Stitching with 72mm on CamboWRS & Sinar54LV

[Aaron]

Hi all,
My first post, thanks for such a great resource, it seems like a great place to ‘hang out’.

So here’s what I am trying to figure out:

I would like to purchase a tech camera, most likely the Cambo WRS and use it with a mfd back for flat stitching. I am trying to figure out what lens to start with.

Apologies for 35mm terminology but I am a bit of a large format virgin . I want to achieve a field of view similar to 24 or 28mm lens on 35 full frame.

So bearing in mind that I will be stitching to achieve this field of view what lens is the best to start with? I have been looking at the image circle of the various Cambo mounted optics and they vary a bit so I am unsure if they are all suitable for stitching. I am thinking that the “WTS Tilt/Swing Lenspanel with Digitar 72 mm Lens” is the right one, its stated on Cambo’s site that the “Image circle of lens at f/11: 90mm”. But a 90mm image circle won’t give enough coverage to use the full area available for flat stitching, so what do I not understand here? Does the image circle expand at smaller apertures?

I am considering purchasing a used Sinar 54 LV back for this project. Are there any issues I should be aware of with using the sinar on the WRS? I expect to have to have to use lens cast calibration frames but other than that, I am in the dark, so to speak with regard to other potential issues.

Finally, focusing. After reading Joseph Holmes’ article on ‘MFD Precision’, I am wondering if the addition of the new Tilt/Swing lenspanel offered by cambo will add further to focusing issues, is anyone using the cambo WDS-619 ground glass for focusing? Any thoughts on this Cambo combo?

Sorry for the meandering post, to summarize, I am considering:

Cambo WRS
Digitar 72 mm Lens (possibly with tilt/swing option)
Cambo WDS619 Ground Glass
Sinar 54 LV (for stitching)

Any thoughts, suggestions or alternatives greatly appreciated,

Aaron

 

[carstenw]

The 54LV has a 48x36mm sensor, and all the various lenses have real focal lengths on them (apart from the Hasselblad HCD lenses; not relevant in this context), so the calculations should be made based on that.

Keep in mind that 35mm has an aspect ratio of 3:2 and the 54LV 4:3, so the equivalent focal length might seem a little wider. Converting from 24mm on 35mm FF to a sensor exactly double that side is a question of multiplying by the ratio of the diagonals, to use the most common approach:

sqrt(24^2 + 36^2) ~= 43mm
sqrt(48^2 + 36^2) ~= 60mm

24mm (35mm-FF) = 24 * 60/43 = 33mm (48x36)

So perhaps one of the 37mm lenses would be okay, without stitching. If you take twice that focal length (the 72mm), then you would need to stitch 4 images, and the image circle would have to cover this. Are you sure you need so much resolution? You could do it in a single shot.

 

[Graham Mitchell]

So bearing in mind that I will be stitching to achieve this field of view what lens is the best to start with?

Do you want to stitch, perhaps for extra resolution?

 

[stephengilbert]

Aaron,

You can find a post with the Schneider image circles here, http://forum.getdpi.com/forum/showpost.php?p=110480&postcount=128, and an illustration of stitching options.

Steve

 

[Aaron]

Thanks Carsten, Graham & Steve.

To give some background on this, i will be shooting a project for an artist friend who creates sculptures in woodland settings. He needs large prints, 60 inch ish on the long side. He's a picky bugger and will probably show up with 10x loupe to see the prints, they will be going on permanent display in his gallery......

So, yes i need as much resolution as i can get which is why i am considering stitching. If cost was no object i guess i could purchase a p65 and go down the single shot route, which would be an easier workflow but at an obscene (for me) financial cost.

My 'analogue thinking brain' also tells me that 4 or 6 stitches on a 22mp back will give me a better file than what a higher res back could achieve in a single shot- especially if done with a mfd body/lens, It would be asking less of the lens i think, but could be wrong.

I think i will need about 60-80mp to get the quality i need, so i guess 4 stitches on the 72mm lens would achieve that.
Thanks for crunching those numbers Carsten, if a higher res back didn't cost more than my house it would be the obvious route with a 35mm.

Looking at the graph linked to by Steve:thumbup:, it seems that the 35mm and 72mm lens give the most versatility with stitching, so i am considering picking up both of those.

Does anyone have experience of using the 54LV on a tech camera? Is LiveView usable out of the studio, untethered? If so i imagine it would make focusing a lot more accurate?

 

[carstenw]

There is no live view out of the studio, untethered. Medium format live view in general is just another way of saying good tethering. To be sure, MF tethering is probably better than anything you will get in 35mm-land. In the field, take the photo, check for composition and histogram on the back. Checking focus and colours is impossible with MF backs, directly on the screen. You will need to bring a laptop if you need that level of workflow.

