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05-29-2010, 02:17 PM   #1
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A* series Lenses and friming

Good morning, as we all know, the series A* of pentax ( ess. A* 85, 135 ...) , exceptional lenses are very resolving.
However the flaw to suffer from friming and CA, you can mitigate this problem, using filters.
Maybe even very good as B + W or higher, which can help us?

Thank you

05-29-2010, 03:01 PM   #2
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Do you mean fringing? I haven't experienced much on my A* 200, which is my favorite from the series (F2.8 version). There's a bit on the 135 and 85, but IMO the best way to reduce it is to just stop down to F4 or lower!
05-30-2010, 10:59 AM   #3
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QuoteOriginally posted by Adam Quote
Do you mean fringing? I haven't experienced much on my A* 200, which is my favorite from the series (F2.8 version). There's a bit on the 135 and 85, but IMO the best way to reduce it is to just stop down to F4 or lower!
Yes purple fringing.

I too have the 200 *, really a nice lens.
The 200 mm suffers little, then comes the 85 mm, then the 135 that is a real disaster
I understand that if shots at f/4 remove the problem, but forgive me,
If I buy a lens from f/1.8, I would like to use, otherwise, I spend half, and I take the version f/2.5.
I can understand?
That's why I wanted to know if a filter can help.

Hello thanks.
05-30-2010, 11:54 AM   #4
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There is no filter available to remove or even reduce CAs or purple fringing. In theory, one of the Baader Planetarium filters (the Fringe Killer for instance) could help a bit. It is a filter for astronomical telescopes which suffer from blue fringing (blue haloing) and it works fairly well with these telescopes. But it also introduces a faint yellow tint to the image. And, more important, it is not available in the usual phtographic filter sizes, the maximum size being 48mm. The Contrast Booster may also be worth a look - but also limited to 48mm size (aka 2-inches thread)

For more detailed info: http://www.baader-planetarium.com/pdf/fringe_killer_e.pdf
Baader Planetarium - Download, pdf-files filter
http://www.baader-planetarium.com/section_prices.pdf

Ben

05-30-2010, 01:13 PM   #5
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Using film can help, though. Hardly any of that stuff shows up on film, as digital sensors are a lot more sensitive to it

At such high wide-open apertures, the laws of optics take over. Not much can be done.

Adam
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05-30-2010, 02:27 PM   #6
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I was trying to figure out where you determined that the A*135/1.4 was a "real disaster" and checked your other threads. I see someone compared the Voigtlander 125 wide open (@2.5) against the 135 (@1.4) when shooting at stars (black background with bold white specs). The first question that comes to mind is why are you going after a lens so wide as the 135/1.4 and what are you expecting to use it for? Ultra wide lenses are extremely expensive to manufacturer and tend to be in limited supply, so they are going to cost a lot more. They are also not known to be "tack sharp" wide open due to the physics involved. They typically produce a background some find more pleasing and can pull off low light shots hand shots that may not be possible with narrower lenses.

Look at the common 50/1.2. People either love it, or they hate it due to it being "soft wide open". When you dig into it more, it's about as sharp as the 1.4 dropped down a few clicks, then tends to be sharper at f16 than the 1.4.

If you tend to shoot white / black edges, then perhaps the A*135 is not for you, but I know I sure would love one...

Steve
05-30-2010, 02:40 PM   #7
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Also remember you can remove some fringing (not all, but the more obvious stuff) in PP.
05-31-2010, 07:14 PM   #8
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QuoteOriginally posted by smc Quote
A*135/1.4
The A*135/1.8 or the A*85/1.4?

05-31-2010, 09:53 PM   #9
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Some notes about the A*135

Firstly, the "fringing" you refer to with the A*85 and A*135 is bokeh (or longitudinal) CA - high-contrast edges behind the plane of focus will have green fringing, while those in front will have purple fringing. This is not unusual for ultra-fast lenses.

What makes these two A* lenses seem a bit worse than others is that the purple fringing can "bloom", depending on how far out of focus the high-contrast edges are. But the good news is that this blooming can be controlled by making fine adjustments to the focus (you can see it change using live view). Or, you can stop down - f2.5-2.8 is enough to take care of the worst situations in my experience.

