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Author Topic: Rodenstock HR digital lenses  (Read 10895 times)
BJL
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« on: March 04, 2006, 06:34:58 PM »
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Michael,
     you have been enthusiastic about the Schneider Digitar lenses, and now suggest in "Whats New" today (March 4) that the Rodenstock HR lenses (Apo-Sironar digital HR?) might be even better. Am I reading to much into this? Do you only mean that the Rodenstock HR s are as more or less as good as as one can currently get, on a par with the Schneider Digitar's? Do you have any idea how these two new "digital large format lens systems" compare?

I note that both these lens systems are assessed for MTF at up to 60lp/mm, which corresponds roughly to the resolution of a Bayer array sensor with 5 micron pixel spacing, fitting your prediction of 5 microns as roughly the lower limit on pixel size for formats this large.

Also, Rodenstock lists 37x49mm (61mm image circle) as the target recommended sensor size, even though the spec. sheets and MTF graphs describe coverage up to 70mm image circle diameter. That 70mm is a perfect fir for 645 film format, but 37x49 matches the current largest sensors.
Is this a hint that Rodenstock has been assured by Kodak and Dalsa that they do not plan to go beyond their current largest sensor sizes, so that lens designers can now target that 61mm image circle diameter? Or am I again reading too much into this?
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michael
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« Reply #1 on: March 04, 2006, 10:07:28 PM »
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As I understand it the Rodenstock Apo Sironars and Schneider Digitars are quite comparable.

Rodenstock takes things a step further though with their HR line. I just bought 3 HR lenses, the 35, 100 and new 180mm. I got the 55mm regular Sironar rather than the 60 HR for the even larger image circle needed for architectural work.

As I understand it these are the highest resolution lenses that one can currently purchase.

I started off going for the 35mm Rodenstock because the 35mm Digitar won't focus at infinity on a camera like my new Linhof 679cs. (It only will on a helical mount setup). Once that decision was made I decided to go for the whole line.

More on this in an article later this week.

I know that Kodak is saying that they believe that they can produce an MF chip with 55-60 Megepixels with noise levels no worse than their current 39MP chip, which is as good as their 22MP chip of two years ago. This would mean roughly 5 micron photo sites. My guess though is that it'll be at least 2 years till we see these, if at all.

As for phycially larger chips, I don't believe that we'll be seeing those at any time soon. There simply doesn't seem to be a need, and the costs would be astronomical.

Michael
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Ralf
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« Reply #2 on: March 05, 2006, 07:31:17 AM »
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Michael,

the Linhof 679 cs is better than its predecessor, the 679 cc, but still not so appropiate to mobile
digitale use as the Arca Swiss.

Linhof 679 cs: 4500 g - no 35 xl - still only little direct shifting

Arca Swiss 6x9 f-metric:  2100 g - 35 mm xl without problems (if you turn the rear standard you'll have no problems bringing lens and back close enough for wide angle lenses) - broad direct shifting in all directions

I had experienced focussing problems when using wide angle lenses with my Arca 6x9 until I found a solution that works perfect for me: Hasselblad Reflex Viewfinder RMfX with a split-image focussing screen. Now reliable focussing is easy, even with wide angle lenses.

Ralf Lange
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Jack Flesher
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« Reply #3 on: March 05, 2006, 10:17:23 AM »
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On the issue of lens' image circles,  I have had the pleasure of testing and using a few Schneider Digitar's and Rodenstock Digital specific lenses.

If you test them on 4x5 film, you can see -- and thus evaluate -- the entire image circle.  The fact is resolution falls off as you get further away from the center of the lens, so a lens might be spec'd with a 61mm IC for 5u sensor sites, 68mm for 7u sensors and 75mm for use with film.  Moreover, the actual total IC might be closer to 90mm, though performance beyond 75mm is sub-par.  

I have to agree on the choice of an A/S for field use, but the new 679cs will be one sweet camera in the studio...  Of course I would probably choose the A/S Monolith for the studio instead
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michael
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« Reply #4 on: March 05, 2006, 10:25:36 AM »
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The F line is very attractive. But what made the Linhof 679cs my preference was the buillt-in optical bench, as they call it.

This means no need for a ballhead or leveling base. I just have an RRS quick release mounted directly on the top plate of the tripod. Sweet.

Michael
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BJL
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« Reply #5 on: March 06, 2006, 12:37:07 PM »
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Quote
I have had the pleasure of testing and using a few Schneider Digitar's and Rodenstock Digital specific lenses.
...
The fact is resolution falls off as you get further away from the center of the lens, so a lens might be spec'd with a 61mm IC for 5u sensor sites, 68mm for 7u sensors and 75mm for use with film.
[a href=\"index.php?act=findpost&pid=59566\"][{POST_SNAPBACK}][/a]
This makes sense of Rodenstock's statements: they give data out to the 70mm of 645 film format for those who might use the lenses with film, but then conservatively recommend smaller maximum sensor formats, to avoid disappointing digital users who might detect and fuss about slight declines of resolution near the corners visible in 100% on-screen pixel viewing.


