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Posted 06/07/2011 - 20:43
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japers45 wrote:
I can see a difference but it is far less obvious.
Can this be right? My humble kit lense can nearly match a ltd lens for sharpness across the frame?
Admittedly the zoom is used more at the extremes of the focal length more often than in the middle but I have to say I am pretty staggered.
Presumably the prime will perform much better than the zoom wide open (and it is considerably faster to boot.
I await a stern defence of the ltd- so many on here own these lenses and I hanker after one myself.
I have to be careful here, as I am not a lens expert..... I can see a difference but it is far less obvious.
Can this be right? My humble kit lense can nearly match a ltd lens for sharpness across the frame?
Admittedly the zoom is used more at the extremes of the focal length more often than in the middle but I have to say I am pretty staggered.
Presumably the prime will perform much better than the zoom wide open (and it is considerably faster to boot.
I await a stern defence of the ltd- so many on here own these lenses and I hanker after one myself.
But IMO you do not buy a FA LTD to use it at f8. There is a lot of talk about their "3D rendering" which has a lot to do with their bokeh, and it is truly something special (at least for the FA 31 and 77, I have never tried the 43mm).
Posted 06/07/2011 - 21:09
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johnwhit wrote:
Both the MkI & MkII kit lenses are decent lenses, however I believe Pentax were right in updating the optical formula as the sensor resolution increased. I still have the 18-55 and used it a couple of years ago on a holiday in Scotland with good results, it was the only lens I took. Optically Nikon make a good kit lens, but the build quality resembles something that fell out of a kids "Lucky-bag" when compared to the Pentax.
John
Exactly my feeling. Got the K-5 today with the kit lens with the intention of selling the kit lens as I have done before cause though the Nikon kits performed reasonably well they just felt far to cheap, heck I was not all that happy with the built quality of the 12-24 Nikkor I used for a few weeks and that was a £600 lens.Both the MkI & MkII kit lenses are decent lenses, however I believe Pentax were right in updating the optical formula as the sensor resolution increased. I still have the 18-55 and used it a couple of years ago on a holiday in Scotland with good results, it was the only lens I took. Optically Nikon make a good kit lens, but the build quality resembles something that fell out of a kids "Lucky-bag" when compared to the Pentax.
John
However the Pentax kit lens feels much nicer, very pleasing materials and smooth operation. Not selling it any more I don't think especially given the going prices. I will just keep it to have a zoom for the gap 16-50 in case I find the primes a bit restrictive.
Posted 06/07/2011 - 23:12
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ChrisA wrote:
I thought the whole point of a rectilinear lens was that the focus distance refers to the perpendicular distance from the film plane, to a plane (containing the subject), which is parallel to the film plane.
In other words, the focus distance of something at the edge of the field is the same as the focus distance at the centre of the field.
I've tried to illustrate it with this diagram:
[IMG]http://i162.photobucket.com/albums/t244/chris5gd/Technical/FocusDistance.jpg[/IMG]
The fact that the slant distance, ie the distance from the camera to the object at the edge of the frame, is greater than the focus distance, is completely irrelevant - or should be if the optics are perfect.
So if an object is within the DOF at the centre, it should be within it at the edge - and if I understand it right, edge softness is when the optical quality means that reality doesn't match the theory.
You've misunderstood me Chris. We haven't seen the picture, so I was asking are the subjects at the edge of the image closer than the main subject and therefore possibly outside the DOF. If so, then perhaps the discussion moves on to the subject of hyperfocal distance.
johnriley wrote:
The distance to the subjects at the edge of the frame might be a factor. If they fall outside the depth of field then sharpness would suffer.
Coming in a bit late on this one, but just to pick up John's point...The distance to the subjects at the edge of the frame might be a factor. If they fall outside the depth of field then sharpness would suffer.
I thought the whole point of a rectilinear lens was that the focus distance refers to the perpendicular distance from the film plane, to a plane (containing the subject), which is parallel to the film plane.
In other words, the focus distance of something at the edge of the field is the same as the focus distance at the centre of the field.
I've tried to illustrate it with this diagram:
[IMG]http://i162.photobucket.com/albums/t244/chris5gd/Technical/FocusDistance.jpg[/IMG]
The fact that the slant distance, ie the distance from the camera to the object at the edge of the frame, is greater than the focus distance, is completely irrelevant - or should be if the optics are perfect.
So if an object is within the DOF at the centre, it should be within it at the edge - and if I understand it right, edge softness is when the optical quality means that reality doesn't match the theory.
