Hasselblad CFV-50 and W/A Schneiders

[f8orbust]

Just wondering if anyone could tell me what is the highest resolution MFDB that will work nicely with the latest Schneider W/A lenses (43/35/28), particularly if shifts are involved.

From my 'research' (i.e. Google) I think it's the 50MP Hasselblad CFV-50 (or its sibling the H3D50). Why? Er, well, if I've got my facts right then:

1. The sensor was made by Kodak - so no microlenses?
2. The sensor is 'only' 37mm x 49mm in size

Taken together, this makes me think it won't have the issues of the high MP and physically larger sized microlens-based 60MP/80MP Dalsa sensors.

Am I correct(ish)?

Thanks in advance.

Jim

 

[Leigh]

Have you downloaded the owner's manual for the CFV-50?

I have a CFV-39. They tell you in the book that there may be issues with WA lenses.

In particular, they warn of possible problems with the 38 Biogon on the SWC/M, so that's a clue.

- Leigh

 

[torger]

I'm very curious about this too, as I'm looking into the CFV-50 as a possible future upgrade. I guess the 35mm and the 28mm is about the same (the 28 is more retrofocus and has about the same flange distance as the 35mm). I doubt the 43mm is problematic.

A test shot with the 35mm with shift would be nice to see, I wonder if the color cast is too severe or not. The pixel size is the same as for the P65+/IQ160 (6 um), so I guess/hope it is at least not worse than those backs.

 

[Leigh]

(the 28 is more retrofocus and has about the same flange distance as the 35mm)

The flange distance is irrelevant.

The angle of incidence of light on the sensor is determined by the location of the rear node of the lens. By definition, the distance on the lens axis from the rear node to the film/sensor at ∞ focus equals the optical focal length of the lens.

That equation is invariant, regardless of the design of a particular lens.

The angle of incidence on a wide-angle lens will get much worse as the lens axis moves away from the film center.

- Leigh

 

[torger]

The flange distance is irrelevant.

The angle of incidence of light on the sensor is determined by the location of the rear node of the lens. By definition, the distance on the lens axis from the rear node to the film/sensor at ∞ focus equals the optical focal length of the lens.

That equation is invariant, regardless of the design of a particular lens.

The angle of incidence on a wide-angle lens will get much worse as the lens axis moves away from the film center.

- Leigh

Huh, is this really true, or maybe should I say relevant?

Sure flange distance is not the whole truth, but you do design with retrofocus to get light fall in at a closer-to-perpendicular angle for a wide angle lens, and/or to increase the distance from rear element to sensor. This is what is done with Rodenstock lenses to a higher degree and makes them work better with IQ180 etc with lower color cast than Schneider lenses despite having the same/similar focal length. If this design was not possible there would be no ultra-wides on DSLRs as the rear element would stick far into the mirror box.

 

[Leigh]

It appears you don't understand the difference between optical focal length (distance from rear node to film) versus flange focal distance.

The two parameters are not related, although they both increase or decrease with focal length for a given lens design.

As an extreme example, look at the Fujinon T 600/12.
It's optical focal length is 600mm, but it's flange focal length is only 383.9mm.

By definition, all light rays from a lens appear to emanate from the rear node. That's why it exists. It's a single point.

- Leigh

 

[torger]

Okay.

I think we need to see some test pictures. I would guess the CFV-50 manual warns about visible color cast *before correction*, rather than color cast so severe that it cannot be corrected with an LCC shot.

With tech cams, color cast is a fact that must be dealt with, it's there for all wides with all sensors. At some point it gets so severe that too much dynamic range is lost and pictures become unusable (i e IQ180 with Digitar 35mm). I get visible color cast with as long focal length as the Digitar 47mm on my Aptus 75 (and the 33 meg sensor has low color cast compared to more modern stuff) but it is easily corrected.

 

[f8orbust]

+1. I'd really like to see some real world examples as well. Now that CI stock Hasselblad, perhaps they could oblige

I did download the Hasselblad brochure, all it says is 'Edge sharpness can be compromized' in respect of the 38 Biogon. Vague.

Interestingly, on the Alpa site, there is no warning associated with the CFV-50 in respect of microlenses and wide-angle lenses. Compare the entry for the H3D31 for example.

 

[DDudenbostel]

I use a CFV39 with a Rodenstock 35mm And have no problems that a LCC doesnt take care of. Even when I shot with the SWCM 38 there were no uncorrectable color issues.

 

[stngoldberg]

I hope this is relevant and helpful. I use an H4D50 and do not have any colorcast issues on my Rodenstock 32mm that are not correctable with an LCC; however I find with a center filter I need less correction from an LCC. On the other hand others have reported on this forum that they have experienced a centerfold issue with the HD460 that is difficult/impossible to correct with an LCC.

Stanley