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BenjaminXYZ Sep 10, 2006 2:24 AM

Does a dSLR have a live dept of field preview?

I ask this because I am usually able to observe the dept of field on my N1 compact. In another words, I get an instant feedbacks of the dept of field.

Can I have such a thingin a dSLR when I select an aperture or do I need to press the DOF button to get it (Always)? Can I hold down the DOF button to keep on getting a life DOF preview as on a live preview LCD camera?

I like to be able to track my subject and see the dept of view changes as the camera focus on it. My N1 does that with continuous focus.

Generally does a dSLR with it's TTL viewfinder even provides you with a DOF preview when you focus on a subject...as on all live preview LCD cameras? (Withoutpressinga DOF previewbutton)




jacks Sep 10, 2006 2:57 AM

No.
Autofocus is disabled on a 350D when you hold down the dof preview. It couldn't work anyway, if you have the aperture set to more than f5.6 as there wouldn't be enough light to focus with. Slrs use a different (and more accurate) focussing system than P&S.
You also want the aperture wide open for focusing and framing as the view finder is much brighter and easier to see. The greater detail you can see through an slr view-finder is pretty good compensation for the lack of live dof preview.
On a P&S you don't have much control over dof anyway as the difference between maximum and minimum apertures is usually only about 4 stops and even at maximum aperture the dof is already quite large.

BenjaminXYZ Sep 10, 2006 3:30 AM

What happens if I bring an R1 into the situation? The R1 is just like a usual ultra compact with thelive preview except that it has an APS-C size CMOS sensorand a huge C.Z. lens. It also have a magnified manual focus center.

I read thatthe R1has a live dept of field preview so I guess that it will be everything like my N1 except that the out of focus areas will be more dramatic?

Thanks for clarifying about the dSLRs to me.



peripatetic Sep 10, 2006 4:00 AM

DOF preview is IMO mainly a useless function on SLR cameras anyway, even film cameras.

Why? Because it doesn't give you an accurate picture of what will and will not be "in focus" in the final print.

Also with the entry level APS sensor cameras, the viewfinder is usually smaller and dimmer and is thus the feature is even less useful than it might be.

And if you claim that you can get a good idea of DOF from a P&S live preview on an LCD screen, then I'm afraid you are mistaken. If you don't agree then you really need to tell me how many lp/mm resolution you are able to distinguish on that screen with live preview.

The correct way to gauge what your DOF is likely to be on an SLR is to commit some basic information to memory about hyperfocal distances for different focal lengths and apertures on the sensor size you are concerned with. Mix that up with lots of practice and you will soon be getting the DOF you want.

BenjaminXYZ Sep 10, 2006 4:15 AM

But don't you think that a live preview image sensor especially on an APS-C camera like the R1 will accurately preview the DOF than a mirror plane a few mm froma dSLRimage sensor? The out of focus areas on the R1 will be more obvious than on a conventional P&S; thus providing more accurate evaluation of DOF right?

I am just curious. Thanks also for enlightening me about the DOF preview on dSLRs.

jacks Sep 10, 2006 5:36 AM

No. The preview image is very low resolution and so you can't really tell what is sharp and in focus at the sensor.
In and out of focus are not like black and white. In fact virtually nothing is in perfect focus. What matters is if it is sharp enough when printed and viewed. This depends on lots of things that happen post-camera such as the resolution of the print, how close the viewer is to it and how good their eyesight is as well as on the aperture, sharpness and resolution of the camera set-up.
In an slr the viewfinder is generally too small (especially on a crop camera) to accurately judge depth of field. If you're trying to get a lot 'in focus' then the lens is probably stopped down and using the dof preview will leave the view finder too dark to see anything at all. You work by remembering settings you have used before and how they looked after x post-processing and y printing. The low-res preview on a p&s is even less helpful - you don't even have access to the image as the sensor will record it.
What exactly is it that you wish to see through the viewer? The dof change as you adjust the aperture in Av mode? If you just want to see the subject stand out from the background then this is the default for an slr. The dof only increases when you preview. The aperture is always wide-open until the shutter button is pressed.


peripatetic Sep 10, 2006 7:23 AM

Yeah, exactly what jacks said.

