Help with process for creating very high resolution images from my large format paintings.

@Kevin Stohlmeyer  Thank you for your suggestion. It is a very practical recommendation and I will do this on a case by case basis for sure.

@Conrad_C  Thank you for the great question and useful notes on PPI and setup equipment. My wife and I have a studio gallery. She is a painter able to work in acrylic and/or oil with a focus on abstract to portrait artworks. My long-view “end goal” is to build and maintain digital archives of all of her artworks (the ones already painted through the ones to come). These archives will be our intellectual property and allow us, now and in the future, to print artworks at any size - from smaller to larger. The format could be inkjet on canvas, inkjet on paper, Digital C-Prints, “fine-art” posters, posters, possibly for screen printing separations, coffee table book, art-book and of course digital. I’ve always loved the Rijksmuseum and their super high resolution digital images of the Dutch masters, but will not be aiming for that level.

The smallest paintings are 4” x 4” and the largest one is the 96” x 72” mentioned above; there is the possibility that paintings even larger than that are on the horizon. I watch people in the studio/gallery and they often run through all the possible viewing angles, from far enough back to view the entire artwork, to nose-practically-on-the-canvas. Once an artwork gets into a home or business, it is unlikely it will get the same level of scrutiny. The goal of a reproduction is to make art more accessible by bringing the cost down. At some point there has to be a reason that a client would purchase the original painting or a commission, and not a reproduction, so for a large painting I’d say a DPI that can satisfy a 24” to 36” viewing distance would be appropriate…

I can certainly do, and am doing, my own research, but if you have any links to specific bubble levels or laser rangefinders that you would use please share them here for reference.

@D Fosse  The setup and right equipment is a big concern for sure. A rig seems critical for the process and I’ve started to draw something out that is very DIY with wood, metal rails, dolly wheels, etc… shooting downwards, with a repro-stand like setup would be great - I will plot something out for that as well to see if it is practical. I have been shooting on the wall and it is destined for flaws if high-quality archival material is the end goal.

The lens - now that is some new information for me. Many of the articles I’ve read spoke so highly of the old manual Micro Nikkor 55. Is this the lens that “runs rings” - https://www.kenrockwell.com/nikon/60mm-afd.htm

Thank you for mentioning the “anchor” frame too. I had read that in an Adobe tutorial before so this is a good reminder.

@Per Berntsen  Yes, indeed, everyone has share some great advice and asked good questions too. As I mentioned above when answering Conrad, I am shooting not for a specific print format but it would certainly include inkjet and potentially C-Print. 180 ppi does seem reasonable, especially for the big ones that require stitching.

How do you get your 33” x 44” prints to 12,960 x  17,280 pixels?

@SemaphoricThank you... do you have any setup guides or links to other websites that provide setup configurations for the type of rig you are talking about to shoot down at the painting on the floor?

Thank you to everyone who provided some insight! I will focus my equipment setup questions towards the photography community and also archivists at museums too as Conrad points out.

That sounds like an interesting project. Do yo plan to print it full size? I remember how impressive it was to walk up to a mural-sized print from 8x10 sheet film, and see details from inches away that were invisible from across the room. I've often wondered how practical/impractical this would be to do digitally.

Are you going to use some sort of rig to do the shoot? It might be easier to move the painting than the camera: set up the camera pointing downward, and place the painting on the floor, face up. Shoot step-and-repeat, the canvas moving across and down . With a stationary camera and a level floor, things should stay in alignment. Lighting would have to be even corner-to-corner, but that's certainly do-able.

You have been given lots of good advice here.

If the end goal is an inkjet print, you may find this useful.

I do my own printing, and routinely make 33 x 44" prints on an Epson P8000 printer.

Print quality is extremely important to me, and I want image detail to appear the same way in print (when viewed up close) as when viewing the image at 100% on my computer.

I have found that 180 ppi is sufficient to achieve this. 150 ppi will affect very fine detail slightly, but this will only be visible if viewed through a magnifying glass. (I can just see it if  I take off my glasses, I'm near sighted, -4)

If you aim for 180 ppi,  you will need 12,960 x  17,280 pixels, which will allow for some overlap.

21,600 x 28,800 will require 300 ppi, which is overkill for large inkjet prints.

+1 to what Kevin and Conrad say.

As for aligning the camera, it's critical that you maintain strict 90° angle throughout, or you will get out of focus areas. If you shoot down, e.g. from a repro stand, you can use a mirror. When you see the lens at dead center of the viewfinder, the angle is correct.

On a wall you can't do that. I have a small laser rangefinder that I use to measure the distance to each corner. When stitching pieces of a bigger artwork, the difficulty is obviously to hit the actual corner of the frame. It's tricky, but I haven't yet found a better way. So I prefer to shoot down to the floor whenever possible and use the mirror.

The lens is critical. It needs to be flat-field, but most dedicated macro lenses are. And then there's geometric distortion which can be a problem even with the best lenses (there's always some). You need generous overlap so you don't need to use the corners.

However, I'm not sure I would recommend such an old lens. Film had nowhere near the resolution of modern digital sensors. Lenses have improved enormously in later years to meet the much higher resolution requirements. Back when I used Nikon, I tried some old micro-nikkors on a D810 (55 and 105), and was very much not impressed. A newer lens such as the micro 60/2.8 runs rings around them.

EDIT - one more thing: to assist with the stitching, it can sometimes help to make one full-frame shot of the entire artwork. Put this at the bottom of the stack, scale up to the desired size, and run auto-align. The bottom frame is the anchor that the others align to. Then discard it when done.

What is the end goal, is it a specific medium (like a coffee table book) or some form of general archiving? Or recording enough information to reproduce or virtually study the painting at actual size in the future? Because for basic documentation of a work it sounds like an unusually and possibly unnecessarily large file in terms of pixel dimensions.

I agree with Kevin that generally, the larger the artwork, the lower the ppi of the file needs to be, because the typical viewing distance is greater. For example, 300 ppi at around three feet viewing distance (arm’s length) is about the same amount of effective detail to the eye as 150 ppi at around six feet away. A 96" x 72" painting is likely to be viewed from more than six feet away if the entire work is to be properly seen at once, so a reasonable ppi for that file can be well under 300 ppi even if you leave some margin for someone to walk up a little closer to a full-size reproduction.

Your best resource is other photographers who specialize in photographing large artworks. They probably have ready made techniques and equipment that they commonly use. If you don’t know any, you might ask the archivists at any museum or gallery near you, to find out which photographers document their large artworks.

I’m not an expert in that area, but if I was doing it I might set up bubble levels and laser rangefinders to ensure that the camera is always oriented consistently from shot to shot. That it is level, pointed precisely perpendicular to the painting, always exactly the same height from the floor for each row, and always exactly the same distance from the painting, with horizontal intervals marked on the floor in advance.

@EonsCreative1 you should speak with your printer first to find out just how large your original image needs to be for printing. Most large format prints are actually lower resolution not full/hi-res at full size.