Arca Swiss factum shift capability for stitching?

[Jim2]

Hi, I'm wondering how much stitching is possible with the new rm3d factum? Can someone illustrate it with a phase back + sample lenses? I know they published the amount of shift possible, but how does it translate into megapixels if added up together, in comparison to its bigger brothers rm3d(i) ?

Thanks

[Paul2660]

Jim, I am assuming you are referring to the R and L total amounts of shift.

From looking at the spec's it appears the new Factum allows 15mm of left and 15mm of right shift.  That is no different that the rm3di which is also 15mm max R/L horizontal shift.  Only the RL3d or new RL3di have 20mm of R and L shift.  It appears that the RL3di is an upgraded version of the RL3d which now looks very similar to the appearance of the rm3di.  The 15mm of shift max in the default camera position is a bit of negative for me and both Cambo and Alpa have 20mm in most of their shifting bodies. 

You can rotate the rm3di 90 degrees and use the default Rise of 30mm and fall of 20mm as R and L shift.  It will require an L bracket with an Acra mount.  Arca makes one as does Really right Stuff.  I am sure there are others.   I use the RRS version. 

If you are using a 60mp back, in landscape orientation, 15mm gives you about 1/5 of a frame of new material,  Not really that much.  I feel you need at least 20mm of shift to really start getting a pano type shot.  This of course brings up another issue, that most of the Schneider and or Rodenstocks in the wider sizes will not hold up to even 20mm of shift before you start to see serious color shifting, detail smearing, and total loss of color saturation.  Here are examples all from using a 60mp back.  For a true pano, the use of a pano head and determination of the nodal point works much better.  This requires being level so many times depending on the shooting situation, it won't work.  Total MP increase maybe 60mp to 80/85mp @ 15mm of total shift.

Rodenstock 28mm IC 70mm about 7mm max horizontal shift (This lens might go further however Rodenstock places a hard disk inside the lens which you start to see visually after 7mm.  The disc puts hard hard edged vignette on the shifted image.  The LCC will correct this problem.   I have not shot the 23mm Rodenstock but it's on the same design as the 28mm, has the same image circle and internal disk so I think it's safe to assume about 7mm of shift with it also. 

Schneider 35mm IC 90mm About 12mm max.  After this color saturation falls off to the point of not useable and the detail smearing gets very harsh, ever at F16.

Schneider 43mm IC 110mm About 18mm max.  At 18mm you will see slight color/sat fall off but very little detail smearing.  I have pushed this lens to 20mm and gotten an OK image with it.  However if there is a lot of sky you will have some problems.  Sky without clouds pure blue.

Schneider 60mm IC 120mm This lens will go to 30mm of shift at F11.  It's an amazing piece of glass.  With the rm3di rotated 90 degrees, I will use this lens 30mm L and 20mm R in horizontal shift.

As you get  past the 60mm focal length, image circles tend to be in the 110mm to 120mm size and most of the lenses will accommodate shifts up to 25mm without loss of details. 

These are all my results with the rm3di on a 60mp back.  I am sure that other photographers results and or opinions will vary from mine. 

Paul

[Guy Mancuso]

I would tend to stick with the 60mm XL as your starting point lens to get out to 20mm to stay out of any trouble. Anything shorter your going to have a fight on your hands. Staying in the 15mm range working with a shorter focal length would be easier. I owned the 60 and it's a beauty of a lens , maybe sharpest one around actually but getting out to 20mm with a LCC is no problem . At least with the IQ 160 back. The IQ 180 I never tested with that lens and 20mm but it could have a issue.

BTW my experience mirrors Paul in all regards to these lenses on my Cambo as well.

The Rodie 23 is about 3mm so not a lot of movement.

[Doug Peterson]

As is often the case with such things there is more than just the numbers. However Guy and Paul have given you some good guidance on which lenses can take large movements. My only addition is to affirm Guy's statement that the 60mm XL can take just about anything you throw at it. With a 120mm image circle and excellent optical characteristics the 60mm XL is a great choice for what you describe.

https://digitaltransitions.com/images/upload/AS_factum-stitching.jpg]
Click above to bring up the full size diagram.

[Paul2660]

Doug,  Thanks for the IC graphs.  As you and Guy pointed out the 60mm Schneider is a special lens, great versatility.  Sharp as a tack and great size and weight.

