[Conqueror]

35mm DA f2.4
35mm FA f2
35mm DA f2.8
40mm DA f2.8

I've been quite pleased with shots in museums from the FA 35mm f2.0 , which I had for quite some time on the K-7 (now K-5iis) and it performed well indoors doing that.

[TER-OR]

I know there are a couple threads here about art photography. Search "painting" and similar terms you should find them.

I have a Sigma 28mm f1.8 macro I like for close work like models, sculptures, miniatures etc. I haven't checked it against the 35mm macro for flat field, but it's pretty good.

[Lowell Goudge]

Hey Pentaxians,

I use my Pentax DSLR to digitally scan paintings and artwork for clients at work.
The process involves shooting the artwork in segments, and stitching them together in post.
This allows the artwork to be printed quite large (I did a 4ft x 5ft print recently) at full resolution.
My clients are very satisfied with the results, but I know there's room to improve.

I want to achieve the sharpest overall images possible with the limited resources at my disposal.

A Little Background:
I Currently use my SMC Tak 50mm/1.4, or my SMC Pentax-F 50mm/1.4 (both at f/5.6)
Because of the crop factor, these equate to about 75mm on my k-5.

Questions

1. Is this the most suitable aperture to achieve best overall sharpness with these lenses?
   
2. (Assuming sharpness gets worse toward the edge of the frame) should I be shooting more frames and cropping them down to avoid losing detail?
   
3. I've heard that "art lenses" are not the best for overall sharpness. I have the (SMC Tak 35mm/2) and the (SMC Tak 55mm/1.8). Would either of these better suit my needs?

With my current setup, I can't go much longer than a 55mm without having to tear down a wall.


Any other suggestions/advice/input is very much welcome. I wouldn't be the photographer I am today if it weren't for these forums, and I'll gladly accept any information you can offer that will help me continue to improve.


All the best,

Pat

Maybe a 50mm macro, because it is a flat field lens. Macros make great copy lenses.

[civiletti]

The longer the focal length, the lower perspective distortion will be.

[Sandy Hancock]

For manageable working distance, sharpness, and flatness of field, I would say it was pretty hard to go past the DA 35mm macro limited.

[TAP]

Wow, thank you everyone. I did not expect to get so many replies with such helpful information.

It appears the consensus is to use either a macro, or the 40mm limited (or xs), or at least a lens with longer FL.

There's a lot more I'd like to say in this reply, but i'm away from my computer until Monday & am posting from my mobile. I'll be sure to post back asap.

Thanks again for the insight, everyone. I really appreciate it.

[John Poirier]

+1 for the 35mm macro Ltd for the reasons already detailed - including your limited space. Yes to using the the central area of the frames in your stitching, so I imagine the edges of the artwork would be mid-frame for those areas. One thing to emphasize, although it has been mentioned, is having the plane of the camera as square as possible to the plane of the artwork at all times to both ensure optimum focus as well as minimise perspective distortion. This means a good solid tripod and using bubble levels. I sometimes used to use a Hasselblad SWC (superwide) for artwork copying - as a rectilinear lens it was brilliant - but keeping everything level was paramount...

I'll add my vote to the 35 macro suggestion. A lower-cost alternative is one of the old 35/3.5 wide angles- Super Takumar, SMC Takumar, or K. They are very low in distortion and sharp on APS-C. I've used all three very successfully for copying paintings. (I would not recommend the old f/2 35s for copy work. They are not as sharp as the 3.5s.)

[TAP]

Brace yourselves! Here's my lengthy reply to all of the input/questions I received.
(One more time) Thanks everyone for all the replies. I really appreciate it.

A macro lens is designed to more effectively focus on a flat plane... ...At a distance, depth of field helps overcome the curved 'plane' of focus of 'normal' lenses.

Thanks for the detailed info- this really helped me understand why macro and a longer FL are a good fit for this scenario.

The DA 40 XS actually had more even sharpness across the whole frame

I would say it was pretty hard to go past the DA 35mm macro limited

35mm DA f2.4 --- 35mm FA f2 --- 35mm DA f2.8 --- 40mm DA f2.8

A lower-cost alternative is one of the old 35/3.5 wide angles

Thanks for the lens suggestions!

