Anyone have a sharp 50mm for the RB67?

[David R Munson]

This has been bugging me for a long time. I have had both RB and RZ setups, and have had 50mm lenses for both. The 50mm I had for the RZ was a later version with a floating element. It was really, reeeeeeeally sharp. On the other hand, I had three different 50mm lenses for the RB, and not one of them was sharp enough to really be usable.

What I'm wondering is if there are actually nice, sharp examples of the 50mm for the RB. Did I get really unlucky or is it just a dog of a lens?

 

[MattKing]

I've been very happy with my 50mm "C" lens for my RB.

It gives me excellent, high resolution results both in the centre and at the edges.

It is a slight bit lower in contrast then my other lenses, but not in any problematic way.

It was very well used when I got it, and the shutter started acting up a bit, but after a CLA it is now working fine.

EDIT: I'm attaching a shot with the 50mm that originated on Ektachrome. What you see is the result of it being scanned at medium resolution, and then resized and sharpened a couple of times, but I think it might give a sense at how much fine detail the lens can handle.

 

[paul ron]

That is very strange because the wide angle 50mm lenses are generally the sharpest of all.

The only times I have ever seen unsharp 50s is when someone has been DIYing n messed with the shims n elements or never reassembled it properly.

Have your lenses put on a collimiter<sp?> to see if they are aligned?

 

[David R Munson]

I'm glad to hear that I may have been mislead by my (apparently uncommon) experience years ago.

 

[mesantacruz]

hi david... I believe all 50mm and 65mm lenses for the rb have a floating element (possibly the rz as well?). I own an original rb67 pro (as well as the original 50mm lens, the photographer sold me the whole set including original instruction manual)... and the 50mm has a floating element... Instructions state...


"-Instructions for the 50mm Lens

This lens has a built-in floating system which moves a portion of the lens system to the front or rear, according to the photographing distance, in order to obtain sharp resolution to the picture circumference.

[picture here pointing to the depth of field scale and floating ring (located just above the shutter speed ring)]

Focusing and photographing method

1. As with a standard lens, adjust focusing by turning the focusing knob on the camera body.
- Merely turning the floating ring will not produce accurate focusing.
2. Next, read the distance to subject, set the distance scale of othe floating ring to the center index mark (red dot), and then take a picture.
- The floating ring may be turned to set the distance scale either before or after focusing.
- When turning the foating ring, a portion of the lens system is shifted to the front or rear; however, no variations can be observed on the ground glass focusing screen.
3. Note the depth of field by observing the depth of field scale on the front frame of the lens, or on the ground glass focusing screen by depressing the depth of field preview lever.

When placing emphasis on spur-of-the-moment snapshots, set the infinity mark (red) of the floating ring to the center index mark (red) when the distance to subject is from infinity to approximately 7ft. (2m.), a sufficiently sharp image can b obtained merely by setting 3.3ft/1m (red) to the index.
-In the case of close-up photography nearer than 3.3 ft. (1m.), set the floating ring to 3.3 ft/1m, then stop down the lens as much as possible.
- The distance to subject implies the distance from the film plane to the subject."


The bold part is not in bold in the original text... just so you know.

ps. "when using the 50mm lens closer than 3 1/4 feet (1 meter) it is necessory to use a lens aperture of f/16, or smaller, in order to obtain satisfactory lens performance"

it says necesory not necessary.

 

[polyglot]

The non-floating versions are OK near infinity (e.g. Matt's example) but become very poor at closer focus. I found that I could get better resolution from 35mm film than I could get from the non-floating RZ67 50mm, which is a bit sad considering the 4x ratio of film area.

In other words, you really need the one with the floating element.

 

[MattKing]

The non-floating versions are OK near infinity (e.g. Matt's example) but become very poor at closer focus. I found that I could get better resolution from 35mm film than I could get from the non-floating RZ67 50mm, which is a bit sad considering the 4x ratio of film area.

In other words, you really need the one with the floating element.

FWIW, my 50mm has the floating element.

 

[David R Munson]

The non-floating versions are OK near infinity (e.g. Matt's example) but become very poor at closer focus. I found that I could get better resolution from 35mm film than I could get from the non-floating RZ67 50mm, which is a bit sad considering the 4x ratio of film area.

In other words, you really need the one with the floating element.

This aligns with my experience, but clearly this is not universal. Plenty of people here and elsewhere love how sharp the 50mm for the RB is, while others find it unbearably soft. I wasn't able to print a sharp 8x10 from negatives made with the examples I tried.

So what gives? Is this just the difference between the Sekor C and the earlier, non-C versions? I am perplexed.

 

[MattKing]

Many 50mm lenses for the RBs are quite old, and may have seen hard usage.

 

[mesantacruz]

Like i said before i have an original 50mm non-c lens... and it does have the floating element. matt never said his doesn't have a floating element....

the only non floating element 50mm lens is the

50mm 4.5 w for the RZ67

ALL 50mm lenses for the RB67 have had floating elements...

when people complained about corner sharpness at close ranges with the 50mm 4.5w.. mamiya introduced the

50mm 4.5 (with ULD) Ultra Low Dispersion glass... it's just a lens coating (nothing to do with the re-introduction of the floating element)

as for not being sharp with a 50mm on an RB, that sounds like being unaware of the floating element, or bad/abused/heavily used copy as mentioned above

 

[Neil Grant]

David, not sure if anyone has suggested slight variation at manufacture as a reason for one, ostensibly identical lens performing differently from another. I've had a couple of 50 C lenses both from new, and the second was superior to the first.

 

[paul ron]

50mm soft? Are you shooting it wide open?.. hten make the floating element adjsutment! OR Stop down a bit, leave the floarter at inf n see the difference? It should blow your mind how sharp this lens is in all series n versions.

BTW did you look carefully inside your lens for fungus or dirt?

 

[paul ron]

David, not sure if anyone has suggested slight variation at manufacture as a reason for one, ostensibly identical lens performing differently from another. I've had a couple of 50 C lenses both from new, and the second was superior to the first.

No not true. The only difference might be in how the lens was serviced over the years... maybe someone forgot to install the proper shims or missaligned it by mistake.. but not from manufacturer variation.

I've serviced lenses that have been CLAed n suposedly well cared for over the years n noticed edge blackening wipped off as a common problem... causing flare n other customer complaints blaming it on Mamiya's quality control.. but that is just aftermarket carelessness.