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Is the A7 better than the A7R at the edges with wides?

tashley

Subscriber Member
I had thought that the difference might be in colour casts and possibly vignetting but this morning I went for a stroll with Jono's A7 and my 35mm F2.8 and took some of my standard shots. I later compared them to some of the same scenes shot with the same lens but on the A7R. When resed to the same size, the A7 files had sharper edges.

Maybe the micro lenses on the A7R 'does' something unhelpful to wides? But it has answered the question as to why Jono thought the 28-70 was great and I thought it was pretty cruddy: my 28-70 (now long gone) was very soft at the edges a lot of the time and nothing you did with stopping down would help much...

Not scientific, though tomorrow I can do some proper side by sides, but in this initial impression the 35 F2.8 looks like a much better lens on the non-R...
 
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johnnygoesdigital

New member
A bit of a contradiction because you mention the A7r is better at the end of the paragraph...

Micro - lenses and wides will usually show color cast because of shallow angles of incidence of light on the sensor, resulting in green or red color casts. Perhaps the EFC of the A7 results in a sharper image? One of the main reasons i'm shooting with the A7 is because it renders color much better when shooting with fast, wide "M" lenses and is capable of sharper photos with the EFC. Doesn't the A7 also have micro - lenses? IMO, 24 mp is the sweet spot for most of today's lens designs.
 
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tashley

Subscriber Member
The aperture doesn't really matter, the files have sharper edges on the A7 at 2.8 thru 8. which is where I have so far shot. The difference is less notable as you stop down but it is there.

Of course the colour cast behaviour is evident with wides. That's why most of my Leica glass has gone, and from what I understand the event of the problem differs between the 7 and the R and a lot of shooters of both have given up with their M wides.

I am merely discussing edge sharpness and I was not aware that there would be a difference, which there does seem to be.
 

Guy Mancuso

Administrator, Instructor
It may be simply resolving power. Given the same lens same apertures the lens may not be able to resolve a full 36 mpx off center
 

iiiNelson

Well-known member
I have both and I would generally agree that this is the general rule regarding the A7 and A7r. I'm sure there are possibly some exceptions to be found adapting glass and there are exception where the wide glass works well on both. I don't know if it's the higher resolving power or what but I do see that most wides work better on the A7 than the A7r but you can't beat the A7r for normal to shorter telephoto (45-180mm.)

Case in point the 24 Elmar has severe CC on the A7r but it's perfectly fine in most real world shots on the A7 using the LR5 lens correction. There's even some differences (though very small) using the Rokinon 14/T3.1 or the Voigtlander 21/1.8. Those are lenses that works well on both after corrections.
 

ZoranC

New member
My non-scientific quick and dirty test with legacy lens showed no advantage to A7. I am afraid that there is no golden rule.
 

philip_pj

New member
Tim, would it not be that the capture is when the result is determined and the downsizing is shutting the gate after the horse bolted? In that you are downloading a compromised file with low contrast and/or mushy corners, incapable of remediation.

My CY Distagon 21mm does very good corners on the a7r, better than on the a99, but like the 21 and 24 SEMs (which sadly have excessive beam angles) it is exceptional.

I believe all lenses must work harder on the a7r, this has been a consistent pattern since day 1. The mighty small one rewards optical excellence but punishes optical weakness. Of course almost all wide angles tend to drop off more and it shows in the MTF data. Same problem with almost all normal lenses - the otherwise great 50 Makro-Planar has just 50% the fine detail performance at the corners as in the image centre.

Photozone found the FE35 to have a significant drop off in midframe and corners, tested on the a7r; and it shows up in the slrgear Blur Index chart as well - tested on the a7r also. You should also see much better image centre resolution from the a7r than the a7.

You can simply get away with more design weakness in the lens with less resolution on the sensor. As sensor resolution goes up the gap between image centre and corners gets wider and much more obvious. D700 owners are well placed!

35mm lenses are simply hard to design for fine corners. People can wait for the next RX1 with the 36Mp non-AA filter inside, it will break the trend as that lens is ready for anything.
 

Godfrey

Well-known member
I suspected this might be the case from the beginning, which is why I bought the A7 for my all-adapted-lenses kit intent. I haven't seen positive proof as yet since I don't have an A7r to compare directly against the A7, but I know that with most of my Leica R and Nikkor lenses I'm getting very good performance across the board, even down to the 18mm.

36 Mpixel sensors are pretty demanding.

I'll be watching to see your test results, Tim.

G
 

tashley

Subscriber Member
Philip, it is well understood that, as you say, when resolution of sensors increases, weaknesses in lenses is revealed. Clearly a full frame sensor with just ten pixels would be undemanding whereas one with 100mp would be very fussy. At some point in between, and it might be at 16mp 24mp or 36mp or 50mp, the lens will reach the limits, at some part of its field of view, of whether it can supply enough resolved information to match the resolution of the sensor.

