Hasselblad 100C and 35XL

[diggles]

Just like a lot of other people on the forum, I am very interested in using wide angle Schneider lenses on the Hasselblad 100C. While testing it out over the last couple of weeks I found an issue that is important to share with everyone here.

Here is a JPG made from the RAW image file.


Here is a JPG made from the RAW LCC file.


Here is a 2400x2400 crop of the top left corner of the LCC file.


As you can see, there are lines that run parallel to the sensor. When I make an image in portrait orientation the lines are vertical. The bad news is that the lines are there, the good news is that it can be fixed using the same process that is used to fix sensor tiling.

How to Fix Sensor Tiling With Photoshop

My first choice for photo editing is ACR/Photoshop. While looking for a way to apply LCC corrections without using C1/Phocus/Lightroom I ran across this article: https://pduncan.com/2015/11/20/vignetting-4/ The steps outlined in the article do a good job of fixing vignetting, but didn't really...

www.getdpi.com

The above images are shifted about 15mm which is extreme for this lens. Even with 5mm camera fall + 5mm shift the lines are present, but not as noticeable. Extreme shifts also introduce noticeable noise in the darker areas of the image. With smaller shifts the noise is not very noticeable.

[Edited: download links removed]

Send me a PM if you are interested in downloading the RAW files and exported Tiffs for a closer look. In order to do the sensor tiling fix you'll need to export the corrected LCC as a tiff file along with the corrected image. Phocus can do this, but I'm not sure if Lightroom can.

Hope this helps!

NOTE: This is just one person's experience with this combo. If there are any others that have the 35XL and 100C, please let everyone know what your experience is.

 

[Paul Spinnler]

Thanks Warren!

Interesting – could this be that this relates to the autofocus on-sensor pixels?

If so, it would make the 100C less interesting for anything besides Rodenstock retrofocus glass.

Its one thing to LCC, another thing to go into PS and tweak layers to get a workable product.

IQ4 does not have this ... except if you do large shifts with each SK XL lens beyond a certain limit which varies by lens.

Very good PSA.

 

[diggles]

Interesting – could this be that this relates to the autofocus on-sensor pixels?

I wondered the same thing.

 

[Paul Spinnler]

It looks like connection lines relating to the autofocus circuitry. Like on each line you have in certain distances these AF pixels.

Given SK is not "officially" sold anymore, it is not a problem for non-specialists, but ofc if you need to run each picture through PS its a big problem.

 

[rdeloe]

I tried one of these and can rise 8mm on a GFX 100S sensor with no sign of lines or other weirdness. Unfortunately 8mm is as far as I can go on an F-Universalis with GFX, so take this with a grain of salt. It looks like the threshold might be just past 8mm.

 

[kinglang]

ES shutter?

 

[Paul Spinnler]

Well there are two points here:

a) Manufacturer specific implementation of the stuff on top of the sensor (bayer filter, PDAF pixels, etc.)
b) BSI tech allowing steep incident angle symmetric optics to be used to a certain extent via LCC

Could be that Hassy has an a) implementation which decreases utility in practice for the wide SK lenses

EDIT: Es shutter vs. copal could also be explored, but you need sync cable for this.

 

[rdeloe]

I'm shooting 100% with an ES on my 100S. No lines at 8mm.

 

[Paul Spinnler]

It is most likely the Hasselblad implementation of AF which creates problems under certain circumstances - eg the Sun stars and lines problem with SK glass.

Alkibiades also has a 100c I think, so maybe he also sees these problems?

 

[diggles]

ES shutter?

This is a good question. I believe I have a sync cord so I can try it with the copal shutter.

 

[diggles]

Given SK is not "officially" sold anymore, it is not a problem for non-specialists, but ofc if you need to run each picture through PS its a big problem.

Since I run all of my images through Photoshop this is not a big problem for me, more of an annoyance and something I would rather not do. Is it a deal killer for me, not sure yet.

I took the same image as above with the 50HR in portrait orientation and 15mm LR stitch. The framing is almost identical, you get a lot more pixels to work with, and it is sharper. Of course these benefits come at a cost– you have to deal with changing light between frames and merging images as panoramas. Even though there are additional variables to deal with and it is a bit of a pain, I would rather use the 50HR and stitch when it is an option.

 

[anyone]

I’ll give it a try tomorrow, with copal and ES.

 

[f8orbust]

Interesting thread. Wonder if the banding has something to do with how the back is reading out the data in ES mode. Hmm. Hope CI do some testing.

 

[anyone]

Same results - no noticeable difference with copal / ES. If anything, the ES image is a bit sharper (shake?).

Linhof Techno, 15mm of rear fall applied (note: this is more than what I'd do usually).

Good news is that Warren also provides the fix for the issue!

 

[Paul Spinnler]

Sensors have a base – the sensor as provided by Sony - a bayer filter and mods by the manufacturer regarding the sensor cover glass including thickness, IR / UV transmission and potentially AF related circuitry. The bayer filter can also be modified by the manufacturer. The S3 has tweaks to the red channel response for better skintone reproduction and the Trichromatic from P1 famously also has a specially tweaked bayer array.

This explains why you might have same underlying BSI sensor tech from Sony with varying compatibility regarding symmetric wide-angles.

Looks to me that the 100C is not ideal for SK glass due to the AF implementation (?), leaving P1 as the only game in town to fully benefit from SK symmetrics.

IQ4 does not have these lines. Rodie glass it is for the Hassy, it seems?

Bit of a bummer for architectural photography.

 

[Vilpo]

Is it possible to fix this issue with LCC in Phocus? Would the banding appear also with SK 43mm or SK 47mm lenses?

 

[Alkibiades]

it is really a joke that the most suitable back for technical cameras has issues that no other back has (even these that are absolutly not fully usable on technical cameras ). So hasselblad simply did not tested the back on technical camera. i think that they dont even know something about these issue. maybe they can fix it when they know this.
similar story as with all H backs- they working well only with speeds slower then 1/15 sek becouse of the tight synchronisation of these backs with H shutter lenses.
So why test own products? the first generation of users make it for free...

 

[Paul Spinnler]

Well SK lenses are not made anymore - Rodie glass works fine … it looks to me though that everyone waiting for a “cheap” IQ4 with BSI to use SK glass should think twice before buying a CFV100c.

It remains to be verified if this behaviour also appears on the 43, 47 and 60 XL, I think it might happen that the 43 is actually less prone to this problem.

This is a big bummer.

Hope IQ5 takes this into account.

 

[Alkibiades]

Well SK lenses are not made anymore - Rodie glass works fine … it looks to me though that everyone waiting for a “cheap” IQ4 with BSI to use SK glass should think twice before buying a CFV100c.

It remains to be verified if this behaviour also appears on the 43, 47 and 60 XL, I think it might happen that the 43 is actually less prone to this problem.

This is a big bummer.

Hope IQ5 takes this into account.

I am not sure if with roddy the 100c will work fine. color correction is color correction, dont matter what lens you use. So why you use 23HR, 32 HR with large movements for example the CC will be also visible on BSI and needs correction. Why it should work with Roddy glass and not with schneider? I am sure this problem will be with roddy also when big movements are done and the CC will be visible.

 

[4x5Australian]

Is this banding effect being caused by minute differences in the height of the sensor stack (from AF circuitry?) being highlighted by the angled light emerging from the lens?