On most lenses you will have only a plane which is actually in focus (matters can be more complicated depending on lens curvature etc. but a plane is good enough for most purposes of discussion).

What appears in focus behind and in front of that plane depends on a very wide range of factors.

Print resolution and viewing distance are vitally important, and that is the crux - the resolution of the small optical viewfinders, and even more so with electronic viewfinders, is simply not high enough to give you any kind of accurate picture of what your prints will look like.

The R1 is no better than any other EVF in this regard.

BenjaminXYZ Sep 10, 2006 11:22 AM

I was actually concerned about tracking subjects withlive DOF previewing as I focus on them. (Kind of like a video camera following the subject with the focus on it and you see the focusing processeslife!)

Anyway, I do appreciate all your helps and hope that you allwill advice me more about TTL viewfindersvs EVFs or live preview LCDs.

Just now I tested a sampleNikon D70s out at a shopping mall and found thatit's TTL viewfinder was actually much better than I had ever thought of it to be. I zoomed the 18-70 mm lens to the max and still found the TTL viewfinder a pleasure to use with no obvious light lost.

If I have to be very honest; I actually think that the TTL viewfinder of the Nikon D70s is far higher in quality than the EVF of the SONYR1. I only found that the focus pointswere a bittoo transparent so that when they glow red to indicate focus, I have to really look out for it. As an aside, I also found that the D70s's main LCDwas nothing short of amazing to me considering I never expected it to be that good. (Sometimes quality matters)

Finally, I cannot help it but to state that the Nikon D70s was one reallyhigh quality camera that I have ever held in my entire life!

Anyway, back to thetopic:

I haven't actually tried to obtain bokeh yet with the Nikon D70s since there was not much time for it during the short test, I am curious to knowif I can observe bokeh (background blur)witha TTL viewfinder? (I could with my N1's live preview LCD on macro mode).

Quote:

The low-res preview on a p&s is even less helpful - you don't even have access to the image as the sensor will record it.

How does a dSLR have access to the image as the sensor will record it?

Code:

What exactly is it that you wish to see through the viewer? The dof change as you adjust the aperture in Av mode?

Actually yes. I would like to select say F/2.8 or maybe F/1.4 and actually see the DOF change at once (Even if it is not 100% accurate).

Quote:

The aperture is always wide-open until the shutter button is pressed.
Sorry, I missed this fact...So you mean that even if I select lets say F8 or F9 I will still not see an F8 or F9 until I press the shutter button to take the shot? I will always be seeing at the lens' largest aperture setting at lets say F/2.8 or F/1.4?












rjseeney Sep 10, 2006 12:53 PM

BenjaminXYZ wrote:
Quote:

I was actually concerned about tracking subjects withlive DOF previewing as I focus on them. (Kind of like a video camera following the subject with the focus on it and you see the focusing processeslife!)
Live DOF is not possible even with cameras that have DOF preview. DOF preview only stops the lens down when activated to give an idea of what DOF is. As has been said, typically the viewfinder is too dark and small to really give an accurate representation of actual DOF. Depending on what focus mode you are in, you can track a subject while maintaining focus.


Quote:

If I have to be very honest; I actually think that the TTL viewfinder of the Nikon D70s is far higher in quality than the EVF of the SONYR1. I only found that the focus pointswere a bittoo transparent so that when they glow red to indicate focus, I have to really look out for it. As an aside, I also found that the D70s's main LCDwas nothing short of amazing to me considering I never expected it to be that good. (Sometimes quality matters)
Optical viewfinders are much easier to use and higher quality than EVF in my opinion. There is no flicker in optical viewfinders which makes it easier to track moving subjects. EVF's just look way to0 artificial.