The corollary of this is that even if that point is reached at, say, 34mp, a file taken on a 36mp sensor and then down-resed to 24mp should be at least as good as a file taken with that lens on a 24mp sensor.

If, as I suspect is the case with the A7 and A7R, a same-aperture file taken with a lens such as the 35mm F2.8 on the A7R, when down-resed to 24mp looks worse at some points in the frame than the A7 file, then there is a specific issue with the higher mp sensor which does not relate purely to the increase in pixel resolution. I suspect it relates to the arrangement of micro lenses.

So I think that you may have misunderstood my point: downresing the A7R file isn't an attempt at bolting the stable door - it is an exercise to determine whether the weakness of the 36mp file is caused by the sensor having out resolved the lens or whether there is some other factor.

If the downresed file looked as good as the A7 file, we would suspect that the problem was that the 36mp sensor had out-resolved the lens at some points in the field of view. But if, as seems the case, the A7R file downresed looks worse, we should suspect other factors such as the micro lenses.

Tim, would it not be that the capture is when the result is determined and the downsizing is shutting the gate after the horse bolted? In that you are downloading a compromised file with low contrast and/or mushy corners, incapable of remediation.

My CY Distagon 21mm does very good corners on the a7r, better than on the a99, but like the 21 and 24 SEMs (which sadly have excessive beam angles) it is exceptional.

I believe all lenses must work harder on the a7r, this has been a consistent pattern since day 1. The mighty small one rewards optical excellence but punishes optical weakness. Of course almost all wide angles tend to drop off more and it shows in the MTF data. Same problem with almost all normal lenses - the otherwise great 50 Makro-Planar has just 50% the fine detail performance at the corners as in the image centre.

Photozone found the FE35 to have a significant drop off in midframe and corners, tested on the a7r; and it shows up in the slrgear Blur Index chart as well - tested on the a7r also. You should also see much better image centre resolution from the a7r than the a7.

You can simply get away with more design weakness in the lens with less resolution on the sensor. As sensor resolution goes up the gap between image centre and corners gets wider and much more obvious. D700 owners are well placed!

35mm lenses are simply hard to design for fine corners. People can wait for the next RX1 with the 36Mp non-AA filter inside, it will break the trend as that lens is ready for anything.
 

tashley

Subscriber Member
My non-scientific quick and dirty test with legacy lens showed no advantage to A7. I am afraid that there is no golden rule.
A lens with weaknesses will quite possibly look weak on both cameras if it is under-resolving both sensors or if it has ray angle issues which afflict both cameras similarly. But what I am getting at is that there seems to be at least one lens, and I suspect quite a few more, which displays problems on the A7R and not on the A7 which are not related to pure lens resolution and which are more likely related to micro lenses and sensor covers.

So as you say, there won't be a golden rule: some lenses will be good on both, some on neither. But I do think it is worth bottoming out which lenses might actually produce more effective resolution on the A7 than on the A7R - and if possible, to understand why!

We all tend to assume as a rough rule of thumb that the more resolution a sensor has, the more it will squeeze out of a lens in some parts of the field of view (usually on or close to centre). But it might well be the case that with some lenses, higher resolution sensor arrays are actively a worse choice even for a print size which both sensor resolutions can easily provide.
 

tashley

Subscriber Member
I suspected this might be the case from the beginning, which is why I bought the A7 for my all-adapted-lenses kit intent. I haven't seen positive proof as yet since I don't have an A7r to compare directly against the A7, but I know that with most of my Leica R and Nikkor lenses I'm getting very good performance across the board, even down to the 18mm.

36 Mpixel sensors are pretty demanding.

I'll be watching to see your test results, Tim.

G
I think you're right but, as in the above two posts, I don't think it is that the pure extra resolution of the A7R that is more demanding: if it were just that, a downresed A7R file would look about as good as an A7 file.
 

johnnygoesdigital

New member
Obviously, all of this is based on subjective interpretation and nothing scientific. With all due respect it's obvious that not all wide lenses will look good on any camera, but that's what defines character in a lenses rendering of a scene. Just because the Sony A7/r's can mount almost any lens ever made, perhaps the glass is half full instead. It's the forest through the trees I think your overlooking here. Besides, you're just going to annoy the ones who purchased the A7r for it's resolution:)
 

tashley

Subscriber Member
Hmm, I am only here referring to the one lens I have tried, the 35mm F2.8 - specifically designed for these two cameras. I think most people would assume (I did) that such a lens would look as good on a downresed A7R frame as it does on an A7 frame.

If as I suspect (and am in the process of testing a little more) the A7 gives better results with at least one of the currently only four lenses in FE mount, then I will personally find it useful to know because I will swap out one of my A7Rs for an A7...

