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Need help camera body selection for my MF lenses
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PostPosted: Sat Dec 09, 2017 3:48 pm    Post subject: Reply with quote

buerokratiehasser wrote:

Sorry to be a spoilsport and spamming that Ken link; however i am being motivated by preventing pain and suffering for original poster


Not at ALL!! Fortunately saw your post in time. Thanks

I believe any MF lens user has to consider this extremely carefully when deciding to go FF. I certainly am.

Act in haste, repent at leisure?

Not if I can help it. This merits serious research.


PostPosted: Sat Dec 09, 2017 4:35 pm    Post subject: Reply with quote

One of the main reasons why I bought my NEX 7 was so I could use all my vintage legacy glass with it. If Sony has built in an optimization for the a9's sensor specific to their lenses, then this detracts from any reason why I might want to buy one. I will much prefer the a7r II or III over the a9 because of this. When I finally upgrade to FF, I will be looking forward to using all my wides, super wides and ultra wides on that camera and I will expect superior results. If that cannot be expected with the a9, then it is permanently off my list.

Not that I could afford it any time soon anyway. Cool


PostPosted: Sat Dec 09, 2017 5:01 pm    Post subject: Reply with quote

cooltouch wrote:
My APS-C NEX 7 has trouble handling ultra wide lenses. Corners are soft and even the centers aren't that great. The received wisdom seems to be the problem has to do with the way the light rays are bent by these UW lenses, and that the sensor's receptors are not designed to capture detail efficiently from those angles of incidence. Or something like that.


Using analog (film) cameras, the light from the lens meets the film surface directly. When using digital cameras, the light must pass a "filter pack" (sensor protection glass, IR filter, often also a anti-aliasing filter). Sony uses a 2.5 mm thick glass with a refractory index (nD) of 1.517 and a disperion of 64.2, directly in front of the sensor. If incoming light rays are 90° to the sensor / glass surface, there's only limited influence (mainly a focus-shift). If the rays are coming in at flatter angles (especially when using non-retrococus wideangles and fast 50mm primes!), the influence of this 2.5mm thick glass may become quite visible towards the corner.

Other manufacturers use thinner filter packs (e. g. Canon for their professional DSLRs, about 1.5mm, or Leica, about 1mm). The thinnest i'm aware of is a Kolari modified A7 camera with just 0.1mm sensor protection. Obvioulsy, there's no IR filter any more, and the color balance of such a modified A7-/A9-series camera is quite different from a camera with IR filter. I have been shooting with such a modified A7. Using the Zeiss ZM Biogon 4.5/21mm (which is quite useless evet at f11 on a normal A7) gave impressive corner detail even wide open, much better than e. g. the Nikkor AiS 2.8/20mm.

cooltouch wrote:

So, after reading through KR's rather rambling diatribe on the subject, it occurred to me that, if what KR is alleging is true, that is, that the A9's sensor's receptors are designed for a certain optimum range of field curvatures,

No.

It's the issue mentioned above.

Stephan


PostPosted: Sat Dec 09, 2017 8:07 pm    Post subject: Reply with quote

buerokratiehasser wrote:
Here with the "curved" sensor

kenrockwell.com/sony/a9.htm#leica

Executive summary: MF lenses acquire curvature of field they didnt have before when shot on A9. Ken demonstrating by using Leica lens


Is it true? I dont know. Ken is an Apple user but certainly he can figure out how not to mess up such a simple test.

Perhaps it's the angle from retrofocus design nodal points bla blah blah combined with a sensor that is picky about what angle the light is coming from. If so it should perhaps not be as bad with normal lenses.

Dont know if A7 has same problem if any.


Sorry to be a spoilsport and spamming that Ken link; however i am being motivated by preventing pain and suffering for original poster


I assume you are referring to this part:
Quote:
adapted wide-angle lenses usually aren't very sharp on the sides at large apertures because Sony's full-frame mirrorless sensors are optimized for lenses with a curved fields. Most other adapted lenses won't seem very sharp on the sides at large apertures due their flat fields not interfacing well with the curved fields needed by Sony's sensors on these cameras.

