TUTORIAL - No Blurry Photos

[MarkBarbieri]

The crop factor is important.

Let's start with a basic assumption - some people have a sensor of size x and some people have a sensor of size 0.6x. Both like to display their pictures at approximately the same size.

In order to get the same size images, the person with the 0.6x sensor must magnify their image more. When they do that, they also magnify defects like the blur caused by camera shake proportionally.

Assume for a second that they are both taking a picture of a brick wall with a 100mm lens. The FF shooter gets 200 bricks in his picture. The 0.6x sensor shooter gets only 120 bricks in his picture because his field of view is cropped to fit his sensor. If they both "shook" their cameras the same amount, each brick has the same amount of blur. The difference is that the blur is more noticable in the more magnified 0.6x photo because each brick takes up more of the frame.

If the FF shoot zoomed in to 160mm, he would get the exact same 120 bricks as the 0.6x shoot. In that case, in the final print, he would have an identical field of view and identical motion blur because he would be maginfying the camera movement the same amount. When shooting with the 160mm lens, he magnified the image more at the time the photo was taken, but less at the time it was printed.

So my conclusion is that the crop factor matters if you are talking about the same size prints because the image magnificantion (and shake magnification) are larger.

 

[MarkBarbieri]

As to the question about the usefulness of such posts, I strongly encourage them. There are some questions that are frequently repeated and are deserving of a FAQ.

I think it would be even more useful for someone to post a series of answers to questions that newbies should as but don't. Most often, newbies focus on equipment questions rather than composition questions. I'd like to see a series of posts on fundamental things like

* filling the frame
* the rule of thirds
* using fill-in-flash in bright sunlight
* getting the depth-of-field that you want
* taking more shots that you need and throwing away the bad ones
* taking pictures of things that mean something to you rather just trying to replicate postcards
* Knowing the limits of what a flash can do for you
* Recognizing situations with excessive dynamic range and how to deal with them

All too often people think that the most important thing for them to know is whether they should get lens A or B or camera X or Y when the reality is that they'd be better with a cheaper, simpler camera and more basic knowledge than a really great camera and no clue about basic composition.

 

[boBQuincy]

The crop factor is important.

Let's start with a basic assumption - some people have a sensor of size x and some people have a sensor of size 0.6x. Both like to display their pictures at approximately the same size.

In order to get the same size images, the person with the 0.6x sensor must magnify their image more.

Mark,

absolutely, magnification affects blur, and in printing we usually magnify the image. To get an 8x10 print from an APS-C crop camera takes about 1.6x the magnification than it would from a full frame camera, thus more blur.

Where we differ is, to me printing is a completely separate process from capturing the image. For me, adding the printing process into the mix confuses the blur/crop issue, which I feel should be limited to the camera and lens.

You understand the difference, and I think I do, but others probably do not. It really becomes blurred (pun intended) when we display an image on a monitor, which has a resolution of maybe 1/3 or less that of the camera. The displayed images may be cropped, resized, sharpened, or who knows what, and the issue of crop vs full frame blur becomes ...

I like the idea of "tutorials", "guides", FAQS, or whatever but most of the ones I see on forums are loaded with opinions, not facts. Of course, anyone is free to keep and/or discard whatever information they choose, but newbies often hang on to every word of anyone who seems to know just a little more than they do, right or wrong.


Ah, well, it's all photography, and it's all fun!


boB

 

[Groucho]

It is also good to have someone proofread the article first, to avoid any spelling or grammar errors (personal crusade).

I'm on that crusade, too, but I've slipped over the years. I find myself making a couple of the same typos consistently, so I try to re-read my stuff but occasionally still make mistakes. But my mistakes are usually spelled correctly, they're just the wrong word.

Mark, I'm sorry but I still have to disagree. You cannot compare an analog photo vs a digital photo in this way. A digital SLR is not recording a "magnified" image whatsoever (that makes it sound horribly like "digital zoom"). The purpose of the various "rules" is to get a sharp photo, no matter if the photographer later crops 50% of the picture away in the darkroom or in software - the sharpness should remain intact.