Best regards, John
Posted 06/07/2011 - 23:43
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johnriley wrote:
You've misunderstood me Chris. We haven't seen the picture, so I was asking are the subjects at the edge of the image closer than the main subject and therefore possibly outside the DOF. If so, then perhaps the discussion moves on to the subject of hyperfocal distance.
Oh I see. Yes, Ok. In the sense that anything the camera hasn't actually focused on could be at any distance at all, and hence either within the DOF range or not.You've misunderstood me Chris. We haven't seen the picture, so I was asking are the subjects at the edge of the image closer than the main subject and therefore possibly outside the DOF. If so, then perhaps the discussion moves on to the subject of hyperfocal distance.
Brick wall or newspaper test, then, as you said.
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Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
.
Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
.
Posted 07/07/2011 - 00:05
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giofi wrote:
But IMO you do not buy a FA LTD to use it at f8. There is a lot of talk about their "3D rendering" which has a lot to do with their bokeh, and it is truly something special (at least for the FA 31 and 77, I have never tried the 43mm).
^^^ What giofi says.japers45 wrote:
I can see a difference but it is far less obvious.
Can this be right? My humble kit lense can nearly match a ltd lens for sharpness across the frame?
Admittedly the zoom is used more at the extremes of the focal length more often than in the middle but I have to say I am pretty staggered.
Presumably the prime will perform much better than the zoom wide open (and it is considerably faster to boot.
I await a stern defence of the ltd- so many on here own these lenses and I hanker after one myself.
I have to be careful here, as I am not a lens expert..... I can see a difference but it is far less obvious.
Can this be right? My humble kit lense can nearly match a ltd lens for sharpness across the frame?
Admittedly the zoom is used more at the extremes of the focal length more often than in the middle but I have to say I am pretty staggered.
Presumably the prime will perform much better than the zoom wide open (and it is considerably faster to boot.
I await a stern defence of the ltd- so many on here own these lenses and I hanker after one myself.
But IMO you do not buy a FA LTD to use it at f8. There is a lot of talk about their "3D rendering" which has a lot to do with their bokeh, and it is truly something special (at least for the FA 31 and 77, I have never tried the 43mm).
You can't make a full comparison between lenses based upon just two 100% edge crops
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283
Posted 07/07/2011 - 09:24
Link
I was just demonstrating that the myth that the Kit Lens
is soft at the edges is absolute nonsense and that it is
actually better than a lot of the older primes 24mm, 28mm
and 35mm. I can see no point in keeping these when the
kit lens is better right across the frame.
The 43mm was included just out of curiosity being probably
the best lens I've got apart from the A series 50mm's. I
also wanted to see if the Kit lens just had a sweet spot
at 24mm - 35mm. I now know it's OK at 43mm as well. I'll
have a look at how well it does at 50mm next
I know it preforms well in the centre and all MTF tests
on the web support that. I've also checked that on the
shots I've cropped the corners off and no problems there
is soft at the edges is absolute nonsense and that it is
actually better than a lot of the older primes 24mm, 28mm
and 35mm. I can see no point in keeping these when the
kit lens is better right across the frame.
The 43mm was included just out of curiosity being probably
the best lens I've got apart from the A series 50mm's. I
also wanted to see if the Kit lens just had a sweet spot
at 24mm - 35mm. I now know it's OK at 43mm as well. I'll
have a look at how well it does at 50mm next
I know it preforms well in the centre and all MTF tests
on the web support that. I've also checked that on the
shots I've cropped the corners off and no problems there
Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
Pentax K-1 + K-5 and some other stuff
Algi
Posted 07/07/2011 - 10:10
Link
Algernon wrote:
Test done in very dull weather... rained 2 mins later.
The 43mm at f/8 is on the Left
The 18-55mm Mk2 Kit Lens is on the Right
Both 43mm focal length f/8 at 1/100th 200ISO K-5
The 43mm is just slightly better as would be expected, but
no sign of any soft corners on the Kit Lens. Now from
all tests 24mm to 43mm
-
Slightly better, by this you mean, higher definition, higher contrast, less CA and better colour rendering:Test done in very dull weather... rained 2 mins later.
The 43mm at f/8 is on the Left
The 18-55mm Mk2 Kit Lens is on the Right
Both 43mm focal length f/8 at 1/100th 200ISO K-5
The 43mm is just slightly better as would be expected, but
no sign of any soft corners on the Kit Lens. Now from
all tests 24mm to 43mm
-
I think a better test for how the lens performs on landscapes would be to try the edges at 18mm, after all this is roughly equivalent to 27mm FoV on a film camera, not far removed from the classic 28mm.
