Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: Paul Wright on April 11, 2018, 07:55:42 pm
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I have a couple of clients I shoot paintings for, and this area looks like it's going to grow as through multiple referrals.
I've been shooting tethered 5D4, 70-200 f/2.8isII at around f/8 with polarizer and also polarized lighting. For large paintings or where there are space constraints, the 24-70 f/2.8II gets the job.
A bit of research on the shooting art suggests I should be using flat field glass for better results, regardless of the lens corrections that Lr can automatically apply. I have a L 100mm f/2.8is macro which I imagine is flat field, but 100mm is generally too long for average painting sizes.
Any suggestions on an appropriate lens? I see Canon has a now obsolete 50 f/3.5 macro and a 60mm macro with useful tripod collar for quick rotation. There are plentiful used, superseded 45mm TS-E to consider too. I need good glass, but the budget doesn't run to Zeiss Otus level.
-pw
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Try a Rodenstock Rodagon WA 60mm enlarger lens. It's a flat field lens, excellent micro contrast, and virtually no linear distortion.
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I have a couple of clients I shoot paintings for, and this area looks like it's going to grow as through multiple referrals.
I've been shooting tethered 5D4, 70-200 f/2.8isII at around f/8 with polarizer and also polarized lighting. For large paintings or where there are space constraints, the 24-70 f/2.8II gets the job.
A bit of research on the shooting art suggests I should be using flat field glass for better results, regardless of the lens corrections that Lr can automatically apply. I have a L 100mm f/2.8is macro which I imagine is flat field, but 100mm is generally too long for average painting sizes.
Any suggestions on an appropriate lens? I see Canon has a now obsolete 50 f/3.5 macro and a 60mm macro with useful tripod collar for quick rotation. There are plentiful used, superseded 45mm TS-E to consider too. I need good glass, but the budget doesn't run to Zeiss Otus level.
-pw
Ideal for what, Web display or reproduction? If the latter, see this: http://renotype.com/2016/06/28/image-capture-for-fine-art-reproduction/#.Ws_RTtPwZBw
If the former, I would say that a dslr with a high-quality macro prime lens of about 50mm to 60mm, with low rectilinear distortion, high flatness of field and high corner-to-corner
sharpness at around its optimum aperture would be satisfactory.
By the way, you seem to be conflating rectilinear distortion and flatness of field, which are different things.
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Lack of field curvature is obviously very important, as paintings tend to be flat.
Beyond that, though, the longer the focal length you can use, the better, since that results in less rectilinear distortion. But, if you want complete geometrical accuracy, you'd still need to correct for that in post-processing, even if you used an 800mm lens.
Also, I'd consider moving to the Sony A7r3 due to the pixel shift function. That would provide far greater detail, colour accuracy and lack of artifacts than any single-frame approach can get. You can increase that further by stitching frames. For a flat subject, a shift-stitching approach using a tilt-shift lens would be ideal - I'd look at the Canon TS-E 135mm for that.
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Beyond that, though, the longer the focal length you can use, the better, since that results in less rectilinear distortion. But, if you want complete geometrical accuracy, you'd still need to correct for that in post-processing, even if you used an 800mm lens.
I'm puzzled by this. Could you explain what you mean?
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I'm puzzled by this. Could you explain what you mean?
Every lens stretches the corners to some degree. It's the nature of rectilinear projection. Put a 1cm line in the corner of a test chart and it will measure longer in pixels than the same 1cm line in the middle of the frame. The distortion is greater for shorter lenses with a greater angle of view, but exists for every lens.
It's simple geometry. Ideally, you'd be recording every point on the painting from an angle perpendicular to the plane of the painting, which is what a scanner does. This way, a 1x1cm square on the painting stays 1x1cm in size no matter where on the painting it is. This does not occur with a photo taken from a single point.
Fortunately, though, since the distortion is mathematical, it can be mathematically reversed, provided you know the focal length or dimensional angle of view of the image. I believe PTGui may have a projection tool that can do this.
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Every lens stretches the corners to some degree. It's the nature of rectilinear projection. Put a 1cm line in the corner of a test chart and it will measure longer in pixels than the same 1cm line in the middle of the frame. The distortion is greater for shorter lenses with a greater angle of view, but exists for every lens.
Are you sure?
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Every lens stretches the corners to some degree. It's the nature of rectilinear projection. Put a 1cm line in the corner of a test chart and it will measure longer in pixels than the same 1cm line in the middle of the frame. The distortion is greater for shorter lenses with a greater angle of view, but exists for every lens.
