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A7r IV and sharpness

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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Topic: A7r IV and sharpness
    Posted: 09 January 2020 at 06:20
Originally posted by Jonas A-R Jonas A-R wrote:

... I did a similar test with 1.54 micron pixels (courtesy of the Pentax Q) posted here: The joy of 1.54 micron pixels
It would be interesting to do a similar test vs the a7rvi.

Yes, I remember that thread. You'll see my comments in it. At the time, I was having trouble seeing a difference between 12MP and 24MP using the same lens. That discussion clued me to the idea that I wasn't shooting images with sufficient detail to easily observe the difference.
 



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Post Options Post Options   Quote Jonas A-R Quote  Post ReplyReply Direct Link To This Post Posted: 09 January 2020 at 05:42
Originally posted by sybersitizen sybersitizen wrote:

Originally posted by QuietOC QuietOC wrote:

The lack of an AA filter on the V3 is an obvious difference. The Sony 16 MP APS-C cameras seem to use a fairly strong AA filter.

AA filters are another factor, but the principle of higher pixel density is sound regardless of that, as you must well know.

One of the benefits of small pixels is the relaxed requirement for anti-aliasing filters. Eventually we will have sensors totally free of aliasing (maybe at something like 700MP on FF sensors)
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Post Options Post Options   Quote Jonas A-R Quote  Post ReplyReply Direct Link To This Post Posted: 09 January 2020 at 05:39
Originally posted by sybersitizen sybersitizen wrote:

I'll post an example to illustrate my comment above.

I just shot a direct comparison using my A55 (16MP APS-C) and Nikon V3 (18MP 1") cameras. Note that the V3's pixel density, with a crop factor of 2.7x, is roughly equal to the pixel density of a 130MP full frame camera. I used a Rokinon 500mm f/6.3 mirror lens, which is decent but not known for great sharpness. Subject distance was kept constant.

The A55 saw this composition:



The V3 saw this composition:



I loaded the RAW images (no PP at all) into Photoshop and displayed them at equal sizes to check flower detail. I'm showing two shots with each camera just to make it clear that the differences in results are consistent and not due to focusing errors or camera shake.

The displayed results:



Full size here:

http://thesybersite.com/public/Resolution-Screen-Grab.jpg

It should be obvious that the much higher pixel density captures much more detail, even when using a modest lens. The principle will be the same regarding the A7RIV compared to previous models: better detail capturing capability with just about any lens, not just the best ones.


Iím on my phone and cannot judge your images, but I did a similar test with 1.54 micron pixels (courtesy of the Pentax Q) posted here: The joy of 1.54 micron pixels
It would be interesting to do a similar test vs the a7rvi.
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 09 January 2020 at 04:27
Originally posted by QuietOC QuietOC wrote:

The lack of an AA filter on the V3 is an obvious difference. The Sony 16 MP APS-C cameras seem to use a fairly strong AA filter.

AA filters are another factor, but the principle of higher pixel density is sound regardless of that, as you must well know.
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Post Options Post Options   Quote QuietOC Quote  Post ReplyReply Direct Link To This Post Posted: 09 January 2020 at 03:44
Originally posted by sybersitizen sybersitizen wrote:

I'll post an example to illustrate my comment above.

I just shot a direct comparison using my A55 (16MP APS-C) and Nikon V3 (18MP 1") cameras.
...
It should be obvious that the much higher pixel density captures much more detail, even when using a modest lens. The principle will be the same regarding the A7RIV compared to previous models: better detail capturing capability with just about any lens, not just the best ones.

The lack of an AA filter on the V3 is an obvious difference. The Sony 16 MP APS-C cameras seem to use a fairly strong AA filter.

Edited by QuietOC - 09 January 2020 at 03:53
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Post Options Post Options   Quote woodrim Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2020 at 23:40
I have uploaded two more pictures to my Flickr where you can see the following test images in full size.

