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!

New Rodenstock 90mm Digaron-SW

dougpeterson

Workshop Member
Just got the word of a new Rodenstock 90mm HR Digaron-SW lens designed for down to 5 micron sensors with a 120mm image circle.

The only thing that matters is the performance of real world tests, but on paper Rodenstock is usually more conservative than Schneider on their stated image circles. So a 120mm promised image circle from Rodenstock is really very impressive.

Cambo and Arca have already confirmed they will be using this lens as soon as possible with their tech cameras systems.

I'll do some charts later this week showing how wide that is with various sensors and amounts of stitching/movement.
 

kdphotography

Well-known member
Very nice! I had the current HR 90mm on my list for my Cambo , but now I think I'll sit and wait for the new HR 90mm to come out. Only the Schneider 90mm is available on t/s panel for the Cambo (not the current HR 90mm), so hopeful, maybe, just maybe---the new HR 90mm can be mounted on the Cambo t/s panel....

ken
 
Last edited:

gerald.d

Well-known member
I've been keeping quiet about his one.

A little birdie told me about it several weeks ago. Will probably be my second lens for the TC :)
 

torger

Active member
Cool... I wonder why they chose to update this focal length? I'd guess the current Digaron-W 90mm performs very well already?
 

gazwas

Active member
Cool... I wonder why they chose to update this focal length? I'd guess the current Digaron-W 90mm performs very well already?
Possibly because the current lens design was formulated and originally released some time in the mid to late 90's?

Are here any MTF charts for this lens yet or any info as to the improventd made over the current lens?

The current Digaron HR-W is the exact same lens as the previous Apo-Sironar 90mm (that I own) apart from the lens barrel marking and already have a whopping 125mm IC.
 

David Klepacki

New member
And from the press release...

The brand-new HR Digaron-SW 90 mm meets the highest standards of modern digital backs with up to 100 megapixel and 5µm pixel size.
Hmm...
Yes, the math does not add up. Even if you extended the chip size to a 645 format of 42mm x 56mm, 100 megapixels would still require using pixels smaller than 5µm. So, in order for their press release to make physical sense with regard to resolving 100 megapixels no larger than 5µm, this would imply a chip larger than 645 format. With the current IQ180 size chip, 5µm pixels translates into less than 87MP.

On another website, it was also mentioned that this lens would have a widest aperture of f/5.6. This also cannot be true if the lens is to be able to resolve a 5µm pixel pitch. To resolve a 5µm pixel pitch, you would need an aperture wider than about f/5.2.

So, it sounds like there is some over zealous advertising going on here, possibly combined with misinformation.
 

dougpeterson

Workshop Member
On another website, it was also mentioned that this lens would have a widest aperture of f/5.6. This also cannot be true if the lens is to be able to resolve a 5µm pixel pitch. To resolve a 5µm pixel pitch, you would need an aperture wider than about f/5.2.

So, it sounds like there is some over zealous advertising going on here, possibly combined with misinformation.
While diffraction mathematically kicks in at very early apertures with a 5ish micron sensor the practical effects, even for those with a very discerning eye and high standards, are very minimal until at least f/7 or higher.

As anyone with an IQ180 (5.2 microns) and a good tech camera lens can attest to f/8-f/11 are still VERY VERY sharp.

Whether this lens will live up to some pretty hefty claims (especially sharpness at the edge of the image circle) is not guaranteed until proven, but the maximum aperture doesn't concern me one iota. If anything it's the kind of compromise I want in designing a lens for these sort of applications; if by designing it as an f/5.6 lens they were able to reduce weight, distortion, size, or increase sharpness at f/8-f/11 then I'm entirely in favor of it.
 

dchew

Well-known member
I agree Doug. Plus relatively light diffraction cleans up very nicely with sharpening.

I would much prefer an f/5.6 design. That is one of the things I like about some of the Schneider options. Lighter and smaller.

Dave
 

David Klepacki

New member
What your image capture is actually able to resolve can be very sharp, especially if made so by sharpening. However, my point was that a f/5.6 lens aperture cannot fully resolve a sensor with 5um size pixels, since that is what Rodenstock is claiming. And, as you further stop down the lens, you will continue to lose resolving power and hence finer details. This is one of the reasons why some photographers have found that their prints made from captures with an IQ180 appear to be indistinguishable from those captured with a Nikon D800.
 