Quote:

I haven't actually tried to obtain bokeh yet with the Nikon D70s since there was not much time for it during the short test, I am curious to knowif I can observe bokeh (background blur)witha TTL viewfinder? (I could with my N1's live preview LCD on macro mode).
Bokeh is not something that you can obtain. It is a non measurable, subjective term used to describe the quality of the blurred background, specifically the highlights and how well they blend together in a pleasing way. All lenses have bokeh at all times. It's the quality that differs, and again there is no clear way to measure that as it is mostly personal preference. It is impossible to judge bokeh through the lens of a DSLR. The viewfinder is too dark and too small to make a judgement. You can only evaluate bokeh in the final image. Bokeh is mostly dependent on the lens and has little if anything to do with the camera body. This is another reason the lens choices are ultimately more important than body choice, especially at the consumer level.

You're far better off learning your camera in and out and understanding how DOF is related to change in aperature values than relying on bells and whistles like DOF preview. It's much quicker, and with practice you'll find yourself not even needing DOF preview to achieve the results you want.

[code]

jacks Sep 10, 2006 8:59 PM

I think you are a little bit confused about what exactly dof is. What you are describing is seeing the focus follow your subject. This is servo mode in autofocus and I suspect that pretty much all modern slrs have it. Because the lens is always wide open the background will be out of focus while the subject is tracked by the autofocus mechanism. If the background is sufficiently o-o-f at this maximum aperture then this will be visible even through the viewfinder.

As to your more specific questions, the ttl viewfinder has access to the actual image as it is the same light that will go to the sensor. It has just been reflected upwards by a mirror (and passed through another element or two and a pentaprism but lets keep it simple here). In a P&S on the other hand the viewfinder shows a low resolution sampling of the picture. The difference is like the difference between looking out the window and looking at a newsprint photo.

What happens when you press the button in an slr are the following:-
1. The mirror flips out of the way of the sensor. Note that you now cannot see through the viewfinder at all. For most shooting the whole process is very rapid so its not a problem.
2. The aperture of the lens closes down to the chosen setting. Until then it is wide open. You NEVER see the image stopped down through the viewfinder as this only occurs after the mirror has popped up (that is why there is a dof preview button instead).
3. The shutter opens, exposing the sensor and then closes again.
4.... everything is reset.
So you always view the subject with the aperture wide open. This is one of the many nice things about having fast lenses - the viewer is much brighter and easy to see. Autofocus generally works better with fast lenses (and so more light) too.

Hawgwild Sep 11, 2006 10:48 PM

One of the great milestones in slr photography was the advent of open-aperture metering. This allowed for composition and metering without HAVING to stop the lens down, making it dark. While there may be a rare occasion where you may wish to stop the lens down and then look through it, for me personally, I can live without it quite happily. Just my two cents...

cheers,

Robert

BenjaminXYZ Sep 11, 2006 11:47 PM

Alright, complicated stuff.

On top of everything (which I certainly had a hard time absorbing), I am curious to know whether can I observe focus with a TTL viewfinder?

I will provide an example below which has been in my mind for quite some time>>>

When I fit a dSLR (Say a Nikon D50 or D70s) with a lens such as the NIKKOR F/1.8 85 MM prime glass which have a very shallow DOF wide open...I know that the out of focus areaswill be very bokeh like am I right? Now, what happens if I try to focus on a person anywhere appropriate enough fora backgroundbokeh to be created; what will happen, will everything be clear or will the person be in focus only with the background in soft focus? (On the TTL viewfinder)

This is my question. (Sorry if I didn't made myself clear in my previous post)

EDIT:

Assuming that I can indeed see background blur while focusingon a person in the appropriate distance with the 85 mm F/1.8 (or otherlarge aperturelenses) mounted; what happens if I select "continuous" focus and then track the guy as he moves, will I keep on seeing the bokeh and the person clearly in focus as I track him?
__________________________________________________ ________________________________________________
BTW, I want to clarify something;

Why you all say it is impossible to check focus with a live preview LCD?

I could in fact observe focus and bokeh on my N1 compact especially in macro mode where background blur and clearly focus objects are easily seen.

Also note that more advance prosumers like the R1 has even more obvious out of focus areas so that you can better judge it.

