Question about FA 31mm sharpness at f/1.8

GeneV · 07-06-2011, 07:24 AM

Definitely try manual focus so you will know exactly where the focus point is. I would agree that the -5 is the best, but whether it is because of the adjustment or not, I would not be able to say. It seems that given the few millimeters involved in these camera adjustments, that -10 would show a bigger difference in focus between the words on the edges such as "Distilled" and those in the middle ("Laphroaig") because one or the other is closer to the true point of focus. I don't have a Laphroaig bottle handy, but on other fifth-sized malt bottles, the position of the edge letters is a couple of millimeters back from the middle.

mr.sinha · 07-06-2011, 04:18 PM

Originally posted by GeneV

Definitely try manual focus so you will know exactly where the focus point is. I would agree that the -5 is the best, but whether it is because of the adjustment or not, I would not be able to say. It seems that given the few millimeters involved in these camera adjustments, that -10 would show a bigger difference in focus between the words on the edges such as "Distilled" and those in the middle ("Laphroaig") because one or the other is closer to the true point of focus. I don't have a Laphroaig bottle handy, but on other fifth-sized malt bottles, the position of the edge letters is a couple of millimeters back from the middle.

I did some more testing at f/1.8 with af adjustment from -1 thru -10, and I do find -4 or -5 to be the best for my lens.
But the original purpose of this thread was to understand the diff between f/1.8 and f/4 sharpness at the same focus adjustment level, where I've found the f/4 to be at significantly more sharpness than the f/1.8, which leads back to my original questioning of the supposedly legendary sharpness of the FA31 even at f/1.8. But then as other members have posted and admitted that even their f/1.8 images are not quite as sharp as f/4 images (the Photozone test analysis report reiterating the same), I guess there is nothing wrong with my lens and it falls in the "as designed" category. Thanks everybody for responding.

deadwolfbones · 07-06-2011, 05:45 PM

Yeah... f/4 is definitely on a different level of sharpness from f/1.8...

GeneV · 07-06-2011, 05:54 PM

Originally posted by deadwolfbones

Yeah... f/4 is definitely on a different level of sharpness from f/1.8...

On just about any lens with both apertures.

selar · 07-06-2011, 09:29 PM

Sometime ago I posted a poll comparing FA35/2 and FA31/1.8. In that poll I posted a link that contained full sized images of the same subject shot at various apertures with both lenses. That link contains images taken with FA31 at various apertures, you might be able to get an idea of whether your copy performs similarly. Here is the link:
https://skydrive.live.com/redir.aspx?cid=611fa57d8d41a33a&page=play&resid=611FA57D8D41A33A!369
I had to spend a couple of hours tweaking AF on the camera before I was satisfied,apparently the FA31 has a habit of exposing AF deficiencies in dSLR bodies. In these images that I posted, yes F4 was sharper but not remarkably so.

GeneV · 07-07-2011, 07:23 AM

Originally posted by selar

Sometime ago I posted a poll comparing FA35/2 and FA31/1.8. In that poll I posted a link that contained full sized images of the same subject shot at various apertures with both lenses. That link contains images taken with FA31 at various apertures, you might be able to get an idea of whether your copy performs similarly. Here is the link:
https://skydrive.live.com/redir.aspx?cid=611fa57d8d41a33a&page=play&resid=611FA57D8D41A33A!369
I had to spend a couple of hours tweaking AF on the camera before I was satisfied,apparently the FA31 has a habit of exposing AF deficiencies in dSLR bodies. In these images that I posted, yes F4 was sharper but not remarkably so.

I remember those shots. As a practical matter, because focus is so critical, F4 ends up in a totally different category for real-world use. I remember on another thread someone discussing how seldom a pro uses any really wide aperture outside of a staged shot. It is just too easy to miss the focus when trying to catch a shot.

RioRico · 07-07-2011, 10:09 AM

Originally posted by GeneV

I remember on another thread someone discussing who seldom a pro really uses any really wide aperture outside of a staged shot. It is just too easy to miss the focus when trying to catch a shot.

