Rolleiflex 2.8C vs 2.8E
I was reading RFF forum this moring and saw an good write-up on comparison between 2.8c and 2.8e, as well as xenotar and planar lens.
If you are in the midst of deciding on whether to get a 2.8c or 2.8e, this post would be very helpful.
Originally Posted by Sarcophilus HarrisiiI don’t think this is correct.
I have never seen a 2.8D with the plastic locks. Every image I have ever seen of one has metal types. My own D has these also. It’s not uncommon for Cs to have one or both missing; my own C does not have the PC connector lock. I have wondered how hard it would be to reproduce these but I suspect the cost of tooling up for a high quality replacement of a limited run of items would put people off price wise.The C is better value for money. It’s also a historically significant model for Rollei.
What are the finest lenses Rollei ever fitted to their TLRs? I don’t want to start a flame war between Tessar/Xenar owners and others, because, honestly, I have never met a Rollei TLR I couldn’t love at first sight–but most would respond that the Xenotar and Planar lenses are the best of the best. Well, both these lenses debuted on the 2.8C model Rolleiflex.
I think the out of focus effects of all the lens and shutter types, from what I have seen, are wonderful, but I do confess I like the way the shutter of the C renders any out of focus highlights as circles, instead of pentagons.
Do you want a built in light meter? I prefer without, personally, and usually incident meter with a hand held meter. The E models have a cover plate for the meter cell if a meter isn’t fitted to a particular camera. One of the things I like about the older models like the B, C & D is that because meters were not fitted, they have a simple “Rolleiflex” plate in front of the viewfinder assembly. I therefore feel that, aesthetically, they are the most beautiful Rolleiflexes. Maybe the D, with those aforementioned chrome metal locks, is the prettiest of all?
Functionally, other differences between the two include the EV system, which is fitted to the D & E model but not the C.
The Synchro Compur shutter fitted to the C is a Compur Rapid type with booster spring for 1/500. There are several implications in practical use as a result of this. Firstly, it’s a reliable shutter. However it’s not possible to select, or de-select, the maximum speed after the camera has been wound and the shutter is cocked. In use it is not a major problem, because the C model was also the first to be fitted with double exposure capability. I have had to train myself not to wind my C on after shooting. If, in the rare instance I need to change on or off of 1/500, I simply stop the lens down to f/22, fire the shutter with the taking lens covered, and use the double exposure release to cock the shutter again after I have re-set it. So there is a work around, but, it is important not to try to adjust on or off 1/500 if it is cocked because it can damage the shutter.
Secondly, and also related to 1/500, you mustn’t set the self timer with 1/500 selected. It will lock the shutter up. Because I do some landscape I will often use the timer to trip the shutter without bumping the camera, so maybe I use a timer more than some. During my first roll with it, I set the timer with 1/500 selected and the timer wouldn’t release, and the shutter wouldn’t trip. I ended up disregarding my own advice, and shifted the shutter speed down to 1/250 (against the not-insubstantial tension from the booster spring) so I could free the shutter. Luckily, I got away with it but it’s not recommended. In any event, unless you need a group portrait in full sun, 1/500 should never be required with timer, but, FYI–it will lock the shutter up.
The last point regarding the C shutter installation is that, it does indeed feature a wonderful ten bladed aperture which keeps the lens opening nearly perfectly round at all stops. However. It also uses the “old” scale of shutter speeds; Ie 1/500; 1/250; 1/100; 1/50; 1/25; 1/10; 1/5; 1/2; 1s; Bulb. The good news is that the shutter can be set to select intermediate speeds Eg. 1/125 or 1/60. According to page 24 of the original owners manual for the C: “Intermediate speeds may be set at any points between 1 sec. and 1/10th sec. and between 1/25th and 1/250th sec.”
The most common lens fitted to the C is the Xenotar. A wonderful lens but sadly coatings are often less than perfect. At least the front cell is a single piece of glass, unlike the 2.8 Planar types, so re-coating isn’t nearly as difficult or, presumably, as expensive as removal is a straightforward affair. You need to check condition closely though, for scratches or coating deterioration.
The last point is that the E model has a nifty sliding depth of field strip inboard of the focus knob linked to the aperture control. So as you adjust the aperture the depth of field range automatically alters. The C has a traditional printed scale showing the numbers of all the stops next to their depth of field. For landscape use I think the old design is actually better suited to hyperfocal focussing because you can see the DOF for all the stops, not just the one that is selected. YMMV.
The most important factor should be condition. Apart from the Rolleimagic models I don’t think there is any such thing as a bad Rollei TLR model (and there are a few die hard who still use the Magics!). I’d love a pre-war model one day, because I believe they all have their own appeal. So by all means look for the preferred model type you want (you can’t really go wrong with any of them) but condition is always key.
