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08-29-2010, 11:52 AM   #16
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QuoteOriginally posted by Pentaxor Quote
the OP needs to clarify his concerns. as mentioned, he doesn't like the 50mm which he never mentioned why, and also he didn't like the 100mm for reasons that I don't know why it doesn't cut it.
I think for some older folks (not me), 50 isn't a "sexy" FL, because it was the everyman's FL in film days.

I look at it as a 75 based on that old frame of mind, which is right near the optimal FL for close portraits at the time--85 and up a little.


Last edited by Ira; 08-30-2010 at 02:20 AM.
08-29-2010, 12:23 PM   #17
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QuoteOriginally posted by Ira Quote
I think for some older folks (not me), 50 isn't a "sexy" FL, because it was the everyman's FL in film days.

I look it as a 75 based on that old frame of mind, which is right near the optimal FL for close portraits at the time--85 and up a little.
I see IRA. if that were the case, then a 70mm - 85mm would suit the OP's need. I myself however, do prefer something within those focal lengths (though I'm not "that old", lol) but more preferably at 85. but since prime maybe out of the equation for the OP, and if the OP doesn't mind something slower than f2.8 zoom telephoto, the DA55-300 can be a very good and also cheap alternative for such use. I had used the DA55-300 and FA135 more recently and was more surprised to find out the zoom lens' IQ capacity alongside the FA135. from the images that I saw, the zoom lens makes it's mark along 55-210mm or 250mm. I did mentioned before that this lens is in fact impressive, but had only been much more impressed to discover it did extremely well alongside an outstanding prime telephoto lens. Yes, it can do very nice portraits as well. hopefully, the OP considers this as well.
08-29-2010, 04:33 PM   #18
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Wow, thanks for all the replys. For some reason the forums haven't been working in Opera for the last 48+ hours (though I now see FireFox works).

To answer some of the previous questions.

I've checked my math based upon the published angle of view for APS-C (from Sigmas website) so unless something is really screwed up my my spreadsheet then I don't think I've got an error. I've shot full body with my 105 from halfway across my back yard and don't really think that's much more than 4m. So I can see a 200mm at 7+.

I've shot a series of portraits with a friends 300mm f2.8, but while it was wonderful, I was a little too far off to talk to the model. I'd love a 200mm f2.

I don't like my 50mm f1.4 as I find the bokeh very busy and harsh, also the off center sharpness is very low (and thats where the subject's head ends up). I find it a fantastic lens at f4, but not open. Also I find I often need to be too close to the subject. Also there is too much of the background visible (The FOV is too short) for what I'm trying to do.

I've taken a number of shots with the 50-200mm at about 150-200mm and find them composition wise what I like to see. It is just too soft, and too slow.

I was thinking of looking for a 135mm f1.8, but if I'm doing that I might as well go elsewhere (Sony or Canon or even Nikon for their DC lens).

I've thought about the 85mm f1.4 as well (even getting the Vivitar) and I might, but from what I've seen it suffers from the same low off centre resolution.

Again thanks for the help. Are there any older lenses with this type of even resolution that I'm looking for? Any of the old russian lenses? Sorry I'm not too familiar with them.

Thanks all (and hopefully Opera and PF will behave soon).

Last edited by omega leader; 08-29-2010 at 04:38 PM. Reason: Can't type, think or spell.
08-29-2010, 04:51 PM   #19
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One thing you need to allow for is room above the head and below the feet in the frame. Although an average person is 1.7m, you need a reasonable amount of room for framing so the photos don't feel too cramped. That would impact your calculations.

It sounds like a 70-200 would be good though if you like to work a long way back and don't mind a 1.4kg lens. Disclosure: I have a 50-135 and love it.

08-29-2010, 04:55 PM   #20
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Your math is just plain wrong - sorry. I checked with a 70-210 mm series 1 and for 1.7 meter vertical I had to be back 15 paces (I have a 3 foot stride confirmed many times on the golf course)

Note in working with fov formulas these usually consider the diagonal. But regardless my formula is correct as long as you are 10x the focal length away

As for confusing bokeh much of this can come from the lack of a round aperture and therefore I repeat my suggestion to look at older presets with 15 plus blades

Also for softness off center note that except for macro lenses most lenses are not flat field and as a result the focus "plane" is actually a sphere. This is why you have multiple focus sensors, you should use them especially with a full body portrait

With respect to the error in focus calculation, don't get fooled with testing using a super zoom which with internal focusing only meets the published focal length at infinity
08-29-2010, 05:16 PM   #21
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Lowell,

Now thats just not fair. One you proved me wrong (I just checked with my 50-200mm and at 8m-the length of my hall- the AOV is about 3ft) and two that means I'm going to have to go over my math to find my error.

As an engineer I should have know better than working out the formula from first principals.

Two that means I've been shooting from a lot further than I thought. I'm often shooting from one side of the street to the other to get textures and colours of building and grafitti in the background.

Oh well. Live and learn. I'm thinking the 70-200mm would be more flexible but I'm worried about the edge sharpness.

Thanks Lowell for pointing that out, I've got to be dividing by 2 somewhere I shouldn't.
08-29-2010, 08:03 PM   #22
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since you are considering some old lenses, the Helios 85/1.5 or SMC Tak 85/1.8 are nice lenses. or you might want to consider the FA*85/1.4.

as far as 135mm goes, the Pentax or CZ 135s does some excellent portraits. I find the 2.8 and 3.5 fine or enough for such occasion and are outstanding from wide open. it doesn't have to be 1.8 all of the time. or you can get the SMC 135/2.5 lens as well. 2.8 and 3.5 usually range from sub-$50 to $100 while the SMC 135/2.5 from above $100-$200.
08-30-2010, 05:56 AM   #23
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QuoteOriginally posted by omega leader Quote
Lowell,
As an engineer I should have know better than working out the formula from first principals.
Don't get me started here. As an engineer, you should always go back to first principles, as opposed to using someone' elses results and formulas because you may not see an error in their work, or understand the limits of the formulas.

