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03-01-2011, 12:31 AM   #76
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QuoteOriginally posted by Jewelltrail Quote
Yes, & its likely to be less expensive then too--like Asahiflex says, way to balance the priorities.

I almost purchased 1 tonight, but am struggling with several options:

1) buy K5
2) buy 70-200 Tammy
3) buy Siggy 85
4) buy 50-135
I'll make it easier for you.

with regards to the K-5, let's say skip that one for now til they clear the sensor stain and flash issue.

the 50-135, why don't you wait til Pentax comes up with something better and atleast won't be counting the days that it might fail or not.

Tammy 70-200 is very good, but how much do you really need it?

Sigma 85, same argument as the Tammy 70-200.

so goodluck between the Tamron 70-200 and Sigma 85.

as for me, I'll guess I'll be fine with the J-9, M85, and S1-90 lenses for now.

03-01-2011, 04:01 AM   #77
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QuoteOriginally posted by Laurentiu Cristofor Quote
I don't think so.
What do you think it is?
It may also be caused by longitudinal CA but most lenses aren't that bad.

QuoteOriginally posted by Laurentiu Cristofor Quote
Here's an example:
I don't see any behind the focal plane?
03-01-2011, 03:41 PM   #78
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Here's another pretty bad example of Bokeh-CA from the FA 77. If one of the best Pentax lenses is allowed to do this, I guess the Sigma 85/1.4 can be excused for the amount it produces.
03-01-2011, 05:46 PM   #79
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QuoteOriginally posted by Class A Quote
Here's another pretty bad example of Bokeh-CA from the FA 77. If one of the best Pentax lenses is allowed to do this, I guess the Sigma 85/1.4 can be excused for the amount it produces.
honestly speaking, that is the only thing that is killing the FA77. wide open is pretty tricky due to that. other than that, it's a marvelous lens.

the Sigma seems to be the lesser evil of the two. eliminating or minimizing pf to a great extent. LoCa's would probably be gone or negligible by f1.8 or f2 which is great.

03-02-2011, 08:34 PM   #80
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QuoteOriginally posted by Class A Quote
What do you think it is?
You mean what causes it? I don't know, but some lenses have it and some don't, and bokeh fringing seems to be independent from it. The FA 100-300, for example, has bokeh fringing but I wouldn't say it suffers from PF because there is no fringing in the focal plane. Some people say it's a sensor issue - that CCD sensors are more likely to show this than CMOS ones - I haven't really looked into the truth of that statement.

QuoteOriginally posted by Class A Quote
I don't see any behind the focal plane?
The focus is on the back of the bird - right below the neck. The head is behind the focal plane, but it still has purple fringing.
03-03-2011, 03:00 AM   #81
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QuoteOriginally posted by Laurentiu Cristofor Quote
The FA 100-300, for example, has bokeh fringing but I wouldn't say it suffers from PF because there is no fringing in the focal plane.
Note for non-APO lenses there is no "one" focal plane. You can go for the one that places two colours into the same plane but then the third colour will be out of focus (achromatic lenses) and hence may cause a visible fringe. Achromats typically focus blue and red into the same plane, so if you focus on green, this causes a purple (red+blue) fringe.

QuoteOriginally posted by Laurentiu Cristofor Quote
Some people say it's a sensor issue - that CCD sensors are more likely to show this than CMOS ones - I haven't really looked into the truth of that statement.
I understand it refers to very old sensors. Modern sensors don't exhibit blooming anymore.

QuoteOriginally posted by Laurentiu Cristofor Quote
The focus is on the back of the bird - right below the neck. The head is behind the focal plane, but it still has purple fringing.
I looked really hard, but I still don't see any purple fringes. You might be referring to a general purple tinge that can easily be addressed by white balancing?
03-03-2011, 06:17 AM   #82
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I just bought an f mount sigma 85, I'll let you guys know what I think. I'm very much in love with the nikon 85 1.8 which is probably somewhat comparable to the pentax 77. I'm not sure if I'll keep the sigma or not.
03-03-2011, 11:46 AM   #83
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QuoteOriginally posted by azimuthal Quote
I just bought an f mount sigma 85, I'll let you guys know what I think. I'm very much in love with the nikon 85 1.8 which is probably somewhat comparable to the pentax 77. I'm not sure if I'll keep the sigma or not.
keep us posted.