And that's why f/8 and be there was and is the photojournalist's golden rule. (It's the rule that brings in the gold.) Look at published photos. In low-light and fast-action shots (some wildlife and sports), you'll see thin DOF. Almost everything else has nice thick sharp DOF. Wider lenses have thicker DOF wide-open, so my 24/2 and 28/2 and 35/2 lenses are just wizard on FF and still pretty good on HF / APS-C. There's a reason the Nikkor 35/2 was the standard PJ's lens -- and it was still used at f/8 mostly.

Stop down. Hit the focus. If the background is too obtrusive, well, BG's can be softened in PP. That's an old tradition. But if your subject isn't sharp, don't bother submitting the photo -- unless you (and your editor) *want* some blur, for drama. But hay, don't just believe me. Study some books and magazines filled with photos. Take notes about DOF, count those that are thick or thin. Surprise yourself.

GeneV · 07-07-2011, 02:17 PM

Originally posted by RioRico

And that's why f/8 and be there was and is the photojournalist's golden rule. (It's the rule that brings in the gold.) Look at published photos. In low-light and fast-action shots (some wildlife and sports), you'll see thin DOF. Almost everything else has nice thick sharp DOF. Wider lenses have thicker DOF wide-open, so my 24/2 and 28/2 and 35/2 lenses are just wizard on FF and still pretty good on HF / APS-C. There's a reason the Nikkor 35/2 was the standard PJ's lens -- and it was still used at f/8 mostly.

Stop down. Hit the focus. If the background is too obtrusive, well, BG's can be softened in PP. That's an old tradition. But if your subject isn't sharp, don't bother submitting the photo -- unless you (and your editor) *want* some blur, for drama. But hay, don't just believe me. Study some books and magazines filled with photos. Take notes about DOF, count those that are thick or thin. Surprise yourself.

When I have used my 1947 Graflex, it is F16 and be there. The RF is pretty dicey on those things.

RioRico · 07-07-2011, 03:32 PM

Originally posted by GeneV

When I have used my 1947 Graflex, it is F16 and be there. The RF is pretty dicey on those things.

Oops, I should have specified the f/8 rule as being for 35mm PJ's. Is your Graflex 6x12cm or 4x5in? A 4x5 would be more in f/32 country. And THAT is why them old-time fedora-wearing cigar-chomping sweat-smelling fotogs used big honking flashes!

**Aristophanes** · 07-07-2011, 05:05 PM

Originally posted by RioRico

And that's why f/8 and be there was and is the photojournalist's golden rule.

I know photojournalists and none of them use primes, so 2.8 is the fastest they'll get, and very rarely used at that.

What they do look for is separation of the subject from the setting for the isolation factor. There's a lot of f/5.6 I've been told.

**Aristophanes** · 07-08-2011, 09:17 AM

Check this article out, especially the MTF bell curve which demonstrates graphically what is "sharp" (on any lens really)

SMC Pentax-FA 31mm f/1.8 AL Limited Lens Review

GeneV · 07-08-2011, 02:31 PM

Originally posted by RioRico

Oops, I should have specified the f/8 rule as being for 35mm PJ's. Is your Graflex 6x12cm or 4x5in? A 4x5 would be more in f/32 country. And THAT is why them old-time fedora-wearing cigar-chomping sweat-smelling fotogs used big honking flashes!

It's the 2x3, so F/16 does fine.

