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05-16-2011, 08:26 AM   #151
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I don't consider it a sensor issue. I consider it a lens issue. For APS-C you need lenses optimized for that size sensor. You need lenses that peak in sharpness at a wider aperture and you need lenses that are faster than their FF equivalents.

FF glass typically peaks in sharpness at smaller apertures than what you need for APS-C sensors. When I shoot with my K-7 I typically stay at f/2.8 or wider with the occasional f/4 shot. I have shot entire events at F/2 - F/2.2. I do this because I want to keep ISO as low as possible and shutter speed as fast as possible. I need glass that is sharp wide open.

IMHO Pentax should have made the 16-50 & 50-135mm an f/2 lens. I realize the size and cost. I shot with Olympus for 3 years and their 14-35 f/2 and 35-100 f/2 are actually bigger and heavier than the Canon/Nikon equivalents.

With lens that are optimized for APS-C (faster/sharper) you can match FF IQ. Of course an APS-C system with that kind of glass would be more expensive than the FF equivalent.

05-16-2011, 08:36 AM   #152
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QuoteOriginally posted by Winder Quote
With lens that are optimized for APS-C (faster/sharper) you can match FF IQ. Of course an APS-C system with that kind of glass would be more expensive than the FF equivalent.
interesting take on it.

No reason for it to be more expensive; Smaller image circle reduces cost, so should offset the cost of higher speed. Still not gonna be cheaper. And FF guys will bolt 'em on their FF machines and PP out the vignetting, so it starts all over.

I think it's a preference issue. "I like images with no DOF" is a statement of preference. So is "Images with less DOF are better".
05-16-2011, 08:52 AM   #153
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QuoteOriginally posted by jstevewhite Quote
I'm not certain in what sense you mean this. The blown out OOF backgrounds are completely unlike anything we see with our own eyes (except for those of us that can focus very, very close with our eyes).
I forgot to put ...vision... in the precedence comment.
Having said that, no one mentioned anything about blowouts(no clue where that came from ). OOF = out of focus rendering.

Doesn't happen with human vision?

Try concentrating on a subject and take note of background, you may or may not notice it getting blurred. The closer the subject the more pronounced the effect becomes(sound familliar?).

Interesting enough.. this effect can also vary based on the level of ambient light present in the scene. Go in the woods on a sunny day, stand in the shade and focus on a tree within 6 feet of you. Again, take note of the background.

Great experiments.
05-16-2011, 09:20 AM   #154
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QuoteOriginally posted by JohnBee Quote
I forgot to put ...vision... in the precedence comment.
Having said that, no one mentioned anything about blowouts(no clue where that came from ). OOF = out of focus rendering.

Doesn't happen with human vision?

Try concentrating on a subject and take note of background, you may or may not notice it getting blurred. The closer the subject the more pronounced the effect becomes(sound familliar?).

Interesting enough.. this effect can also vary based on the level of ambient light present in the scene. Go in the woods on a sunny day, stand in the shade and focus on a tree within 6 feet of you. Again, take note of the background.

Great experiments.
Well, the image in the comment you were replying to is an example; the normal human eye doesn't reproduce that level of OOF blur.

The FF/APS-c discussions (like this thread) invariably revolve around the *amount* of OOF blur. I was merely pointing out that the examples offered to illustrate the "FF Advantage" *always* represent far more OOF blur than the human eye does.

This comment wasn't an attack on your statement, but a *use* of your statement to illustrate something. I'm sorry if it came off differently.

I'm familiar with the experiments you outline. Suffering from presbyopia makes the value of stopped down irises VERY apparent . I can read without my reading glasses in bright sunlight.

EDIT: Just to be clear, I'm not saying photography must necessarily reflect human vision, either. I'm just pointing out the subjective nature of the idea that "Less DOF==good".