I do agree that some basic photography lessons might be valuable/fun (especially since it's been about 15 years since I took Photography 101!) although I'm not such a fan of "style" rules - if someone is too busy thinking about "rule of thirds" or whatnot, they may be taking away from their own unique take on photography. I like when photographers think outside the box, to use an overused phrase. But technical guides are often good - and I do think there is value on having some healthy discussion afterwards.

 

[timned88]

a final note on crop factor and i will say no more about it... if you don't agree then let's just agree to disagree and move on...

my old sony dsc-v1 point and shoot had an actual physical focal length of 7-28 mm. with the crop factor, the focal length is 34-136. a 1/30sec shutter at the long end (136mm) would be way too slow to comfortably hand hold the camera for most persons. so, in my opinion, yes the crop factor does indeed matter.

 

[handicap18]

I know that most others will disagree with me, but I do feel a level of disquiet over these types of posts on Discussion Forums. That's not to say the information isn't useful, nor that it's not provided with the best of intentions, but I would prefer to see it in response to another member's specific question.

You did ask . I haven't voted in the poll - there doesn't seem to be a relevant option for me .

I also completely and fully disagree.

Part of coming to this board is to learn about photography. Its not all just about posting and talking about pictures. Some people have a wealth of information to share about taking pictures and maybe even taking pictures better.

I say keep up the tutorials. Its been shown in the past that the vast majority of people like them, use them, and learn a lot from them.

Thank you Tim for taking them time and making the effort to help. Excellent work.

 

[JR6ooo4]

a final note on crop factor and i will say no more about it... if you don't agree then let's just agree to disagree and move on

Ok, there are lots of pages here and at www.dpreview.com and many other sites for additional reading on the crop factor subject. I was just asking questions to clarify if I misunderstood any aspects...

timned88
you are a braver man than I. I have been thinking about how many people here have missed the sticky tutorials, that anyone wrote. I myself could not put together more than a few sentences without copying and pasting from elsewhere. Be assured many (including myself) appreciate your efforts.

thanks,
Mike

 

[0bli0]

first off, it's a general rule - not a law. if you're using a medium or large format film, then the rule applies (or fractionally). the reason crop factor is used (loosely) in the 1 over FL calculation is because the resulting field-of-view on the sensor will demonstrate the same magnification of movement. with a 10 megapixel 1.6 cropped sensor, let's say we could see 3 cars with a 250mm lens. now with a 10 megapixel full frame (not cropped) sensor, we are going to see those same 3 cars with a 400mm lens. relatively speaking across the resulting 10 megapixel images of the 3 cars from both cameras are going to be very very similar. any micro movement of the end of the lens is going to result in the same magnified motion of the resulting image on the sensor.

but at the end of the day, it's just a rule. with lots of practice, you can break the rule, and not spend the afternoon in the principal's office.

here is one - hand held leaning out of an open top land rover in africa. this is with the Sigma 50-500 which is a pretty heavy lens (on my already heavy 1dmk2 body)
417mm (on a 1.3x camera), 1/250, F7.1, ISO 800

with a much shorter focal length and lighter lenses, i've been able to get longer exposures handheld - elbows in and exhale while taking the shot.
Tokyo DisneySea
51mm (again on 1.3x camera), 1/5 second, F7.1 ISO 800

my DW has, in addition to her 10d, a Canon SD 400. it's so small (and she's not so great at holding it steady) that the finger motion from taking photos often leaves vertical motion blur. i really need to get her one with IS (she has a 28-135 IS for her 10d).

 

[MarkBarbieri]

I've slept only 2 of the last 40 hours, so don't shoot me if I sound insane.

Where we differ is, to me printing is a completely separate process from capturing the image.

Change printing to displaying and you get the same problem. Whether you display on screen, projector, or paper, the important thing for knowing what you can or cannot hand hold is how much you are magnifying the movement of the camera. That's a factor of both focal length (how much the image is magnified before capture) and display size (how much the image is magnified before viewing). No one sees images that aren't displayed, so you always have to deal with both. It is the combination of the two that matters. So if you are displaying the same image from a 160mm lens on a FF camera and a 100mm lens on a 1.6x camera, you want the same shutter speed. Therefore, if you accept that the rule of thumb was correct for full frame, it should be multiplied for smaller sensor cameras (assuming you intend to view your photos in the same way).

You cannot compare an analog photo vs a digital photo in this way.

