50mm lens – field of view & subject width/distance

[Crashbangwallop]

I have a question a about the field of view of a 50mm lens which I hope someone here can answer.

Firstly, the context. I'm a painter and I usually takes photos of my progress, and finished work, on my easel, which is in the ideal place in my studio and will not be moved.
The paintings are usually in 'landscape' aspect and rarely exceed I metre in width.
My workspace is restricted. I have about 1.5 metres from the paintings' surfaces to where I can practically operate the camera on its tripod.

I have recently bought a Canon E7, with its 18-55mm zoom lens, but find that the resulting images are not particularly fine – and no great improvement on the images from my Canon G10. A friend has advised getting a fixed lens for better clarity – a 50mm.

My question is – how far away from the painting must the camera (fitted with a 50mm lens) have to be in order that a painting 1 metre wide sits within the photograph?

[Manfred M]

Why is a 50mm focal length so important to you? While it is a "normal" lens / focal length for a full frame camera, your Eos 7 is a crop frame and the normal field of view is going to be around 30mm. Frankly, I'm not quite sure what you are trying to do and don't see going for a fixed focal length lens is going to make a lot of difference to the final output.

We would have to see an example of what you are having problems with to diagnose your quality issue.

Reproducing a painting is all about proper lighting equipment, light position and camera position.

If you could post an image here, that would be useful. Posting at CiC is not 100% straight forward, so please look at the following link for instructions.

HELP THREAD: How can I post images here?

[Crashbangwallop]

Thank you for your prompt reply Manfred

To explain my position a little further. I'm not a tech photographer. Replacing my zoom lens with a fixed lens in order to photograph my work was suggested by a photographer acquaintance, who herself isn't particularly techy. She told me that a zoom is a compromise lens, and that a fixed lens is always going to have more clarity.

If that's not the case, then I have been misadvised, and have started a pointless thread – for which I apologise

The 50mm lens choice is, to some extent, arbitrary. I have heard and read elsewhere that it's a good general lens as it sees the world as the human eye sees it, which sounds interesting, and if I'm going to fork out on extra kit, then it would be nice if it had more than a single function i.e. just photographing my work. It wouldn't be worth it

I think what I'm looking for here is, hopefully, a fairly simple answer about how far away the camera has to be in order to photograph an object 1 metre wide. Practical geometry, if you like

Any helpful supplementary suggestions about what type of lens or lenses would be most suitable for my specific circumstances would, of course be welcome

[Manfred M]

The answer is not as straight forward as one might think as the distance markings on your lens are actually only valid for a subject at "infinity" and the measured focal length will be different (often significantly different). My 70 - 200mm lens at its closest focus distance is effectively only a 135mm focal length, even though that is marked as 200mm.

I would approach this a bit differently. Put your tripod / camera as far back as you can comfortably go (you suggest 1.5m) and zoom out so that you fill the frame in your viewfinder. Don't worry about the focal length. Just make sure that the camera's sensor plane is parallel to your easel. Try that to see if it gives you a good shot.

When I take my wife's crop sensor camera and point it at a 40" wide target (which is just wider than 1m), at an 18mm focal length I can put the camera about 34" away from the target to get it all in. While there will be some level of distortion, most cameras will correct for that if you are looking at shooting a JPEG image. If I pop a different lens onto the camera, I might have to move it in or out a few cm.

Don't worry about focal length at this point; just try to capture the whole subject. If that is not working, we can continue the discussion.

[pschlute]

Can you post the images that you dont like then maybe we can see a solution. I am very sure it will not involve buying a new lens.

ps How are you focussing on your painting ?

[Cantab]

Hi Crashbangwallop. Yes, as a very general principle, a fixed (“prime”) lens will typically have better quality than a zoom; however, many zooms can produce fine images. My guess, as Manfred has hinted at, is that your issue may not be the lens but other factors (lighting, etc.)

As for a 50mm lens, as Manfred says, it is a neutral (my term) lens for full frame cameras and for film 35mm SLR’s. But you are not using a full frame camera and the neutral focal length for most crop frame cameras is in the low 30’s. So I'd be very surprised if purchasing a 50mm lens provides any assistance.

I’ll leave to others more technical explanations of how you can improve the photos you want to take in your studio. Again, as Manfred suggests, an example of what you’re trying to accomplish would help.