I own a 54LV (which I sadly find very little time to use these days; I am not a pro) but haven't tried tethering in the field. It works well tethered in the studio, or un-tethered in the field, but to be honest, I am not quite sure why they call it LV.

Graham is a pro, and is much more experienced with his back than I am, and should be able to add more information.

 

[Chris Barrett]

On another note, Aaron, without doing the math, I don't think you're going to get there with shifting. The WRS has 20mm in each direction (I believe), which I'm sure won't cover 4 shifts.

 

[carstenw]

In that case, the 72mm is too long. Getting the 47mm might be better then, but would get you closer to 60MP than to 80MP, if I guesstimate right.

 

[Chris Barrett]

Aaron, just read above that you are considering the 35mm. Do NOT buy this lens for stitching! Regardless of the image circle available, the lens has to be so close to the sensor to focus that image softness (due to diffraction) occurs within 7mm of shift. I have tested the Schneider and the Rodenstock, finding this a problem with both.

 

[thomas]

i will be shooting a project for an artist friend who creates sculptures in woodland settings. He needs large prints, 60 inch ish on the long side.

as to the motif ... I guess you don't have to place your camera extremely close to the sculptures. So a longer lens is certainly better than a wide angle as you don't want to stitch to get a wider angle of view but to gain higher resolution. The 72mm is probably the better choice here - unless there is really no way to keep a certain distance to the motif.

As to the resolution ... the more you move the lens the less effective resolution you'll get. Though a higher pixel pitch is basically more foregiving regarding shift I'd say this a job for a P45 or the Sinar 75LV or so - you'll get roughly twice the resolution within the same frame.
On the other hand 4 frame stitching (overlapping of course) with a 22MP back will be sufficient.

As to the WDS619 Ground Glass... you can order it with a fresnel screen. It's brighter and clearer as the regular matte screen. Upside is it's much easier to focus with the fresnel screen. Downside is that the clear view on the fresnel screen is limited to the center of the image... when you move the center of the screen away from the center of the lens you can't see the edges very good (unless you look at the screen from a steep angle).
For your job I'd recommend a small laptop and to shoot tethered.

 

[Aaron]

Wow, nothin is ever straightforward!

Carsten:
Thanks for the update on the 54LV, its diappointing to learn that its not really live view but thats what i feared. I think a small laptop will have to be factored in.

Chris:
You may have saved me a bi chunk of money on the 35mm. It was definitely on my short list. And your right about the shift capability of the WRS, 20mm in each direction so 40mm total, for some reason i thought it covered closer to the traditional 5x4 area but it seems to be quite a bit smaller which is relevant as i was basing my decision on the 72mm being similar to a 24mm on 35mm slr. which its not if the usable stitch area is reduced.

Thomas:
Thanks for the info. As to the relationship between the sculpture and its surroundings/lens focal length, i think the actual surroundings are considered part of the 'art piece' so i may need to include as much of it as possible as a back drop to the sculpture, so am veering towards wider lenses.
As to the groung glass, i am concerned that since its not incorporated with a sliding adaptor that between focusing, removing the groundglass and attaching the digital back that i will have movement negatively affecting focus. Do you think this is an issue?

So no i think i need the 47mm which has a very wide coverage for stitching and am still considering the sinar54lv but now tethered with a small laptop also.
Any ideas on this combo, does the 47mm cut the mustard?

 

[carstenw]

I should point out that Sinar has stopped making backs. They still sell what they have, and they continue to support them fully. Having said that, you can get some excellent prices on them (about €7000 new including adapter and taxes, closer to €5000 used), much lower than Phase One, for example. The new Leaf backs are another option, but they may only come in Mamiya mount, which may or may not be what you want. The Sinars have adapter plates for most cameras.

 

[thomas]

As to the groung glass, i am concerned that since its not incorporated with a sliding adaptor that between focusing, removing the groundglass and attaching the digital back that i will have movement negatively affecting focus. Do you think this is an issue?

no, I always use the groundglass. You are replacing the entire back-frame so the fit is accurate.

Any ideas on this combo, does the 47mm cut the mustard?

I use the Digitar 47XL and I'd say it's a great lens. You have to stop down. But when you are stitching you have to stop down to f11 or f16 in any case.
note that the image circle is specified for infinity. At closer distances couverage is a bit less.

 

[Don Libby]

Kicking back from cooking my Yosemite images and decided to offer my 2¢ worth.

As many of you know I have the WRS1000 and a P45+ along with the following Schneider lenses - 24mm no movements whatsoever and you had better make certain the camera is centered; 35mm and have been able to achieve good results with shifting out to 10mm; 72mm and have been able to achieve good results with shifting out to 15mm; and the 120mm and have shifted out to the max with little problems. I also have and occasionally use the WDS-619 Groundglass. In hindsight I wish I also had the 47mm - maybe next year.