Also, unlike what many might assume, the A*135 is not soft at f1.8 - in fact I wouldn't hesitate to describe it as being "tack sharp" here. And given the typical lighting conditions where you might need to shoot at such wide apertures, the bokeh CA I mentioned above is not an issue. So that makes f1.8 and 2.2 very usable on the A*135, and is one reason why this is my most treasured lens.
06-02-2010, 10:12 AM   #10
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QuoteOriginally posted by Ben_Edict Quote
There is no filter available to remove or even reduce CAs or purple fringing. In theory, one of the Baader Planetarium filters (the Fringe Killer for instance) could help a bit. It is a filter for astronomical telescopes which suffer from blue fringing (blue haloing) and it works fairly well with these telescopes. But it also introduces a faint yellow tint to the image. And, more important, it is not available in the usual phtographic filter sizes, the maximum size being 48mm. The Contrast Booster may also be worth a look - but also limited to 48mm size (aka 2-inches thread)

For more detailed info: http://www.baader-planetarium.com/pdf/fringe_killer_e.pdf
Baader Planetarium - Download, pdf-files filter
http://www.baader-planetarium.com/section_prices.pdf

Ben

Exact, since I had seen the filters of that talk, I thought there was something even for photography.


QuoteOriginally posted by Adam Quote
Using film can help, though. Hardly any of that stuff shows up on film, as digital sensors are a lot more sensitive to it

At such high wide-open apertures, the laws of optics take over. Not much can be done.
I know that the problem is only on digital
06-02-2010, 10:20 AM   #11
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QuoteOriginally posted by smc Quote
I was trying to figure out where you determined that the A*135/1.4 was a "real disaster" and checked your other threads. I see someone compared the Voigtlander 125 wide open (@2.5) against the 135 (@1.4) when shooting at stars (black background with bold white specs). The first question that comes to mind is why are you going after a lens so wide as the 135/1.4 and what are you expecting to use it for? Ultra wide lenses are extremely expensive to manufacturer and tend to be in limited supply, so they are going to cost a lot more. They are also not known to be "tack sharp" wide open due to the physics involved. They typically produce a background some find more pleasing and can pull off low light shots hand shots that may not be possible with narrower lenses.

Look at the common 50/1.2. People either love it, or they hate it due to it being "soft wide open". When you dig into it more, it's about as sharp as the 1.4 dropped down a few clicks, then tends to be sharper at f16 than the 1.4.

If you tend to shoot white / black edges, then perhaps the A*135 is not for you, but I know I sure would love one...

Steve


Hi, I owned a * 135, I have recently been stolen
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/101725-my-ex-p...5960418-a.html

I did just two shots,
A white dove in a park, friming is scary, thrilling.
Now my indecision arises if it again, I wait and dreaming about a * 135 f1, 8
My fear is given by friming, because I know that besides this issue, is a lens that makes beautiful photos
06-02-2010, 10:25 AM   #12
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QuoteOriginally posted by kerrowdown Quote
Also remember you can remove some fringing (not all, but the more obvious stuff) in PP.
Too bad I'm not capable, but please do not say it around

QuoteOriginally posted by photogerald Quote
Firstly, the "fringing" you refer to with the A*85 and A*135 is bokeh (or longitudinal) CA - high-contrast edges behind the plane of focus will have green fringing, while those in front will have purple fringing. This is not unusual for ultra-fast lenses.

What makes these two A* lenses seem a bit worse than others is that the purple fringing can "bloom", depending on how far out of focus the high-contrast edges are. But the good news is that this blooming can be controlled by making fine adjustments to the focus (you can see it change using live view). Or, you can stop down - f2.5-2.8 is enough to take care of the worst situations in my experience.

Also, unlike what many might assume, the A*135 is not soft at f1.8 - in fact I wouldn't hesitate to describe it as being "tack sharp" here. And given the typical lighting conditions where you might need to shoot at such wide apertures, the bokeh CA I mentioned above is not an issue. So that makes f1.8 and 2.2 very usable on the A*135, and is one reason why this is my most treasured lens.
Too bad I'm not capable, but please do not say it around

Hello, nobody ever said that the 135 is soft, in fact ....
My only fear is the friming, and bothers me to have a lens that I use only with difficulty at f / 1.8
if I'm always close to f / 3, the time I buy the 135 f2, 5 ...
07-06-2010, 01:10 AM   #13
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QuoteOriginally posted by bollicina31 Quote
Too bad I'm not capable, but please do not say it around

Hello, nobody ever said that the 135 is soft, in fact ....
I didn't mean to criticize your skills, I just wanted to mention that the 135/1.8 is sharp wide open because some folks say it's not.

QuoteOriginally posted by bollicina31 Quote
My only fear is the friming, and bothers me to have a lens that I use only with difficulty at f / 1.8
if I'm always close to f / 3, the time I buy the 135 f2, 5 ...
Since the fringing happens with out-of-focus objects, you can learn to control it. Yes, in certain lighting conditions it can be difficult.

Also, the K135/2.5 suffers from lateral CA @ f2.5 (this shows up even on film).

I'm sorry to hear that your copy of the A135/1.8 was stolen. I hope you can find a replacement for a reasonable price.
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