Confused by OM 50mm lenses

Hi, I have been surfing the web all the morning (waiting for a bed to be delivered) regarding the OM 50mm 1.8 lenses. It appears that the most recent lens is in fact similar in layout to an enlarger lens, with 6 elements in 4 groups:
http://www.star.ucl.ac.uk/~rwesson/esif/om-sif/lensgroup/manuals/50mm_f1.8.pdf

Can anyone say whether this is also the case for the "Japan" version?

Do I need to get an older one (F-Zuiko) in order to have the lens design similar to the 1.4 and Pentax M 1.7 50 which I am used to, as shown in the front page of the same UCL site, where the front group doesnt have the doublet?
http://www.star.ucl.ac.uk/~rwesson/esif/om-sif/lensgroup/50mmf18.htm

Thanks.

 

Thanks I've already looked at the Mir site: the lens diagram relates to the old 5 group 6 element 50/1.8. There is a 50/2 lower down with the same enlarger type lens diagram as the MIJ.

I have just had a OM1n refurbished (by Michael Spencer, highly recommended). I am intending on moving over to Olympus in order to make full use of my Tamron SP 90/2.5 which I find to be an excellent lens. It focuses in the opposite direction to my Pentax lenses and often catches me out, whereas its the same direction as the Olympus lenses.

Prior to committing to the move from Pentax to Olympus, I thought I would compare the Oly lenses to the Pentax lenses. Both the OM 28/2.8 and OM 135/3.5 I have seem to perform very well, even in comparison to my Pentax M 28/3.5 which is a very sharp lens, and also in comparison to the Tamron SP 90/2.5 which can act as a control, as it can be mounted to both the Pentax and Olympus cameras. Looking at my test negatives (x25 scope under a Nikkor EL 50/2.8N in the enlarger) I was struck by the MIJ being softer than the Pentax 50/1.7. In order to exclude the possibility of mucking up the test, I will simply shoot the test again.

The significance of this is that I don't think I can print larger than 5x7 with the MIJ shots and have a sharp photo, whereas 12x16 would not be out of the question with the Pentax M 50/1.7.

 

yep, referring to the common 4 group 6 element design of Nikkor 50/2.8N or componon S 50/2.8 etc

 

Thanks for this, this is the kind of specific information I am trying to dig up. I will get a Zuiko MC then and do a comparison. My MIJ is in literally perfect condition, as was the camera it came on. I guess that maybe there is potentially some lens alignment/collimation issue, but the surfaces of the glass look perfect and there is no sign of it having been dropped. The other explanation is that its been incorrectly focused by me during the testing, which is possible when I was fiddling with the MLU.

I used a hood on all the lenses, and was shooting at 1/250 on a Manfrotto tripod with a FOBA ball head.

 

oh well, in the UK these are about the same price as 3 rolls of film, so there is little or no cost associated in buying up several and finding the pick of the bunch, other than annoying the wife with a lens collection which is multiplying like a collection of gremlins under the stairs

 

yep, its been checked over by Michael Spencer, who is a former Olympus repair guy...also, I was shooting 3 other lenses at the same time, all of which were recording 60-70lp/mm.

 

I believe that the assertion that if a print is viewed from far enough away, resolution doesn't matter is commonly used to oversimplify or simply dodge thinking about print requirements. Further, who has the right to someone else what the correct viewing distance is to his own prints?! Taking the argument to the extreme, if you stand a mile from a print, the print resolution will indeed not matter.

Its simple to quantify print resolution requirements, just using geometry. This is a simple experiment I have done: print a pattern of line pairs/mm up on a sheet of paper, alongside a smooth grey tone, and walk away from it. At the point the texture of the line pairs disappears, the two pictures will start to appear the same. Measure this distance. From here you can calculate the given number of line pairs a print requires for a given viewing distance, for you. You might pick a pattern with a frequency of 1.0 lp/mm. If the viewing distance at which this appears to become a smooth tone without texture is 4m, and one views prints at 50cm, then you have a print resolution requirement of 8lp/mm.

Yeah, and the additional irony is that I also use a Bronica ETRSi!