[Chataignier]

I'll try to answer your question as put - and you would need about 2m between you and the canvas to include all of a 1m wide subject in the frame using a 50mm lens on a Canon EOS 7D.
However, it might be worth confirming that we are talking about an EOS 7D - E7 does not appear to exist...
The next point is about focal lengths. Yes, 50mm is about the same field of view as a human eye, but your camera is not a human eye - as Manfred has already said, the EOS 7D has what is called a crop sensor and the focal length of a 50mm lens on this camera is equivalent to 80mm. To have a 50mm equivalent, you would need a 30mm lens on the EOS 7D.
As for zoom versus fixed focal lenses, yes a fixed focal lens generally outperforms a zoom, all other things being equal. But to get much benefit you would need a very good 30mm lens.
My guess is that you are viewing your images on a general purpose computer screen which has only around 2000 pixels in the width (less than half the resolution of the camera) and that is the limiting factor. It would be hard to see much difference between a very good and a mediocre lens by viewing the images on a modest size laptop computer screen that is probably not even calibrated for colour - they vary a lot. You would need to make prints of around 60cm at least to see much benefit.
If you plan to use the images only by viewing on a computer screen, dont bother to change the lens. If you want to make "life size" prints, then it might be worthwhile, but that opens a whole new bag of worms !!!

[xpatUSA]

I have a question a about the field of view of a 50mm lens which I hope someone here can answer.

Firstly, the context. I'm a painter and I usually takes photos of my progress, and finished work, on my easel, which is in the ideal place in my studio and will not be moved.
The paintings are usually in 'landscape' aspect and rarely exceed I metre in width.
My workspace is restricted. I have about 1.5 metres from the paintings' surfaces to where I can practically operate the camera on its tripod.

Firstly, even lenses with the same marked focal length can vary quite a bit in Angle Of View. For example:

https://www.photonstophotos.net/Gene..._Primer_19.htm

Secondly, Angle Of View generally refers to image circle diameter but you are discussing Field of View (kind of like binoculars, the horizontal width seen by the sensor). Still, lenses will vary, even from that point of view.

Thirdly, to capture one meter wide from one and a half meters, that's 37 degrees. Your sensor is 22.3mm wide. A perfect 50mm lens would give a horizontal field of view inside the camera of 25 deg when focused at infinity but, focused at 1.5 meters, about 24 deg. What we can deduce from that is that you'd be better off with a marked 28 or 35mm lens. Your call, of course.

My question is – how far away from the painting must the camera (fitted with a 50mm lens) have to be in order that a painting 1 metre wide sits within the photograph?

The theoretical 'perfect lens' answer is 2.35 meters for a 50mm marked focal length, as Dave just now said..

[William W]

You have the answer to the question regarding a 50mm lens on a 7D. (I assume the camera is a 7D?)

However,

. . . the context. I'm a painter and I usually takes photos of my progress, and finished work, on my easel, which is in the ideal place in my studio and will not be moved. . . .

I think that you are asking all the wrong questions.

All the advice you cite in your Post #3 is either misinformation or irrellevent information with respect to addressing the outcomes that you have stated.

. . . Any helpful supplementary suggestions about what type of lens or lenses would be most suitable for my specific circumstances would, of course be welcome

If you cannot get very good to excellent quality images of an art work in progress using a Canon G10, then the key issues are with Technique and Lighting.

Post a couple of examples of your Photos with the EXIF data and seek assistance from those well versed in these two areas - there are many here at CiC.

WW

[xpatUSA]

The 50mm lens choice is, to some extent, arbitrary. I have heard and read elsewhere that it's a good general lens as it sees the world as the human eye sees it ...

What you heard or read does not apply to your camera. It applies to a film camera or to a camera with a much bigger "full frame" sensor. For your camera, a factor of 1.6 applies, therefore you would need a 50/1.6=31.25mm lens, Perhaps 28mm would work. Still your call ...

Good luck,

[Crashbangwallop]

The answer is not as straight forward as one might think as the distance markings on your lens are actually only valid for a subject at "infinity" and the measured focal length will be different (often significantly different). My 70 - 200mm lens at its closest focus distance is effectively only a 135mm focal length, even though that is marked as 200mm.

