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07-23-2009, 02:05 PM   #16
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QuoteOriginally posted by djupdal Quote
Sorry, I did not mean to say the FA35/2 is not sharp. My point was that you need skills to use f2 in low light properly, which I clearly do not have. I get much better results at smaller apertures. I therefore reacted to the statement that fast lenses are mandatory in low light. Not so for me.
It has nothing to do with skill but simply the preciscion of the camera/lens system. I did a lot of aurora photography years ago (on film).

https://www.pentaxforums.com/forums/post-your-photos/39927-aurora-borealis.html

Using lenses wide open always gave unacceptable results at infinity. Infinity is a very precise point with a only a fraction of a mm error margin. I used all the Limited lenses (and others) at F:4 in order to let DOF cover some of the error margin ensuring sharp images. AF don't work and isn't precise enough anyway at very wide apertures at infinity. The camera/film(sensor) distance ins't necessarily precise enough and within fraction of a mm of the camera finder tolerance level. Then theres also thermal expansjon/extraction of camera/lenses. Infinity is not necessarily at the same place from day to day. That depends on temperature.
A Pentax lens designer said that the only way to do this precisely enough was to use a ground glass on the film plane and focus via a loupe. Then load the film! For digital you can try and use focus bracketing and check the image until you find the precise focus. Stopping down and crank the lens to infinity is the easiest way.

07-23-2009, 02:27 PM   #17
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QuoteOriginally posted by Pål Jensen Quote
It has nothing to do with skill but simply the preciscion of the camera/lens system. I did a lot of aurora photography years ago (on film).

Using lenses wide open always gave unacceptable results at infinity. Infinity is a very precise point with a only a fraction of a mm error margin. I used all the Limited lenses (and others) at F:4 in order to let DOF cover some of the error margin ensuring sharp images. AF don't work and isn't precise enough anyway at very wide apertures at infinity. The camera/film(sensor) distance ins't necessarily precise enough and within fraction of a mm of the camera finder tolerance level. Then theres also thermal expansjon/extraction of camera/lenses. Infinity is not necessarily at the same place from day to day. That depends on temperature.
A Pentax lens designer said that the only way to do this precisely enough was to use a ground glass on the film plane and focus via a loupe. Then load the film! For digital you can try and use focus bracketing and check the image until you find the precise focus. Stopping down and crank the lens to infinity is the easiest way.
Pål, whatever you write is ofcourse correct. But in real world imaging, the rules need not be that strict. The hyperfocal distance for a 35mm lens at f/2 is just above 32m (on a K20), so simply turning the lens to its infinity stop, should be well within the DOF, even taking varying temperatures into account. With longer lenses, focusing is a harder act and one needs to invest more time and brains to get the best result - as you wrote.

Ben
07-23-2009, 05:12 PM   #18
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QuoteOriginally posted by djupdal Quote
Sorry, I did not mean to say the FA35/2 is not sharp. My point was that you need skills to use f2 in low light properly, which I clearly do not have. I get much better results at smaller apertures. I therefore reacted to the statement that fast lenses are mandatory in low light. Not so for me.
I understand your predicament regarding that matter. but I would argue the necessity of using wider apertures under lowlight. the thing is, I had undergone thru a lot of bad experience using slower lens, be it primes or zooms. and I saw the necessity to have fast lenses. I would had never appreciate the need for them unless I saw the significance of their use and advantage. the extra openings sets the difference between missing shots or getting the shots. I do say by experience that I missed a lot of shots due to poor or slower lenses. going manual focus does not even help. you can just imagine how frustrating it is to have the perfect moment of taking the shot go to waste, just because your equipment doesn't have the capacity to shoot it under challenging circumstances. that's why you could see a lot of people, including myself go after fast lenses or the demand for it is high especially when sold at a bargain compared slower ones sold at much cheaper price.
07-24-2009, 04:12 AM   #19
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FA50 is very usable at 1.4.
FA50 has excellent bokeh rendering.

This lens is an absolute steal for the price/quality.

FA35 is extremely sharp, especially from f2.8-5.6 (still very sharp at 2.0). If it's build quality was like the FA31 no one would by the FA31.