From my understanding, the sensor isn't designed for lenses with field curvature, the issue comes from the relatively thick cover glass, which adds field curvature to lenses with exit pupils close to the sensor(which causes low angle ray paths) Sony has designed their lenses with the cover glass in mind, as far as I know most non-native lenses have not done this, long lenses with their nearly perpendicular ray paths are largely unaffected..
I base this on the Kolari thread and the PCX filter thread on FM Alt forum.
Kolari:
http://www.fredmiranda.com/forum/topic/1340474/0
http://www.fredmiranda.com/forum/topic/1392833
http://www.fredmiranda.com/forum/topic/1465200/0

PCX filters
http://www.fredmiranda.com/forum/topic/1453834/0

The NEX-7 and A7r are the 2 most picky sensors in Sony's lineup, I would not use them as characterizations on how the rest of their sensors perform with regard to colour shift, A7r has the same smear as all the A7 & A9, the NEX-7 doesn't show the smearing because the FOV is much smaller, m4/3 has a thicker cover glass and you don't hear about smearing corners, well, at least I haven't heard of it.
My CV15III and OM 21/3.5 works great on my NEX-7.


PostPosted: Sat Dec 09, 2017 11:24 pm    Post subject: Reply with quote

So, if my understanding is correct, problem is limited to rangefinders lenses (such as Leica M) and does not apply to say Minolta SR (MC/MD) lenses as the distance of the back lens to the sensor is much longer.

I have never had A7rii/A7ii nor A7riii but I now understand the latter is much better for manual focusing. but very high premium to pay.

No easy solution...


PostPosted: Sat Dec 09, 2017 11:51 pm    Post subject: Reply with quote

Sony has somehow compensated for more curvature in projected dof, causing degrading performance of legacy wide and fast lenses. How appears to be unknown.

Simple geometry suggests the distance, between the rear element and the top filter on the sensor, varies the angle of incidence of light rays striking the edges of the sensor. The angle will be steeper if the lens element is closer. Thus Sony E-mount angle will be steeper than, say, M42 angle, because the distance is less.

The diameter of the rear element also affects the angle of incidence. Light rays from opposite edge of larger element to sensor filter will arrive at steeper angle, thus larger rear elements closer to the sensor == greater angle of incidence.

We theorize the Sony E-mount register is so short, E-mount wide angle lenses project at so steep an angle, the curvature of the wide-angle dof is missed at the edges, appear out of focus.

What can be done about that? If we angle the microlenses on the sensor filter, toward the lens, adding a tiny refraction sufficient to bring edges of len's projected dof into focus, how is telephoto performance affected? Problems with some legacy wide angles indicate there has been some kind of compensation made, useful only for short E-mount. Telephoto effects are minimal. Improvements on performance for E-mount wide angles and fast normals cause problems with legacy wide angles and fast normals. Also, the corrections applied at the sensor filters must degrade E-mount edges, from what lens projects, affecting edges of all E-mount lenses equally. Focus corrections at edges of len's projected image circle are degrading. Thus E-mount lenses can be better than body can capture.


Last edited by visualopsins on Sun Dec 10, 2017 5:12 am; edited 1 time in total


PostPosted: Sun Dec 10, 2017 3:02 am    Post subject: Reply with quote

I don't have problem on focusing manual lens with A7 or A7RII using magnify/peaking. I use mainly use the LCD and only occasionally use the EVF.


PostPosted: Sun Dec 10, 2017 10:07 am    Post subject: Reply with quote

calvin83 wrote:
I don't have problem on focusing manual lens with A7 or A7RII using magnify/peaking. I use mainly use the LCD and only occasionally use the EVF.


Although I prefer to use the EVF over the LCD screen I have to echo Calvin's basic point. I have never had a problem with manual focusing the A7 or A7II (or even the NEX-3 and A6500). It barely impresses me that reviewers are claiming that manual focusing with the A7RIII is improved over earlier models. The manual focusing experience with those earlier models is just fine. The cost differential between the models does not justify, in my opinion, the purchase of the RIII if it is to be used primarily with legacy rangefinder and/or SLR lenses.

I'm not knocking the A7RIII. From what I have read and watched it is an amazing camera, but it's strengths are concentrated on its autofocus capabilities.

One other caution. While the previously cited reviews were praising the improved manual focusing of the A7RIII, those reviews called out improved MF performance with autofocus, focus by wire lenses. Sony cameras and lenses are tightly integrated electronically, with the camera recognizing the lens and performing electronic corrections to the image to correct optical flaws in the lens. I don't know whether the improved EVF performance in the A7RIII may depend on using native E mount lenses that communicate with the camera body.


