Re: Opinions about Tokinas (Was Sigmas)
Question for Mark Cassino: Re: My conclusion was that a low resolving lens with low CA and high edge sharpness - which is what my tests showed the ATX 400 to be - will create an image with clean edges and a high degree of _apparent_ detail. Mark, I have this lens and am interested in your observations. Would you please define your terms, though? What do you mean by low resolving? I am having trouble understanding how a lens with high edge sharpness can be low resolving. I'm not questioning your observations, just trying to understand what you mean. According to Photodo, at f8 the Tokina scores the same as the FA 400 f5.6. It is weaker than the Pentax wide open. Thanks, Joe
Re: Opinions about Tokinas (Was Sigmas)
From: Joseph Tainter [EMAIL PROTECTED] Hi Joe - Question for Mark Cassino: Re: My conclusion was that a low resolving lens with low CA and high edge sharpness - which is what my tests showed the ATX 400 to be - will create an image with clean edges and a high degree of _apparent_ detail. Mark, I have this lens and am interested in your observations. Would you please define your terms, though? What do you mean by low resolving? I am having trouble understanding how a lens with high edge sharpness can be low resolving. Here's an example: a long time ago I did a comparison of the Tokina ATX 400 f 5.6 vs the Pentax 500 f4.5 (screwmount version.) I set up an eye chart of ever diminishing numbers, letters, punctuation marks etc. Then I set up the lenses so the magnification was the same, shot the chart, and compared the results, I was using Kodachrome 25. When I looked at a large simple letter, like a 16 pt. capital 'I' at high in a high res scan, I was disappointed to see noticeable chromatic aberrations with the Pentax 500mm. There was a clear magenta blur to one side and a clear yellow blur to the other. The same character with the Tokina had virtually no CA - it came very close to going from black to white (I think there was a very little bit of yellow fringing.) But then I looked at smaller characters, and found that the Tokina did not resolve them as well as the 500mm. So, for example, an small '@' sign was just a black circle with the Tokina, albeit with crisp edges. The same figure was still discernable as an '@' sign with the 500mm, even though it was fringed with magenta. Similarly, when you evaluate film (or digital sensors) you look at acuatance (edge sharpens / edge definition), resolution (the ability to display fine detail) and grain / noise (I'd refer you Ansel Adams' The Negative for more on that.) I think that in evaluating lenses, the same concepts of acuatance and resolution come into play. (Obviously, grain or noise is not an issue with lenses.) I don't know why, but when speaking of lenses 'sharpness' seems to be used as opposed to 'acuatance.' Anyhow, sharpness looks at the ability to render a change in contrast abruptly - the quicker, the better. Resolution measures the ability to capture fine detail - you can almost think of it as the 'amount' of info captured. The two are clearly related in that high sharpness is needed for high resolution, but high sharpness does not guarantee high resolution. The same is true of film, and there are films with lower resolving power but higher acuatance that can produce a sharp image, but one lacking in fine detail. According to Photodo, at f8 the Tokina scores the same as the FA 400 f5.6. It is weaker than the Pentax wide open. I had the Sigma for a short period of time, and traded it for the Tokina. To be honest, I'm basing my perceptions on the Sigma more on what I've heard and read about it, than based on my actual (and very limited) use of it. So, the two lenses may be closer in performance than I think. But, looking at Photodo, the Sigma actually does somewhat better in the overall weighted average at f8 (0.77 vs 0.73). There are some real limits on the usefulness of the weighted average info on Photodo. It's a shame they pulled the raw MTF charts from their site. But if you compare the weighted averages at 10, 20, and 40 lpm, the Sigma does do better in these. You'd expect a lens that has low resolution and high sharpness to do well at the low lpm figure, and then drop off quickly at the higher lpm figures. The Tokina does that, though not radically worse than the Sigma. - MCC - - - - - - - - - - - - - - - - - - - - Mark Cassino Photography Kalamazoo, MI www.markcassino.com - - - - - - - - - - - - - - - - - - - -
RE: Opinions about Tokinas (Was Sigmas)
