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02-14-2011, 04:07 AM   #16
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QuoteOriginally posted by Jewelltrail Quote
Obviously the sensor on the Point & Shoot can not produce shallow depth of field, but neither can the sensor on the Pentax produce the tremendous depth of field the P & S produces. All systems are a trade off.
Not to be pedantic, but the P&S lens (not the sensor) produces the large DOF. At the long end, the H55 lens is at FF-equivalent f/20 wide open. You could get the same large DOF if you found an APS-C lens that can be stopped down as much as the H55 lens.

Also note that such high f-stops require a lot of light and have a very negative impact on image sharpness due to diffraction effects. For quality images, I don't think there is a way around focus stacking with larger lenses.

While you might be right about the price/value ratio regarding P&S' and DSLRs, I know that the P&S quality isn't good enough for me, no matter at how low cost it comes.

02-14-2011, 05:51 PM   #17
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While the P&S cameras have improved a lot in the last several years, you can't get away from the noise (or detail smearing noise reduction) at high ISOs and the limited dynamic range. I just can't use mine anymore, I can't stand the blown highlights.
02-14-2011, 09:40 PM   #18
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QuoteQuote:
Class A: Not to be pedantic, but the P&S lens (not the sensor) produces the large DOF. At the long end, the H55 lens is at FF-equivalent f/20 wide open. You could get the same large DOF if you found an APS-C lens that can be stopped down as much as the H55 lens.
pe·dan·tic   /pəˈdæntɪk/ –adjective
1.
ostentatious in one's learning.
2.
overly concerned with minute details or formalisms, especially in teaching.


In order to be pedantic, one must, at the very least, present facts--you have not done this. Here are some facts about DOF:

Firstly, DOF is inversely proportional to format size, & format size is inversely proportional to the "digital multiplier". The bigger the "digital multiplier", the smaller the format and thus the greater the depth of field. This is one reason why large format cameras need tilts and swings to get adequate depth of field. With an 8x10 camera you have about 8.5 times LESS depth of field than you do with 35mm for the same image. This also explains why consumer digicams, some of which have sensors 1/6 the size of 35mm film, have such a large depth of field and one of the reasons why it's almost impossible to get blurred backgrounds when using them.

Also, more importantly I think, we need to crush the myth that DOF is black & white: that it is defined by an infocus & out of focus area. Though it might be nice, things are not this simple; rather, "The depth of field is the range of distances reproduced in a print over which the image is not unacceptably less sharp than the sharpest part of the image". (1) Now this definition is truly pedantic, but needs to be in order to be accurate. For the Math people, here is what we have:





Where F is the focal length
D is the subject distance
c is the circle of confusion
fn is the f# (f-stop) of the lens

*Note* The equation is only true over the range of focus distances which aren't in the macro range i.e., (where D approximates F) & which are not close to the hyperfocal distance (where D = F*F/fn*c), so the equation can not be taken as a standard.
02-14-2011, 10:04 PM   #19
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QuoteOriginally posted by Class A Quote
Not to be pedantic, but the P&S lens (not the sensor) produces the large DOF. At the long end, the H55 lens is at FF-equivalent f/20 wide open. You could get the same large DOF if you found an APS-C lens that can be stopped down as much as the H55 lens.
You're right that it's the lens that makes biggest difference in the DOF, but the key factor in P&S lenses and DOF is not the aperture, but the focal length. Ignore all this "equivalent focal length" nonsense. Lenses have a true focal length that is a physical property of the optics, and is usually marked on the front of the lens. For example, the Canon SX20 IS superzoom has an advertised "equivalent" focal length of "28-560", but its actual focal length is 5-100mm, as marked on the lens itself. Imagine what the DOF on your DSLR would look like if you used a 5mm lens, if one existed.

It is a well known phenomenon that for a given magnification (absolute terms, not scaled to sensor size) DOF will appear roughly the same (with some exceptions at the extreme ends). Magnification is a ratio between actual object size and absolute size of the image projected into the plane of the sensor (regardless of size of sensor). Magnification is dependent on two things: focal length and distance from subject. For a P&S, the absolute magnification requirements (size of the image) are far less because the image sensor is much smaller.

Thus you can look at it two ways:

- The focal length on the P&S is far shorter than the focal length of a lens used to produce the same frame on a larger sensor at the same distance.

or

- The distance between the P&S and the subject is far greater than that needed to produce the same frame on a larger sensor with the same focal length.