In this case, working with field of view is not first principles. You should start with only lens focal length and the formulas for focal length, distance and magnification.

The formula I provided is an approximation, because I exclude from this the lens extension when focusing at other than infinity, but when focusing on distant subjects, the lens extension is negligable and the formula simplifies a lot as a result.

Howerver, at least we now agree on the working distance.

What lenses have you used in the past, in total? and are all your shots outdoors?

As I said earlier, for outdoors I like 135mm myself. and have also played with 105mm. at 105mm I have an smc 105F2.8 and a new addition a Vernon Edonar 105mmF2.8 preset (m42) lens with 14 blade aperture. I find the SMC 105 F2.8 a little soft wide open.

08-30-2010, 10:18 AM   #24
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I have a degree in math, and no way in a million years would I consider using any sort of formula to calculate this if I had access to a 50-200 or other telephoto that would allow me to get the answer empirically. And I agree with everyone else - 200mm seems crazy long. I'd actually worry about the 70-200 being too long at the short end for many spaces. I think the 50-135 is the obvious choice here on APS-C for exactly the same reasons that 70-200 were obvius choices on FF - and even then, I'd fully expect to want shorter than 50 sometimes.
08-30-2010, 10:56 AM   #25
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QuoteOriginally posted by Marc Sabatella Quote
I have a degree in math, and no way in a million years would I consider using any sort of formula to calculate this if I had access to a 50-200 or other telephoto that would allow me to get the answer empirically.
I use the formula often, but tested last night with a real lens just to make sure I was not full of hot air. Manu times the issue arises where you need to pick a lens, without the opportunity of trying it first, but you know where you are going and the shooting distance. As a result the formula helps pick out a lens in advance.
QuoteQuote:
And I agree with everyone else - 200mm seems crazy long. I'd actually worry about the 70-200 being too long at the short end for many spaces. I think the 50-135 is the obvious choice here on APS-C for exactly the same reasons that 70-200 were obvius choices on FF - and even then, I'd fully expect to want shorter than 50 sometimes.
I think the OP selected 200mm based upon a desired DOF, more than anything else.
08-30-2010, 03:21 PM   #26
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Marc, without a spreadsheet (or dread paper) how am I supposed to trend anything? And without the lens I can't very well verify empirically.

I'm more concerned with DOF (8" is ideal) and a limited angle of view to remove distractions. I use my 105mm /2.8 extensively and know it is too short.

It's just a different style. I will look into some of the old russian lenses, but I'm not sure if there going to give me the even resolution I'm looking for.
08-30-2010, 04:48 PM   #27
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If you can stand slightly more DOF how about an old preset takumar 200mm F3.5.

Sharpness is all there for you, and as I stated earlier, the early presets, with dfferent aperture location between lens groups seems to offer better foreground / background separation

only downside is 2 meter minimum focus, but for a body shot with 45 foot working distance that should not be too much inconvenience.

otherwise for sharpness, but again at F3.5 vs F2.8 look at the series 1 70-210 F3.5 (version 1) This gives the advantage of being a zoom

one of the sharpest out of the entire series one line up,

I have both of the above lenses, and they are great lenses, although each is betweenb 800 and 1000 grams, so a little on the heavy side.

comparing the two, the tak is more precise on focus with 330 degree focus throw, vs 180 for the vivitar, but 180 degree is quicker for aquiring focus.
08-30-2010, 11:20 PM   #28
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QuoteOriginally posted by omega leader Quote
Marc, without a spreadsheet (or dread paper) how am I supposed to trend anything? And without the lens I can't very well verify empirically.

I'm more concerned with DOF (8" is ideal) and a limited angle of view to remove distractions. I use my 105mm /2.8 extensively and know it is too short.

It's just a different style. I will look into some of the old russian lenses, but I'm not sure if there going to give me the even resolution I'm looking for.
how bout the manual focus Zeiss Jenna Sonnar 180/2.8 or it's other 180mm siblings. those 180mm lenses would give you more than enough DOF that you are looking for.
08-31-2010, 08:22 AM   #29
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I'm pretty curious to see some examples of these long-range, wide-open, full-length portraits. The FL seems way long for me/my style (I feel like I'd need to make a cell phone call to give the model directions) but the project is intriguing. Plus, the Voigtlander 90mm APO that arrived yesterday (not that I'm suggesting an alternative ) has me itching to do some portraits outdoors.
08-31-2010, 09:11 AM   #30
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QuoteOriginally posted by omega leader Quote
Marc, without a spreadsheet (or dread paper) how am I supposed to trend anything? And without the lens I can't very well verify empirically.
I meant, you could use the 50-200 you already have to see for yourself how far you really need to be from the subject with a 200mm.

QuoteQuote:
I'm more concerned with DOF (8" is ideal) and a limited angle of view to remove distractions. I use my 105mm /2.8 extensively and know it is too short.
Got it. I was responding more to the bit about working distance, where it seemed you had underestimated it pretty several and there mistakenly assumed it wouldn't be a problem. But sure, if it's the only way to get the effect you want in terms of FOV and DOF, and you are willing to accept the consequences in terms of perspective (and also realize that no 200mm lens is going to be as sharp as the various shorter options for the same subject magnification), then of course, that's the way to go.
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