Regards,
Brett
Exposure Index
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Exposure Index
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Exposure index (EI) is the measure of the amount of exposure received by the image receptor (IR). It is dependent on mAs, total detector area irradiated, and beam attenuation. The exposure index is indicative of the image quality. Equipment manufacturers provide a recommended EI range for optimal image quality (Bontrager & Lampignano, 2005, p. 52).EI in digital radiography can be compared to film speed and blackening in film-screen. When film was used, the accuracy of the exposure was obvious based on the appearance of the image. Digital systems post-process images and display adequate contrast and brightness at a much wider range. Therefore, adequate exposure can only be assessed through image noise or burn-out. Secondary workstations such as those used by technologists for image review, are often of lower resolution and brightness than those used for diagnosis. Because of this, it is often difficult to assess whether an image is noisy or not. The exposure index is meant to be an indication of whether the noise levels are acceptable (AAPM, 2009).
Errors in the calculation can occur resulting in an inaccurate EI. This can arise when the software fails in determining which part of the image is the patient anatomy, for example, in the presence of gonadal shielding or prosthesis. EI cannot be solely relied on, therefore the technologist must remain critical of the appearance of the image and the accuracy of the EI (AAPM, 2009). EI is derived from the mean detector entrance exposure which is derived from the mean pixel value of the image. Most systems use a histogram analysis in order to calculate the mean pixel value (Neitzel, 2004, p. S231). 
This is a histogram created from an AP pelvis radiograph. The x-axis represents the pixel value while the y-axis represents the number of pixels with that value. The mean pixel value here is 104.381.
Although EI is always derived from the IR exposure, equipment manufacturers calculate the numeric value differently, resulting in different ranges and definitions (Carlton & Adler, 2006, p. 367; Neitzel, 2004, p. S231). Also, there is variation between units purchased from the same manufacturer based on different IRs and software (Carlton & Adler, 2006, p. 367). Different IRs have different detective quantum efficiency (DQE). A high DQE results in lower noise levels (AAPM, 2009, p. 3). Therefore, all systems have a different index and are difficult to compare across systems. Fuji CR Fuji uses a sensitivity number (S) that is related to the amount of amplification required by the photomultiplier tube to adjust the digital image. S is inversely proportional to exposure. Properly exposed images should have an S between 150-250 (Carlton & Adler, 2006, p. 367). Kodak CR Kodak uses the term Exposure Index, which is directly proportional to exposure. Properly exposed images should have an EI between 1,800-2,200 (Carlton & Adler, 2006, p. 367). A change of 300 in the EI indicates a change of a factor of 2 in the exposure to the IR. Agfa CR Agfa uses log median exposure (LgM). This system compares the exposure level of the image to a baseline established for the department. Since it is based on a log system, an increase of 0.3 means the dose was doubled (Carlton & Adler, 2006, p. 367). An optimal exposure lies between 1.9 and 2.5.
Imaging Dynamics uses f#. The f# compares the exposure to an established target exposure. Negative values represent underexposure, while positive values indicate overexposure (AAPM, 2009). Canon DR Canon uses a reached exposure value (REX). REX is a function of the brightness and contrast as selected by the operator (AAPM, 2009). GE DR GE uses the detector exposure index (DEI) which compares the detector exposure to the expected exposure value (AAPM, 2009). Siemens Future Developments In 2008, the International Electrotechnical Commission (IEC) developed and published the International Standard IEC 62494-1 on the definition and scaling of the exposure index for digital radiography. According to the standard the EI shall be proportional to the exposure (air kerma) and shall be scaled as EI = 100 * X, where X is the air kerma at the detector, at the calibration beam quality. It is expected that this standard definition will be implemented in future digital radiography systems. The American Association of Physicists in Medicine (2009), published a document in July, 2009 with the purpose of identifying a standard index which reflects the adequacy of the exposure received by the IR. References American Association of Physicists in Medicine. (2009). An Exposure Indicator for Digital Radiography. Retrieved from http://www.aapm.org/pubs/reports/rpt_116.pdf Bontrager, K. L., & Lampignano, J. P. (2005). Textbook of radiographic positioning and related anatomy (6th ed.). Elsevier Science. Carlton, R. R. & Adler, A. M. (2005). Principles of radiographic imaging: An art and a science. Delmar Learning. International Electrotechnical Commission (2008). IEC 62494-1 ed. 1 Medical electrical equipment – Exposure index of digital x-ray imaging systems – Part 1: Definitions and requirements for general radiography Neitzel, U. (2004). Management of pediatric radiation dose using Philips digital radiography. Pediatric Radiology, 34(Suppl 3), S227-S233. |
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