Last edited by jstevewhite; 05-16-2011 at 09:22 AM. Reason: clarity
05-16-2011, 09:21 AM   #155
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QuoteOriginally posted by jstevewhite Quote

No reason for it to be more expensive; Smaller image circle reduces cost, so should offset the cost of higher speed. Still not gonna be cheaper.
You reach a point with each format where the lens selection starts to get unfriendly to the wallet, or even disappears into the theoretical.

You can shoot a $199 35 f/1.8 or $300 35 f/2 on FF - the aps-c equivalent in Nikon mount for example would cost $2100 and would be huge (24 f/1.4G - if you want to approximate the same FOV and DOF capability.)

The 20mm f/2.8D can be found used for under $300. They don't make a 13mm f/1.8 for aps-c. 24mm f/2.8 = $250 used, no 16mm f/1.8 around. etc, etc.

And with FF, you start to go long, you start to feel pain both in the back and wallet.


.
05-16-2011, 09:26 AM   #156
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QuoteOriginally posted by jstevewhite Quote
interesting take on it.

No reason for it to be more expensive; Smaller image circle reduces cost, so should offset the cost of higher speed. Still not gonna be cheaper. And FF guys will bolt 'em on their FF machines and PP out the vignetting, so it starts all over.

I think it's a preference issue. "I like images with no DOF" is a statement of preference. So is "Images with less DOF are better".
I think it would be more expensive. You are optimizing for critical sharpness at a wider aperture. Typically faster and sharper = more expensive regardless of image circle.

Sigma seems to already be doing this. Most of their new glass appears to be optimized for sharpness at wider apertures. The reason I bought the Sigma 50mm f/14 over the DA* 55mm and the 43mm LTD was performance from F/1.4 - F/2.0. There is no question the both the DA* 55mm and the 43mm LTD are sharper from 4.0 and up, but since I don't shoot at those apertures very often it was not relevant.

Pentax does not have a FF option so nobody would be bolting them on to FF bodies. I really think Pentax needs to introduce a line similar to what Olympus did with the SHG glass. Don't worry about size and keep cost competitive with FF pro grade glass. Go for speed and sharpness are large apertures.
05-16-2011, 09:29 AM   #157
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QuoteOriginally posted by jsherman999 Quote
You reach a point with each format where the lens selection starts to get unfriendly to the wallet, or even disappears into the theoretical.

You can shoot a $199 35 f/1.8 or $300 35 f/2 on FF - the aps-c equivalent in Nikon mount for example would cost $2100 and would be huge (24 f/1.4G - if you want to approximate the same FOV and DOF capability.)

The 20mm f/2.8D can be found used for under $300. They don't make a 13mm f/1.8 for aps-c. 24mm f/2.8 = $250 used, no 16mm f/1.8 around. etc, etc.

And with FF, you start to go long, you start to feel pain both in the back and wallet.


.
Yeah, but we're talking about theoretical. I'm just saying there's no reason for an APS-C only, say, 35 f1.4 to cost $2100 (See Sigma 30mm f1.4, for instance); the smaller image circle significantly reduces engineering costs. The LTD lenses cost what they do because of the metal, not because of the glass. Not that they haven't got excellent glass; I just think Pentax doesn't make a 35mm (or ~30mm) 1.4 because they don't think they'll sell enough to be profitable. The 55 1.4, for instance; they could probably have made it a 1.2 (APS-c circle) or so for twice what it costs now, or $1200; and some of US would buy it. However, without the THOUSANDS AND THOUSANDS of pro shooters CaNikon has, it probably wouldn't sell enough to justify the production retool.
05-16-2011, 09:30 AM   #158
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QuoteOriginally posted by jsherman999 Quote
You reach a point with each format where the lens selection starts to get unfriendly to the wallet, or even disappears into the theoretical.

You can shoot a $199 35 f/1.8 or $300 35 f/2 on FF - the aps-c equivalent in Nikon mount for example would cost $2100 and would be huge (24 f/1.4G - if you want to approximate the same FOV and DOF capability.)