This is the uncropped test image from the A7rIV and my Steinheil Quinon 55mm at f/1.9. Following it is an extreme crop from the same image. At full aperture, I think this is pretty impressive and in my mind, defeats the arguments about classic glass not resolving to the level of this sensor. The Mirror lens shot I posted about earlier is another that I thought stood up well and maybe even looks better on this sensor.



Crop
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woodrim
 



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Post Options Post Options   Quote woodrim Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2020 at 23:24
Originally posted by sybersitizen sybersitizen wrote:

Originally posted by Jonas A-R Jonas A-R wrote:

My point is that image sharpness is a convolution of sensor sharpness and lens sharpness. A sharper sensor will make ALL of your lenses sharper. It does not require a sharp lens to gain from smaller pixels. 61MP is a gross undersampling of even the cheapest lens.

Another point is that better sensor resolution will never give worse sharpness.

As we probably all realize, moving to a significantly higher pixel density tempts people to think of 'enlarging' (or cropping) their images more, rather than thinking of improving sharpness at the same viewing size they would use at a lower pixel density. It's just the 'enlarging' that is liable to result in 'worse sharpness'.


I agree, especially about cropping, which is the first thing I thought about when learning about the new sensor. There are many times my lenses don't give the reach I would like. I think it's a reasonable expectation.

Pixel density is definitely important to details and this 61pm sensor definitely has greater density than other Sony FF sensors up to this point. I have observed images from smaller sensors with greater density that impressed me as sharper than my current 24mp FF. There are trade-offs but eventually, we'll reach a point?
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2020 at 18:32
I'll post an example to illustrate my comment above.

I just shot a direct comparison using my A55 (16MP APS-C) and Nikon V3 (18MP 1") cameras. Note that the V3's pixel density, with a crop factor of 2.7x, is roughly equal to the pixel density of a 130MP full frame camera. I used a Rokinon 500mm f/6.3 mirror lens, which is decent but not known for great sharpness. Subject distance was kept constant.

The A55 saw this composition:



The V3 saw this composition:



I loaded the RAW images (no PP at all) into Photoshop and displayed them at equal sizes to check flower detail. I'm showing two shots with each camera just to make it clear that the differences in results are consistent and not due to focusing errors or camera shake.

The displayed results:



Full size here:

http://thesybersite.com/public/Resolution-Screen-Grab.jpg

It should be obvious that the much higher pixel density captures much more detail, even when using a modest lens. The principle will be the same regarding the A7RIV compared to previous models: better detail capturing capability with just about any lens, not just the best ones.
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2020 at 16:35
Originally posted by Jonas A-R Jonas A-R wrote:

My point is that image sharpness is a convolution of sensor sharpness and lens sharpness. A sharper sensor will make ALL of your lenses sharper. It does not require a sharp lens to gain from smaller pixels. 61MP is a gross undersampling of even the cheapest lens.

Another point is that better sensor resolution will never give worse sharpness.

As we probably all realize, moving to a significantly higher pixel density tempts people to think of 'enlarging' (or cropping) their images more, rather than thinking of improving sharpness at the same viewing size they would use at a lower pixel density. It's just the 'enlarging' that is liable to result in 'worse sharpness'.
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Post Options Post Options   Quote Jonas A-R Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2020 at 16:18
Originally posted by Miranda F Miranda F wrote:

Originally posted by Jonas A-R Jonas A-R wrote:


Originally posted by Miranda F Miranda F wrote:

Shutter speed needs to be 4x faster than in film days (unless you were doing large prints then ...)


Not according to Jim Kasson's test. You can use 1/focal length if you have stabilization. Otherwise you probably need 1/5x focal length as recommended by Ansel Adams
Jim kasson's test


Originally posted by Miranda F Miranda F wrote:

Remember we're talking about pixel-peeping 60MP sensors here. The 1/FL was for acceptable blur on a normal print. It clearly doesn't work for the other. But I wouldn't argue about either the 1/5FL or 1/FL for stabilised.