They are both excellent lenses.

c[_]

07-24-2009, 04:43 AM   #20
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QuoteOriginally posted by bdery Quote
It seems most users here agree that for low light photography, a fast lens such as the FA 50 f1,4 is mandatory. I agree. I have used a SMC-M 50 f2 and found it excellent but not quite fat enough. I then got a SMC-A 50 f1,4, found it amazing, but never dared to use it at f1,4, because of the much lower contrast and sharpness at this aperture. I now have an SMC-F 50 f1,7, and feel confortable using it wide open.

Most people say the FA 50 f1,4 also lacks contrast and sharpness wide open. So my question is : does it make sense to get a wider lens if the widest setting is so "poor" (all things being relative). Would a, f1,7, or even an f1,9 lens like the 43 mm, make more sense? to me it does, but not all people agree.

What are your opinions?
I just have a simple question here. What sort of subjects are you going to be shooting in low light? At the subjects themselves going to be dimly lit? Or will it be like a stage show where the room itself is dark but the subject is pretty well lit, though still not brightly lit? And from what distances will you be shooting?

I as because I have had times when I was shooting from a distance in basically a dark room or venue but the subject was well lit to get the shots I was after I was easily able to get away with a 150-200mm at f/2.8 up to about f4, though f2 would have been better but I made it work.

I don't often need or want a wide fast lens, I almost always am after a longer faster lens. Though these limiteds have me kinda looking forward to some my up close low light shots.
07-24-2009, 05:58 AM   #21
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I have shot the SMC 50mm F1.4 (K mount) wide open for more than 20 years. Much of this is at night with ISO 3200 B&W film (Tri-X 400 pushed 3 stops in processing) at 1/30 of a second.

Basically I am shooting in ultra low or no light situations.

Compared to the film grain, (or sensor noise in the DSLR world) image movement abd blurr (because 1/30 of a second does not freeze motion) and camera shake (even with good technique), some loss of contrast is simply not relevant in the image quality you get.

I have also used it to shoot indoor sports, wide open to get shutter speed under typical high school gym lighting.

I can't comment about other lenses but the origonal K mount 50mm F1.4 is very sharp even wide open.
07-24-2009, 06:57 AM   #22
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People would be surprised at how much effect a slight adjustment of the focus has. For example on my FA31, turning all the way to infinity does not always work (depending on the temperature) and shifting the focus by even 1mm will make a huge difference in sharpness at F1.8 so be careful.
07-24-2009, 08:23 AM   #23
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Great comments, very interesting opinions...

QuoteQuote:
Some say the 50 f/2 is really the same optically as the 1.7 but it's just restricted to f/2. There was a thread here a few weeks ago about that.
This surfaces from time to time. It's not true. The optics are different, and I can testify that the performances are different. The F 1,7 is much shrper than the M f2.

QuoteQuote:
The FA50 1.4 you get a trade off between the speed and softness wide-open. But stop down the lens and you get as sharp an image from the lens as any other in the right conditions.
Correct. I am not shopping for a lens right now, the F50 1,7 is perfect for me. I am just curious about the opinions of others, since many people (me among them) think the 50s f1,4 are not excellent wide open.

QuoteQuote:
You need to take into account the prupose of the fast aperture, you either need it for an extremely shallow DOF, (and I really think, that many complaints about poor contrast can be traced back to not correctly focused images at such a shallow DOF) or because the light is extremely poor. In that condition, lack of contrast is simply a none-issue, as a slower lens wouldn't get you the shot.
That is correct, in theory, but even them I could never convince myself to use my A f1,4 wide open. That's why I went for the F f1,7, since I find it better than the 1,4 at f1,7 (or 1,8 in the case of the A).

QuoteQuote:
whoever thinks the FA50 is bad at 1.4 is wrong.
Never said it was bad. I said that it's celarly not as good as closed down

QuoteQuote:
At f2 in low light, autofocus is not working at all
A wider lens helps for this, more light helps the AF system.

QuoteQuote:
For those of you who own a FA 50 f1.7, how sharp are the pictures, when stopped up, for general purpose photography, such as street action, group shots, running children/pets, action shots, etc?
closed down it is impossible to decide which is the sharpest, my F 50 f1,7 or my FA 50 f2,8 macro. The latter is reknowed as one of the sharpest lenses ever made, ever. To my eyes they look similar stopped down. At f2,8 the macro is better, at f4 and beyond there is no difference. But I rarely use my 50 f1,7 when light levels are not very low.