It's simple geometry. Ideally, you'd be recording every point on the painting from an angle perpendicular to the plane of the painting, which is what a scanner does. This way, a 1x1cm square on the painting stays 1x1cm in size no matter where on the painting it is. This does not occur with a photo taken from a single point.
Fortunately, though, since the distortion is mathematical, it can be mathematically reversed, provided you know the focal length or dimensional angle of view of the image. I believe PTGui may have a projection tool that can do this.
And how exactly do you keep a square painting square after having corrected this?
Cheers,
Bernard
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I believe you'll find the rectilinear "distortion" simply proportionalizes the distance differences between the lens and film/sensor center and edge, to the target distance differences, center to edge. They net out so that the photographed image looks like the target.
I've always found it interesting that the brain makes our mental images rectilinear, whereas the eye is certainly not a camera with a flat sensor that makes the image rectilinear optically.
I like doing multi-image panoramas. If it's just a couple of shots I'm combining, the setting in the photomerge Photoshop procedure that maintains the rectilinear perspective can work, but for large panoramas, the corner stretching looks ridiculous. I, personally, think some of the superwide lenses produce images that are also ridiculous. In my view our brain is only willing to accept as "normal" a certain amount of that rectilinear stretching. After that limit, the "cylindrical" photomerge approach looks more believable. But in city scenes people might notice the perpendicular streets are no longer perpendicular.
Trying to make an image of a three dimensional reality fit our two dimensional prints & screens and look "normal" has its challenges.
Paul
www.PaulRoark.com
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OP, it doesn't matter what lens length as long as you're aligned to the center of the image being copied and the film/sensor is parallel. As a practical matter, it's easier to do this with a longer lens. So, use the longest flat field lens you have that fits the area being photographed.
Paul
www.PaulRoark.com
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I was actually thinking of rotational stitching to a rectilinear projection when I wrote that (after having done ten stitched panos in a row) - areas away from the designated centre are stretched radially from the centre, due to the need to convert a frame that was taken perpendicular to the lens axis to one which is now oblique to the virtual 'lens'.
Regardless, you still want to use the longest flat-field lens you can get, especially if you're shooting heavily-textured oil paintings. Otherwise, you can get subtle distortions in the appearance of the texture due to its three-dimensional nature and the fact that you're shooting the top of the painting from a significantly different angle to the bottom.
But the key thing is lighting. Head-on lighting, from the same direction as the camera, is ideal, eliminating shadows due to texture, but only if the painting is completely matte. A heavily-textured painting with significant gloss can be a nightmare to light.
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I use an old 85mm f1.8 nikkor, or the 60mm micro nikkor. Put a mirror flat on the wall to make sure camera is square to the wall (center the lens of the camera in reflected image). I have my camera on a camera stand, and can take multiple overlapping shots, which are stitched together by Photoshop. Works slick 99% of time, using collage option.
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I have found with art reproduction that artists are very particular about the color reproduction and some what less so about sharpness and contrast. So including a color chart/white balance cards in the image can be really useful. Good light control is essential for this type of work and you have to take into account light that may be reflecting onto the artwork from the surrounding area. The wall color, or say the color of a hardwood floor or even a gilt frame on the artwork can cause problems with the color fidelity.
I think in most circumstances, flat lighting is better than directional lighting. But I think it can also be argued that if your photograph was going to replace some painting that was going to be temporarily removed for restoration or other some reason, that it might be more appropriate to photograph it using the existing light (maybe +/- a bit of help) so that it more closely resembles the original when displayed in that location. That means that if the painting was say, an oil painting with a textured surface, it should have the shadows cast by the surface texture recorded in your image.
I think you can make things a bit easier for yourself if you use a prime lens (think portrait focal lengths - I've used the Sony 55mm/1.8 for some artwork) and shoot at the sweet spot for that lens, most commonly in the f/4 - f/5.6 range. Don't fill the camera image frame with the artwork, just use the inner 2/3's of the frame and crop later. That way you are cropping off those parts (corners) with the most potential for distortion. Even if there are good lens corrections for your lens, the corrections can reduce contrast, etc in the areas corrected.
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Size of painting? Are you going to take multiple pictures and merge? Have you a good way to light the size painting you are shooting? Will you need a polarizing setup to get rid of reflections? (see https://chsopensource.org/2013/02/27/polarized-light-photography-for-art-documentation/ for info). How (print v screen) are you going to show the results, how big does image have to be? Color checker and grey card highly useful.