I would approach this a bit differently. Put your tripod / camera as far back as you can comfortably go (you suggest 1.5m) and zoom out so that you fill the frame in your viewfinder. Don't worry about the focal length. Just make sure that the camera's sensor plane is parallel to your easel. Try that to see if it gives you a good shot.

When I take my wife's crop sensor camera and point it at a 40" wide target (which is just wider than 1m), at an 18mm focal length I can put the camera about 34" away from the target to get it all in. While there will be some level of distortion, most cameras will correct for that if you are looking at shooting a JPEG image. If I pop a different lens onto the camera, I might have to move it in or out a few cm.

Don't worry about focal length at this point; just try to capture the whole subject. If that is not working, we can continue the discussion.

Thanks Manfred, I'll give that a go

[Crashbangwallop]

I'll try to answer your question as put - and you would need about 2m between you and the canvas to include all of a 1m wide subject in the frame using a 50mm lens on a Canon EOS 7D.
However, it might be worth confirming that we are talking about an EOS 7D - E7 does not appear to exist...
The next point is about focal lengths. Yes, 50mm is about the same field of view as a human eye, but your camera is not a human eye - as Manfred has already said, the EOS 7D has what is called a crop sensor and the focal length of a 50mm lens on this camera is equivalent to 80mm. To have a 50mm equivalent, you would need a 30mm lens on the EOS 7D.
As for zoom versus fixed focal lenses, yes a fixed focal lens generally outperforms a zoom, all other things being equal. But to get much benefit you would need a very good 30mm lens.
My guess is that you are viewing your images on a general purpose computer screen which has only around 2000 pixels in the width (less than half the resolution of the camera) and that is the limiting factor. It would be hard to see much difference between a very good and a mediocre lens by viewing the images on a modest size laptop computer screen that is probably not even calibrated for colour - they vary a lot. You would need to make prints of around 60cm at least to see much benefit.
If you plan to use the images only by viewing on a computer screen, dont bother to change the lens. If you want to make "life size" prints, then it might be worthwhile, but that opens a whole new bag of worms !!!

Indeed. It is...
All good sound advice, and the business with the two types of sensor clearly explained. Computer screens both colour calibrated BTW - very important when sending stuff off for online show selections nowadays - it is not nice getting rejected because when the selectors see the actual piece and it doesn't match the the online application image. Going to persevere with the zoom
(Also like to thank you for addressing the actual question in my terms)

[Crashbangwallop]

Thank you for all your inputs and advice, it's truly been an education. Yesterday evening was spent researching crop and full frames and how that alters the value of the numbers on the zoom lens that came with the camera – and yes, it is a Canon EOS 7D!! (sorry about that).

I'm fairly sure lighting's not the problem – I'm aware of the angular set-up to avoid glare, and of basic polarised light. For the final RAW pics once a painting's done I get organised with reflectors (no shortage of large sheets of white paper in our house) – and I'd rigged up a diffuse daylight lighting system onto and over the easel to boost winter light for painting years ago anyway. I'm using autofocus, and I'm also aware of having to turn off IS when using a tripod. I'm not having any problems with colour – using custom white quite happily in a 'Neutral' setting. Desk monitor is not enormous, but big enough to work up all my photoshop pre-painting compositions, and is properly colour calibrated – as is the laptop I work off when at the easel. Each painting's right side is marked with it's mid-point. With the painting at a convenient height, this is also marked on a long stick which is then used to find the correct height of the lens: each painting has it's own height mark, so the camera is always at the right height. Paintings are vertical on the easel, parallelled by the camera's focal plane so that distortion is minimised.

I've decided not to go ahead with buying a new lens – there doesn't seem any point in acquiring expensive new kit that I obviously haven't a clue how to use. I think my best option just now is to learn how to get the best of what I have, and work with the zoom lens. As I'm not photographing for printing/reproduction, and certainly not at a large scale, it seems there is little difference a prime lens will make. It seems that I've been misled by my own sense of expectation.

I'm sure I'll get there in the end with the Zoom, and can use my runaround/compact G10 for close-up details (at which it excels) – and ease into the huge increase in ISO, speed, and focal length that comes with the EOS 7D

I won't post any of my photos up, there seems little point just now, but I will share my Artwork blog, http://keithepps.blogspot.com/ , which will give you an idea of the sort of thing I'm trying to do with paint, and may perhaps explain why I describe what photography I do, as 'Utilitarian'

Once again, thank you for all helpful suggestions and education, and if any of you want advice or guidance about artists' pigments or the various painting oils, just let me know

Keith

[Chataignier]

Thanks for posting the link, I really like your landscapes, the soft focus effect reminds me a bit of the backgrounds of some of Claude Lorrain's works , with more recent influences from Turner.