Either way, it means that that P&S produces far less magnification, and thus far greater apparent DOF for the same frame. There are other factors involved, such as the "circle of confusion" (which not only depends on the sensor, but how closely you examine the final image), but fundamentally the focal length is the biggest difference.


Last edited by Cannikin; 02-14-2011 at 10:30 PM.
02-14-2011, 10:17 PM   #20
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QuoteOriginally posted by Tom in Delaware Quote
While the P&S cameras have improved a lot in the last several years, you can't get away from the noise (or detail smearing noise reduction) at high ISOs and the limited dynamic range. I just can't use mine anymore, I can't stand the blown highlights.
Tom:

I have owned some more recent P & S camera which do well @ high ISO, up to 800 anyway, which is amazing when you think of it. It is rare that I print larger than 4 x 6, but when I do, my better P & S cameras will allow me to do good prints, @ ISO 400, in 8 x 10 size--amazing. And I know there are other "P & S cameras" which can do even better.

I would say 90 % of all my shots are done @ ISO 100, though I realize this is not tue for everyone.

Tom, there is no need to get blown highlights with a P & S camera, just like you should not get blown highlights with your Pentax camera, so long as you take the controls and control metering. I am amazed how few people ever shoot in manual.

I do not get blown highlights with my P & S cameras, because I shoot them in manual, and control my own metering--it can be that simple if you want it to be. Heck, you'll get blown highlights on expensive DSLRs if you always trust the camera to get your exposure variables.

Dollar for dollar, it is an amazing return for your money with a P & S camera. However, like I said earlier, for the enthusiast, DSLRs have a potential for IQ whose allure is inescapable. But you shell out a lot more money, for relatively small gains. Most people are perfectly content with their P & S cameras, and would be happier, if only they would learn how to get the most out of them.

Last edited by Jewelltrail; 02-14-2011 at 10:27 PM.
02-15-2011, 01:23 AM   #21
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With the Tamron, you get to work with Raw files. If you shoot in JPG only, you get cleaner high ISO photos. This will be helpful if you do find yourself having to shoot in low light. With my Canon Powershot S5 IS, I had to do quite a bit of work in post to get my lower light shots to look decent enough for web viewing.

Other than that, I've seen some pretty nice shots from those super zoom cameras in good light. If you're on a budget and plan to shoot outdoors most of the time, you can't go wrong with a super zoom camera.

Case in point, I photographed this event with my then brand new K-x with kit lens and my S5 IS. I was so used to taking close up shots with my S5 IS that I had to bring it along just in case. In the end, people ended up liking the results regardless of what camera the photos came from.
02-15-2011, 01:46 AM   #22
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QuoteOriginally posted by Jewelltrail Quote
In order to be pedantic, one must, at the very least, present facts...
  1. Your dictionary definition says nothing about the necessity of facts being presented.
  2. I referred to "2." of your dictionary definition in the sense that I didn't want to be perceived as being "overly concerned with minute details".
  3. Not that it matters in the context of being pedantic or not, but I did present facts.
I regret that you didn't see those facts (e.g., about the FF-equivalent f-ratio range of the SONY H55).

QuoteOriginally posted by Jewelltrail Quote
Firstly, DOF is inversely proportional to format size,...
Wrong, if you keep the lens and the subject distance constant.

Do you realise that (keeping sensor technology fixed) low light performance and DOF control are governed by lens properties and not format size? Of course there is a relationship between sensor size and lenses available for it, but that shouldn't lead one to believe that somehow using a bigger sensor suddenly gives you shallower DOF.

You may want to check the very good "https://www.pentaxforums.com/forums/pentax-dslr-discussion/71896-low-noise-be...uals-zero.html" thread again, about what a larger sensor does and what it depends on the lens to do.

Last edited by Class A; 02-16-2011 at 01:16 AM.
02-15-2011, 02:07 AM   #23
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QuoteOriginally posted by Cannikin Quote
You're right that it's the lens that makes biggest difference in the DOF, but the key factor in P&S lenses and DOF is not the aperture, but the focal length.
I appreciate your systematic approach to this topic and your way to compare systems is a valid one.

However, I strongly disagree that the notion of "equivalent focal length" is "nonsense" as it very easily allows one to see which lens provides what kind of DOF range independently of the particular system it is used for.

It is indeed nonsense, to convert focal lengths to understand what FOV one lens yields in terms of another sensor format but not to do the same for its f-ratio range. You didn't do this, but many do.