I mention print sizes as I think they are easier to interpret than raw lp/mm on the negative. When I shoot a batch test of lenses, I am in fact just calculating the resolution they are capable of laying down on a negative (this is a convolution of developer, agitation, tripod, focus accuracy etc etc). Its important to shoot a batch as then the relative performance can be seen easily and as resolution testing is a bit subjective in that the limit of the resolution is determined by the definition of acceptable minimum visible resolution. This is inherently dependent on the operator, or "nut behind the camera". By doing several lenses at once, it ensures some consistency though, and I can end up with a relative measurement. Whole thing takes about half an hour, I note it down in a book where I have previous results, and when I get a spare minute once the film is developed, check it out under the enlarger using a 25x scope and good enlarging lens.

I think the first thing I need to do is retest the lens, with a F Zuiko 50/1.8 and a Zuiko MC Japan 50/1.8 for comparison. Will post back in case anyone ends up reading this thread and finding it vaguely interesting to know the difference between the various incarnations of the slower Zuiko 50's.

 

I personally need 8lpmm in a print, which necessitates EFx8 in the negative, EF being the enlarging factor. Now if I am looking at a 12x16, which I suspect may be a sensible upper limit, I would need 96lp/mm on the negative. There are documents floating the web about using high res Adox CMS film which means this is entirely possible with 135, just google gigabit film. However, I'd rather just use my 120 negatives for that size of print, given arguments about tonal information being lacking prior to resolution limits being hit. Back to the point in hand though, the 50mm lens I have been testing scored 35lp/mm as its resolution limit. This means the upper limit of a print would be 5x7, but at that point, the lens is already being stretched, meaning it would lack contrast and tonal information in a 5x7. There is a benefit in having a lens which could reach higher resolution levels used in a smaller print, as the tonal information will be more detailed for any given level of resolution.

 

The Mij is better than thought, here are some updated results. Make of them what you will. I am reading a book which I could recommend in terms of spirit of testing, written by Richard Henry "Controls in black and white photography". Notably, he makes the point that no one can be more accurate than 1 group in rating the resolving power of a lens using a tricolumnar test pattern. In this spirit, a key lens in my testing is the Tamron 90mm SP 50B, which I have as a reference and can be used as a control as it can be mounted on different camera bodies through the various available adapters. Further, its a notoriously sharp lens in an absolute sense, so it gives an indication of the upper limits available due to other factors in the testing such as the resolving power of the film used. So in this instance, I used the Tamron in identical testing of a MX about half an hour later, with a fleet of Pentax M lenses. I dont include the results as they are not really relevant to an Olympus group. The conclusions I would draw are: a) the MIJ is capable of hitting 60lp/mm at f8 b) at f5.6 its softer than the Tamron SP c) The Tokina made Vivitar S1 lens is pretty respectable compared to the Oly 135 prime. Further testing could include impact of tripod, cable release, filters, hoods, developer, film, exposure.

Setup:
25/05/2013, 15h10, sunny
tmax 400
190 tripod fully extended, Foba ball head, manual shutter (not cable release), no MLU
target 36 inch wide Edmund test patterns, contrast reported to be 100:1
metered using Lunasix F incident reading
XTOL 1:2 10.5mins 20.0deg, 30s + 3 inversions every 30s
Nikon 50/2.8, Microsight 25x
f4 shots were overexposed by a stop, as the meter would have recommended shooting at 1/2000.

name lens, focal length, distance to target, f4, f5.6, f8, f11
Olympus 28mm 2.8, 28, 3000, 27, 67, 67, 53
Olympus 50mm MIJ, 50, 3000, 42, 47, 59, 53
Tamron SP 90 2.5, 88.5, 6000, 60, 60, 53, 60
Olympus 135mm 3.5, 135, 6000, 43, 43, 55, 55
Olympus 135mm 3.5, 135, 6000, 39, 43, 55, 55
Vivitar S1, 70, 6000, 48, 48, 60, 67
Vivitar S1, 210, 6000, 35, 44, 49, 49

NB step in line spacing between patterns is 12%, so that 6 increments results in a doubling of the line frequency