lol ... I said that's what they *look* like, not what they *are*. ;-) Godfrey --- Jens Bladt [EMAIL PROTECTED] wrote: Very informative, Fred! Bravo! Jens Jens Bladt mailto:[EMAIL PROTECTED] http://hjem.get2net.dk/bladt -Oprindelig meddelelse- Fra: Fred [mailto:[EMAIL PROTECTED] Sendt: 23. februar 2005 19:47 Til: Godfrey DiGiorgi Emne: Re: Opinions about Tokinas (Was Sigmas) That lens has done an *excellent* job of capturing the breast feathers' structure. I used to keep birds (parrots mostly) and that's what their breast feathers look like when seen close up. Robins are much the same. Well, I'm not so sure... http://trc.ucdavis.edu/mjguinan/apc100/modules/Integument/hair/feathers2/fea thers5.html http://www.peteducation.com/article.cfm?cls=15cat=1829articleid=2776 http://www.ummz.lsa.umich.edu/birds/Anatomy/feathers/feather_parts.html I think that the photo is showing the barbs but not the barbules, and (as mark has suggested) has sort of sharpened the barbs to provide a high ~apparent~ detail without actually showing the detail. Fred __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Re: Opinions about Tokinas (Was Sigmas)
I posted this before (over a year ago), but I think it's an interesting illustration of what is being discussed in terms of how lenses differ between film and digital: http://www.markcassino.com/temp/robin/ This shot was taken with the Tokina 400mm ATX, handheld. In the actual pixel shot, the degree of apparent detail in the birds breast is remarkable. But I have found this lens to be pretty mediocre with film in the past. I guess I'd have to find a bird and hold it in my hand to know for sure, but I really question the detail in the feathers. They look like hairs, not feathers. My conclusion was that a low resolving lens with low CA and high edge sharpness - which is what my tests showed the ATX 400 to be - will create an image with clean edges and a high degree of _apparent_ detail. I say apparent detail because I don't think the birds breast feathers would really look like that, I think that the primary ribs of the feathers have been exaggerated and the connecting fibers have been all but lost in this shot. Psychologically, one looks at that and thinks Wow - what detail! but I really question that. Maybe I can find a natural history museum with a robin specimen and can confirm my suspicions... - MCC - - - - - - - - - - - - - - - - - - - - Mark Cassino Photography Kalamazoo, MI www.markcassino.com - - - - - - - - - - - - - - - - - - - - - Original Message - From: Fred [EMAIL PROTECTED] To: Mark Cassino pentax-discuss@pdml.net Sent: Wednesday, February 23, 2005 12:04 PM Subject: Re: Opinions about Sigmas Lastly, I briefly owned the Sigma 400 f5.6 macro, but wound up switching to the Tokina ATX 400 f5.6. I don't know about build quality (the Tokina is built like a tank) but the Sigma was better optically. I was never (optically) impressed with the AT-X 400/5.6, either. Fred
Re: Opinions about Tokinas (Was Sigmas)
Mark, That lens has done an *excellent* job of capturing the breast feathers' structure. I used to keep birds (parrots mostly) and that's what their breast feathers look like when seen close up. Robins are much the same. Godfrey --- Mark Cassino [EMAIL PROTECTED] wrote: http://www.markcassino.com/temp/robin/ This shot was taken with the Tokina 400mm ATX, handheld. ... I guess I'd have to find a bird and hold it in my hand to know for sure, but I really question the detail in the feathers. They look like hairs, not feathers. My conclusion was that a low resolving lens with low CA and high edge sharpness - which is what my tests showed the ATX 400 to be - will create an image with clean edges and a high degree of _apparent_ detail. I say apparent detail because I don't think the birds breast feathers would really look like that, I think that the primary ribs of the feathers have been exaggerated and the connecting fibers have been all but lost in this shot. Psychologically, one looks at that and thinks Wow - what detail! but I really question that. Maybe I can find a natural history museum with a robin specimen and can confirm my suspicions... __ Do you Yahoo!? Read only the mail you want - Yahoo! Mail SpamGuard. http://promotions.yahoo.com/new_mail
Re: Opinions about Tokinas (Was Sigmas)
I think that the primary ribs of the feathers have been exaggerated and the connecting fibers have been all but lost in this shot. Psychologically, one looks at that and thinks Wow - what detail! but I really question that. I would tend to agree. The fuzziness of those hairs has been lost - the smaller branches on those hairs are not being resolved. It is almost as if it's been sharpened by some photo software. Maybe I can find a natural history museum with a robin specimen and can confirm my suspicions... Well, I don't have any robin feathers handy myself (here in February - g), either... Fred
