Canon 350D

[Chip NoVaMac]

The 85mm is great. (I have Nikon gear but I'm sure Canon is the same here) My 85mm opens up to f/1.8 I can't can't get a 135mm f/1.8 lens With the smaller format of d350 vs. 35mm film the 85 acts like a 135mm f/1.8 lens

You can get a 135mm f2.0 Nikkor however (http://www.bhphotovideo.com/bnh/con...487&is=USA&addedTroughType=categoryNavigation)

All this talk about I don't need a fast lens I have "IS". Well, if you use a flash for daytime fill in light to control shadow depth you DO want a fast tele. The effective range in feet of a strobe depends on the f-stop. Shooting animals at the zoo in bright daylight, a fill flash helps but at 50+ feet you'd need a studio strobe setup if the lens can only do f/5.6

Good point. And the other aspect is being able to have less DOF in order to separate your subject from the background.

 

[kwajo.com]

I recently had to do a archive and install to fix a hard drive problem, and ever since reinstalling CS2 the "save for web" feature seems to desaturate the crapola out of my images, as can be seen by this one. ^^

same thing for me too, it's very very annoying

 

[jared_kipe]

Have you found the problem with it yet? I guess it will only matter if it does it on my new imac, which I'm installing software on now (except aperture cause Apple is greedy about the Pro apps and want to force everyone to pay $50 per app again to have it run on new machines, which should be illegal).

EDIT: This is gonna be one hell of a machine once everything gets universal and compiled properly, 2GB ram, 256VRAM, 2GHz Core Duo.. mmm

 

[Abstract]

Good point. And the other aspect is being able to have less DOF in order to separate your subject from the background.

Yeah, but with the 70-300 mm IS you'd have a comparably small DOF anyway when compared to the 70-200 mm, even at f5.6 at the 300mm end, no?

 

[Chip NoVaMac]

Yeah, but with the 70-300 mm IS you'd have a comparably small DOF anyway when compared to the 70-200 mm, even at f5.6 at the 300mm end, no?

I hope I have my math right.

If you focus at a subject at 300mm at 20 feet at f/5.6 your depth of field would be 19.9 feet to about 20.1 feet (.2 feet of DOF). In order to get the same FOV at 200mm you would need to reduce your distance to 26 feet (33% difference in focal length). In order to get the same field of view (FOV) with the 200mm compared to the 300mm, you need to get 33% closer. In this case I rounded that to 26 feet for the example below.

The DOF though changes due to the closer focus distance. In this case at f/5.6 the DOF at 200mm at 26 feet the DOF is 25.5 to 26.6 feet (1.1 feet of DOF). But at f/2.8 that becomes 25.7 to 26.3 feet (.6 feet of DOF).

But that does not factor in the differing perspective change. And that perspective is why some would choose 300mm (more compressed at a given distance) or visa verssa by going to 200mm (less compressed) with the same FOV.

Edited to correct for bad data, thanks Abstract! Relooked at all numbers and made the corrections above. Hope it is more clear now.

 

[jared_kipe]

Depth of field is such a subjective quantity because it all depends on what you consider your circle of convergence to be in the first place. Its pretty easy to get a blurry backgroud, but its very hard to get a very diffuse looking background. In fast this is a question on compression, and not DOF. The longer the lens is, the less of the background there will be to blur, thus a more diffuse blurry looking background. This and working distance are the two reasons to get a longer macro lens.

 

[eXan]

Nice photo! Though the end of bird's beak is slightly out of focus, it's still a good pic

 

[Abstract]

The DOF though changes due to the closer focus distance. In this case at f/5.6 the DOF at 200mm at 26 feet the DOF is 25.8 to 26.2 feet. But at f/2.8 that becomes 25.1 to 26.1 feet. Not much in this instance, but at closer distances it becomes more apparent.

When your subject is 26 feet away, why would the depth of field range increase from 25.8 to 26.2 feet (a range of 0.4 feet) at f/5.6, to a DOF of 25.1-26.1 feet (or a range of 1 ft) when changed to f/2.8?? Shouldn't the focal range decrease as the aperture is increased (when subject distance and focal length are kept constant)??