The best type of lenses for this would then be adapted enlarger lenses.

What a thorough response! I'll definitely look into the possibility of using an enlarger lens.

I usually stop down to ƒ/8 when I want optimum sharpness.

Awesome; I'll give that a shot & compare results with my f/5.6 shots.

---------- Post added 02-25-2015 at 05:52 PM ----------

I don't understand why a longer lens can't be used.

I have a very small physical space to work with. I could likely use a longer macro lens (and shoot more frames), but I perform consistency checks (for focus and camera angle) each time I move the camera- so Increasing the amount of frames will take a lot more time. I'm currently designing a rig that will dramatically reduce the shoot time though. Once it's built, a 90 or 100mm macro would make a lot more sense.

---------- Post added 02-25-2015 at 06:01 PM ----------

• How much overlap do you allow now?
• How do you keep the camera parallel to the art work?
• Are you moving the camera or the art?
• What about your lighting?

I'm more than happy to share my process, just keep in mind it's FAR from perfect (haha)

• For overlap, short answer is "not enough". I leave about 1/4 so the image will stitch properly. I've had a lot of success using Photoshop's automated "Photomerge" feature for stitching the frames. I may allow for more overlap in the future for better overall sharpness.
• I use an extremely crude method for keeping things parallel. I basically lean the piece of art against a wall, and then match the tilt of the camera to the piece. I'll usually sit the artwork on top of something a few inches from the ground. Then I find a large picture frame or stretched canvas and lay it at the base of the piece. This gives me a guide for moving the tripod. I still check focus between shots just to make sure.
• If it's a large piece of artwork, I can't always shoot the entire piece due to limitations with the tripod (can't go low enough or high enough). In that case, I flip the artwork upside down halfway through the process to shoot the other side. Then I rotate them back in Photoshop before using Photomerge.
• Lighting has been my number one problem since I started. I have two manual flashes (both Yongnuo YN560's) but I haven't used them for scanning in quite a while. I would read countless tutorials on using flashes for shooting artwork. Despite my best efforts, they caused more problems than they solved. Now I just shoot at long shutter speeds with a polarizer. My light comes through the windows from two adjacent rooms. It's pretty dim (I'm usually around 8 to 10 seconds at f/5.6 with the polarizer attached) but it works. I've used overhead lighting as well- it cuts down exposure time exponentially, but requires more work in post.

I'm designing a rig that will really simplify the process.
If you're interested, here's the parameters so far:

• Fully manual operation to save on cost
• Horizontal movement via track & trolley
• Height adjustment via clamps/locking pins
• Flash mounts with adjustable length
• Bubble levels for angle compensation
• (maybe) laser tape measure to align rig with artwork

This will hopefully allow me to shoot much closer,
with a lot more frames, at much greater detail.

Let me know what you think!

[Abbazz]

What you have to consider is the size of the artwork and the distance you will be shooting at. Based on these parameters, you will be able to determine the ideal focal length. Then it will be much easier to identify a suitable lens.

Cheers!

Abbazz

[K-Three]

I would suggest you consider continuous light sources; photo floods, or LEDs,
Flash, without a modeling light, can be a real problem, as it sounds like you have found out.
If the art has any texture, or raised elements (oils or acrylics) there are reflections and highlights you won't see until you are in post processing,
A continuous source allows you to see what the camera sees, and study it before you take the shot.
I used a simple set of work lights with photo floods for years with film, and finally bought a simple set of soft boxes and light stands for a few hundred dollars. I use matched bulbs and shoot RAW, so color balance is not an issue.
The language used while copying art has gone from R to G rated.

You may want invest in a good hand held, incident light meter to check the evenness of your lighting set up too.

[TAP]

I would suggest you consider continuous light sources

Not a bad idea. That would simplify the process of configuring the lighting setup. What size softboxes are you using, and what is your shooting distance? Do you use polarization as well?

You may want invest in a good hand held, incident light meter

Evenness of lighting isn't a huge concern at the moment, but it might be helpful in the implementation of the scanning rig I'm designing. Thanks.

