CFI 250 Superachromat vs CFE 350 Tele-superachromat

I did email to Hasselblad on their website on the distinct advantages of the 250mm Sa a few months back as this particular lens did hold my imagination. They replied that apart from its suitability for general application, this lens really stands out on its own when big enlargements are needed as the primary objective. This assumption extends for colour transparencies which are intended for big projection. I understand it is perfectly compatible with the 1.4XE and 2XE converters. The other Apo 1.4XE is not usable with this lens. So if I were just a weekend photographer contended with 8x10 or 11x14 prints, I'll happily save a bundle by opting for the other normal CF/CFi version. The costs for a new CFi 250 Sa with a 1.4X converter are just slightly cheaper than the CFE 350 Sa but you have the advantage of having 2 focal lengths with a lighter load and taking lesser space in your bag. Then again, the majority of us never get their prints enlarged to 30"x40" every week or the privilege of owning a PCP80 projector to justify the cost of this lens in the very first place.

The 250mm has a slightly better MTF graph than the 350 and uses special optical glass and crystals[probably Calcium Fluoride--(Flourite)]. Both correct for four colors and use low dispersion materials but what is more important is the ratio of the focal length to tertiary spectrum. 20,000 to 1 would be quite outstanding but do you really need that level of longitudinal chromatic correction in the work you do with your camera? Not sure Zeiss will publish ratio information. Both of these lenses can be shot wide open due to low spherochromatism. My opinion is that this level of color correction is usually not needed until you reach the 600+mm focal lengths. These two lenses are perfection but you pay for it.

CFI 250 SA and CFE 350 TSA are just the best lens for each focal lenth avaliable. Hasselblad published MTF graph of both I have here on my desk. CFI 250 values are slightly "different" not "better" than CFE 350 TSA (350 at f/5.6 is better in the center at 20 and 40 lp/mm, much better at 20 mm at 10, 20, 40, lp/mm exept for the tangential at 40 lp/mm, 250 is slightly better in the center at 10 lp/mm at 20 lp/mm for the tangential). There is a big difference in the angle of view therefore if you need a 250 mm is better the 250 SA if you need a 350 is better mm the 350 TSA. I would not "mortify" the CFI 250 SA with the 1.4X converter. I would rather use converters with the normal CFI 250 "not" SA. I can tell you that the level of color correction of 250 SA and 350 TSA is usually much needed and very important if you enlarge your slide with a good projector (I use a Rollei + Schneider 150 f/2.8 at 6 m with a 220x220 cm picture). If you get close to the picture you can easely see lateral chromatic aberrations in the lateral areas of the frame with very contrasted subjects when using 250 CF and 350 CF ( like a white statue with a dark backgroud, an experience I personally had). I own a CFE 350 TSA. I like this focal lenth very much becouse give me the the chance of cutting down background areas obtaining blurred and undisturbing background in portraiture or selecting areas and perspective control in landscape. The image quality is superb ( I would say at the same level of the 250 SA I had a chance to use and evaluate). The 350 CFE has a very stiff tripod collar within the mount of the lens in the center of gravity of the lens+camera set. This ensures a better holding on the tripod and a better balance in case you use a monopod. The internal focusing is extremely smooth and gives you a very fast focusing. I just have not a personal experience in the use of Apo 1.4X. Stefano

Stefano, the color fringing you talk about on the 350CF and 250CF with high contrast subjects is not caused from lateral chromatic aberration. This aberration is easily corrected without the use of special glass or superachromatic correction. What you are seeing is due to spherochromatism(the change in spherical aberration by color). The 250 and 350 CF should not have this fringing when stopped down one or two stops. This is because the designer could only control the longitudinal correction in the paraxial and zonal areas of the lens and not the marginal zone. Conventional glass telephotos will fringe in the marginal zones but this can be prevented by stopping down. My recommendation to David is to use the CF lenses and stop down slightly, unless he has plenty of money.

The Sonnar Superachromat 5,6/250 was introduced in 1972. It was the result of years of optical calculations with the goal to build a telephoto lens with a performance that was only limited by diffraction. To achieve this goal, chromatic aberrations needed to be corrected on a level never before achieved in a telephoto lens. In other words: The secondary spectrum had to be reduced below the "Rayleigh limit". Apochromatic correction (developed by Prof. Dr. Ernst Abbe at Zeiss in the 1880s) would not be sufficient to achieve this goal. Something had to be done which goes even beyond apochromatic correction: Superachromatic correction. This level of correction was envisaged and theoretically described by Max Herzberger in the late 1950s, but he was unable to achieve it in real world optical design. At Zeiss, Determann eventually came up with a usable solution in the late 1960s.

Photo magazines that have seriously evaluated this Superachromat 5,6/250 ever since came to the conclusion that the Zeiss Superachromat is the best camera lens ever conceived.

All of this is why my heart of a lens liking person loves this 250 mm Superachromat. The NASA also loves it. And since they used it in multi spectral camera systems including infrared imaging channels, Zeiss T* multi layer coating was not applicable with the Superachromat, since that would have limited transmission for infrared. So other measures had to achieve stray light control with "only" single layer Zeiss T coating. This fact, and the very demanding manufacturing process (= only few could be made back then) led Hasselblad to target it at scientific applications.