I'd suggest the 47mm should be the lens you'll be needing and also agree that shooting tethered will be the easiest/fastest way to go for this project. I use a 64bit laptop and C1 currently does not support tethered shooting however I believe that will catch up by the end of the year.

Good luck!

Don

 

[Aaron]

I should point out that Sinar has stopped making backs. They still sell what they have, and they continue to support them fully. Having said that, you can get some excellent prices on them (about €7000 new including adapter and taxes, closer to €5000 used), much lower than Phase One, for example. The new Leaf backs are another option, but they may only come in Mamiya mount, which may or may not be what you want. The Sinars have adapter plates for most cameras.

Yes i was aware they have exited the back market but since i am buying second hand, the value is already depreciated, so if i got a years use out of it then i would happy.

 

[Aaron]

Kicking back from cooking my Yosemite images and decided to offer my 2¢ worth.

As many of you know I have the WRS1000 and a P45+ along with the following Schneider lenses - 24mm no movements whatsoever and you had better make certain the camera is centered; 35mm and have been able to achieve good results with shifting out to 10mm; 72mm and have been able to achieve good results with shifting out to 15mm; and the 120mm and have shifted out to the max with little problems. I also have and occasionally use the WDS-619 Groundglass. In hindsight I wish I also had the 47mm - maybe next year.

I'd suggest the 47mm should be the lens you'll be needing and also agree that shooting tethered will be the easiest/fastest way to go for this project. I use a 64bit laptop and C1 currently does not support tethered shooting however I believe that will catch up by the end of the year.

Good luck!

Don

Thanks Don! I think i am definitely going for the 47mm with a tethered back and small laptop. (my artist friend/client will be used as a mule).
My only decision now is whether to go with the standard 47mm or the newer tilt/shift mounted option. I called calumet UK yesterday (i am in Ireland)but they dont seem to know what i am even talking about so thats not promising. Depending on whether they are stocked in the Calumet NY, i could pick up one there. I would rather purchase as close to home as possible in case i get a bad lens.
How have you found the quality control on these Cambo mounted optics are?

 

[thomas]

My only decision now is whether to go with the standard 47mm or the newer tilt/shift mounted option. I called calumet UK yesterday (i am in Ireland)but they dont seem to know what i am even talking about so thats not promising.

The TS mount was announced to be available in autumn; maybe it's not ready by now. But you can buy without TS mount and retrofit the lens later when the TS mount is available (doesn't help you now, but still).

BTW: here's an example of the 47XL shifted to the maximum on the WRS with an P45.
http://forum.getdpi.com/forum/showpost.php?p=114836&postcount=21
You have to be logged in to see the full rez JPG with an indication of the shift in mm on the top: http://forum.getdpi.com/gallery/showimage.php?i=5177&original=1&c=newimages&cutoffdate=1

 

[Aaron]

The TS mount was announced to be available in autumn; maybe it's not ready by now. But you can buy without TS mount and retrofit the lens later when the TS mount is available (doesn't help you now, but still).

BTW: here's an example of the 47XL shifted to the maximum on the WRS with an P45.
http://forum.getdpi.com/forum/showpost.php?p=114836&postcount=21
You have to be logged in to see the full rez JPG with an indication of the shift in mm on the top: http://forum.getdpi.com/gallery/showimage.php?i=5177&original=1&c=newimages&cutoffdate=1

Yes that may be the best option, just purchase the standard 47mm now and retrofit later. I assume this tilt/shift adaptor is intended to be left on the lens permanently, so if you have 3 lenses you need 3 t/s adaptors?

Thanks for the link to the images, the quality there speaks for itself. I'd rather not be looking at files from P45s though! Expensive, Slippery slope..

 

[thomas]

Thanks for the link to the images, the quality there speaks for itself. I'd rather not be looking at files from P45s though!

no, no... a 22MP back will be very similar. Actually sharpness falloff with large movements should be less with the wider pixel pitch. So IQ should be a bit better at the edges but resolution overall, of course, is less.
If you need to do some uprezzing I highly recommend the application "Blow Up2" from "Alienskin". I am finding it much better than Photozoom Pro or anything else I've ever used.
Basically I feel 200% enlargement of the native image size is still very, very good. Even more is possible within limitations. Usually the word is that the diagonal of the image size should be considered as viewing distance for prints. Me personally I am considering half the distance as my critical limit... and I am finding enlargements of around 250% based on good captures (without shake etc.) with the right scaling tool and sharpening technique is still really good (depends on the motif as well, of course).

 

[Peseecot73]

Stitching with 72mm on CamboWRS Sinar54LV

I agree. Ive started scanning and stitching my 12x12s and double layouts again because I keep getting "wonky" pictures and always have some of the table showing somewhere on one or two of the sides of my layout pics.

I dont use photoshop to stitch my layouts though. I used IPPLUs --- a program that came with my computer.