Sorry, just trying to learn something from someone who obviously knows what he's doing.

 

[groovebuster]

I bought my EOS 350D in Oktober and I am very satisfied with it... I think I know a little bit more about photography than the average guy, but the "expert talk" in here is a little bit too much for me... I don't really enjoy going on and on about technical things for hours.

groovebuster

 

[-hh]

When your subject is 26 feet away, why would the depth of field range increase from 25.8 to 26.2 feet (a range of 0.4 feet) at f/5.6, to a DOF of 25.1-26.1 feet (or a range of 1 ft) when changed to f/2.8?? Shouldn't the focal range decrease as the aperture is increased (when subject distance and focal length are kept constant)??

Sorry, just trying to learn something from someone who obviously knows what he's doing.

FWIW, I'm confused too - - - I think there's something wonky in those numbers that's either a typo, or we've missed some aspect of the explanation that Chip NoVaMac was trying to provide.

I do know that the general rule of thumb is that depth of field (DOF) will decrease with faster f/stop ... but this is a when "all other factors are equal" rule.

What I think was the additional complexity here was a "not all other factors equal" type of question. If I was following correctly, I think the basic question was:


"If I have a DOF of "A" @ 300m f5.6 at subject distance of 40ft, what happens when...?"

The first Option is:

"...when I have a 200mm lens and I choose to move closer to the subject until the field of view (FOV) is the same. At this point I'll then be at "X" feet (26ft?), and at f/"Y", my DOF will be "Z".


DOF "Z" versus DOF "A" is ______, which means _______.


-hh

 

[-hh]

...I think I know a little bit more about photography than the average guy, but the "expert talk" in here is a little bit too much for me... I don't really enjoy going on and on about technical things for hours.

Some of it can very easily go overboard into esoteric ...I've seen some stuff that gets down into the minutia of quantum mechanics on photons received per receptor as it relates to digital camera noise levels, etc. Heavy stuff.

The level of 'appropriate' technical detail is one of personal preference. For me personally, I'm of the opinion that having a better understanding of how your equipment works can only help you to take better images overall. From there, its only a question of "how deep" you want to dig on a particular topic to get good enough comprehension as to what's going on.

For example, knowing that depth-of-field descreases with faster f/stops is a good-to-know and isn't IMO all that technically "deep". Exactly why this is, I'll skip for now, thanks ("deeper" than I probably need to know right now). But it is also useful to then take this factor into account when trying to compare the DOF of a 300mm lens versus a 200mm lens, particularly if/when that starts to lead towards a purchase decision.

Yes, its starting to become a more complicated question, but since it costs us all real money out of our own pockets, it is usually good for us to have a basic idea what the trade-off's are, before we buy ... instead of discovering it afterwords, for the latter would be a "planning to not plan" approach.


-hh

 

[Chip NoVaMac]

When your subject is 26 feet away, why would the depth of field range increase from 25.8 to 26.2 feet (a range of 0.4 feet) at f/5.6, to a DOF of 25.1-26.1 feet (or a range of 1 ft) when changed to f/2.8?? Shouldn't the focal range decrease as the aperture is increased (when subject distance and focal length are kept constant)??

Sorry, just trying to learn something from someone who obviously knows what he's doing.

Sorry to leave you confused. It was a mistake on my part from using the DOF Calculator here (http://www.dofmaster.com/dofjs.html). Evidently you need to refresh before each calculation.

I now know that I will need to double and triple check my number when posting.

 

[ChrisA]

Is that a function of specific dslr bodies or is it a function of the lens? I'm not sure all bodies can do this do they?

The best answer is "It depends"

The newer SRL bodys allow you to set to f-stop from a control dial on the body. You can set it by either 1/3rd or 1/2 stops. (You can choose either 1/3 or 1/2 per "click") Also when the body is set to shutter priority or auto the system may select an f-stop that is acurate to the nearest 1/3rd stop. But if you use the lens ring that ring it clicks is full stops (or 1/2 stops in some cases). But note that on some camera you must lock the lens ring

Typically on the high-end bodies you can use the ring on the lens. With Nikon the answer varies a lot because you can use the old manula focus lenes on the new bodies and there are 100 possable combinations of bodies and lens types.