RE: Opinions about Tokinas (Was Sigmas)
I have two Tokina 400mm F5.6 lenses. One is a RMC 400mm F5.6 IF in M42 mount and the other is the AT-X 400mm F5.6 IF in PK mount. Both are exceptionally good on film. I can recommend them strongly as they are not very expensive and represent great values. JCO -Original Message- From: Godfrey DiGiorgi [mailto:[EMAIL PROTECTED] Sent: Wednesday, February 23, 2005 1:28 PM To: pentax-discuss@pdml.net Subject: Re: Opinions about Tokinas (Was Sigmas) Mark, That lens has done an *excellent* job of capturing the breast feathers' structure. I used to keep birds (parrots mostly) and that's what their breast feathers look like when seen close up. Robins are much the same. Godfrey --- Mark Cassino [EMAIL PROTECTED] wrote: http://www.markcassino.com/temp/robin/ This shot was taken with the Tokina 400mm ATX, handheld. ... I guess I'd have to find a bird and hold it in my hand to know for sure, but I really question the detail in the feathers. They look like hairs, not feathers. My conclusion was that a low resolving lens with low CA and high edge sharpness - which is what my tests showed the ATX 400 to be - will create an image with clean edges and a high degree of _apparent_ detail. I say apparent detail because I don't think the birds breast feathers would really look like that, I think that the primary ribs of the feathers have been exaggerated and the connecting fibers have been all but lost in this shot. Psychologically, one looks at that and thinks Wow - what detail! but I really question that. Maybe I can find a natural history museum with a robin specimen and can confirm my suspicions... __ Do you Yahoo!? Read only the mail you want - Yahoo! Mail SpamGuard. http://promotions.yahoo.com/new_mail
Re: Opinions about Tokinas (Was Sigmas)
That lens has done an *excellent* job of capturing the breast feathers' structure. I used to keep birds (parrots mostly) and that's what their breast feathers look like when seen close up. Robins are much the same. Well, I'm not so sure... http://trc.ucdavis.edu/mjguinan/apc100/modules/Integument/hair/feathers2/feathers5.html http://www.peteducation.com/article.cfm?cls=15cat=1829articleid=2776 http://www.ummz.lsa.umich.edu/birds/Anatomy/feathers/feather_parts.html I think that the photo is showing the barbs but not the barbules, and (as mark has suggested) has sort of sharpened the barbs to provide a high ~apparent~ detail without actually showing the detail. Fred
Re: Opinions about Tokinas (Was Sigmas)
Interesting theory, Mark. Please report any further findings on this. Lasse From: Mark Cassino [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Wednesday, February 23, 2005 8:02 PM Subject: Re: Opinions about Tokinas (Was Sigmas) I posted this before (over a year ago), but I think it's an interesting illustration of what is being discussed in terms of how lenses differ between film and digital: http://www.markcassino.com/temp/robin/ This shot was taken with the Tokina 400mm ATX, handheld. In the actual pixel shot, the degree of apparent detail in the birds breast is remarkable. But I have found this lens to be pretty mediocre with film in the past. I guess I'd have to find a bird and hold it in my hand to know for sure, but I really question the detail in the feathers. They look like hairs, not feathers. My conclusion was that a low resolving lens with low CA and high edge sharpness - which is what my tests showed the ATX 400 to be - will create an image with clean edges and a high degree of _apparent_ detail. I say apparent detail because I don't think the birds breast feathers would really look like that, I think that the primary ribs of the feathers have been exaggerated and the connecting fibers have been all but lost in this shot. Psychologically, one looks at that and thinks Wow - what detail! but I really question that. Maybe I can find a natural history museum with a robin specimen and can confirm my suspicions... - MCC
Re: Opinions about Tokinas (Was Sigmas)