From a photographer's perspective, one can reasonably argue that focal length is not a variable one has any control over in a format comparison. After all, one wants a certain framing from a certain distance and after that the only thing still left to influence DOF is the aperture.

So I don't agree that focal length is the primary key to understanding DOF differences but there are many ways to skin a cat, i.e., tackle this issue.

02-15-2011, 10:10 PM   #24
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QuoteQuote:
Class A: Your dictionary definition says nothing about the necessity of facts being presented.
I referred to "2." of your dictionary definition in the sense that I didn't want to be perceived as being "overly concerned with minute details".
Not that it matters in the context of being pedantic or not, but I did present facts.
I regret that you didn't see those facts (e.g., about the FF-equivalent f-ratio range of the SONY H55).
When I said you need to present facts, it was to this quotation of yours I was referring: "Not to be pedantic, but the P&S lens (not the sensor) produces the large DOF." And I understood which meaning of the word you were employing when you used "pedantic."

This topic is 1 of the most often-confused topics in photography. In fact, if you visit other forums, you will see the same discussion going back & forth. If you want to see, there is one of these discussions here: Depth of Field vs Sensor Size? - Photo.net Canon EOS Forum One of the problems is the perspective from which you view the argument--it can frame your conclusion. But an inescapable fact is this: DOF is NOT an inherent aspect of a lens. The other problem is the discussion is more complicated than can really be addressed here, in a thread like this. However, for anyone interested, there is a full explanation here:

Depth of Field, Digital Photography and Crop Sensor Cameras - Bob Atkins Photography

That is all I have to say about this.

Last edited by Jewelltrail; 02-15-2011 at 11:06 PM.
02-16-2011, 01:28 AM   #25
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QuoteOriginally posted by Jewelltrail Quote
But an inescapable fact is this: DOF is NOT an inherent aspect of a lens.
Have you visited the "https://www.pentaxforums.com/forums/pentax-dslr-discussion/71896-low-noise-be...uals-zero.html" thread I suggested to you? I think it might be instructive.

Appealing to authorities is not a good argument, but just to instill a little bit of doubt into you, note that you are disagreeing with our resident forum expert on optics, falconeye (again see the above thread).

Note that this article is exactly in accordance to what I wrote in the "lens properties and not format size" post I pointed you too.

Again, I appreciate that it is easier to associate DOF and noise, etc. to sensor size but I feel this practice is a verbal shortcut that is highly confusing to anyone not entirely sure about the underlying principles. N.B. DOF is associated to sensor size in that it is bigger for larger formats, but that is exactly the opposite direction that people typically associate with larger formats. The direction reverses because one changes perspective and/or lenses.
02-16-2011, 03:19 PM   #26
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The discussion has gone a little far afield from the OP's question. I would say that equivalence is really useful when comparing formats. It lets you understand why you have trouble taking photos in dark places with point and shoots/bridge cameras, why you have trouble blurring the background with them, etc. Whether you think of it as a sensor problem or a lens problem, equivalence is the only way to compare different size sensors and the systems associated with them.

To the OP: from what I read, you would be better off going with a super zoom/bridge camera. It doesn't sound like the benefits of SLRs would really be that important to you. The one question you need to ask yourself is if you think that you will want a more capable camera in the not-to-distant future, if so, then an SLR gives you more options.

Edit: One other thing that I think is not emphasized enough is how much dynamic range suffers on these cameras. Look at the Dxo Mark graphs of dynamic range on the kx versus say the Fujifilm s100. What you find is that the kx dynamic range at 12,800 (not that great) is the same as the bridge camera has at iso 800. This tends to make photos, even in good lighting get blown out highlights, detail lost in shadows that is not recoverable.

Last edited by Rondec; 02-16-2011 at 08:09 PM.
02-16-2011, 10:35 PM   #27
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QuoteQuote:
Clockwork247: Tamron 18-250 VS a super zoom.
The more I think about it, the more I think I'm leaning toward a superzoom P&S..
1) a hyperzoom like the tamron is quite a slow lens, and will only be use with enough light, same with a P&S
2) IQ wise, I think some P&S in daylight does really well, some of the superzoom P&S (are midrange to highend P&S) are equip with quite lens lens from the manufacture... so the IQ isn't all that bad.
3) Price, a superzoom (good one) can be have at 100-200 dollars, the tamron 18-250 is probably in the 300.