A much more effective way to control glare if you are photographing glossy artwork is to use cross-polarization

I've looked into this method in the past, but never got around to acquiring the polarizer sheets for the flashes. How do you go about ensuring the lens polarizer is perpendicular to the flash polarizers? Is it more of a "trial and error" kind of thing?

[dms]

Edmonds optics has inexpensive PL sheets. Buy one and cut it in half. You hang them in front of two lights--in same orientation, each light 45degree from the normal, and then turn PL filter on lens till you get the degree of glare reduction and color saturation that you want. In my experience for paintings with a lot of uneven surface it is the single biggest improvement one can make. I also suggest an incident light meter and check that everywhere it is +/- 1/3 stop or better.

[K-Three]

Not a bad idea. That would simplify the process of configuring the lighting setup. What size softboxes are you using, and what is your shooting distance? Do you use polarization as well?

Evenness of lighting isn't a huge concern at the moment, but it might be helpful in the implementation of the scanning rig I'm designing. Thanks.

I've looked into this method in the past, but never got around to acquiring the polarizer sheets for the flashes. How do you go about ensuring the lens polarizer is perpendicular to the flash polarizers? Is it more of a "trial and error" kind of thing?

I thought about suggesting cross polarization,
it's easy, you put the polarizing gels on your lights, both filters in the same direction (polarizers for lights are usually marked in a corner) then look through the one on your lens and rotate it until you have the effect you are looking for, perfectly crossed (90-degrees apart) is not necessarily the best, it's going to vary with your subject. Like using a polarizer for the sky, the effect is obvious, and you adjust it through the camera.
Most of my wife's work is colored pencil and water color, so I have not had to worry about reflections for a while.

For in front of the lights you want to look at something like these at B&H you need to buy them at a size for your lights, if you are using hot lights, they will melt if you get them too close.

i've got a pair of soft boxes that I run 500W photo floods in, they have a front about 20-inches square on them. I've run them with and without the front diffusers, depending on the subject. I usually set them up about 8 to 10-feet from the art, and 45-degrees off the camera. Using a constant source, it's easy to see the coverage and the evenness of the light. I'm usually around 1/8 @ƒ/8
my "studio" is my garage, back the car out and the door becomes my easel, for the art. Usually just shooting art pieces on paper, that I can tack to the door. I've done works on canvas before, takes a bit more to support them.

[TAP]

A much more effective way to control glare if you are photographing glossy artwork is to use cross-polarization, which entails mounting a polarizer on the lens, then putting polarizing film on your flash(es) at 90 degree angles to your lens polarizer. Large polarizing sheets that can be used for this purpose can often be cannibalized from the inside of older LCD monitors. Note that on newer monitors, the polarizing sheet is usually fastened with adhesive, making it difficult to impossible to remove.

Here's a very detailed PowerPoint presentation I came across on the subject.

I just took a longer look at the Powerpoint you linked to.
Wow. You weren't kidding when you said "very detailed" (haha)!
Today I venture back into shooting art with flash- so thanks for the link!

---

I just got polarizers for my lens and flashes off of Amazon this week.
I paid under $20 USD for everything- including shipping.
Links provided below for anyone who's interested.

(Polaroid 49mm Polarizer- $8 and has great reviews)
http://www.amazon.com/gp/product/B0085YG34K/

(Set of 10 Polarizer Sheets- $11)
Polarizer Sheets: Amazon.com : Polarizing Film Sheet - set of 10 : Home And Garden Products : Camera & Photo

I could have bought just 2 sheets from another seller,
but the total cost with shipping would have been $15..
so I figured it's better to pay less and have extras

[ramatsu]

I routinely copy my wife's artwork, I have both the DA100 2.8 Macro and the DA 35 2.8 Macro, I use either depending on the size of the piece. Mostly the 100 just to keep a decent working distance,
But, I'm not stitching, just single shots of each piece, usually the pieces are between 11x14 and 20x24, anything smaller we throw on the scanner.
...
You may want to look at one of the macros, 35, 50, 100, for better edge sharpness and flatter field lenses.

How far from the art is your camera with each of these lenses, say for a 20x24 painting? I have a small space to work in, and have been trying to find a way to understand the trade offs and whether a particular lens setup will work in the space I’m in.

Thanks!