The 20mm f/2.8D can be found used for under $300. They don't make a 13mm f/1.8 for aps-c. 24mm f/2.8 = $250 used, no 16mm f/1.8 around. etc, etc.

And with FF, you start to go long, you start to feel pain both in the back and wallet.
.
APS-C is going to have trouble matching the wide glass of the FF or MF systems. FF and MF systems will have trouble matching the long glass of APS-C and 4/3. Each format has some trade offs, but the middle of the line (35mm - 135mm) is really very practical for all systems.

05-16-2011, 09:37 AM   #159
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QuoteOriginally posted by Winder Quote
I think it would be more expensive. You are optimizing for critical sharpness at a wider aperture. Typically faster and sharper = more expensive regardless of image circle.

Sigma seems to already be doing this. Most of their new glass appears to be optimized for sharpness at wider apertures. The reason I bought the Sigma 50mm f/14 over the DA* 55mm and the 43mm LTD was performance from F/1.4 - F/2.0. There is no question the both the DA* 55mm and the 43mm LTD are sharper from 4.0 and up, but since I don't shoot at those apertures very often it was not relevant.

Pentax does not have a FF option so nobody would be bolting them on to FF bodies. I really think Pentax needs to introduce a line similar to what Olympus did with the SHG glass. Don't worry about size and keep cost competitive with FF pro grade glass. Go for speed and sharpness are large apertures.
But your example argues against you. The Sigma 50mm 1.4 is $500. The Sigma 30mm 1.4 is $500. Aren't they both nominally FF lenses? Reducing the image circle reduces engineering costs (it's easier to make a lens sharper in a smaller circle)

Like I said, the Pentax LTDs costs what they do because of the metal, not the glass. The glass is great, sure, but a more conventional construction would cost much less. (I think they're cool, too, I'm just saying).

I bet if PTX used more conventional materials, a ~30mm f1.4 wouldn't have to cost any more than Sigma's. And they could make a ~30mm f1.2 DA LTD for what the FA 31 1.8 costs, I betcha. They just don't believe there is sufficient market for it to make it profitable.
05-16-2011, 09:39 AM   #160
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QuoteOriginally posted by Winder Quote
APS-C is going to have trouble matching the wide glass of the FF or MF systems. FF and MF systems will have trouble matching the long glass of APS-C and 4/3. Each format has some trade offs, but the middle of the line (35mm - 135mm) is really very practical for all systems.
I think that's largely because they both exist. If everyone was shooting APS-c, we'd see DA 30mm f1.2s (APS-c image circle) for the price of the FA 31 f1.8.
05-16-2011, 05:45 PM   #161
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QuoteOriginally posted by jstevewhite Quote
I think that's largely because they both exist. If everyone was shooting APS-c, we'd see DA 30mm f1.2s (APS-c image circle) for the price of the FA 31 f1.8.
A DA 30mm f/1.2 would be on the top of my list of Pentax glass if it existed.
05-16-2011, 05:54 PM   #162
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QuoteOriginally posted by jstevewhite Quote
But your example argues against you. The Sigma 50mm 1.4 is $500. The Sigma 30mm 1.4 is $500. Aren't they both nominally FF lenses? Reducing the image circle reduces engineering costs (it's easier to make a lens sharper in a smaller circle)

Like I said, the Pentax LTDs costs what they do because of the metal, not the glass. The glass is great, sure, but a more conventional construction would cost much less. (I think they're cool, too, I'm just saying).

I bet if PTX used more conventional materials, a ~30mm f1.4 wouldn't have to cost any more than Sigma's. And they could make a ~30mm f1.2 DA LTD for what the FA 31 1.8 costs, I betcha. They just don't believe there is sufficient market for it to make it profitable.
Sigma can spread out production and design costs across FF, APS-C and 4/3 lens sales. That makes Sigma hard to beat. Pentax does not have that option unless they work a deal with Tokina to produce glass for other mounts.