07-07-2011, 07:23 AM	#36
GeneV Veteran Member Join Date: Oct 2008 Location: Albuquerque NM Photos: Albums Posts: 9,830	Originally posted by selar Sometime ago I posted a poll comparing FA35/2 and FA31/1.8. In that poll I posted a link that contained full sized images of the same subject shot at various apertures with both lenses. That link contains images taken with FA31 at various apertures, you might be able to get an idea of whether your copy performs similarly. Here is the link: https://skydrive.live.com/redir.aspx?cid=611fa57d8d41a33a&page=play&resid=611FA57D8D41A33A!369 I had to spend a couple of hours tweaking AF on the camera before I was satisfied,apparently the FA31 has a habit of exposing AF deficiencies in dSLR bodies. In these images that I posted, yes F4 was sharper but not remarkably so. I remember those shots. As a practical matter, because focus is so critical, F4 ends up in a totally different category for real-world use. I remember on another thread someone discussing how seldom a pro uses any really wide aperture outside of a staged shot. It is just too easy to miss the focus when trying to catch a shot. Last edited by GeneV; 07-07-2011 at 02:19 PM.

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07-06-2011, 07:24 AM	#31
GeneV Veteran Member Join Date: Oct 2008 Location: Albuquerque NM Photos: Albums Posts: 9,830	Definitely try manual focus so you will know exactly where the focus point is. I would agree that the -5 is the best, but whether it is because of the adjustment or not, I would not be able to say. It seems that given the few millimeters involved in these camera adjustments, that -10 would show a bigger difference in focus between the words on the edges such as "Distilled" and those in the middle ("Laphroaig") because one or the other is closer to the true point of focus. I don't have a Laphroaig bottle handy, but on other fifth-sized malt bottles, the position of the edge letters is a couple of millimeters back from the middle.

07-06-2011, 04:18 PM	#32
mr.sinha New Member Join Date: Jul 2011 Posts: 15 Original Poster	Originally posted by GeneV Definitely try manual focus so you will know exactly where the focus point is. I would agree that the -5 is the best, but whether it is because of the adjustment or not, I would not be able to say. It seems that given the few millimeters involved in these camera adjustments, that -10 would show a bigger difference in focus between the words on the edges such as "Distilled" and those in the middle ("Laphroaig") because one or the other is closer to the true point of focus. I don't have a Laphroaig bottle handy, but on other fifth-sized malt bottles, the position of the edge letters is a couple of millimeters back from the middle. I did some more testing at f/1.8 with af adjustment from -1 thru -10, and I do find -4 or -5 to be the best for my lens. But the original purpose of this thread was to understand the diff between f/1.8 and f/4 sharpness at the same focus adjustment level, where I've found the f/4 to be at significantly more sharpness than the f/1.8, which leads back to my original questioning of the supposedly legendary sharpness of the FA31 even at f/1.8. But then as other members have posted and admitted that even their f/1.8 images are not quite as sharp as f/4 images (the Photozone test analysis report reiterating the same), I guess there is nothing wrong with my lens and it falls in the "as designed" category. Thanks everybody for responding.

07-06-2011, 05:45 PM	#33
deadwolfbones Veteran Member Join Date: Sep 2007 Location: La Crescenta, CA Posts: 7,450	Yeah... f/4 is definitely on a different level of sharpness from f/1.8...

07-06-2011, 05:54 PM	#34
GeneV Veteran Member Join Date: Oct 2008 Location: Albuquerque NM Photos: Albums Posts: 9,830	Originally posted by deadwolfbones Yeah... f/4 is definitely on a different level of sharpness from f/1.8... On just about any lens with both apertures.

07-06-2011, 09:29 PM	#35
selar Veteran Member Join Date: Jul 2007 Location: Sydney, Australia Photos: Gallery \| Albums Posts: 2,042	Sometime ago I posted a poll comparing FA35/2 and FA31/1.8. In that poll I posted a link that contained full sized images of the same subject shot at various apertures with both lenses. That link contains images taken with FA31 at various apertures, you might be able to get an idea of whether your copy performs similarly. Here is the link: https://skydrive.live.com/redir.aspx?cid=611fa57d8d41a33a&page=play&resid=611FA57D8D41A33A!369 I had to spend a couple of hours tweaking AF on the camera before I was satisfied,apparently the FA31 has a habit of exposing AF deficiencies in dSLR bodies. In these images that I posted, yes F4 was sharper but not remarkably so.