Read the following excerpt about the R1's focus>>>

Quote:


Manual focus
During manual focus (as you turn the MF ring) the center of the frame is magnified up to full size, the R1's large sensor and large maximum apertures make it easy to locate the focus point (because when not in focus the image is more blurred than it would be on a consumer digital camera). The magnified display is very detailed, much better than most live view manual focus implementations.






http://www.dpreview.com/reviews/sonydscr1/page7.asp

I am not trying to defend the R1, I just found it (incidentally) convenient to use it as agood example of what I am talking about.

As an aside: If my DSC-N1 compact (supposedly) have a large APS-Cimage sensor and a F/1.4 prime (I only made it VERY obvious here), I can be very sure that I will be looking for what I want.Because now I could even observe bokehand live focusing processes with my N1. I bet if it has a large sensor and aperture, Iwill be able to frame a non-macro subject and evaluate both the subject and the bokeh on the LCD. (That is what I want)

Sometimes when I select continuous focus on my N1, I could see it focusing on moving subjects. Imagine ifit had a large sensor and aperture, won't I be able to notesomething more dramatic given the shallower DOF?Looking at the R1, it is just like a dSLR in terms of this areabut with a live preview thatseems good enough for me to observe focus and bokeh.

-----------------------------------------------------------------------------------------------------------

Okay, Idid notmeant to sound like a super pro being able to evaluate bokeh and focus with myN1's tiny sensor and aperture. I was in fact interested inhaving everything like my N1 except with a large image sensor and aperture to seriouslyget bokeh andeasier focus due to the more obvious out of focus characteristics of large sensors/apertures. I was hoping that a dSLR could provide me with those, since I really want to observe the bokeh and focus first before capturing the shot. (It will be easier for me tolook at the framing [see how the settings take place] before capturing)

In the end, Iwon't mind a dSLR as long as it can show me background blur and focus on it's TTL viewfinderor else I might just find myself looking through a piece of glass...











peripatetic Sep 12, 2006 2:20 AM

Quote:

I know that the out of focus areaswill be very bokeh like am I right?

You don't understand the meaning of the term "bokeh". It refers to how pleasing to the eye is the area of the photograph that is out of focus.

It does not refer to the degree to which the background is blurred.

It is possible to observe out-of-focus areas while looking through any kind of viewfinder, what it is not possible to do is tojudgethe appearance of the final print by what you are looking at through the viewfinder. The viewfinder is simply not that accurate.

Quote:

I really want to observe the bokeh and focus first before capturing the shot.

If you want to do that sort of thing you need a large-format camera and a magnifying loupe.




Quote:

Why you all say it is impossible to check focus with a live preview LCD?
That's not what anyone has said. It is often possible, though the worse the viewfinder the harder it is, to check focus through the viewfinder. You can often see that the plane of focus is close to correct.

Some of the more expensive cameras have interchangeable focus screens to make this easier - for example the Canon 5D and 1D series. (They are not provided with the camera, but can be purchased.)

These screens were common before cameras had AF. Nowadays however most people cannot focus as accurately by eye as the autofocus algorithms can, certainly they cannot do it as quickly and accurately.

So of course the easiest way to judge focus for most SLR users is now to check when the AF markers light up.

What you cannot do is accurately judge how much DOF you will have in a final print, with experience you can get a pretty good idea of how much DOF a particular lens will give at a given aperture and focus distance.

Follow this link and do some reading, use the online calculator to play with various values.

http://www.dofmaster.com

rjseeney Sep 12, 2006 4:53 AM

As I said before, (and what peripatetic has said) you're mixed up about the meaning of bokeh. Bokeh is not something tangible that you can "get" or achieve. It is a subjective, non measurable term that refers to how pleasing the out of focus background is. Since it is subjective, and because the viewfinder (or even LCD for that matter) is small, there is no way to evaluate bokeh prior to the shot. Larger aperatures typically provide the most pleasing bokeh, but your bokeh will be roughly the same for a particular lens at given aperatures. That means bokeh for you're 85 mm lens will have roughly the same characteristics for each aperature (with the results at each aperature being slightly different). With experience using the lens, you'll have a pretty good idea of what bokeh will be like at say f 1.8 before taking the shot. And ultimately bokeh is what it is for any given lens at any given aperature. It is not changeable, or tweakable. That being said, you can really only "evaluate" bokeh once.