A last technical point - focus. When you get close up to a flat subject such as one of your paintings, the difference between the distance to the centre and the distance to the sides becomes significant in relation to the focus. If you cant go further back then use set the camera to mode Av, aperture priority, and select a small aperture such as f11 to give as much depth of field as possible. This will increase the exposure time but should not be a problem if you are using a tripod. However, remember to use a cable or other remote release to avoid shaking the camera at the critical moment. Around £15 for a third party cable release for the canon on Amazon.

[DanK]

You've received a lot of very good advice and explanation. I'll just add a few points:

Focal length is relevant for several reasons, but it seems to me that only one is potentially relevant in your situation: angle of view. You need a wide enough AOV that you can include the entire piece in the photograph, given the amount of room your studio gives you. Other than that, the issues associated with focal length, e.g.., perspective and background blur, aren't relevant when you are photographing a flat piece of art. The notion of "normal" perspective isn't relevant in your situation.

Re depth of field: there are numerous depth of field calculators on line, including one in the tutorials section of this site, https://www.cambridgeincolour.com/tu...calculator.htm.

Re zoom vs. prime: this is a red herring in your application. It's true that it is simpler to design a prime, and it's also true that primes are often optically better than zooms, but (1) it depends on the specific lenses, and (2) it won't matter for your purposes. With respect to the first: ranked in terms of optical quality, my best and worst lenses are both primes. Among the common issues with zooms are vignetting at some focal lengths and barrel or mustache distortion. Both are trivial to fix in postprocessing, if you notice them in the final product.

[rpcrowe]

I have read the excellent advice above. Without seeing any of your images, there is very little that I can add except...

Today's lenses are excellent - even kit lenses can do a very good job... I would recommend that you shoot your images at around f/8 or f/11 using ISO 100. A tripod is just about a must for copy work in order to position your camera so that the sensor plane is absolutely parallel to the plane of the subject - that is imperative.

Shoot in Aperture priority mode and trip your shutter remotely or use the camera's two second timer to delay the shutter until any movement from pressing the shutter is dampened.

I would shoot in RAW and use a white balance target to establish my white balance when opening the image in Adobe Camera RAW.

I have been using a Whibal target for over ten years and have been very happy with it. https://www.youtube.com/watch?v=yKM-fwYnaIg

When I first purchased the Whibal. I thought that $29.95 USD was expensive but, pro-rated it has cost me only $3 USD per year since I am still using my original G-7 card.

[Crashbangwallop]

Thanks Dan. Yes, it was the AOV problem with an unknown lens that was bothering me initially - I went as far as to make scale diagrams to try and work out what was possible. Given the paucity of both the information I was seeking AND my knowledge of lenses, I'm glad I decided not to go ahead.
Was updating a Works in Progress earlier today, and am happy to say that there was negligible distortion correction needed in post-production

Useful wee calculator there too

Keith

[Crashbangwallop]

Thank you very much, David. Chuffed to be compared to Claude Lorrain and Turner. If only!

I've been thinking about a cable release for a while, but never got round to it. So far the 2 sec delay seems to be doing the trick. It's mentioned in a lot of the Art-based forums doing 'How to photograph your artwork', but it's reassuring to have it confirmed. Another good reinforcement is using Av and f11, and letting the exposure take as long as it takes. so thanks for that

(Not at all sure how to 'like' posts here, and I don't want to appear mean and uncharitable. PLease consider your posts 'liked' )

[xpatUSA]

(Not at all sure how to 'like' posts here, and I don't want to appear mean and uncharitable. PLease consider your posts 'liked' )

Click on the little 'thumbs up' icon at bottom left of someone's post and wait a few seconds. The number in the little box should increment. Click again at any time later to change your mind.

HTH

[Crashbangwallop]

Click on the little 'thumbs up' icon at bottom left of someone's post and wait a few seconds. The number in the little box should increment. Click again at any time later to change your mind.

HTH

Um... That's what I thought, but not working. May be a forum permissions thing as I'm a very recent registration...