07-07-2011, 10:09 AM	#37
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Originally posted by GeneV I remember on another thread someone discussing who seldom a pro really uses any really wide aperture outside of a staged shot. It is just too easy to miss the focus when trying to catch a shot. And that's why f/8 and be there was and is the photojournalist's golden rule. (It's the rule that brings in the gold.) Look at published photos. In low-light and fast-action shots (some wildlife and sports), you'll see thin DOF. Almost everything else has nice thick sharp DOF. Wider lenses have thicker DOF wide-open, so my 24/2 and 28/2 and 35/2 lenses are just wizard on FF and still pretty good on HF / APS-C. There's a reason the Nikkor 35/2 was the standard PJ's lens -- and it was still used at f/8 mostly. Stop down. Hit the focus. If the background is too obtrusive, well, BG's can be softened in PP. That's an old tradition. But if your subject isn't sharp, don't bother submitting the photo -- unless you (and your editor) want some blur, for drama. But hay, don't just believe me. Study some books and magazines filled with photos. Take notes about DOF, count those that are thick or thin. Surprise yourself.

07-07-2011, 02:17 PM	#38
GeneV Veteran Member Join Date: Oct 2008 Location: Albuquerque NM Photos: Albums Posts: 9,830	Originally posted by RioRico And that's why f/8 and be there was and is the photojournalist's golden rule. (It's the rule that brings in the gold.) Look at published photos. In low-light and fast-action shots (some wildlife and sports), you'll see thin DOF. Almost everything else has nice thick sharp DOF. Wider lenses have thicker DOF wide-open, so my 24/2 and 28/2 and 35/2 lenses are just wizard on FF and still pretty good on HF / APS-C. There's a reason the Nikkor 35/2 was the standard PJ's lens -- and it was still used at f/8 mostly. Stop down. Hit the focus. If the background is too obtrusive, well, BG's can be softened in PP. That's an old tradition. But if your subject isn't sharp, don't bother submitting the photo -- unless you (and your editor) want some blur, for drama. But hay, don't just believe me. Study some books and magazines filled with photos. Take notes about DOF, count those that are thick or thin. Surprise yourself. When I have used my 1947 Graflex, it is F16 and be there. The RF is pretty dicey on those things.

07-07-2011, 03:32 PM	#39
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Originally posted by GeneV When I have used my 1947 Graflex, it is F16 and be there. The RF is pretty dicey on those things. Oops, I should have specified the f/8 rule as being for 35mm PJ's. Is your Graflex 6x12cm or 4x5in? A 4x5 would be more in f/32 country. And THAT is why them old-time fedora-wearing cigar-chomping sweat-smelling fotogs used big honking flashes!

07-07-2011, 05:05 PM	#40
Aristophanes Site Supporter Join Date: Jul 2008 Location: Rankin Inlet, Nunavut Photos: Albums Posts: 3,948	Originally posted by RioRico And that's why f/8 and be there was and is the photojournalist's golden rule. I know photojournalists and none of them use primes, so 2.8 is the fastest they'll get, and very rarely used at that. What they do look for is separation of the subject from the setting for the isolation factor. There's a lot of f/5.6 I've been told.

07-08-2011, 09:17 AM	#41
Aristophanes Site Supporter Join Date: Jul 2008 Location: Rankin Inlet, Nunavut Photos: Albums Posts: 3,948	Check this article out, especially the MTF bell curve which demonstrates graphically what is "sharp" (on any lens really) SMC Pentax-FA 31mm f/1.8 AL Limited Lens Review

07-08-2011, 02:31 PM	#42
GeneV Veteran Member Join Date: Oct 2008 Location: Albuquerque NM Photos: Albums Posts: 9,830	Originally posted by RioRico Oops, I should have specified the f/8 rule as being for 35mm PJ's. Is your Graflex 6x12cm or 4x5in? A 4x5 would be more in f/32 country. And THAT is why them old-time fedora-wearing cigar-chomping sweat-smelling fotogs used big honking flashes! It's the 2x3, so F/16 does fine.