P. S. One of the nice things about reading product spec. sheets from sources like Schneider-Kreuznach, Rodenstock, and the Kodak and Dalsa sensor divisions is that they know they are speaking to technically competent and demanding customers (such as customers using these lenses and sensors in scientific equipment), so they tend to be very precise and even conservative in their performance claims. For example, who else besides large format lens makers documents differences in resolution at different focusing distances?
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Ray
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« Reply #6 on: March 06, 2006, 07:29:58 PM »
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I've just been looking at a PDF document which provides MTF data for the Rodenstock HR lenses, here , and find the plots for MTF at 60 lp/mm unbelievable. The APO Sironar HR 35mm f/4 appears to have an MTF response, at 60 lp/mm and f/5.6, which never falls below 60% within an image circle suitable for 35mm format.

If this lens were fitted to camera with a 16mp 35mm size digital back, I'd expect it to produce sharper results than a 1Ds2 with Canon 50/1.4 standard lens.
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Jack Flesher
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« Reply #7 on: March 06, 2006, 09:59:45 PM »
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Well Ray, as is often the case, what one assumes to be true and what is actually true are not the same.  

And all it takes is getting hold of the equipment and testing it for yourself...

I tested a 90mm Schneider digitar with a Betterlight super 6K (9000x12000) scanning back.  At the lens' center, I was able to resolve 65 LPmm on my target -- which was at the limits of the back -- and I have no doubts it would resolve more.  

FWIW, again center readings, my Rodenstock 150mm APO S generated the same 65 LPmm(!) and my 55mm APO Rodenstock made nearly 60.   These lenses were the exceptions, and most of the other current LF lenses I tested fell in the mid 40's to low 50's for resolution (still excellent by LF standards), while most of the older glass I tested was in the mid 30's to low 40's (normal).  

So, the bottom line is that lens design has come a long way in the last few years...

Cheers,
« Last Edit: March 06, 2006, 10:01:58 PM by Jack Flesher » Logged

Ray
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« Reply #8 on: March 07, 2006, 03:23:59 AM »
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Quote
Well Ray, as is often the case, what one assumes to be true and what is actually true are not the same. 
[a href=\"index.php?act=findpost&pid=59659\"][{POST_SNAPBACK}][/a]

Jack,
That is particularly true when one doesn't have access to accurate and/or sufficient information. But I can't work out from your above post if the APO Sironar Digital HR 35mm f4 would or would not deliver sharper results with a 16mb digital back (of 35mm size sensor) than a Canon 50mm f1.4 on a 1Ds2, as I predicted it might.

Cheers!
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michael
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« Reply #9 on: March 07, 2006, 04:41:28 AM »
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I'll be able to test this in a few weeks. I colleage is putting together a rig that will allow me to mount the 100mm Apo Sironar HR on my 1Ds MKII. This will let me waste a great deal of time doing such comparisons.

Michael
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Jack Flesher
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« Reply #10 on: March 07, 2006, 09:15:35 AM »
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Ray:  My comment implied the answer for you -- BUY the gear and test it out directly!  

There are some things you just simply cannot work out by applying logic -- especially when the base assumptions may be false to begin with.
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Jack Flesher
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« Reply #11 on: March 07, 2006, 09:20:43 AM »
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Michael: FWIW, I would not spend a lot of time or energy (or money) building the test rig.  I tested a few of the Digitars and Rodenstock Digital lenses on my 1Ds2 a while back using the outfit below.  Bottom line is the 1Ds2 sensor is capable of rendering about 52-53 LPmm tops; I suspect this is lower than the Nyquist limit due to the effect of the AA filter.  Anyway, ALL of the digital-specific lenses I tested maxed out at the sensor limit across the entire frame.  

Here is the camera I built a year ago to test them (which BTW, you can buy almost the same thing directly from Horseman now):

« Last Edit: March 07, 2006, 09:23:36 AM by Jack Flesher » Logged

Ray
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« Reply #12 on: March 07, 2006, 08:12:24 PM »
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Quote
My comment implied the answer for you -- BUY the gear and test it out directly!

Hey! Jack, I can't afford such self indulgence. I'm relying upon wealthy and successful photographers like you and Michael to carry out these sorts of comparisons. Until you do, I can only speculate and try to draw logical conclusions from the data, statistics and MTF graphs that might be available, but often are not, and which might be accurate but often are not.

Quote
There are some things you just simply cannot work out by applying logic.

And what things are those?  
« Last Edit: March 07, 2006, 08:13:44 PM by Ray » Logged
darrylbaird
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« Reply #13 on: May 04, 2006, 07:30:36 AM »
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Late to this discussion, but I have a question of anyone with experience using the Schneider 28/2.8 Digitar on any of the hybrid/view camera solutions.

I'm working to add one or two of these to the school's arsenal and have looked at the Ultima 35 solution, but hate the price. So now I'm looking at the Horseman LD and while researching (hard to do since Horseman seems to have gone quite silent lately) I got a reply back from a dealer:
"the LD is designed for table top product type work....it is not designed to
convert your camera in to a view camera for architectural or landscape work
for example...just in case this is what you had in mind."

if so, what's the point of the 28mm lens, that has a flange to film distance of 69.6?

I'm not married to Schneider, so if the 35mm Rodenstock will work better I'm happy.

thanks for any help with this decision

-D
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