computer to finish it's work. How large are homes these days? That dictates the size of prints. What is the largest monitor these days? I mean 30" is just huge!

I think that 40mp is the sweet spot for cropping and post processing for common sized prints and viewing. Instead of improving the number of pixels that it can create I would like to see improvements in all other areas of imaging.
Title: Leica S lens image circles
Post by: bradleygibson on September 16, 2009, 11:10:52 am
Thank you, thomas.

Like Christopher, I too had hoped for a different answer.  The cost premium for creating larger sensors will continue to diminish into the future.  I had hoped the lenses were actually designed with this in mind.  It is hardFor me to see how an S3 or S4 will compete noise and DR-wise with a 56 x 42mm Phase One P90+...  I'm a bit surprised they'd give themselves this kind of competitive disadvantage.

Well I look forward to hearing Peter in his own words soon.

Best,
Title: Leica S lens image circles
Post by: narikin on September 16, 2009, 12:02:14 pm
he clearly states "no larger" for the image circle.
and "there is no space for more" which might mean in the body, or in the image circle... I think he meant the body has no space for a bigger sensor.

a little worrying for me is the fact that he says a major consideration was the leaf shutter, which explains the not-so-impressive speed, bulk and size of these lenses.
"the size is set by the central shutter" - so even in non CS lenses, which I suspect will be by far the bigger seller, we have a lens designed around a shutter that is not present, and is consequently restricted in its max Aperture + bigger + heavier than it needs be, for maybe 10% of users?

interesting to know he rates the new generation Phase/Mamiya 80mm D lens highly too - it is an excellent lens, and resolves P65+ sensor requirements.

thanks for the interview, Michael.
Title: Leica S lens image circles
Post by: narikin on September 16, 2009, 12:20:49 pm
Quote from: xinchenc
Bigger image circle and bigger sensor need bigger mirror, then the camera body will be thicker.
Xin
good point.
I'd imagine they can squeeze 1 or 2 mm around, while keeping existing sensor-lens 'thickness', but thats it.
Title: Leica S lens image circles
Post by: bradleygibson on September 16, 2009, 12:35:09 pm
Quote from: xinchenc
Bigger image circle and bigger sensor need bigger mirror, then the camera body will be thicker.

Xin

True, until the shutter becomes electronic.
Title: Leica S lens image circles
Post by: pcunite on September 16, 2009, 01:45:50 pm
Quote from: narikin
a little worrying for me is the fact that he says a major consideration was the leaf shutter, which explains the not-so-impressive speed, bulk and size of these lenses. "the size is set by the central shutter" - so even in non CS lenses, which I suspect will be by far the bigger seller, we have a lens designed around a shutter that is not present, and is consequently restricted in its max Aperture + bigger + heavier than it needs be, for maybe 10% of users?

More than 10% of users want faster sync speeds... more like 90%. But yeah... you have the cheaper lenses that are not really cheaper for them to make most likely... mostly the same cost for both I would imagine.
Title: Leica S lens image circles
Post by: BJL on September 16, 2009, 02:21:28 pm
Quote from: tho_mas
in short: the S2 lenses are designed for the sensor size of the S2. But, according to P. Karbe, they outresolve the current pixel pitch so they are designed for future sensors as well (sensors with same size, but smaller pixel pitch).
Which is the only sane way to do it for a high end system: choose a format size for a particular system once and for all, and design everything to work optimally for that format:
- lens mount dimensions that allow just enough room for the mirror box, rather than having extra depth for the larger mirror of a future larger format, which would restrict lens designs to have rear elements further from the sensor, hampering optical design optimization (retro-focal design needed more often and more severely with wide angle lenses).
- lenses, wide to normal in particular, optimized over the needed image circle, rather than constraining designs to cover larger image circles, which for example forces wides to have a wider angular FOV that the current format requires, leading to larger lenses and/or optically worse performance within the current image circle requirement.
- lens focal lengths that provide desirable field of view choices with the chosen format. Covering a future format size increase means either focal lengths that will be a bit shorter than ideal with the future larger format, or focal lengths that are a bit too long/narrow for the current format. [Here Leica S should have an immediate advantage over alternatives like 44x33mm sensors used with 645 lenses.]

I can see some argument for Leica choosing a larger format right from the start, but the argument for starting out with the dreaded "sensor crop" imposed on the bodies and lenses is bizarre: isn't that exactly what people complained about with the M8, and the 1.5x and 1.6x crop formats used with 35mm format lens mounts and lenses? To repeat larger sensors are available right now at a cost that is reasonable relative to S2 pricing, so that argument of waiting till prices come down to upsize the sensor makes little sense in this case.


