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06-03-2011, 05:43 AM   #46
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QuoteOriginally posted by mhaws Quote
This is interesting to know. The main reason I want a longer lens than the 50 I already have is for more compression. But if you think it doesn't make too much difference.....I can't seem to get a decent full body shot of someone with a ton of bokeh....even stopped down to 1.4 I don't get it as blurred as the ones I'm trying to do. are you saying a 77 wouldn't give me that either? That it's basically the same except my distance from my subject?
If you are most interested in full body shots with luscious bokeh, then I don't think that you can beat the FA43 Limited. The rendering of that lens is absolutely gorgeous. To get full body shots with the FA77, you have to be standing fairly far from the subject, which is not always possible. The FA43 is also very good for upper body and environmental portraits.

The DA*55 can be a great lens for general portraiture, if you get a good copy. Unfortunately, it is notorious for focusing defects. This has been well documented by dpreview, and it was also my personal experience. If you get one, test it rigorously.

Rob

06-03-2011, 05:45 AM   #47
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QuoteOriginally posted by robgo2 Quote
This is not quite true. A lens's DOF remains the same whether it is mounted on a FF or an APS-C sensor, even though its angle of view does change. This means that a 50mm lens on APS-C is not quite equivalent to a 75mm lens on FF, despite its having the same angle of view. Most people would never notice the difference, but others would prefer the shallower DOF for portraits. Of course, you may be able to compensate by opening the aperture, if you are using a fast 50mm lens.

Rob
But you have to move farther back with a 75mm in order to get the same FoV you get with a 50mm. When you move back the DoF increases and you end up with basically the same DoF if you compose for the same FoV.
06-03-2011, 06:13 AM   #48
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QuoteOriginally posted by Winder Quote
But you have to move farther back with a 75mm in order to get the same FoV you get with a 50mm. When you move back the DoF increases and you end up with basically the same DoF if you compose for the same FoV.
I'm not sure about this point. It is often stated that one of the advantages of FF over APS-C is its ability to achieve shallower DOF. I have always assumed that this took FOV into account, but I may be wrong.

Rob
06-03-2011, 06:25 AM   #49
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QuoteOriginally posted by Winder Quote
But you have to move farther back with a 75mm in order to get the same FoV you get with a 50mm. When you move back the DoF increases and you end up with basically the same DoF if you compose for the same FoV.
This is (almost) true if you are comparing the 50 @ 1.4 with the 77 @ 1.8. That said, in real life (where you would stop the lens down a little) the differences are subtle.

06-03-2011, 06:59 AM   #50
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QuoteOriginally posted by robgo2 Quote
I'm not sure about this point. It is often stated that one of the advantages of FF over APS-C is its ability to achieve shallower DOF. I have always assumed that this took FOV into account, but I may be wrong.

Rob
Just google "DOF calculator"; there are lots of them that let you punch in numbers and play. They often have different COC factors, but usually they give similar results if you can adjust that number.

The important thing to remember is that you have control of the photographic situation. If you increase the distance between your subject and the background, you will increase visual isolation at the same aperture and FOV. If you want to exaggerate the effect, you can use the Brenizer method - which even many FF users are doing. FWIW, a full length portrait done with the "bokeh panorama"/Brenizer method can be done with just three images (three horizontal images with some overlap) and will give you *similar* DOF to a FF (since you're using the same focal length at the same distance); adding a few more will make the DOF of the panorama much narrower. People stitch 16, 24, 48 images (even from FF cameras!) to exaggerate the effect because the difference between FF and APS-c is fairly subtle by comparison with MF or large format.
06-03-2011, 07:08 AM   #51
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DoF of a 75mm f/1.8 lens at 10' = .57' (full frame body)
DoF of a 50mm f/1.4 lens at 10' = .68' on an APS-C body

2" at 10' is typically not field relevant for most people shooting portraits.

The issue is that on APS-C cameras you have to use a wider aperture to match DoF, and most older glass is optimized for sharpness at f/5.6 or f/8. FF bodies can make better use of the older glass and stop down. APS-C bodies need lenses that are optimized for the smaller size and are sharper at wider apertures.
06-03-2011, 07:45 AM   #52
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QuoteOriginally posted by robgo2 Quote
I'm not sure about this point. It is often stated that one of the advantages of FF over APS-C is its ability to achieve shallower DOF. I have always assumed that this took FOV into account, but I may be wrong.
It does, in a way. There are quite a few lengthy discussions of the topic in other threads, but the gist of it is, if you keep the same f-stop, then indeed, the FF camera has less DOF. So 77 @ f/1.8 on FF has less DOF than 50mm @ f/1.8 on APS-C. You get "equivalent" DOF by matching the physical aperture size rather than the f-stop (which is a ratio of aperture size to focal length).