John
Posted 07/07/2011 - 10:46
Link
Kit Lens 18-55mm Mk2 at 50mm -v- Pentax_A 50mm f/1.7
Both at f/8
Pentax K-5 200ISO
Poor light drizzle on/off
I was that surprised by the results of this test that I did
it again and got the same results.
Both shots are the best of 4. The Kit Lens blows away the
Pentax_A 50mm f/1.7 ..... and it's the same right across
the frame.
I have had this Pentax_A 50mm f/1.7 from new and have compared it
with about 10 other 50mm lenses over the years and it is the best
50mm I have ever had. In the film days I tested the resolution and
it was off the scale over 140 lpmm on Pan F.
TOP RIGHT HAND CORNER OF FRAMES ONLY
LEFT: Pentax_A 50mm f/1.7 ---------------- RIGHT: Kit Lens 18-55mm Mk2
-
Both at f/8
Pentax K-5 200ISO
Poor light drizzle on/off
I was that surprised by the results of this test that I did
it again and got the same results.
Both shots are the best of 4. The Kit Lens blows away the
Pentax_A 50mm f/1.7 ..... and it's the same right across
the frame.
I have had this Pentax_A 50mm f/1.7 from new and have compared it
with about 10 other 50mm lenses over the years and it is the best
50mm I have ever had. In the film days I tested the resolution and
it was off the scale over 140 lpmm on Pan F.
TOP RIGHT HAND CORNER OF FRAMES ONLY
LEFT: Pentax_A 50mm f/1.7 ---------------- RIGHT: Kit Lens 18-55mm Mk2
-
Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
Pentax K-1 + K-5 and some other stuff
Algi
Posted 07/07/2011 - 10:54
Link
Pentaxophile wrote:
Wow! I'll be doig my own tests now.. the gauntlet has been thrown down!
But... How does the kit lens fare at f1.7?
If you want a good lens at f/1.7 ......... get a Yashica ..... unbeatable!
Wow! I'll be doig my own tests now.. the gauntlet has been thrown down!
But... How does the kit lens fare at f1.7?
Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
Pentax K-1 + K-5 and some other stuff
Algi
Posted 07/07/2011 - 10:58
Link
johnwhit wrote:
Slightly better, by this you mean, higher definition, higher contrast, less CA and better colour rendering:
WYSIWYG
I think a better test for how the lens performs on landscapes would be to try the edges at 18mm, after all this is roughly equivalent to 27mm FoV on a film camera, not far removed from the classic 28mm.
John
I've only got a Sigma 10-20mm that goes to 18mm and to be honest the Kit lens would eat it for breakfast
Slightly better, by this you mean, higher definition, higher contrast, less CA and better colour rendering:
WYSIWYG
I think a better test for how the lens performs on landscapes would be to try the edges at 18mm, after all this is roughly equivalent to 27mm FoV on a film camera, not far removed from the classic 28mm.
John
Posted 07/07/2011 - 11:13
Link
johnwhit wrote:
John
I've already sold the Pentax 12-24mm because the SigmaAlgernon wrote:
I've only got a Sigma 10-20mm that goes to 18mm and to be honest the Kit lens would eat it for breakfast
Well I'd sell itI've only got a Sigma 10-20mm that goes to 18mm and to be honest the Kit lens would eat it for breakfast
John
was identical in performance
Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
Pentax K-1 + K-5 and some other stuff
Algi
Posted 07/07/2011 - 11:16
Link
We could go on forever but Algi is showing that lenses designed for digital do have advantages.
I'm interested in the rendition of the aerial's reflector, which loses its integrity in the kit lens picture. I'm wondering how both images will respond to different sharpening techniques and whether there's more to the rendition here that meets the eye. In common with slower/faster films, they actually show the same amount of detail but the kit lens has higher contrast.
If you look at the roof tiles carefully, the nearest one on the left is reproduced better by the 50mm lens.
I'm interested in the rendition of the aerial's reflector, which loses its integrity in the kit lens picture. I'm wondering how both images will respond to different sharpening techniques and whether there's more to the rendition here that meets the eye. In common with slower/faster films, they actually show the same amount of detail but the kit lens has higher contrast.
If you look at the roof tiles carefully, the nearest one on the left is reproduced better by the 50mm lens.
Best regards, John
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18 years
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