I guess, the real question is, what can the tamron 18-250 do that a superzoom P&S can't do.
Clockwork, if you do get a superzoom, I suggest you go another $100 and get one of the better ones--there are several which are very, very nice. Also, get one which gives you the option to PP with Raw-this gives you the flexibility you may someday desire. Use sites, like DPReview, which are an amazing research tool. I know it can be tedious, but all you learn will go into a better decision and, after all, you will probably own the camera for some time.

I have owned many P & S cameras, and have immense respect for them, especially the superzooms: they give the ultimate value for your money. I know the Panasonic line has gotten much better of late with controlling noise, and the features they pack into their cameras is amazing. Whatever you do, do not buy a P & S and keep t in Auto mode--use everthing you can on the camera--learn, learn, learn. Good Luck.

JT
02-17-2011, 10:07 PM   #28
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Clockwork:

Don't let anyone fool you--Point & Shoots more than hold their own and have several advatages IMO. And remember, cameras do not blow highlights, people do. Here are Point & Shoot shots from 3 different cameras, all of which nail White Balance better than my K20d, all of which are Jpegs out of camera, all of which were made with cameras costing far less than many lenses in the Pentax lineup. I'm sure, if they were shot Raw and PPed competently, you would be amazed. Oh, and BTW, these cameras range from 10 years old, to 5 years old. Newer point and Shoots do much better.















02-18-2011, 12:43 AM   #29
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QuoteOriginally posted by Jewelltrail Quote
Clockwork:

Don't let anyone fool you--Point & Shoots more than hold their own and have several advatages IMO. And remember, cameras do not blow highlights, people do. Here are Point & Shoot shots from 3 different cameras, all of which nail White Balance better than my K20d, all of which are Jpegs out of camera, all of which were made with cameras costing far less than many lenses in the Pentax lineup. I'm sure, if they were shot Raw and PPed competently, you would be amazed. Oh, and BTW, these cameras range from 10 years old, to 5 years old. Newer point and Shoots do much better.

I'd agree with that except the bit about the newer ones doing better. I'm not sure they do. My old Olympus C760UZ performs very well against the more recent P&Ses I have, and it was only 10x and 3.2Mp. Prints up well to A4 size, too. Thats why I won't ever get rid of it. I still use it, sometimes. Against an 18-250 though, nope.

I think it does depend on what you expect of the camera. My friend who's heading off to the UK and Europe is hell bent on getting a Fujifilm HS20 and cannot be convinced he will be better off with the 18-250 I'm selling him, because the Fuji is 720mm at full stretch and the Tammy is only 250mm (he says he wants to get detail inside cathedrals etc... I think he will get all the detail he could possibly need, with the Tammy). I wish I could get him to understand the concept of the crop, and the issues to do with light, small sensors yada yada. He says he does, and then follows it up with a comment that the Fuji will still be better. If weight is the issue, it certainly will, but... I'd rather crop down from a dslr shot than shoot with the full length of a 36x lens.
02-18-2011, 05:28 AM   #30
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QuoteOriginally posted by kyteflyer Quote
I'd agree with that except the bit about the newer ones doing better. I'm not sure they do. My old Olympus C760UZ performs very well against the more recent P&Ses I have, and it was only 10x and 3.2Mp. Prints up well to A4 size, too. Thats why I won't ever get rid of it. I still use it, sometimes. Against an 18-250 though, nope.

I think it does depend on what you expect of the camera. My friend who's heading off to the UK and Europe is hell bent on getting a Fujifilm HS20 and cannot be convinced he will be better off with the 18-250 I'm selling him, because the Fuji is 720mm at full stretch and the Tammy is only 250mm (he says he wants to get detail inside cathedrals etc... I think he will get all the detail he could possibly need, with the Tammy). I wish I could get him to understand the concept of the crop, and the issues to do with light, small sensors yada yada. He says he does, and then follows it up with a comment that the Fuji will still be better. If weight is the issue, it certainly will, but... I'd rather crop down from a dslr shot than shoot with the full length of a 36x lens.
This is true. At this point, camera companies are putting 12 to 14 megapixels on a sensor the size of a corn flake. At a certain point you just start magnifying noise, rather than getting real data. The older sensors weren't so pixel dense and so they actually perform better in many respects.

The reality is that if a superzoom- bridge camera has a zoom that even goes to 350 mm, you are going to need a tripod to get a sharp shot with it in anything but great light settings.
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