Deluxe version #1: Canon new 50mm T/S macro lens - if you can get one in stock
Deluxe version #2: Someone suggested the Sony A7RIII - if so, look at Voigtlander macro APO 65mm for Sony E mount, goes to 1:2, most macro lenses are flat field, and if this is like the other APO Voigtlanders, it ought to be smashingly good. Michael Erlewine has undoubtedly tested it, he tests all sorts of macro lenses - search this forum.
But, most macro lenses are pretty good nowadays, including many of the inexpensive non-OEM versions. The Canon 50 f/2.5 might still be around as an existing inventory item. The Canon 60 mm macro is an APS-C lens, not going to cover full frame. Should you have old camera equipment or enlarger lenses around and want to fiddle, you can mount enlarger lenses with helicoid, or medium format lenses (large image circles) on a shift adapter bought from ebay - fotodiox may make one. Consult someone wiser than me about this option. The advantage of getting a standard macro lens is that you can use it for other things as well, not just the paintings.
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I believe you'll find the rectilinear "distortion" simply proportionalizes the distance differences between the lens and film/sensor center and edge, to the target distance differences, center to edge. They net out so that the photographed image looks like the target.
Correct, provided that the resulting image is viewed from the correct/proportional distance relative to the size, there will be no projection distortion. So, an object sized 1 x 1 metre, when viewed from the same distance as it was shot, and sized 1 metre square, will have no projection distortion. When sized 50x50 cm, and looked at from 50cm, it will also look distortion free.
I like doing multi-image panoramas. If it's just a couple of shots I'm combining, the setting in the photomerge Photoshop procedure that maintains the rectilinear perspective can work, but for large panoramas, the corner stretching looks ridiculous.
Only because we will be viewing it from too far away, which is typical for such wide angle images if printed relatively small. If we were to look from the correct (uncomfortably) close distance that corresponds to the simulated wide angle lens' focal length, it would look perfectly normal.
Reproduction of 2-dimensional subjects is usually best done with relatively long focal lengths, which will then more likely be viewed from relatively close, thus achieving the opposite effect i.e. somewhat compressed (but one needs to get really close to get that sense of compression). Since longer focal lengths have narrower Fields of View, one may need to stitch, but that only helps resolution and automatic adjustment of geometrical lens distortion.
Projection distortion is just that, caused by a mismatch between the viewpoint and original shooting distance, a case of the wrong perspective.
Cheers,
Bart
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Deluxe version #2: Someone suggested the Sony A7RIII - if so, look at Voigtlander macro APO 65mm for Sony E mount, goes to 1:2, most macro lenses are flat field, and if this is like the other APO Voigtlanders, it ought to be smashingly good. Michael Erlewine has undoubtedly tested it, he tests all sorts of macro lenses - search this forum.
I tested it. It's a fantastic lens.
https://blog.kasson.com/?s=apo+lanthar
jim
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Well thank you all very much for the great input and suggestions. For the percentage of my business that will be coming from shooting art, lenses like the new 50mm TS-E, not to mention other premium exotics don't make business sense at this stage with highly questionable ROI. However there are a number of pre-owned 45mm TS-E lenses around for well under $1000, no doubt from photographers updating to the newer lens. Any thoughts or direct experience with the 45mm TS-E?
-pw
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> ... Any thoughts or direct experience with the 45mm TS-E?
Yes, I have one, and it's not very sharp. As a fan of that series (loved the 24mm and 90mm), I found it a disappointment.
Paul
www.PaulRoark.com
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Yikes, I'll keep clear of the 45 TS-E then. Brian Carnathan's review at the Digital Picture https://www.the-digital-picture.com/Reviews/Canon-TS-E-45mm-f-2.8-Tilt-Shift-Lens-Review.aspx seems to concur.
I might just get myself a Sigma 50 f/1.4 Art (Canon) for the job.
-pw
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I've been shooting tethered 5D4, 70-200 f/2.8isII at around f/8 with polarizer and also polarized lighting. For large paintings or where there are space constraints, the 24-70 f/2.8II gets the job.
A bit of research on the shooting art suggests I should be using flat field glass for better results, regardless of the lens corrections that Lr can automatically apply. I have a L 100mm f/2.8is macro which I imagine is flat field, but 100mm is generally too long for average painting sizes.
