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Hasselblad back on Horseman SW-DII

Woody Campbell

Workshop Member
My Horseman SW-DII arrived last week together with a 35mm Rodenstock APO Sironar. I thought I would share a few notes on it.

The Horseman is beautifully made -it's precision machined out of solid blocks of metal. It weighs a little over four pounds with the lens. The back shifts all four directions up to a maximum of 17 cm. Shifts are not geared, but they are very smooth. There are detents at the center and at 10 mm shift. I thought that I would be using sifts primarily to stitch but was surprised to find the Hasselblad has implemented a live view feature in Phocus 1.0 and the new version of FlexColor so it's possible to compose view-camera style when working tethered. (This works in interiors but not in daylight because the sensor maxes out in daylight in live view mode, even at f22).

The Hasselblad back (in my case an H 39) attaches to the camera via an adapter plate. The adapter in turn attaches to the camera with two knurled cams - very elegant - the adapter is square so the back can be rotated in 90 degree increments. The viewfinder mask can also be rotated 90 degrees.

The Hasselblad back is not powered, so you need to work tethered or attach a Hasselblad Imagebank, a 100 gig external hard drive + battery that Hasselbad sells at the bargain price of $2K, via a firewire 800 cable. I found that it was quite possible to use the camera as a walk around point and shoot with the Imagebank in my pocket.

Here's what it looks like:

View attachment 5052

View attachment 5051
 

Guy Mancuso

Administrator, Instructor
Woody I have the identical setup myself as i bought it as a option with the Phase 25 plus back . Same lens and such. The one big difference is Phase backs have the battery on the back itself so no need for having a image bank like Hassy uses and i do not have to be tethered although i can be. Really a cool setup and really looking forward to working with mine. I do have a small lens issue that was lose so it went back for replacement or repair but CI is sending me a lens until that all get's straightened out. i did do a couple quick tests and it is a awesome setup and fairly small but I did ask Lance to get me a hassy V plate so I can use a Hassy SWC focusing screen on it and use it that way also . i can focus than replace with back when ready to shoot when being tethered is not a option. Look forward to seeing some images .

Jim Collum has the same setup also and soon a few others here as well:D
 

Guy Mancuso

Administrator, Instructor
I was actually looking at a Silvestri Bicam and Flexcam and trying to figure that out . Be nice to have a technical camera that maybe able to do the same thing.
 

Woody Campbell

Workshop Member
After a number of false starts (instructions are scant on the subject of using Hasselblad backs on third party cameras) and trial and error I got the combination working reliably. The key issue in my mind was how do deal with the color casts across the frame that you expect when shooting non-retro focus wides digitally. This image illustrates the problem (f8 shifted 10 mm in the direction of the left side of the frame):

View attachment 5056

Nasty isn't it.

On another thread where I first raised this issue I learned that FlexColor includes the ability to shoot a white reference frame - FlexColor applies corrections to subsequent frames based on the reference frame. Phocus 1.0 does not include this feature - this is an absolute must for the next release. In FlexColor shooting tethered you shoot the reference frame (I use an Expodisk), identify it as a reference frame; FlexColor uploads it to the back and subsequent frames are properly corrected. This too took some trial and error - the reference frame seems to work best if exposed to the middle grays. The most common mistake I made was not turning this adjustment off when shooting a new reference frame - otherwise the adjustment is corrected with the last adjustment leading to very weird results. You can use this feature shooting untethered, making the corrections when you import the images to FlexColor, but you need to tether the camera to activate the feature (think of the camera as a gigantic dongle).

So here is the white reference frame for the above image:

View attachment 5057


And here's the image as corrected by FlexColor:

[View attachment 5058

Even on the web you see one of the advantages of the Hasselblad - absolutely lovely color straight out of the box.

Note to Hasselblad: Please, please include this feature in the next release of Phocus.
 
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Woody Campbell

Workshop Member
Finally, on the lens: this is a very, very fine lens. It almost no barrel/pincushon distortion which is terrific for architectural subjects, but the laws of nature for wide angle lenses are what they are so there is some distortion of the shapes of objects at the edge of the frame. It's very sharp at the center. I can't really comment on edges at this point. The samples below were shot at f8 (I decided to work with light from the window to avoid mixed lighting). Focus is perfect on the central wine bottle (Phocus has a very cool focus aid in live view) but the focus plane may not be parallel to the wall so the lower left wine bottle may be out of focus a tad.

Here is the center crop:

View attachment 5060

Here is the corner crop. Note the geometric distortion. As noted above it looks like focus is slightly off in the corner.

View attachment 5061
 
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Guy Mancuso

Administrator, Instructor
Woody I have a special calibration target that Phase included in my package . So all I would do is take the reference shot with the target over the lens than C1 will create a calibration for the lans and make the corrections as you did in Flexcolor . I agree Phocus should also have this feature.