More soon.
 

jonoslack

Active member
I'm with Tim
1. The A7 is better with a number of wide angle lenses than the A7r
2. It's to do with the sensor, and not the lens (although some lenses exacerbate the situation)

As I recall the A7r has angled micro lenses and the A7 doesn't - Angled micro lenses will certainly make colour casts more likely unless corrected for in firmware. . . . which is why M mount lenses are more prone to colour casts on the A7r than on the A7.

Some M lenses (for instance the 28 summicron) have mushy corners on the A7r, and less so on the A7 - this is not to do with the lens design (it's sparkly and sharp on the M240) . . once again, I suspect the Angled Microlenses on the A7r

It's ironic that we expected the A7r with angled micro lenses to be BETTER with wides than the A7 . . . but lots of experience with Leica and their firmware shows that angled micro lenses are, at best, part of the solution, and there has to be lens specific firmware adjustments as well . . . which is why the M240 does NOT have angled micro lenses, and why it's less prone to nasty corners and colour shifts than the M9.
 

jonoslack

Active member
I suspected this might be the case from the beginning, which is why I bought the A7 for my all-adapted-lenses kit intent. I haven't seen positive proof as yet since I don't have an A7r to compare directly against the A7, but I know that with most of my Leica R and Nikkor lenses I'm getting very good performance across the board, even down to the 18mm.

36 Mpixel sensors are pretty demanding.

I'll be watching to see your test results, Tim.

G
HI Godfrey
I've found all the R lenses to be fine on the A7r - the problem is with non-telecentric rangefinder lenses.

I would have thought ALL lenses which were designed for use with an SLR and it's mirror box would be good on both cameras.


. . . . . by which I mean "It's fine - go ahead and buy an A7r" :)
 

tashley

Subscriber Member
I just did some side by side shots but I am loath to publish them because the light is very murky but they do back up my initial observations that at wider apertures the 35 F2.8 does better in terms of pure detail at the edges on the 7 than the R. The same is true for the 24mm end of the 24-70 zoom*. I do certainly suspect that the 28-70 has the same issues and is probably going to please 7 owners and mildly irritate R owners.

I am going to buy a 7. For print sizes up to 30" it will most likely give better results with at least these lenses as an average over the frame even if the & has more detail on centre. I detest fluffy edges, unless I have purposefully arranged for them to happen. They make certain types of landscape work look badly done.

The A7 gives more of an 'RX-1' style look with these lenses and makes the 24mm end of the 24-70 look pretty good. But the A7R leaves you reaching for the crop tool...

* method: tripod, two plates, one on each camera, same everything on both bodies, RAW files given my normal sharpening (same of both but could be tweaked) and then exported to Photoshop for downresing to 4000 pixels (so they have BOTH been re-sized) and then compare in LR.
 

Godfrey

Well-known member
I think you're right but, as in the above two posts, I don't think it is that the pure extra resolution of the A7R that is more demanding: if it were just that, a downresed A7R file would look about as good as an A7 file.
I didn't mean to imply that it was only the increased resolution that increased the issues, Tim. But as we've seen with the Nikon D800 and D800E ... same sensor with and without AA filter ... they're both quite demanding on the lenses to produce their best results. I just had a gut feeling that the A7's sensor would be more compatible with the lenses I want to use.

I am intrigued to see what the A7r does with the same lenses because at some point I'll want to acquire a second body. I have to decide whether it's worth buying an A7r or just getting another A7. Certainly the EFCS in the A7 is worthwhile having for the majority of situations I encounter, and the 24Mpixel resolution is more than enough to make superb prints at the sizes I print. :)

G
 

Godfrey

Well-known member
HI Godfrey
I've found all the R lenses to be fine on the A7r - the problem is with non-telecentric rangefinder lenses.

I would have thought ALL lenses which were designed for use with an SLR and it's mirror box would be good on both cameras.

. . . . . by which I mean "It's fine - go ahead and buy an A7r" :)
Well, hmm, I was noticing that the Summicron-R 35mm does show a small bit of smearing at f/2 and f/2.8, cleans up nicely by f/4 or so. Others of my R lenses show some at distance settings, not at my usual test target distance.

Normally, I'm not all that fussy about it ... important subject matter is rarely at the extreme corners of the frame, and it only becomes an issue when stitching frames were detail is important right to the edges (at which point, why use a wide anyway? use something that is easier to deal with ... ;-).

No rush. I'm enjoying what I've got well enough. Just made the first few prints from the A7 exposure the other day and I have to say they look terrific. Not more terrific than similar quality exposures from the M9 or E-M1, but terrific all the same. ]'-)

G
 

johnnygoesdigital

New member
Maybe the micro lenses on the A7R 'does' something unhelpful to wides? -tashley

That seems to imply more than just the 35mm f/2.8.

Micro - lenses in the A7r are probably more to offset the short back flange distance because of the shallow angles of incidence. Lens design is also prone to many variables, so what one lens does on a particular camera may not in fact, do the same on another. Although some of your inputs are thought provoking, I'd be careful not to do "something unhelpful" to A7r just because of a casual observation from one shoot.
 
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