BenjaminXYZ Sep 12, 2006 7:31 AM

Yeah, I actually got mixed up with bokeh and background blur. :mad:

[SORRY] What I want is NOT evaluating bokeh on the TTL viewfinder actually...I am curious whether can I observe background blur on the TTL viewfinder. (It was my bad)

I assume that the answerwill be a yes considering that the lens willalways be wide open as youhave allsaid?

So I can focus on a subject and observe the background blur around the subject? With continuous focus selected, I should be able to track the subject and still see the background blur?

I appreciate all your advice.

rjseeney Sep 12, 2006 7:47 AM

BenjaminXYZ wrote:
Quote:

Yeah, I actually got mixed up with bokeh and background blur. :mad:

[SORRY] What I want is NOT evaluating bokeh on the TTL viewfinder actually...I am curious whether can I observe background blur on the TTL viewfinder. (It was my bad)

I assume that the answerwill be a yes considering that the lens willalways be wide open as youhave allsaid?

So I can focus on a subject and observe the background blur around the subject? With continuous focus selected, I should be able to track the subject and still see the background blur?

I appreciate all your advice.
Not really. You may be able to see a bit of what you're looking for, but not enough to really judge how it will appear in the final print. The viewfinder is too small and dark to be able to see what you're looking for clearly.

BenjaminXYZ Sep 12, 2006 8:27 AM

I forgot to ask you what you meant by;

Quote:

you can really only "evaluate" bokeh once.
Quote:

Not really. You may be able to see a bit of what you're looking for, but not enough to really judge how it will appear in the final print. The viewfinder is too small and dark to be able to see what you're looking for clearly.

So it seems like a live preview LCD is better than, considering I can clearly see the "out of focus" areas using macro mode on my N1 compact. It is not dark or small at all. (Icould just see it allvery clearly and the final picture also turns out as it is on the LCD -A leaf against a blurred out background.)

Here is an example picture I had posted before>>> (It looks justlike that on my N1's LCD even while framing it.)

http://img61.imageshack.us/img61/996...410copyfj1.jpg












rjseeney Sep 12, 2006 12:21 PM

As I said, bokeh is dependent on the lens, not the camera. Bokeh is not subject to change, or fluctuation, as how the lens is constructed,and the quality of the optics and lens coatings is what determines bokeh (as well as how we percieve it....again it is mostly subjective). So at any given aperature, regardless of all other settings, bokeh will be failry consistent...it is what it is. Sure, the type of scene and the background your shooting has something to do with it (an ugly background is an ugly background..great bokeh will not change it), but bokeh will be consistent from shot to shot at the same aperature for a particular lens. Since its consistent, regardless of how many times you look at it, your results will roughly be the same.

In terms of whether a live preview lcd is better, since you can clearly see your background maybe for you it is. With the amount of shooting I do, I don't need to see how out of focus the background is....I know how the lens will perform at a given aperature. I'm more concerned with focus, which in my opinionis much easier to see through an optical viewfinder. As long as I use a large aperature, I know how out of focus the background will be. This comes from practice, and I think you'll find over time, getting the focus right is more important than worrying about the background, especially since there a many ways that you can blur a background easily in post work...there is no way to fix focus.

BenjaminXYZ Sep 13, 2006 3:33 AM

Alright, I am disappointed.

Maybe the TTL viewfinder is better for speed and clarity only.

Perhaps a dSLR is not for me after all; I prefer something clear, bright, sharp, accurate, and crisp for me to frame my images.

When I took a lookthrough the live preview LCD on the R1, it is much sharper looking thanit's 235,000 pixels EVF with only 134,000 pixels on a 2.0" surface area. I am guessing that the EVF magnified the 235,000 pixels too much to make it so "pixelize looking".