Maybe Jim can chime in and tell us what he uses for his Aptus 75. I am new to the Horseman so may take me a little bit to get going
 

Woody Campbell

Workshop Member
Finally, some stitches. I set the back on the camera in portait orientation and did horizontal shifts. This setup is a joy to work with compared rotating the camera. Of course if working in color you need a separate white frame for each shift. 10 mm left and right shifts are comfortably within the lens's image circle at f8 and result in and 8400x7200 file. I was surprised that the full 17mm shifts were also within the image circle at f8 - this results in a roughly 10000x7200 file. The latter pixel count is getting up into the scanning back range, which is the reason to do this.

Here is the stitch (PTGui) with 10mm shifts (the geometry of this image suggests that the focus is actually slightly behind the bottle on the floor):

View attachment 5065

Here is the stitch (Autopano Pro) with 17mm shifts:

View attachment 5066
 

PeterA

Well-known member
Interesting..vignetting with these wides is a fact of life - but fortunately pretty easily corrected with thsoftware these days..you didn't think of the Rodenstock 28 instead of the 35?
 

Guy Mancuso

Administrator, Instructor
Peter the Phase package is the 35mm but if you want a 24mm it is a little more. Thought about a 28mm myself
 

Guy Mancuso

Administrator, Instructor
See the one issue is the natural distortion of these lenses as Woody has mentioned. I would think the longer lens would be better since there is less of that and a 3 vertical stitch can still get you pretty wide.

Be interesting to know what focal length like the 24,28,35 and 50 would be the new effective focal length with a three vertical stitch. Does anyone have that type of info. Would be nice to know after a 3 stitch what the new effective focal length of the images is
 

Woody Campbell

Workshop Member
Interesting..vignetting with these wides is a fact of life - but fortunately pretty easily corrected with thsoftware these days..you didn't think of the Rodenstock 28 instead of the 35?
The 28 has a fairly limited image circle that doesn't give much scope for shifts. Since I bought the Horseman primarily for the shift capability the 28 didn't seem like the best choice. In any event I've got the HC 28 when I need that focal length.
 

Woody Campbell

Workshop Member
See the one issue is the natural distortion of these lenses as Woody has mentioned. I would think the longer lens would be better since there is less of that and a 3 vertical stitch can still get you pretty wide.

Be interesting to know what focal length like the 24,28,35 and 50 would be the new effective focal length with a three vertical stitch. Does anyone have that type of info. Would be nice to know after a 3 stitch what the new effective focal length of the images is
I could make the calculations but its not necessary. Here's where you M8 kit comes into play: pop you Frankenfinder on the Horseman. There is a slight bit of play which you can fix by putting a small patch of the fuzzy side of velcro on the bottom of the finder shoe - I've done this with all of my finders after losing while carrying the m8 under my arm.

You'll need to make some mental adjustment for the difference in aspect ratio but the 24mm lines fairly accurately frame the unshifted 35mm; the 21mm lines fairly accurately frame the 10mm shift stitch, and the 18 mm lines fairly accurately frame the 17 mm stitch. Since the Frankenfinder doesn't rotate the ability to rotate the back is important. The parallax correction works pretty well. If you set up the camera tethered with liveview and the frankenfinder you can sort this out for yourself in a few minutes
 

Guy Mancuso

Administrator, Instructor
Thanks Woody I may have to explore other external finders and been thinking about that . The one supplied is very very nice but BIG
 

Woody Campbell

Workshop Member
Here is another image - this one demonstrating the Horseman + 35 in action as a "view" camera. The image below takes advantage of 10mm of shift, dropping the field of view while preserving geometry. It turns out that 10mm is quite a useful amount of shift. The image is a composite of 3 focus bracketed shots put together with Helicon Focus. Exposure was at f16. With this setup you really see the trade off as you stop down to reduce vignetting and enlarge the image circle - diffraction significantly reduces contrast and resolution in the center.

Full image (the horizon gives you an idea of how far the shift is):

View attachment 5206

Center crop (180% sharpening - diffraction really has had an impact here; note the moire in the brick):

View attachment 5207

Crop showing Hellicon Focus working flawlessly between the foreground and the background (there was a bit of wind - Helicon's rendering of the plant on the right, which moves between images, looks like it results from a long shutter time - a good result):

View attachment 5208

Edge crop, showing a fair amount of general funkiness - 10mm is about the limit shifting this lens unless you are looking to create an effect:

View attachment 5209
 

lance_schad

Workshop Member
Woody sorry I am bit late in responding to this. We offer a small plexi plate that we use for the PhaseOne systems, that I am sure should work for the Hassy system. Here is what it looks like. I am going to send one out to you today.
BTW looks like you are getting the hang of the system. Enjoy.


Lance Schad
Capture Integration - Miami/Atlanta
305-394-3196 cell | 305-534-5702 office
Capture Integration
My Blog
[email protected]
 

Bob

Administrator
Staff member
Lance,
Does that replace or work better than a center filter or do you use both?
-bob
 
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