I think Pentax's production costs are due to the small production runs that they make with Ltd glass. I think Pentax is in an good position to produce small production runs of high quality glass.
05-16-2011, 06:25 PM   #163
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QuoteOriginally posted by jstevewhite Quote
Of course it's possible with APS-C (not my picture - check the name at the bottom and look through his gallery).

The only part of that "particular look" that's related to FF is the DOF@FOV. It requires more work with an APS-C system, though (I've shot a couple recent tests with my 180mm f2.5 wide open and my 100 f2.8 wide open using stitching that look very much like this, as an exercise). I would say, however, if the bulk of the images you create are going to look like this, by all means, go FF, it will save you time.

I routinely stitch images together. Outside in good light wide open with a 180mm f2.5, even in the golden hour, at ISO 100, I can often get 1/1000 shutter speed. With that shutter speed I can almost use the continuous high to acquire a stitching set. I've been mostly shooting the subject in one shot (so they don't have to sit still) and adding several frames on either side (using manual focus and exposure, of course), above, and below, and the result is amazing. When I get a chance, I'll do some that aren't just tests of my dog in the backyard and post 'em. You can see 'em all over flickr, though.

I'd ask myself, though, if I wanted to dedicate my money, my time, and my creativeness, to replicating the style of another photographer, or if it's just a style that I want in my arsenal. If that's the images I want to produce, then FF or bust. If I want to do that once in a while, then it's worth the extra work, IMO, to carry the lighter gear and save the FF money - and stay with Pentax glass, which I why I came here to start with.
QuoteOriginally posted by crossover37 Quote
Yea I use that technique too. Here's a shot from a session I had this week using that stitching method. I love it but it's not possible all the time with portraits, especially with kids. It seems the resolution is at another level with FF but maybe I'm just imagining it.



How many shots do you need to stitch before you get appreciable gains in shallow DoF?
05-16-2011, 06:36 PM   #164
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QuoteOriginally posted by Eruditass Quote
How many shots do you need to stitch before you get appreciable gains in shallow DoF?
Based on rough calculations I'd say you could get away with as little as 3 portrait frames with a 135/2.8 wide open. Plenty of good candidates for that Id say. Of course more frames will allow for a shallower DOF, but I think the above recipe could get you close to medium format output.
05-16-2011, 06:42 PM   #165
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QuoteOriginally posted by Eruditass Quote
How many shots do you need to stitch before you get appreciable gains in shallow DoF?
You don't get shallow DOF by stitching 'em, you get the shallow DOF and increase the FOV by stitching. So pick, say, a 135 f2.8 and shoot from a distance that requires two vertical shots to get a full length image. I think I got about 12" of DOF that way; say "Hold Still!" and shoot the two frames, then fill in all around the subject (without refocusing!! I use manual exposure and manual focus so that nothing changes between images); it's like painting with your sensor. So if you shoot an image that's four vertical frames tall and eight wide (32 shots + ) you get a picture that looks like it was shot with a - shoot, I dunno; a 35mm f.8??

I've gotten quite interesting results with my 180 f2.5 @ f4, and shooting images three horizontal frames wide and four tall (12+ images). This is 3x FOV, so... Calculator says 7.5 degrees for 180, so about like a 60mm lens (22 degrees), with the DOF of the 180. At 12 feet, the DOF of the 180 at F4 is from 11' 10.8" to 12' 1.2", or about four inches.

That help?

I've been using autopano Giga for this, and if you shoot your images properly, and have a fast computer, it's painless and fast. I shot a 42 shot pano and the thing that took the longest/most trouble was selecting all the images and exporting them, then opening them and starting the pano stitch.

We're supposed to have sun tomorrow; I'll try and get my girl outside for a portrait in the grass and post an example.

Last edited by jstevewhite; 05-16-2011 at 06:45 PM. Reason: more info
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