Any suggestions on an appropriate lens?
Why change if what you've been using works ? Keep polarizing as you have been and use your 100.
The Canon 100 Macro should be fine. There are better 100 Macros out there but if you're client is happy and the image is sharp who cares.
I've shot art with 4x5 chromes, then the Better light and now digital for many L.A. galleries and museums for over 2 decades. As long as the image is sharp and color as close as it can be I never have a complaint. There are some paints you can't reproduce exactly but the printers are more likely to choke on those colors than you are.
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Any thoughts or direct experience with the 45mm TS-E?
-pw
I've never owned the old 45TS-E but many years ago I had a project that needed something in the 50mm range with tilt capability. I tested the Canon 45TS-E against an old Zeiss 50mm Flektagon in a tilt adapter and found it to be superior in sharpness and chromatic aberration control.
However I've been very pleased with the new EF 50TS-E so far.
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Thanks Kirk, I'd use the 100 more often if I could, but space constraints mean it's too long for many works. Most work is shot in artists studios.
-pw
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Could you stitch images where the camera was translated between frames rather than rotated? At least for horizontal paintings, it might be possible to move the camera laterally, keeping the camera and lens parallel to the subject for each shot. Not sure how well the stitching software would handle this.
It might be interesting to test this idea, and some of the other ideas on this topic, by photographing a test pattern consisting of a rectangular grid on a wall. Once you figure out how to correct distortion on this target, use the same technique for a painting. Depending on environment, you might even be able to mount rulers around the painting to guide the correction, then crop them out of the final image.
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In theory, yes. Tony Northrup reviewed a third party lens ring for the Canon TS-E 17mm and 24mm lenses. The ring mounts to the tripod, so shifts move the camera body. Someone on this forum (months or years ago) designed a painting holder with x and y (but not z) axis translation, so that the picture could be moved past a stationary lens.
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Could you stitch images where the camera was translated between frames rather than rotated? At least for horizontal paintings, it might be possible to move the camera laterally, keeping the camera and lens parallel to the subject for each shot. Not sure how well the stitching software would handle this.
Hi Eric,
Dedicated stitching software such as PTGUI can deal with flat surfaces very well. The idea was first implemented in a software solution by Max Lyons in his PTAssembler software. An example of e.g. a mural is shown on the following page:
http://www.tawbaware.com/pta_help/ptasmblr_help_camera_position.htm
Cheers,
Bart
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In theory, yes. Tony Northrup reviewed a third party lens ring for the Canon TS-E 17mm and 24mm lenses. The ring mounts to the tripod, so shifts move the camera body. Someone on this forum (months or years ago) designed a painting holder with x and y (but not z) axis translation, so that the picture could be moved past a stationary lens.
Yes, for frequent use, Ted Dillard's "X-Y Easel" solution is superior (also because one only needs to get the lighting setup optimized for a limited surface area). He has a dedicated webpage about it here:
https://xyeasel.wordpress.com/
He has also discussed it here on LuLa as he was developing it.
Cheers,
Bart
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Could you stitch images where the camera was translated between frames rather than rotated?
Stitching? Additional shooting time added to increased post-production time makes the stitching option entirely impractical when a typical project may involve shooting 30-40 works in one day. Most artists and many galleries barely have the budget to commission me as it is.
If I like the artists work, I'll occasionally negotiate a swap. Depending on the standing and reputation of the artist, this may mean a partial or straight swap of a work for shooting for a day. I've done swaps with more established artists where I'll need to do 2-3 days which may be spread over a couple of years to secure a work. Over time I have a house full of really fantastic original paintings, prints and drawings. It's a great way to collect, and I feel a personal connection with each one of them. There are more far paintings on my walls than photos!
-pw
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Thanks Kirk, I'd use the 100 more often if I could, but space constraints mean it's too long for many works. Most work is shot in artists studios.
Yes I see you alluded to that in your original post.
How about the Leica R Macro Elmarit 60mm (https://www.l-camera-forum.com/leica-wiki.en/index.php/60mm_f/2.8_Macro-Elmarit-R) ? It's a great lens, can be found used for reasonable money and is easily adapted (https://www.bhphotovideo.com/c/search?Ntt=Leica%20%22R%22%20Lens%20to%20Canon%20EOS%20Body&N=0&InitialSearch=yes&sts=hist-ma&Top+Nav-Search=) to the EF mount.