QuoteQuote:
What sort of subjects are you going to be shooting in low light?
For me it's mainly city walks, nature walks, that sort of things. When doing low light photogrpahy I either bring my tripod, my f1,7, or both, depending on the situation.

QuoteQuote:
shifting the focus by even 1mm will make a huge difference in sharpness at F1.8
Absolutely correct, that's one reason why I like the F1,7, too. Its AF system is so reliable, I cannot do better by focusing manually, even with live view magnification on a tripod.

--

I'm a bit surprised (but I guess I shouldn't be) that so many people use the FA35 in low light. It's a very good compromise indeed. Thanks for the input, everyone, it makes an interesting read.

07-24-2009, 08:40 AM   #24
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I just got an SMC Pentax-M 1:2 50mm f2 prime lens on ebay, and I'm pretty frustrated with it. I bought it so I could take more handheld low light photos, but it is VERY hard to get a sharp shot at the lower f stops. At f3.5 or f4, it is quite sharp, but focusing below that is hit or miss.

More often than not, my subject looks out-of-focus, not just un-sharp. I can practice the same f2 shot 10 times, and randomly get 2 shots that come out crisp and the others fuzzy. I use the AF indicator beep, but it doesn't seem very accurate. The crazy thing is that everything usually shows up good in the viewfinder, but the actual picture comes out blurry.

Is this just a problem with this lens? It's also weird that the focus ring turns REALLY FAR, almost 3 hand twists, but it seems like only about 20% of that range is focusable to me. Does the difference in digital sensor size to film have something to do with its focus? I also find that at infinity, I'd like to go a little further to focus, but the focus ring is already maxed out. And sometimes in my blurry shots, I find that other areas in my shot are very crisp, but not the subject under my center focus point. Any ideas?

But I have found a trick that works most of the time. I set my camera to auto focusing, which forces a focus lock before allowing the shutter to release, even though I'm manual focusing the lens. I found that if I hold down the shutter all the way, and VERY slowly focus the ring, it will trigger automatically when it first hits the AF point. Most of these shots are considerably clearer than those I try to do 100% manual at f2. However, this is only practical for portraits, you'll miss a lot of shots if used for action.
07-24-2009, 10:07 AM   #25
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QuoteOriginally posted by jhonny0099 Quote
I just got an SMC Pentax-M 1:2 50mm f2 prime lens on ebay, and I'm pretty frustrated with it. I bought it so I could take more handheld low light photos, but it is VERY hard to get a sharp shot at the lower f stops. At f3.5 or f4, it is quite sharp, but focusing below that is hit or miss.

More often than not, my subject looks out-of-focus, not just un-sharp. I can practice the same f2 shot 10 times, and randomly get 2 shots that come out crisp and the others fuzzy. I use the AF indicator beep, but it doesn't seem very accurate. The crazy thing is that everything usually shows up good in the viewfinder, but the actual picture comes out blurry.

Is this just a problem with this lens? It's also weird that the focus ring turns REALLY FAR, almost 3 hand twists, but it seems like only about 20% of that range is focusable to me. Does the difference in digital sensor size to film have something to do with its focus? I also find that at infinity, I'd like to go a little further to focus, but the focus ring is already maxed out. And sometimes in my blurry shots, I find that other areas in my shot are very crisp, but not the subject under my center focus point. Any ideas?

But I have found a trick that works most of the time. I set my camera to auto focusing, which forces a focus lock before allowing the shutter to release, even though I'm manual focusing the lens. I found that if I hold down the shutter all the way, and VERY slowly focus the ring, it will trigger automatically when it first hits the AF point. Most of these shots are considerably clearer than those I try to do 100% manual at f2. However, this is only practical for portraits, you'll miss a lot of shots if used for action.

the M 50/2 really shines at high aperture, specifically at f8. just fix the aperture at that range and you won't have any problem with regards to focus and sharpness. I got this lens btw, and I don't use it. it is practically useless since my 2 other fast 50s has taken up that slot.


but mind you that the M 50/2 is a gem in it's own right. at f8, you'll get excellent pictures.