PostPosted: Sun Dec 10, 2017 10:13 am    Post subject: Reply with quote

Thanks for these 2 answers... This settles it for me.


PostPosted: Sun Dec 10, 2017 1:26 pm    Post subject: Reply with quote

Forum members following this thread might find of interest this write up:

http://ilovehatephoto.com/2015/02/23/3-detailed-reasons-not-to-switch-to-sony-full-frame-mirrorless-system/

Reading my own OP now I find it remarkably naive. Here I sit with a couple hundred MF lenses and I thought I could just go out and buy a FF digital mirrorless camera body and a few adapters and go to town and have fun.

I'm very early in my research on all this. There remains a whole lot I do not understand. Suffice it to say for now that my concentration is not, and has not been, on issues of focus. There are other issues when certain FF sensors are paired with our shorter focal length legacy glass in a mirrorless setting. And all along, for me, it had been that shorter focal length legacy glass that I was especially looking forward to enjoying with FF mirrorless digital.

At this point for FF I'm giving more than passing consideration to returning to film. At least with film, with the emulsion side of the film facing the lens, you have a first surface, high resolution, receptor for those light rays. I can buy and process a LOT of film for the very high cost of a digital mirrorless FF camera body, and the cost of a good quality film camera body is nearly free. In fact, I already own several such camera bodies including a couple which will work splendidly with my Konica Hexanon MF lenses.

Of course far less of this analysis applies to APS-C sensors, and even less to (for example) m4/3 sensors. That is how I became snookered in the first place. I ignored that the angle of light rays incident upon the sensor becomes more and more and more severe as the sensor itself becomes wider and wider. And these sensors, unlike with film, are not first surface sensors. They have significant depth, which becomes an increasingly salient issue as the incident light ray angles become more severe.

Sony has addressed all this, at least to some extent, in its higher resolution FF sensors. But in the lower resolution Sony 24 megapixel FF sensor I can (barely) afford, the issue has not been addressed.


PostPosted: Sun Dec 10, 2017 1:40 pm    Post subject: Reply with quote

We understand Sony's addressing of the issue in some bodies is what causes the problem for mf lenses with those bodies, correct? They get better performance from E-mount at the expense of less performance from mf lenses. For mf lenses use a body in which the issue is not addressed.


PostPosted: Sun Dec 10, 2017 1:53 pm    Post subject: Reply with quote

While I personally haven't had any issues using wider lenses with my A7/A7II I admit that I rarely shoot at wider than 35mm. That said, this issue of Sony sensors not working well with some wide angle legacy lenses isn't new. It has been around for years and I have been in on the discussions for just as long.

Things to consider:

The major complaint of incompatibility between wide lenses and Sony sensors is based on the performance of rangefinder lenses. SLR lenses are far less often considered a problem.

There is a relatively inexpensive modification available for the Sony 24mp sensors that is designed to eliminate this issue with wide angle lenses. It is called the Kolari modification and you can learn more about it here:

https://kolarivision.com/product/sony-a7-series-thin-filter-legacy-lens-upgrade/

I wish you the best in whichever direction you finally decide to go.


PostPosted: Sun Dec 10, 2017 1:55 pm    Post subject: Reply with quote

visualopsins wrote:
We understand Sony's addressing of the issue in some bodies is what causes the problem for mf lenses with those bodies, correct? They get better performance from E-mount at the expense of less performance from mf lenses. For mf lenses use a body in which the issue is not addressed.


I do not have the answer to that at this time.

I can say Sony is (at least) considering addressing the situation with a sensor having a curvilinear cross section:

https://www.engadget.com/2014/07/08/sony-shows-off-first-picture-taken-with-curved-sensor/

What I take from that is that Sony knows there is a problem. I'm certain their scientists and engineers know about and understand the problem a WHOLE LOT better than I do. But before I spend the kind of money one of these FF mirrorless camera bodies costs, right now roughly US$1300, I'm gonna know a whole lot more about what is going on. That is not lunch money for me. I cannot afford a fundamental error, of either physics or geometry or both, that large.


PostPosted: Sun Dec 10, 2017 2:03 pm    Post subject: Reply with quote

newst wrote:
While I personally haven't had any issues using wider lenses with my A7/A7II I admit that I rarely shoot at wider than 35mm. That said, this issue of Sony sensors not working well with some wide angle legacy lenses isn't new. It has been around for years and I have been in on the discussions for just as long.