In the meantime Zeiss has more than doubled the manufacturing capacity for this lens. From a background of quantities there is no reason any more to limit this lens to NASA, scientists, and myself. However, there is one more consideration: Contrary to popular belief not all lenses with the same focal length produce the same depth of field at the same aperture! A typical example is the Superachromat 5,6/250: It produces extreme sharpness (250 linepairs per millimeter)at the plane of best focus. But slightly off (which may be caused by photographer's focusing error, film position error, curvature of film, humidity, registration error of mirror or focusing screen, magazine wear, to name just a few), the sharpness drops dramatically. It can drop even below the levels the sharpness of a Sonnar 5,6/250, or the one of a Tele-Tessar 4/250. In other words: The performance of the Superachromat is extreme, but nervous. It requires advanced technique on the part of the photographer and also well aligned and maintained equipment, to actually utilize the full potential of this lens. Once all this comes together, the Superachromat shines. No other lens in the world ever gave me fine details with this clarity! This lens is perfection for perfectionists.

Photographers who prefer to engage less with these aspects may even achieve "better" results with the normal Sonnar 5,6/250.

For converter lovers: Your converter results are better when the prime lens is better, simply because the converter magnifies everything, including the lens errors. This means: With a lens like the Superachromat 250 you should have an excellent basis for good converter results. However, at the resulting speed of f/8 or even f/11 accurate focusing is not easy, to say the least.

Why would my brain prefer the Tele-Superachromat 5,6/350? Well, most of my applications for super sharp telephotos clearly require a narrower angle than the Superachromat 250 does deliver. Also, the internal focusing of the 350 allows me to set the focus with stunning precision. So far, I did not have the opportunity to subject the Tele-Superachromt to the same testing procedure that I did the Superachromat. One owner of this lens, previously responsible for qualifying optical equipment for semiconductor fabrication at Intel and obviously very qualified, did stringent tests with his Tele-Superachromat 350 and reports about extremely good results. I will check my Superachromat 350 as soon as time permits and compare it with the Superachromat 250. I will then make the results available either here or at www.zeiss.de/photo or in "Camera Lens News".

I wish to ask Dr Fleischer which films he would use to best take advantage of the 250 lines-per-millimetre resolution of the 250 f5.6 AC?

Are there any that can manage that, and if not, which come nearest?

Sincerely,

Brian Swale

My comment: As I have said many times on this forum, the 250 SA is stunning. In the real world, in the field, I don't think I can notice any difference between the 350 SA and 250 SA. But in the real world the 250 SA just makes the standard 250 CFi look bad. Granted, I'm very critical, but in the Hasselblad system no lens has gotten in my way of enjoying my work, except the 250 CFi. Thank God it did, this forced me to the 250 SA!

If the SA is that critical to focus, I don't notice it on a tripod anyway. Whatever level of focus I get, it sure beats the standard 250.

Hello Armando, Is it possible to see some "SA" photo from you on the internet? I just wonder how special a 250SA lens compare to a normal 250 is. If you can post it on the internet for the comparison, that will be much help! Thank you in advance!

I have no scanned images and I don't have a scanner! But who knows what you could see over the web anyway!

But you can easily see in an 8 x 8 or 8 x 10. Folks talk about the resolution and contrast (both exceptional), but what is not mentioned is the amazing color rendition. If there is a great color in the scene you will see it in the image! I have a few images of Venice where there is some deep purple and blue on boats, and the saturation in the image is eye-popping. Another image of a church backlit at sunrise over water with stray light and reflections galore was captured so dramatically with bright yellow light jumping out of the image that when I got the film back I just had to stare with a lupe to believe it. This is not color-shifted oversaturation like Velvia, (I use Provia and E100S)it is just intensity as it exists in the scene. Sometimes I feel as if I'm cheating when I see folks dwell on these images as I flip through the mock up of the book for them. It's as if you had a portfolio of 35mm images and then snuck in a medium format or 4 x 5 shot here and there and watched people stop and "oohh and aahh" over each of those.

For me, these 3 images alone would have been worth the price of admission for the lens. Financially they should be worth it, they will be 3 of the defining images in a book on Venice, but even if they never made it to publication the personal satisfaction of the images would have made this lens worth it.

Armando, thank you! Comments like your's really motivate us here at Carl Zeiss. It is so good to see that photographers appreciate special lenses like Zeiss Superachromats and use them for demanding work. If your photos will turn into a book, please let me know where I can get a copy of it. I wish you fun and success with your projects.

It is hard to compare two different lenses at two differnt focal length even at same aperture. 250 is Sonnar design and the 360 is tele design (not knowing tele sonnar or tele-tessar) That is another hard to compare excuses Lawrence Leung

Does anyone know where/how I could obtain the 250 SuperAchromat? I want one for both color and infrared work to be used on Canon bodies (color and infrared).

It is no longer made, so this means finding someone who is willing to sell one.

ALSO, the 250 is -not- a T* lens, making it suitable for infrared work. The 350 SuperAchromat is apparently a T* lens, which will attenuate infrared.