I didn't say anything about analog of film photography, or at least I didn't mean to. Even in the digital world, sensors that are the same size as 35mm film are often referred to as full frame. This would be true for the Canon 1Ds line and the Canon 5D.

digital SLR is not recording a "magnified" image whatsoever

It's not recording anything magnified, but surely you magnify all of your photos when you display them. I can't imagine someone with a DSLR displaying their pictures at the size of their sensor. I also don't know of anyone that displays their photos in sizes relative to their sensor size. If you capture the same image with a larger sensor and a smaller sensor and display them at the same size, the one taken with the smaller sensor has been magnified more from the point of capture to the point of display.

I have to say that, although I enjoy debating the finer points of this on principle, the reality is that the rule of thumb is so vague that a 1.6x difference isn't all that significant. After all, as I have argued, motion blur is magnified when displaying the image, so to be accurate, the rule should include not just the focal length but the display size. I imagine you also need to consider the viewing distance and the resolution of the sensor and output device. The rule isn't leading you to what it takes to get perfectly sharp photos (if there is such a thing); it's giving you an approximation to what is good enough for most uses. I'd use the rule as starting point and then learn what works for you with different lenses and shutter speeds through actual use.

Some other great points to waste time debating:

1) Your focal length has no effect on perspective. Perspective is strictly a function of the relative position of the sensor and the objects photographed.

2) Regardless of your aperture and sensor size, only objects in a single plane are actually in focus. For everything else, it's just a question of how out of focus.

3) The effect of sensor size on depth-of-field. This one gets terribly complicated. I've known guys that know far more about optics than I could ever hope to argue this one without resolution.

 

[Groucho]

It's not recording anything magnified, but surely you magnify all of your photos when you display them. I can't imagine someone with a DSLR displaying their pictures at the size of their sensor. I also don't know of anyone that displays their photos in sizes relative to their sensor size. If you capture the same image with a larger sensor and a smaller sensor and display them at the same size, the one taken with the smaller sensor has been magnified more from the point of capture to the point of display.

Yes, but the term "magnified" makes me all itchy, and not in a good way.

As far as I'm concerned, a digital sensor is no more "magnified" compared to a 35mm than a 35mm is magnified compared to a medium-format camera. (or 16mm movie film vs 35mm movie film - the resolution is higher but focus is even more important on the larger film.)

I guess my question is - is the "rule of thumb" the same for medium or large-format cameras? I honestly don't know. Of course, I don't generally think about that, and just go by the seat of my pants. I probably lose a couple photos due to sharpness but gain a couple by being able to shoot with less prep - that's one of the beauties of digital photography; since there's no per-picture cost, there's no downside to making a ton of pictures and learning how your own camera works in your own hands. It's probably just as worthwhile to take several of your own pictures (good and bad) and compare exif data.

 

[Anewman]

How do I feel about these type of "tutorials"? they are great.

Where I have had issues is where the creator feels that their tutorials are the holy grail and are the only possible way that a "real photographer" must shoot. That is obviously not the case with this one.

In fact I feel that parts one and two do not really give any advice, they do help explain things but do not tell the reader how to focus or give any other instructions.

Example.

TUTORIAL.
1. FOCUS you MUST use center focus point only.

2. You MUST use a TRIPOD



I prefer the type of tutorials like this that you explain things and let the shooter work out the details.

i think you might be making this more technical and complicated that it needs to be


maybe you do need to account for it, maybe you don't but i wrote the thread as a guide to novices and if it helps them but having a shutter faster than necessary, so be it.

I agree with Jann on this, the whole mention of "crop factor" is what is making things more complicated and technical than it needs to be.

Take any one of the superzoom point and shoots, if it is listed as 400mm does the novice really need to understand that it is a crop factor and the lens is actually just a 70mm lens??????

Not in my opinion, they just need to know that it is(acts like) a 400mm lens and should really aim for a 1/400th of a second shutter speed. They do not need to know if this was achieved by magnification or crop factor.

 

[Laura]

let's not make this thread into anything more than it was intented to be. a helpful guide so people can get some better images. there have been a lot of theads about "all my photos are blurry", etc etc. so i was trying to help

True. There have also been several posts about retrieving deleted photos, and someone else started a thread about what to do when that happens.