Things to consider:

The major complaint of incompatibility between wide lenses and Sony sensors is based on the performance of rangefinder lenses. SLR lenses are far less often considered a problem.

There is a relatively inexpensive modification available for the Sony 24mp sensors that is designed to eliminate this issue with wide angle lenses. It is called the Kolari modification and you can learn more about it here:

https://kolarivision.com/product/sony-a7-series-thin-filter-legacy-lens-upgrade/

I wish you the best in whichever direction you finally decide to go.


Steve, thank you. That is a very, very valuable reference in my view. Even just knowing what they are revealing there is extremely valuable . . . and thought provoking!


PostPosted: Sun Dec 10, 2017 2:20 pm    Post subject: Reply with quote

Hi all I acquired an a7 in August 2014 and upgraded to an A7II in July 2015. I have been lurking for a long time.

The big issue is with Rangefinder lenses of focal length not greater than 35mm. Ok this is a bit broad the real issue is the distance of the lenses exit pupil from the focal plane. This usually is related to focal length, but not always so that 35mm only works as a guide. The solution was posted above and there is a summary of solutions here: https://vahonen.info/secure/wiki/index.php/Sony_A7_-_Thick_filter_stack_issues Note this is only for high performing lenses from Zeiss, CV and Leica at present.

Retrofocal lenses tend to be ok, but 24Mp can embarrass some old designs, Olympus stopped at 18mm F3.5 and wider were Fisheye. The widest Zoom was 28mm. I still have a Canon 5DmkII which was my basic test bed as I stated to acquire MF lenses, not sure many have passed muster on the canon but failed on the Sony. Whilst on this I wish people praising lenses on APS-C and M4/3 would say they are not testing the peripheral bits of the image circle.

Now with all that said you can have problems with adapters. The best are matt and or baffled. But a shiny one can give multiple artefacts if a strong light source is in or near the frame.

Rod


PostPosted: Wed Dec 13, 2017 6:51 am    Post subject: Reply with quote

I'd been thinking about posting this question on the forum myself, so I'll tag mine on to this.
I've been using a Fuji xe1 for about 3 years with my various manual lenses and will shortly be upgrading. I have a couple of Fuji af prime lenses as well.
My shortlist is down to two cameras.
Firstly a Fuji xe3 as I have a couple of lenses already and plenty of adapters or secondly a Sony a7ii. Then I'll be able to use my lenses at their true focal length.
My main concern with the Sony was as has been commented on the use of a thick filter stack. However I don't really have any super wide angle lenses. I have a Tokina 17mm f3.5 and an Olympus 21mm f3.5. I don't really have any significant rangefinder lenses either, just standard industars, jupiters and an old 90mm f4 Leica elmarit ltm.
I prefer not to process files too much, I mostly try to use the Fuji jpegs and I don't really pixel peep either but I do want the best system in this price range for the many manual lenses that I have.
Which do you think would be best for me.
Thanks.


PostPosted: Wed Dec 13, 2017 9:10 am    Post subject: Reply with quote

Braddanman wrote:

My main concern with the Sony was as has been commented on the use of a thick filter stack. However I don't really have any super wide angle lenses. I have a Tokina 17mm f3.5 and an Olympus 21mm f3.5. I don't really have any significant rangefinder lenses either, just standard industars, jupiters and an old 90mm f4 Leica elmarit ltm.


You should find with good adapters, no reflections, Tokina 17mm f3.5 and an Olympus 21mm f3.5 are fine, on the range finders as I said above over 35mm and it willl all be ok.

Also a link to an excellent list of MF lenses for A7 series. https://phillipreeve.net/blog/affordable-manual-lenses-for-the-sony-alpha-77r7ii7rii-and-7s/

A link to a guide on adapters https://phillipreeve.net/blog/adapters-manual-lenses-sony-a7-series-guide/


PostPosted: Sun Dec 17, 2017 7:41 am    Post subject: Reply with quote

I loved using the A7 for manual lenses. I half regretted selling it because I wanted IBIS. But I still miss the more elegant and smaller form factor of the first gen Sony Alphas. Might still get a good used one as a backup although the a6000 serves well enough.