03-03-2011, 10:50 PM   #84
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QuoteOriginally posted by Class A Quote
Note for non-APO lenses there is no "one" focal plane. You can go for the one that places two colours into the same plane but then the third colour will be out of focus (achromatic lenses) and hence may cause a visible fringe. Achromats typically focus blue and red into the same plane, so if you focus on green, this causes a purple (red+blue) fringe.
This doesn't explain much. I estimated the focal plane based on the detail in the bird's feathers - even if the primary colors would be focused differently around that plane, it wouldn't be a difference large enough to account for the purplish tint across all the bird's body, don't you think? Why is there only a purplish fringe? And why some lenses are more prone to this issue than others? Why don't I see this effect with the FA100-300, for which I can clearly see the bokeh fringing?

QuoteOriginally posted by Class A Quote
I looked really hard, but I still don't see any purple fringes. You might be referring to a general purple tinge that can easily be addressed by white balancing?
You may call it tinge, fringe, or blooming. It's not a white balance issue though.
03-05-2011, 06:35 PM   #85
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I went back to the RAW file for that bird shot, to fiddle with the white balance. The purple fringing doesn't go away, but if I warm the shot, it looks less annoying on the feathers. And I may have been wrong about the focal plane - it could be behind the bird's head (because on a branch that seems to be behind the head, I can see the purple fringe changing into a green one) and the blur might be because of head movement, not defocusing. So it looks like this could be correlated with bokeh fringing, but I still don't understand why some lenses are much worse than others. Need more research - I'll examine more carefully future shots with PF - I usually don't keep the worst ones around.

Thanks for the argument.
03-07-2011, 12:22 AM   #86
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QuoteOriginally posted by Laurentiu Cristofor Quote
So it looks like this could be correlated with bokeh fringing, but I still don't understand why some lenses are much worse than others.
Different lens designs lead to different bokeh CA. Symmetrical designs and low dispersion glass help to reduce it but it is impossible to completely avoid it.

Not sure that explains everything you see but I don't have a better explanation.
05-24-2011, 12:08 PM   #87
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QuoteOriginally posted by Pentaxor Quote
I'll make it easier for you.

with regards to the K-5, let's say skip that one for now til they clear the sensor stain and flash issue.

the 50-135, why don't you wait til Pentax comes up with something better and atleast won't be counting the days that it might fail or not.

Tammy 70-200 is very good, but how much do you really need it?

Sigma 85, same argument as the Tammy 70-200.

so goodluck between the Tamron 70-200 and Sigma 85.

as for me, I'll guess I'll be fine with the J-9, M85, and S1-90 lenses for now.
About a month ago I made serious, long-lasting decisions. I went full-frame with the D700. This gives me a plethora of lens choices hitherto unknown. For example, I bought a Nikkor AF 85mm f1.8D, which is close to a flawless lens, and gets 5 stars @ Photozone on Crop & Full Frame sensors. It is half the price of the Sigma 85mm 1.4. I could not be happier.
05-24-2011, 01:04 PM   #88
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QuoteOriginally posted by Jewelltrail Quote
About a month ago I made serious, long-lasting decisions. I went full-frame with the D700. This gives me a plethora of lens choices hitherto unknown. For example, I bought a Nikkor AF 85mm f1.8D, which is close to a flawless lens, and gets 5 stars @ Photozone on Crop & Full Frame sensors. It is half the price of the Sigma 85mm 1.4. I could not be happier.
that lens has been a solid performer eversince it came out. actually it is one of the rare Nikon lenses that I liked in the Nikon line-up.
05-24-2011, 08:14 PM   #89
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QuoteOriginally posted by Pentaxor Quote
that lens has been a solid performer eversince it came out. actually it is one of the rare Nikon lenses that I liked in the Nikon line-up.
Yes, it is a hard lens not to fall in love with--for sure. The Nikon 5 Year Warranty makes swiping the old credit card a much easier thing to do as well. There are many Nikon lenses besides this 85 which I like, but I love the fact that even inexpensive glass looks fantastic on the D700. AF speed & accuracy is shockingly excellent.
05-24-2011, 11:26 PM   #90
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QuoteOriginally posted by Jewelltrail Quote
Yes, it is a hard lens not to fall in love with--for sure. The Nikon 5 Year Warranty makes swiping the old credit card a much easier thing to do as well. There are many Nikon lenses besides this 85 which I like, but I love the fact that even inexpensive glass looks fantastic on the D700. AF speed & accuracy is shockingly excellent.
it is no surprise the 85/1.8 has a faster AF and basically it is made as such for fast AF uses. although one would be surprised to see the huge price difference between the slower Nikon to it's faster 85mm brother. and Pentax doesn't have one to offer.
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