Hi Mark, Here's a robin I shot a few weeks ago. http://www.photo.net/photodb/photo?photo_id=3095297size=lg It's not as sharp as your pic. It's handheld with the a 400/5.6 and the A2X-S converter at 5.6, 1/500. But you can get some idea of the feather texture. The branch he's perched on provides somewhat of a gauge for relative sharpness and detail. Paul I posted this before (over a year ago), but I think it's an interesting illustration of what is being discussed in terms of how lenses differ between film and digital: http://www.markcassino.com/temp/robin/ This shot was taken with the Tokina 400mm ATX, handheld. In the actual pixel shot, the degree of apparent detail in the birds breast is remarkable. But I have found this lens to be pretty mediocre with film in the past. I guess I'd have to find a bird and hold it in my hand to know for sure, but I really question the detail in the feathers. They look like hairs, not feathers. My conclusion was that a low resolving lens with low CA and high edge sharpness - which is what my tests showed the ATX 400 to be - will create an image with clean edges and a high degree of _apparent_ detail. I say apparent detail because I don't think the birds breast feathers would really look like that, I think that the primary ribs of the feathers have been exaggerated and the connecting fibers have been all but lost in this shot. Psychologically, one looks at that and thinks Wow - what detail! but I really question that. Maybe I can find a natural history museum with a robin specimen and can confirm my suspicions... - MCC - - - - - - - - - - - - - - - - - - - - Mark Cassino Photography Kalamazoo, MI www.markcassino.com - - - - - - - - - - - - - - - - - - - - - Original Message - From: Fred [EMAIL PROTECTED] To: Mark Cassino pentax-discuss@pdml.net Sent: Wednesday, February 23, 2005 12:04 PM Subject: Re: Opinions about Sigmas Lastly, I briefly owned the Sigma 400 f5.6 macro, but wound up switching to the Tokina ATX 400 f5.6. I don't know about build quality (the Tokina is built like a tank) but the Sigma was better optically. I was never (optically) impressed with the AT-X 400/5.6, either. Fred
Re: Opinions about Tokinas (Was Sigmas)
I think Fred has managed to express it better than I did. The breast feathers in the robin are overlapping fan shaped structures. If you think of a paper fan as sort of a model for what they look like, the barbs are the ribs and the barbules are the paper connecting them. The feathers overlap and lay on the breast of the bird to keep it warm (and obviously for display purposes.) Not only in my robin photo, but in many a bird photo over the past few years, I've seen this kind of atrifacting. The combination of the way the lens resolves the image (low res/good edge detail) leads the digital camera to render the image sharpened so the barbs are prominent, but the rest is all but lost. Subjectively, it looks goods - unless you think about or have seen a lot of birds. Of Fred's links - http://www.ummz.lsa.umich.edu/birds/Anatomy/feathers/feather_parts.html I spent several happy years (too many years ago to recount) working for the Museum of Zoology (and the other affiliated museums) in Ann Arbor - it's always a trip down memory lane to re-visit their web site. I should of looked at the bird collection more closely while I was there! - MCC - - - - - - - - - - - - - - - - - - - - Mark Cassino Photography Kalamazoo, MI www.markcassino.com - - - - - - - - - - - - - - - - - - - - - Original Message - From: Fred [EMAIL PROTECTED] To: Godfrey DiGiorgi pentax-discuss@pdml.net Sent: Wednesday, February 23, 2005 1:47 PM Subject: Re: Opinions about Tokinas (Was Sigmas) That lens has done an *excellent* job of capturing the breast feathers' structure. I used to keep birds (parrots mostly) and that's what their breast feathers look like when seen close up. Robins are much the same. Well, I'm not so sure... http://trc.ucdavis.edu/mjguinan/apc100/modules/Integument/hair/feathers2/feathers5.html http://www.peteducation.com/article.cfm?cls=15cat=1829articleid=2776 http://www.ummz.lsa.umich.edu/birds/Anatomy/feathers/feather_parts.html I think that the photo is showing the barbs but not the barbules, and (as mark has suggested) has sort of sharpened the barbs to provide a high ~apparent~ detail without actually showing the detail. Fred
RE: Opinions about Tokinas (Was Sigmas)
Very informative, Fred! Bravo! Jens Jens Bladt mailto:[EMAIL PROTECTED] http://hjem.get2net.dk/bladt -Oprindelig meddelelse- Fra: Fred [mailto:[EMAIL PROTECTED] Sendt: 23. februar 2005 19:47 Til: Godfrey DiGiorgi Emne: Re: Opinions about Tokinas (Was Sigmas) That lens has done an *excellent* job of capturing the breast feathers' structure. I used to keep birds (parrots mostly) and that's what their breast feathers look like when seen close up. Robins are much the same. Well, I'm not so sure... http://trc.ucdavis.edu/mjguinan/apc100/modules/Integument/hair/feathers2/fea thers5.html http://www.peteducation.com/article.cfm?cls=15cat=1829articleid=2776 http://www.ummz.lsa.umich.edu/birds/Anatomy/feathers/feather_parts.html I think that the photo is showing the barbs but not the barbules, and (as mark has suggested) has sort of sharpened the barbs to provide a high ~apparent~ detail without actually showing the detail. Fred