PostPosted: Sun Dec 17, 2017 1:02 pm    Post subject: Reply with quote

Slalom wrote:


Also a link to an excellent list of MF lenses for A7 series. https://phillipreeve.net/blog/affordable-manual-lenses-for-the-sony-alpha-77r7ii7rii-and-7s/



What I find of interest about that list is that the shortest focal length lens reviewed there is 24mm. And there was only one of those!

All Sony A7 and A7 II sensor pixels are straight ahead looking, which is not a happy circumstance for those pixels out on the extreme edges of the sensor. I think Sony can design and manufacture a better FF sensor than they now offer, a sensor better suited to MF lenses.

But will they? I dunno. If their aim is building a better camera body, they will. If their aim instead is to sell Sony AF lenses, they likely will not.


PostPosted: Sun Dec 17, 2017 2:26 pm    Post subject: Reply with quote

guardian wrote:
I think Sony can design and manufacture a better FF sensor than they now offer, a sensor better suited to MF lenses.

But will they? I dunno. If their aim is building a better camera body, they will. If their aim instead is to sell Sony AF lenses, they likely will not.

They won't. It would make all their own existing lenses perform worse.

KolariVision has a 0.2mm replacement for the Sony filter stack. This makes a Sony equal to Leica in terms of total glass in the optical path (around 0.9mm I believe). They are also working on removing the sensor cover glass (0.7mm from my understanding). Together with a BSI sensor, or a a7s series and you should be very close to film ie only 0.2mm of extra glass in the optical path.


PostPosted: Sun Dec 17, 2017 7:34 pm    Post subject: Reply with quote

Can you show me examples of noticeably bad results outside of the rangefinder wides with older SLR lenses? I've used Canon and Minolta 24 and 28mm lenses, as well as the Nikon AI 20mm f4 on an A7 and A7rii with no real problems. The Canon nFD 35 f2.8 is my go to 35mm for full frame (better for me than the Leica 35mm R, the modern Zony 35mm/2.8 FE, and the Voigtlander 35.) The Voigtlander 12mm LTM has issues on FF but is a very nice effective 18mm wide for the A6000. And I have an adapted Sigma 10-20mm for APS-C that works well with a dumb adapter on the A6000 and combined with a 1.4x adapter (as per ProfHankD's suggestions on Dpreview) works well as a slow 15-30mm on full frame.

I think someone with a huge manual lens collection will find it easy to do well with an A6000 or A7 series except for a few problem RF lenses. And no one familiar with the vagaries of manual lenses can really be **that picky** on every margin. Legacy manuals give you quality and a certain character, but rarely optical perfection. At the same, they can avoid the sterility of the modern look that most designs today produce.


PostPosted: Sun Dec 17, 2017 8:56 pm    Post subject: Reply with quote

Can somebody tell us at what angle do light rays begin to disperse or othewise fail to go completely onto the sensor?

Then we can calculate the focal length/distance from sensor to len's exit pupil.

A simple glance at lens specs would reveal whether there could be a problem.


PostPosted: Mon Dec 18, 2017 12:01 pm    Post subject: Reply with quote

Interestingly Ken Rockwell states that even telelenses are negatively affected by the sensor design of the modern A7-series cameras.
I've just read his test about the Minolta AF 80-200mm/F2.8 APO G lens (which is my only zoom I'm really using) and surprisingly he states that it performs better on the DSLR style of cameras (like mine) than on the new A7 mirrorless ones:
http://www.kenrockwell.com/minolta/maxxum/80-200mm-f28.htm#rex
However, I'm not able to verify that myself because I didn't see any sense yet to go for any of those A7 cameras with my existing set of lenses and cameras.

Maybe Stephan could eventually comment on this issue as he might have all the necessary equipmend on hand.


PostPosted: Tue Dec 19, 2017 4:51 am    Post subject: Reply with quote

He has problems with 80-200mm that is in a-mount, half a light year away from the sensor??

That would be surprising.

The funny thing is 10 years ago he said himself this cannot happen with modern retrofocus lenses:
http://www.kenrockwell.com/tech/wideslr.htm

Also, I do not know how you would "optimize" lenses for a sensor that is not strictly speaking curved but befellen with a glass plate. Sounds pretty arbritrary to me. Unless he means retrofocus so that the light goes perpendicular. All that retrofocus eats a lot of glass, too.

I guess someone has to click through a lot of hires images to find out whether SLR lenses are affected.

Note that K.R. has a policy of dissing adapted lenses every third paragraph. bla bla bla bla Nikon gear plays best with Nikon.