it would suit those who are really tight on a budget, costs almost nothing (like 10-25 bucks or for free). and it is a tank. it is suitable for beginners who just entered into the world of SLR cameras.
07-24-2009, 10:31 AM   #26
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QuoteOriginally posted by Just1MoreDave Quote
..........had a S-M-C Takumar 35mm f2 and a Pentax-M 35mm f2, and neither lens was great at f2. ..........
Wow. I thought these 2 had similar lens formula compared to the FA 35 f2. I was hoping to get the MF 35 f2's instead of the AF since the FA 35 has increased in value. I should have bougth 100 shares of the FA 35

I'll have to look at Stan's website to see if there are any differences between the Takumar 35f2, M 35f2, and the FA 35 f2 - but for now, I'll take your word on it since you've actually used them.
07-24-2009, 10:34 AM   #27
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QuoteOriginally posted by bdery Quote

Absolutely correct, that's one reason why I like the F1,7, too. Its AF system is so reliable, I cannot do better by focusing manually, even with live view magnification on a tripod.

--

I'm a bit surprised (but I guess I shouldn't be) that so many people use the FA35 in low light. It's a very good compromise indeed. Thanks for the input, everyone, it makes an interesting read.
reasons for this is the AF on the 35 is faster as compared to the 50 1.7. the FOV equivalent on a dSLR. the 50 1.7's sharpness is unmatched at 1.7, so does the 35's sharpness at f/2 is unparalleled. but at equal apertures at 2.8 up to 5.6, the 35 is just sharper. I mean mad razor thin sharp. probably that's the reason why people prefer the 35 more than the 50 1.7.

the A 50 1.2 however, is another story.

Last edited by Pentaxor; 07-24-2009 at 03:54 PM.
07-24-2009, 11:30 AM   #28
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QuoteOriginally posted by PentHassyKon Quote
Wow. I thought these 2 had similar lens formula compared to the FA 35 f2. I was hoping to get the MF 35 f2's instead of the AF since the FA 35 has increased in value. I should have bougth 100 shares of the FA 35

I'll have to look at Stan's website to see if there are any differences between the Takumar 35f2, M 35f2, and the FA 35 f2 - but for now, I'll take your word on it since you've actually used them.
Here's a comparison between the FA and K version.

FA35/2AL vs. K35/2

The K version is different than the M or A. I don't know if it's the same as the Takumar, but it appears to be the same size. [Another reason I got the FA was that the older lenses were hard to distinguish from other lenses. The Takumar was really similar to the 105/2.8 and the M was like many other M primes. Not the top reason, or applicable if you have a lot of FAs, but it was annoying.]

From the same guy, a sharpness test including several versions:

http://www.takinami.com/yoshihiko/photo/lens_test/pentax_35.html
07-24-2009, 11:34 AM   #29
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Good discussion of an important topic. I'll just add my two cents:

"Most" of the time, I don't really like shooting wider than f/2.8. Sure, if the whole point of the shot is to have a shallow DOF, then that's the way to go. But if your reason to go beyond f/2.8 is for faster shutter speed on an "ordinary" picture, I'd usually rather get there by increasing ISO or even underexposing/push-processing as necessary, or I'd rather simply use flash and I say that as someone who normally very much dislikes using flash). Between the very shallow DOF, the difficulty placing focus accurately - especially in the low light levels that typically make these kind of apertures seem appealing - and the softness of most faster lenses used wide open, it just doesn't seem worth it to me most of the time.

That said, everything I've seen from and read about the FA35/2 suggests it might be one lens I'd be OK with using at f/2 on a regular basis if I had it, both because it is unusually sharp and contrasty at f/2, plus its focal length gives you a bit more DOF at f/2 than you'd get with a 50. Still, for my purposes, I just don't mind shooting f/2.8 and increasing ISO / push-processing as necessary most of the time. It all depends on your respective tolerances for noise, PP, and very shallow DOF.
07-24-2009, 11:47 AM   #30
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QuoteOriginally posted by Just1MoreDave Quote
Here's a comparison between the FA and K version.

FA35/2AL vs. K35/2

...............

From the same guy, a sharpness test including several versions:

http://www.takinami.com/yoshihiko/photo/lens_test/pentax_35.html
thx for the links...
Quick look at his results.
According to him, the FA35 is sharper in the center than the FA43 wide open. 78 vs 55 lpm.
Like marc, though, most of us in reality will probably use our lens' a couple of stops down from wide open. When I use a wide angle (24, 28, 35mm), I tend to keep in mind hyperfocal and manually focus.
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