This subject is not specific to digital cameras and applies to film as well. It's justthat the film camera don't record the odd ball f/7.8 stop and 1/133 shuter so you son't notic it later.

I whish they'd make a digital back for my Nikon F2. I stil like the way the F2 handles

 

[-hh]

Sorry to leave you confused. It was a mistake on my part from using the DOF Calculator here (http://www.dofmaster.com/dofjs.html.

Nice tool.

Here's some numbers that I think helps to illustrate the general questions.

Measurement of merit for each is "Total Depth of Field"

35mm, 300mm f/5.6, focus distance 40ft: 1.79 ft
35mm, 300mm f/4.0, focus distance 40ft: 1.27 ft
35mm, 300mm f/2.8, focus distance 40ft: 0.9 ft

35mm, 200mm f/5.6, focus distance 40ft: 4.08 ft
35mm, 200mm f/4.0, focus distance 40ft: 2.88 ft
35mm, 200mm f/2.8, focus distance 40ft: 2.04 ft


Given: a 200mm lens at 26.55 ft produces the same field of view as a 300mm lens at 40ft.

35mm, 200mm f/5.6, focus distance 26.55ft: 1.78 ft
35mm, 200mm f/4.0, focus distance 26.55ft: 1.26 ft
35mm, 200mm f/2.8, focus distance 26.55ft: 0.89 ft


Okay, now this is interesting, for this suggests that the DOF is nearly identical at the same f/stop and field of view. As such, if you have a situation where you can't change your f/stop, if you need more DOF, you can back off the focal length ...and recompose later by cropping it in. Of course, you'll lose some image resolution (pixels and/or grain), but it at least affords the option of starting out with more (ALL?) of the subject actually in focus. Correct?


-hh

 

[Chip NoVaMac]

Nice tool.

Here's some numbers that I think helps to illustrate the general questions.

Measurement of merit for each is "Total Depth of Field"Okay, now this is interesting, for this suggests that the DOF is nearly identical at the same f/stop and field of view. As such, if you have a situation where you can't change your f/stop, if you need more DOF, you can back off the focal length ...and recompose later by cropping it in. Of course, you'll lose some image resolution (pixels and/or grain), but it at least affords the option of starting out with more (ALL?) of the subject actually in focus. Correct?


-hh

But in doing the 350D:

350D, 200mm f/5.6, focus distance 26.55ft: 1.13 ft
35mm, 300mm f/5.6, focus distance 40ft: 1.79 ft

The differences between formats IIRC is due to the Circle of Confusion (COC).

So note that both of the respective focal lengths for a given format will give the same FOV; but at the telephoto end one would have less DOF in the 350D in this example.

You had me look at the wide angle end.

350D, 18mm f/3.6, focus distance 7.98ft: 10.8 ft
35mm, 28mm f/3.6, focus distance 6ft: 3.14 ft


But the opposite is true when looking at the wide angle end.

 

[Chip NoVaMac]

Thanks to OutThere for a great link showing what focal lengths do to perspective.

http://en.wikipedia.org/wiki/Perspective_distortion_(caused_by_camera_to_subject_distance)

 

[-hh]

But in doing the 350D:

350D, 200mm f/5.6, focus distance 26.55ft: 1.13 ft
35mm, 300mm f/5.6, focus distance 40ft: 1.79 ft

The differences between formats IIRC is due to the Circle of Confusion (COC).

I think we'll need to have a workshop on Circle of Confusion to help us all understand it a lot better.

In any case, I'm not sure that its appropriate to use the 26.55ft focus distance with the 350D. For one thing, I was assuming that both the 200mm and 300mm lenses were being used on the "same camera" (and that it was 35mm) when I derived where the 26.55 ft distance came from...

Since I didn't document it, bascially, what I did was a straight trigenometric calculation based on a 35mm's 300mm having a defined horizontal coverage of 6.8673 degrees, and a 200mm being 10.2855 degrees. These two values came from Rui Salgueiro's field-of-view calculator. The resulting formula was then:

40ft * TAN(6.8673)/TAN(10.2855) = distance = 26.55ft

In looking at this specific to the 350D, since due to its 1.6x crop factor, wouldn't this suggest that a 200mm would be an effective 320mm for field of view, and that we would need to take this into account? If so, this would suggest that for purposes of varying distance-to-subject to match what the 35mm with 300mm sees, the 350D with 200mm should then end up needing to be be slightly further away than 40ft, not closer.