Paul   

[Doug Peterson]

Wideness
If stitching panoramic aspect-ratio images interests you here is a comparison of the view provided by the following:

• 60mm XL with IQ160 Single Shot
• 60mm XL with IQ160 2-frame Stitch on Factum
• 60mm XL with IQ160 3-frame Stitch on RM3Di

Resolution
The frame size of an IQ160 is 53.9 x 40.4mm. You can calculate the increase in resolution by comparing the area with and without stitching. For instance:

IQ160
Single shot: (53.9 x 40.4): 60mp
Factum 2-Frame Pano Stitch (+/-15mm): 83.9 x 40.4mm = 93mp
Factum 2-Frame Std. Stitch (+/-15mm):  53.9 x 70.4mm = 105mp
RM3Di 3-Frame Pano Stitch (+30mm, -20mm): 103.9mm x 40.4mm = 116mp
RM3Di 3-Frame Std. Stitch (+30mm, -20mm): 53.9mm x 90.4mm = 134mp

Again for those stitches, especially the 100mp stitches, to hold to the high-quality that is expected of these systems you'd need a lens with great image circle. The RM3Di 3-Frame Pano Stitch may not be possible in practice even with the 60mm XL. As you can see from the diagram it would hit the extreme edge on one side of the image circle (and Schneider tends to be a few mm optimistic/generous on their stated image circles).

[Guy Mancuso]

Doug,  Thanks for the IC graphs.  As you and Guy pointed out the 60mm Schneider is a special lens, great versatility.  Sharp as a tack and great size and weight.

Paul  

It really was my favorite lens . Most people seem to ignore though and go 40/43/47 as there base lens than jump the 60 and get a 70/72 lens. In a 4 lens kit makes some sense. The 60 seems to fit better in a 3 lens kit or maybe I should say most popular kits. Great 3 lens kit would be 32/35, 60 and 120. I dragged it out further to 28,60,120.

Popular 4 lens kit 23, 40/43, 70/72 and 120. Obviously depends on needs but my advice find your base lens like 32/35 or 40/43 than build around that. I kind of in later time with the Cambo based it around my 60 I liked it so much and sold my 35 and went 28. The 60 you can just hammer it all over the place with movements and stay out of any real trouble.

It's also a great focal length for doing Panos with as well and I did that a lot.

[Jim2]

Thank you Paul for a VERY clear and easy to understand explanation. Thanks Doug for the example, chart and the added details.

[Rod.Klukas]

Some more information for you:
The dimensions of the Rm3d factum are the following:

Body only, without VarioFinder attachment, tripodhead plate and Adapter or Ground glass:

13.5 x 14 x 4cm  or 5.3 x 5.5 x 1.6"


Body withVarioFinder attachment, tripod-head plate, and ground glass:

13.5 x 18 x 5.5cm  or 5.3 x 7 x 2.2"

Weight: 640gr.

Rod

[Jim2]

Thanks rod. Is that weight with the "tum" or just the "fac" ?

[Christopher]

Should be weight for the full factum.

[Yat]

Couple questions.

1. What is the rise/fall on the factum? This is separated from the L/R shift I assumed.

2.  Does the ground glass option covers more than the single frame or the whole stitchable frame?

Thanks.

[Doug Peterson]

1. There is one direction of movement; oriented in the standard position this movement is a rise/fall. You turn the camera to the side for shift. If you want compact with rise/fall and shift at the same time I suggest the full RM3Di. The beauty is if you get the full RM3Di you can add a factum to your kit just by buying a "fac" frame (since you already have the "tum" as part of the full RM3Di.

Alternatively the Cambo Wide RS1250 is compact, hand holdable and has both rise/fall and shift natively.

[Doug Peterson]

2. The whole stitchable frame.

[Yat]

Thanks Doug. Look forward to the pricing on factum.

[Rod.Klukas]

Doug,
The factum has tilt and rise fall in normal position.  When tipped to the side, it then has lateral shift and swing.
Rod

[Yat]

I guess another option for stitching while maintaining the rise and fall is use a rail to rotate the camera. Assuming the nodal point is set properly, is there any draw back for using this method rather than back stitching? Is there anything I should be aware of?

[andyptak]

Guy - What would you call a perfect 3 lens kit for Architecture? I currently have a 35 and a 47 and was considering a 43, but the image circle on the 60 is very compelling for stitching - might be too long though ??

[Rod.Klukas]

May, I please also note that while a camera's specifications may say that it can move 20+ - for shift, for example,  the lens mount design on some cameras is such that with they have narrow snoot and position it may mechanically vignette much sooner than a camera with a large throat and and larger lens mount.  Thus having the larger throat and mount,  would then actually allow for greater movement than a camera which on paper seems capable of more.

[ChristopherBarrett]

Guy - What would you call a perfect 3 lens kit for Architecture? I currently have a 35 and a 47 and was considering a 43, but the image circle on the 60 is very compelling for stitching - might be too long though ??

The Schneider 43 is my go to lens for architecture.  My favorites on 4x5 were 90 & 115, so this makes sense on the P65+.  I also carry the 35 and Rodenstock's 55 and 70.  Sometimes you need a little wider than the 35.  I prefer using the 5d2 and 17mm TS-E on those occasions.  Once you get to 60mp and beyond, the 24 is useless and the 28 didn't seem worth the effort.