P. S. The idea that 30x45mm is too small to be successful in the long run is also a bit strange; does anyone still believe that Canon and Nikon are doomed by being so tied to the even "tinier" 24x36mm as their largest format? Does anyone still believe that sensor costs at a given size are going to come down so much in the future that all serious photographers will shift from 4/3, EF-S and DX to 35mm, from 35mm to "intermediate digital medium formats" like 30x45mm, 33x44mm and 36x48mm, and from those intermediate formats to "full medium format" of 42x56mm (645)? Maybe some people still even believe that the future belongs to an Hy6 with 56x56mm sensor!

The main tasks for Leica to establish a niche for the S system are achieving and maintaining some cost/size/weight advantage over larger formats, and an IQ advantage over smaller formats.
Title: Leica S lens image circles
Post by: Misirlou on September 16, 2009, 02:50:56 pm
Quote from: BJL
Which is the only sane way to do it for a high end system: choose a format size for a particular system once and for all, and design everything to work optimally for that format:
- lens mount dimensions that allow just enough room for the mirror box, rather than having extra depth for the larger mirror of a future larger format, which would restrict lens designs to have rear elements further from the sensor, hampering optical design optimization (retro-focal design needed more often and more severely with wide angle lenses).
- lenses, wide to normal in particular, optimized over the needed image circle, rather than constraining designs to cover larger image circles, which for example forces wides to have a wider angular FOV that the current format requires, leading to larger lenses and/or optically worse performance within the current image circle requirement.
- lens focal lengths that provide desirable field of view choices with the chosen format. Covering a future format size increase means either focal lengths that will be a bit shorter than ideal with the future larger format, or focal lengths that are a bit too long/narrow for the current format. [Here Leica S should have an immediate advantage over alternatives like 44x33mm sensors used with 645 lenses.]

I can see some argument for Leica choosing a larger format right from the start, but the argument for starting out with the dreaded "sensor crop" imposed on the bodies and lenses is bizarre: isn't that exactly what people complained about with the M8, and the 1.5x and 1.6x crop formats used with 35mm format lens mounts and lenses? To repeat larger sensors are available right now at a cost that is reasonable relative to S2 pricing, so that argument of waiting till prices come down to upsize the sensor makes little sense in this case.


P. S. The idea that 30x45mm is too small to be successful in the long run is also a bit strange; does anyone still believe that Canon and Nikon are doomed by being so tied to the even "tinier" 24x36mm as their largest format? Does anyone still believe that sensor costs at a given size are going to come down so much in the future that all serious photographers will shift from 4/3, EF-S and DX to 35mm, from 35mm to "intermediate digital medium formats" like 30x45mm, 33x44mm and 36x48mm, and from those intermediate formats to "full medium format" of 42x56mm (645)? Maybe some people still even believe that the future belongs to an Hy6 with 56x56mm sensor!

The main tasks for Leica to establish a niche for the S system are achieving and maintaining some cost/size/weight advantage over larger formats, and an IQ advantage over smaller formats.

I agree completely, but I'd still like to see an offshoot of the S2. Same image circle size, but in a square format. Square mirror, square sensor, everything.

I'd also be happy with a camera based on the standard image circle of 35mm cameras, only in a square format.

I know, I know; it's completely ridiculous and won't ever happen.
Title: Leica S lens image circles
Post by: Christopher on September 16, 2009, 08:28:27 pm
Well the downside is that we know for sure, that for S2 lenses we will always need a S2 camera or a smaller sensor camera. There will never be the chance for a full 645 to use these lenses :-(
Title: Leica S lens image circles
Post by: madmanchan on September 17, 2009, 09:55:25 am
My interpretation of Peter's comments is that the image circle size is fixed and is not subject to change. The comment regarding "room to grow" had to do with setting the optical performance bar so high in the current set of S series lenses, specifically targeting close to 80% MTF at 40 lp/mm (frankly, astounding), so that future sensors of the same total physical dimensions, but with smaller pixels (e.g., 5 microns or 4 microns, instead of 6 microns) would be able to take advantage of the lenses.
Title: Leica S lens image circles
Post by: BJL on September 17, 2009, 12:19:14 pm
Quote from: Christopher
Well the downside is that we know for sure, that for S2 lenses we will always need a S2 camera or a smaller sensor camera. There will never be the chance for a full 645 to use these lenses :-(
Yes, as I said, adopting a larger format right from the start might have been another viable option: maybe using the recent 36x54mm Dalsa sensor to stay with "Barnack shape" of 3:2! What makes no sense to me is the idea of starting out with the wrong sensor size for a brand new high quality lens system.