I suggest you reread his test. With IBIS on (which is a perfectly reasonable shooting scenario), 1/100sec works just as well as 1/500sec at 135mm focal length. The curve is flat, so further improvement should not be expected beyond 1/500. It is busting your statement about required shutterspeeds.

As I said, Ansel Adams suggested 1/5x focal lenghth for 35mm film formats. It is confirmed by Kasson's test where the sharpness is nearly as good without IBIS at 1/500 at 135mm.


Originally posted by Miranda F Miranda F wrote:

Originally posted by Jonas A-R Jonas A-R wrote:


Originally posted by Miranda F Miranda F wrote:

Personally, I feel that 60Mp is a pointless endeavour unless you are selling large-format commercial prints or something equally demanding - and in that case, you need to revise your whole methodology (and probably most of your old equipment, including tripods).


This statement is equivalent to stating that sharp lenses are a pointless endeavour.


No, I don't believe so. My point was that sharp lenses are not enough - you will (often) need a lot more care with aperture and shutter speed and camera shake if you're going to benefit from the difference between 24Mp and 61mp. Unless you're prepared to take that care, you won;t see the benefit. All it does is make your pixel-peeping a miserable experience instead of a pleasing one.

My point is that image sharpness is a convolution of sensor sharpness and lens sharpness. A sharper sensor will make ALL of your lenses sharper. It does not require a sharp lens to gain from smaller pixels. 61MP is a gross undersampling of even the cheapest lens.
Another point is that better sensor resolution will never give worse sharpness.   
However, you are correct that good technique is required to get best possible results whether you wish to gain the max of your precious lenses or your system as a whole. And of course you can nullify the benefit of your sensor with bad technique.

Originally posted by Miranda F Miranda F wrote:

Originally posted by Jonas A-R Jonas A-R wrote:

Originally posted by Miranda F Miranda F wrote:

I think tempting casual photographers into buying 60Mp+ cameras is indescribably foolish and will produce endless heartache.

Only if you have unreasonable expectations

What are reasonable expectations? I think people who buy a 60Mp camera are likely to expect the resolution of their images to be proportionately better than the 24Mp alternative. Maybe we're both agreeing that they will be disappointed unless they take a lot more care with their images.
Personally, I think that pixel peeping leads to a lot of unhappiness, except on those pleasant occasions when you get everything right and you can zoom into your wide-angle cityscape images and read every 'no parking' notice perfectly legibly.


I never recommend pixel peeping. Compare images and you will see that a7RIV will comfortably provide sharper images than 24MP systems even at relatively small image sizes.

Edited by Jonas A-R - 09 January 2020 at 08:14
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2020 at 13:16
Originally posted by Jonas A-R Jonas A-R wrote:


Originally posted by Miranda F Miranda F wrote:

Shutter speed needs to be 4x faster than in film days (unless you were doing large prints then ...)


Not according to Jim Kasson's test. You can use 1/focal length if you have stabilization. Otherwise you probably need 1/5x focal length as recommended by Ansel Adams
Jim kasson's test



Remember we're talking about pixel-peeping 60MP sensors here. The 1/FL was for acceptable blur on a normal print. It clearly doesn't work for the other. But I wouldn't argue about either the 1/5FL or 1/FL for stabilised.


Originally posted by Jonas A-R Jonas A-R wrote:


Originally posted by Miranda F Miranda F wrote:

Personally, I feel that 60Mp is a pointless endeavour unless you are selling large-format commercial prints or something equally demanding - and in that case, you need to revise your whole methodology (and probably most of your old equipment, including tripods).


This statement is equivalent to stating that sharp lenses are a pointless endeavour.


No, I don't believe so. My point was that sharp lenses are not enough - you will (often) need a lot more care with aperture and shutter speed and camera shake if you're going to benefit from the difference between 24Mp and 61mp. Unless you're prepared to take that care, you won;t see the benefit. All it does is make your pixel-peeping a miserable experience instead of a pleasing one.