Anyway my point is;

The live preview LCD of the R1 is sharp, vibrant, crisp, bright, clear, and nice. In fact, I think it looks higher in quality than my N1's 230,000 pixel 3.0" touch screen (clear photo LCD plus). The R1's live preview LCD doesn't seems tolook like a small & darkdSLR TTL viewfinder as you've described it.

The only issue with the LCD (asonall the others as well) is; "There's refresh rate"

If only the TTL viewfinderof a dSLR can allow me to evaluate background blur and tosome extend "bokeh"as on a high quality live previewLCD, I won't have any problems with it.

I am not demanding perfect bokeh and focus evaluations on any preview method ofcouse, I just wantedsomething "good quality" that can provide me with some idea of howthe images will eventually look like. (Just asthe live preview LCDon my N1 can provide me)

I thought I expected more on a dSLR's TTL viewfinder...expecially with a much bigger image sensor and aperture. Funny, so that means that the Sony R1 with it's clear live preview LCDwill be the best choice for me (For what I have been looking for since the start).

Noticed how obvious theout of focusareas could look on the R1's LCD: It seems wasted that a dSLR's TTL viewfindercannot show such an effect (Unless I am mistaken).

http://www.dpreview.com/reviews/Sony...res/r1_050.jpg

EDIT:

Perhapes I did mistaken>>>

http://www.steves-digicams.com/2004_...iewfinder2.jpg

I could observe some background blur on this OLYMPUS E-500's TTL viewfinder^

I am still trying to findmore examples if I could.

http://www.dpreview.com/reviews/Sony...finderview.jpg

Found another...I may have to take back all my words...:shock:

And another;

http://www.dpreview.com/articles/Can...erviewdiag.jpg

It seems that I can have what I want on a dSLRTTL viewfinder then??? This is clearly what I am looking for.

http://www.dpreview.com/reviews/Niko...finderview.jpg

I think I have already found what I have been looking for. (To observe background blur on a TTL viewfinder). I always like to frame my subject before I capture it, if it looks nice on the viewfinder; then I capture it. (Yes, that also applies to my other aspects of photography as well)

I know I can't have everything with a TTL viewfinder, but a TTL VF does offer me some superiority in the image quality and speed department. When I look through the D70s' TTL VF, I know; I can see the scene very clearly unlike an EVF and there is also no lag at all since everything is at the speed of light without any pixels.

Earlier I did mistakenthe fact that one cannot see background blur in a TTL viewfinder, if I recalled, some in here did say I could see the effect, but duetoexperienced user telling me it isnot easy to observe it has lead me into thinking that live previews are better.In fact, they are looking very similer to me now with the above examples at hand. Thoseare exackly what I wanted.


Earlier some of the commentswere making me think that TTLviewfinders are just like a neutral piece of glass that can't show you any dept of field, bokeh, or background blurat all. I mean, all I need is justbeing able to observe the background blur (To some extend: focus) like what you canmake outin those examples above^

lol, what kept you'll thinkingthat I wanted ultra precision& 100% accurate representation of focus, bokeh, and background blur on TTL viewfinders?? :-)


















rjseeney Sep 13, 2006 7:56 AM

Remember, you are seeing greatly enlarged images of these viewfinders. Yes, you will be able to get an idea of what the background will look like, but your actual view through the viewfinder will be much smaller and you will be less able to make out details. Also, unless your shooting wide open, when the lens stops down to the actual aperature when you press the shutter, the amount of background blur will change, as when composing the shot the camera is wide open. I still contend that you should be more worried about getting accurate focus, rather than the background blur. Once, you understand how your lens renders the background at a given aperature, you won't need to see the amount of background blur, because you'll know what the effect is going to be.

BenjaminXYZ Sep 13, 2006 8:36 AM

Thanks rjseeneyfor your great help! :|

Now I have begun to understand more about dSLR TTL viewfinders and how they relate to everything elseassociated with them.

I don't have any problems going for a dSLR anymore if I ever have to go for one in the near future.
8)

[.-.-.-.-.]


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