But with about 99.9% of digital camera sales destined to be in formats smaller than 30x45mm, it is not at all clear to me that looking to a larger format is looking in the right direction ... at least if the goal is the profitability and survival of the system, rather than just impressing forum connoisseurs.
Title: Leica S lens image circles
Post by: bradleygibson on September 17, 2009, 01:04:33 pm
Quote from: BJL
Yes, as I said, adopting a larger format right from the start might have been another viable option: maybe using the recent 36x54mm Dalsa sensor to stay with "Barnack shape" of 3:2! What makes no sense to me is the idea of starting out with the wrong sensor size for a brand new high quality lens system.

But with about 99.9% of digital camera sales destined to be in formats smaller than 30x45mm, it is not at all clear to me that looking to a larger format is looking in the right direction ... at least if the goal is the profitability and survival of the system, rather than just impressing forum connoisseurs.

Good points.

They clearly thought about this.  The performance of the lenses definitely got my attention.  Bottom line is that lesser lenses in front of of a larger, higher resolution sensor aren't necessarily going to make me happier (probably the opposite, actually)--so I am open to Leica convincing me that 45x30 is "all I'll ever need"...
Title: Leica S lens image circles
Post by: photo570 on September 18, 2009, 01:58:43 am
Can anyone, perhaps Michael, summarize the lenses that have been "mentioned".

I know that Leica won't talk about future products, like most other companies, but they have publicly mentioned several future lenses they intend to build, including a zoom. The 24mm is mentioned in the video. Any others?

Cheers,
Jason.
Title: Leica S lens image circles
Post by: georgl on September 18, 2009, 02:48:30 am
It's only important to use the given sensor-size efficiently: designing a compact body, SLR-system and lenses for this sensor-size. That's why so-called full-frame-systems are superior to crop-solutions, not necessarily because of the larger sensor itself, but because of a whole system which is designed to match this sensor-size perfectly. On the other side, you and your clients have certain requirements regarding IQ/quality in print and Leica seems to think that recent state-of-the-art 33-40MP-backs deliver enough megapixels to begin with (new sensors will achieve higher resolutions anyway) and so they asked Kodak how far they  can push the pixel-pitch today (6µm as it seems) and then calculated the necessary sensor-size.

Of course a bigger sensor has advantages regarding IQ, but the cameras/systems will always be bigger and I don't think any of these lens-designs (like the 2.5/35mm) would have been possible (not at this price with this IQ and size) with an image diameter of 70mm (645) instead of 54mm, you would have propably lost a stop of lens-speed and less DoF so you'll have to push ISO again and at one point, you're turning in circles - so it's always a compromise - otherwise we would all end up with 8x10"...
Title: Leica S lens image circles
Post by: PeterAit on September 18, 2009, 06:38:58 pm
Quote from: bradleygibson
It struck me as curious that the Leica's new S system considers the 70mm lens the normal lens, when the S2's sensor has a 58mm diagonal.

Does anyone know if the S lenses actually have a 70mm image circle, perhaps sufficient to cover 645 (56x42mm) (or since Leica likes 3:2, 58x28mm or 56x37mm, if sensor manufacture is limited to 645 sizes)

Even looking at the MTF graphs Leica published it seems they're easily able to substitue a new value on the X-axis, the way they're written...

Overactive imagination?  Or has Leica left themselves some room for expansion for later generations of the S family?

Take a ruler and a piece of white paper. Use the lens to project an image on the paper. Measure.

Peter
Title: Leica S lens image circles
Post by: uaiomex on September 18, 2009, 07:37:30 pm
My experience:
I've done this before with viewcamera, Pentax 67 and Hasselblad glass. You have to focus the image at infinity, of course. The image is really deceiving. It will look very big because you are seeing the whole entire circle. Once you measure the diameter, look for heavy vignetting. This usually cuts a few milimeters off. Also important, many projected images really degrade image quality towards the end of the circle, making them in effect much smaller than measured. One way to get to a conclusion (close) would be to attach the lens @f8 to a view camera and load a 4x5 holder with a 4X5 cutoff piece of silver paper. Expose and develop. Then inspect with a good magnifier. Good luck
Eduardo

 
Quote from: PeterAit
Take a ruler and a piece of white paper. Use the lens to project an image on the paper. Measure.

Peter
Title: Leica S lens image circles
Post by: bradleygibson on September 18, 2009, 08:24:02 pm
Quote from: PeterAit
Take a ruler and a piece of white paper. Use the lens to project an image on the paper. Measure.

Peter

Even assuming these lenses were readily obtainable, you'd need to hold the lens at the system's mount flange distance; and the edge of illumination is not really the useable image circle.  On high performing lenses, the image circle is often quoted much more conservatively to maintain a certain minimum resolution across the frame, or maximum amount of vignetting...  This exercise would put an upper bound on the figure (assuming correct flange distance, of course..)

Peter Karbe has given the definitive answer in Michael's video of 54mm--it's designed for the 45x30 sensor and "no larger" (his own words).

Thanks Michael, for posting the video.  It was really interesting to watch.

Best,