Anyhow, my point mainly had to do with the fallacy that a lens has some inherent "perspective" that creates some specific amount of "distortion" that is a function of focal length. Those qualities are actually a function of subject distance, which in turn is a function of angle of view. So for two camera/lenses combos that produce the same angle of view, perspective/distortion is precisely the same even if the focal lengths involved are different. The post to which I had been responding appeared to be implying otherwise. But it is true you need different f-stop values (but the same physical aperture size) to match DOF.
06-03-2011, 07:52 AM   #53
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QuoteOriginally posted by Winder Quote
DoF of a 75mm f/1.8 lens at 10' = .57' (full frame body)
DoF of a 50mm f/1.4 lens at 10' = .68' on an APS-C body

2" at 10' is typically not field relevant for most people shooting portraits.

The issue is that on APS-C cameras you have to use a wider aperture to match DoF, and most older glass is optimized for sharpness at f/5.6 or f/8. FF bodies can make better use of the older glass and stop down. APS-C bodies need lenses that are optimized for the smaller size and are sharper at wider apertures.
I tend to agree with your assessment, with some caveats. Sometimes, the DOF doesn't tell the whole story. Your 2" difference ( around 20% ) in DOF also means a 20% larger COC in the background blur, which might make a much more significant difference in appearance than the simple difference in sharp range. ( yes, Marc and Jsherman, I've thought about our marathon discussion in re FF vs APS-c, and think you had a good point in this respect )

06-03-2011, 08:34 AM   #54
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This page is three computer screens wide. How freakin annoying.
06-03-2011, 09:44 AM   #55
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QuoteOriginally posted by jstevewhite Quote
I tend to agree with your assessment, with some caveats. Sometimes, the DOF doesn't tell the whole story. Your 2" difference ( around 20% ) in DOF also means a 20% larger COC in the background blur, which might make a much more significant difference in appearance than the simple difference in sharp range. ( yes, Marc and Jsherman, I've thought about our marathon discussion in re FF vs APS-c, and think you had a good point in this respect )
This makes sense to me. There are qualitative differences between APS-C and FF that are not fully explained by focal length alone. In practical terms, it probably does not make much of a difference, but some particularly sensitive users may care, just as some people care about the different rendering characteristics of the DA and FA Limiteds (which are actually not so trivial.)

Rob
06-03-2011, 10:14 AM   #56
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QuoteOriginally posted by audiobomber Quote
This page is three computer screens wide. How freakin annoying.
Either someone already edited a post, or something is wrong with your browser, or with my eyes. Are you still seeing this? Which page?
06-03-2011, 11:20 AM - 1 Like   #57
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QuoteOriginally posted by jstevewhite Quote
I tend to agree with your assessment, with some caveats. Sometimes, the DOF doesn't tell the whole story. Your 2" difference ( around 20% ) in DOF also means a 20% larger COC in the background blur, which might make a much more significant difference in appearance than the simple difference in sharp range. ( yes, Marc and Jsherman, I've thought about our marathon discussion in re FF vs APS-c, and think you had a good point in this respect )
I agree there will be some differences, I just have not found them to be field relevant. Most people doing portrait work have some degree of control over lighting and background. As photographers we over analyze and split hairs way too much. The paying customer does not have a clue.
06-15-2011, 01:33 PM   #58
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only one portrait lens? oks, i'll pick the da21mm...
06-15-2011, 02:09 PM   #59
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I`d say 55mm on crop camera

For me, the K 55mm f/1.8 is grrrreat to work with!

I love the distance I get to the person and I got the lens for just 40$...
Wide open isn`t really an option for any lenses I own, but stopped down to around f/4.5-14, the old 55 is excellent!

This one`s shot with my wife`s K-r (I borrowed it while waiting for my K10D to be replaced with a K20D
06-15-2011, 02:37 PM   #60
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I like my FA77 and FA85, maybe FA85 more cos it is faster.
from various examples, Sigma 85 seems good too.

but if you cannot find a FA*85, 77 ltd is the lens for portraits.
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