You had me look at the wide angle end.

I'll try to look at this tomorrow.

-hh

 

[Chip NoVaMac]

I think we'll need to have a workshop on Circle of Confusion to help us all understand it a lot better.

I will look at that later.

In any case, I'm not sure that its appropriate to use the 26.55ft focus distance with the 350D. For one thing, I was assuming that both the 200mm and 300mm lenses were being used on the "same camera" (and that it was 35mm) when I derived where the 26.55 ft distance came from...

But in the discussion of the effect a lens has in 35mm vs lets say the 350D has on DOF; it is important. For the 26.55 ft distance is what a 350D would need to focus at with a 200mm lens in order to equal the FOV of a 35mm camera with a 300mm lens at 40 feet.

The smaller sensor has a cropping factor as called by some, the more proper phrase would field of view (FOV).

In looking at this specific to the 350D, since due to its 1.6x crop factor, wouldn't this suggest that a 200mm would be an effective 320mm for field of view, and that we would need to take this into account? If so, this would suggest that for purposes of varying distance-to-subject to match what the 35mm with 300mm sees, the 350D with 200mm should then end up needing to be be slightly further away than 40ft, not closer.

Right you are. I used the easier method of using a FOV factor 1.5x, figuring differences would be small between FOV factors of 1.5x and 1.6x when compared to the 35mm format.




I'll try to look at this tomorrow.

-hh[/QUOTE]

 

[scu]

After reading most of this thread, I am no closer to figuring out which lens to buy. I own a Rebel which I love, but would like to buy a new zoom lense and a better regular lense. Any recommendations.

 

[Chip NoVaMac]

After reading most of this thread, I am no closer to figuring out which lens to buy. I own a Rebel which I love, but would like to buy a new zoom lense and a better regular lense. Any recommendations.

Depends on your total budget.

 

[scu]

Depends on your total budget.

My friend recommended this lens.

http://www.bhphotovideo.com/bnh/con...629&is=USA&addedTroughType=categoryNavigation

What do you think?

 

[Chip NoVaMac]

My friend recommended this lens.

http://www.bhphotovideo.com/bnh/con...629&is=USA&addedTroughType=categoryNavigation

What do you think?

The 28-135IS is a great lens. But with a DSLR it covers a range 45 to 216mm in 35mm FOV. It may not cover the wider FOV that you desire for general picture taking. For about $100 more (US) a better choice may be the 17-85IS (28-135 -35mm FOV).

 

[Abstract]

Anything that starts from 28 mm isn't useful, IMO. If it goes from 28-135mm, it isn't wide enough at 28 mm to be useful. I actually don't have a problem with the 135mm part of the lense, but the "28 mm" part stands out for me. Either own a wide angle lense and a separate telephoto lense, or get a single lense that starts from 17 or 18 mm and goes up from there, like that 17-85mm that Chip suggested.

 

[arogge]

The Canon 28-135 is a good lens. It isn't really wide-angle, but it has IS and a short telephoto length for a low price. What focal lengths and apertures do you need, and what is a "regular" lens?

 

[Chip NoVaMac]

Anything that starts from 28 mm isn't useful, IMO. If it goes from 28-135mm, it isn't wide enough at 28 mm to be useful. I actually don't have a problem with the 135mm part of the lense, but the "28 mm" part stands out for me. Either own a wide angle lense and a separate telephoto lense, or get a single lense that starts from 17 or 18 mm and goes up from there, like that 17-85mm that Chip suggested.

It depends on ones "personal vision". Some see "wide angle" others see more telephoto. [In SF I found my most used lens was a 12-24 Tokina on my XT (35mm FOV of a 19-38mm). So on my up coming trip, it will be interesting to see how I make out with a 35mm FOV of 27-300mm on my D50 + my 10.5 fisheye.] I have had many customers totally happy with their use of the 28-135IS on the DSLR's.