S

SCHWARZZEIT

Guest
What your image capture is actually able to resolve can be very sharp, especially if made so by sharpening. However, my point was that a f/5.6 lens aperture cannot fully resolve a sensor with 5um size pixels, since that is what Rodenstock is claiming. And, as you further stop down the lens, you will continue to lose resolving power and hence finer details.
David,
how did you come up with the math that an aperture of f/5.6 cannot resolve finer details than 5 microns?
As noted by others, diffraction starts to creep in and reduces contrast/sharpness as you stop down but it's a long way until you hit the wall where the contrast is too low to resolve finer details. You have to keep in mind that the Airy discs caused by diffraction do overlap, and oversampling still allows for a higher resolution (than the Airy disk diameter) at reduced contrast. It's only when there is too much overlap and the contrast drops below a critical threshold (e.g. Rayleigh criterion) that you're reaching an optical hard limit.
In our tests with microfilm we could resolve more than 250 lp/mm on film at f/5.6 in the IC center.
100 lp/mm at the center shouldn't be a problem for most normal 35mm and MF lenses at f/11 and wider. The challenge for Rodenstock was to reach 100 lp/mm up to 60mm off axis at the edge of the IC to allow for large shift and stitch options.
This is one of the reasons why some photographers have found that their prints made from captures with an IQ180 appear to be indistinguishable from those captured with a Nikon D800.
I guess they were not printing large enough.

-Dominique
 
Last edited:

torger

Active member
I also like the simpler Schneider designs... at some point it just gets overdone. Resolution is fun, but pushing to 100 megapixels and more does not to me seem to be what should be prioritized at this moment in the medium format world.

If we would stay at say 60 megapixels for a while and make sensors with less color cast (to allow for simpler lens designs) and higher full-well capacity I'd be happier. Perhaps re-invent long exposures while at it :)

Not the task for lens makers though, but to me it seems like the MFDB makers don't care much about tech camera segment (low sales volume?) and make sensors only for SLR cameras (large flange distance), and then Rodenstock et al are forced to adapt. IQ180 has waaay too much color cast to be a good tech camera sensor if you ask me.
 

David Klepacki

New member
Dominique,
Yes, you are correct in that oversampling will allow an increased resolution at the cost of lower contrast. I was basing my estimates on a fairly high contrast level (MTF-80). I justify this because my experience with the Rodenstock Digaron-S lenses has been the same as reported here: Understanding Lens Diffraction. Please do not misunderstand me, as I am a very happy user of these Rodenstock Digaron-S lenses. However, when Rodenstock actually recommends an optimal working aperture from f/4 to f/5.6 with these lenses for sensors down to 5um, they appear to have good reason.

As for the print comparison size issue, I was referring to the 60x40 landscape print recently done here: Audioboo / Nikon D800E v Phase One IQ180 comparison - 60x40 inch print comparison yields SHOCK result
 

GrahamWelland

Subscriber & Workshop Member
Obligatory Alpa post in an Arca/Cambo/Rodie thread:

Also now available with the new catchy name that just rolls off the tongue: Rodenstock/ALPA HR Alpagon 5.6/90 mm, SB34

Personally I'm pretty happy with my 90 HR-W but then again I slummed it with only an IQ160. The shame ... I keep it under a brown paper bag when I shoot with IQ180 folks. :grin:
 
Last edited:

kdphotography

Well-known member
Obligatory Alpa post in an Arca/Cambo/Rodie thread:

Also now available with the new catchy name that just rolls of the tongue: Rodenstock/ALPA HR Alpagon 5.6/90 mm, SB34

Personally I'm pretty happy with my 90 HR-W but then again I slummed it with only an IQ160. The shame ... I keep it under a brown paper bag when I shoot with IQ180 folks. :grin:
Yeah, now say, "Rodenstock/ALPA HR Alpagon 5.6/90 mm, SB34" three times really fast... :D

You know, Graham, if it really bothers you, I've got these neat little "IQ180" decals that we can put on your IQ160.... :ROTFL:

See you at the next Pigs in a Blanket! :p

ken
 
Top