Originally posted by Jonas A-R Jonas A-R wrote:




Originally posted by Miranda F Miranda F wrote:

I think tempting casual photographers into buying 60Mp+ cameras is indescribably foolish and will produce endless heartache.

Only if you have unreasonable expectations

What are reasonable expectations? I think people who buy a 60Mp camera are likely to expect the resolution of their images to be proportionately better than the 24Mp alternative. Maybe we're both agreeing that they will be disappointed unless they take a lot more care with their images.
Personally, I think that pixel peeping leads to a lot of unhappiness, except on those pleasant occasions when you get everything right and you can zoom into your wide-angle cityscape images and read every 'no parking' notice perfectly legibly.
Miranda F & Sensorex, Sony A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras . . .
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Post Options Post Options   Quote Jonas A-R Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2020 at 08:55
Originally posted by Miranda F Miranda F wrote:

Originally posted by terryg terryg wrote:

Hi everyone,

I haven't had time to be here recently - just wanted to add that for critical focus with MF lenses on high MP cameras such as a7R3 and a7R4 you really need to be using one of the camera's Focus Magnifier options.

Focus Peaking gives way too many false positives on focus.

Agree 100% And also, pixel-peeping at 60Mp puts such a premium on sharpness and movement blur that you can throw out of the window your previous ideas abut shutter speed and DOF.

Essentially, DOF is zero on a portrait lens and even on an ultra-wide it is less than you think when you zoom in to find your 60Mp.

Well, if you understand that DoF calculations depend on the magnification and viewing distance and adjust the CoC accordingly, there would be no surprise

Originally posted by Miranda F Miranda F wrote:

Shutter speed needs to be 4x faster than in film days (unless you were doing large prints then ...)


Not according to Jim Kasson's test. You can use 1/focal length if you have stabilization. Otherwise you probably need 1/5x focal length as recommended by Ansel Adams
Jim kasson's test


Originally posted by Miranda F Miranda F wrote:

Personally, I feel that 60Mp is a pointless endeavour unless you are selling large-format commercial prints or something equally demanding - and in that case, you need to revise your whole methodology (and probably most of your old equipment, including tripods).


This statement is equivalent to stating that sharp lenses are a pointless endeavour.

Originally posted by Miranda F Miranda F wrote:

I think tempting casual photographers into buying 60Mp+ cameras is indescribably foolish and will produce endless heartache.

Only if you have unreasonable expectations
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2020 at 07:26
We never doubted that you knew how to manually focus lenses - we just gave you some pointers since you asked what could have the reason your neighbour (not you!) got less then stellar results.

Reading your post and seeing the picture, it seems the camera is just fine. Am I right? What did your neighbour do wrong?
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Post Options Post Options   Quote woodrim Quote  Post ReplyReply Direct Link To This Post Posted: 07 January 2020 at 23:55
I didn't have much time with the camera today since the sun was setting quickly.

I do want to make clear that I understand very well how to manually focus lenses. I've been doing it for 48 years and since 2009 with digital cameras. That said, I did notice today that the A7rIV sensor/resolution seems to make precise focusing more difficult from that I have experienced in the past and today with my 24mp FF sensor. However, I also found that the second level of magnification is in my opinion, more helpful that with my current camera. Still, it seems difficult to see that perfect point pop into focus. I may need to check that point again when given another opportunity since the viewfinder diopter was not adjusted for my eye.

I tested with four lenses, selecting two that I consider very sharp and two others; Primotar 3.5/135 which is not a razor but acceptably sharp. The other is my Rubinar 5.6/500 mirror lens. Mirrors are never as sharp as a very good refractor of the same specs.

I'll be adding a couple more pictures to a test album but for now, I have one up here

I found this mirror image to provide quite good sharpness, especially given the claims that the sensor challenges lenses.
Regards,

woodrim
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