Home · Register · Join Upload & Sell

Moderated by: Fred Miranda
Username  

  New fredmiranda.com Mobile Site
  New Feature: SMS Notification alert
  New Feature: Buy & Sell Watchlist
  

FM Forums | Leica & Alternative Gear | Join Upload & Sell

1      
2
       end
  

Archive 2014 · Recommended f/stop.......

  
 
Svenning
Offline

Upload & Sell: Off
p.2 #1 · p.2 #1 · Recommended f/stop.......


Dear Philip_PJ,

Thank you for a very educational answer.
I have saved it for future references.

I have tested my Olympus OM 55mm F/1.2 & Contax Planar 85mm F/1.4 lenses - and they are not good at full open aperture, however when you use F/2.8 they start to become useable. From my days of using diapositive films - I had no problem by using F/16. But when starting to using the Canon EOS 5D MK2 (Full frame) - I hardly go any further than F/8.

Am I wrong on this?



Dec 22, 2014 at 04:23 AM
J.D.
Offline
• • • •
Upload & Sell: Off
p.2 #2 · p.2 #2 · Recommended f/stop.......


You should see what happens to HD television lenses when you stop down beyond f/11.

I suspect it is linked to some of the things discussed here.



Dec 22, 2014 at 06:56 AM
bushwacker
Offline
• • •
Upload & Sell: Off
p.2 #3 · p.2 #3 · Recommended f/stop.......


Svenning wrote:
Dear Philip_PJ,

Thank you for a very educational answer.
I have saved it for future references.

I have tested my Olympus OM 55mm F/1.2 & Contax Planar 85mm F/1.4 lenses - and they are not good at full open aperture, however when you use F/2.8 they start to become useable. From my days of using diapositive films - I had no problem by using F/16. But when starting to using the Canon EOS 5D MK2 (Full frame) - I hardly go any further than F/8.

Am I wrong on this?


dude you need to see and read tons of samples and tests like when a lens starts losing its IQ, each lens model is different... different in IQ, bokeh, corner sharpness, curvature, CA etc.

here www.photozone.de this site has tons of it... it describes most of everything down to focus shift.

things like f4, best at 5.6, 2 stops below wide open are baloney... like i said each lens is different. Some starts tack sharp wide open but soft at mid apertures. some produce dreamy character and some don't.

about your film vs 5d2, they're two different technologies.

Here's one sample difference:

Film = almost no light reflection

Image Sensor = prone to light reflection [ when you have this reflection you'll get lower contrast, ghosting or some glare ] this is the reason why you'll see ads like, anti-reflection coating double side, T* coating, multi-coating, etc on lenses.

so what these has to do with your f8 vs f16 settings? we all know that all Lenses starts having diffraction at some point maybe earlier say 5.6 or some starts at f16 and some in between.

add that diffraction to film or to electronic image sensor which one do you think is better at rendering the image?


then on sensors... you add more variables like: pixel density like others are saying here... and there's more.












Dec 27, 2014 at 05:39 AM
Toothwalker
Offline
• • •
Upload & Sell: Off
p.2 #4 · p.2 #4 · Recommended f/stop.......


bushwacker wrote:
Here's one sample difference:

Film = almost no light reflection

Image Sensor = prone to light reflection



https://www.fredmiranda.com/forum/topic/1031745/1&year=2011#9804254



Dec 31, 2014 at 05:43 AM
pandorf
Offline
• • •
Upload & Sell: Off
p.2 #5 · p.2 #5 · Recommended f/stop.......


Or stick to lenses that are made specifically for the camera body being used.


Dec 31, 2014 at 06:09 PM
jcolwell
Offline
• • • • • • •
Upload & Sell: On
p.2 #6 · p.2 #6 · Recommended f/stop.......


pandorf wrote:
Or stick to lenses that are made specifically for the camera body being used.


That's safe, but boring.

Besides, some of the "non specific" lenses are probably better, in at least a few important ways.



Dec 31, 2014 at 07:14 PM
galenapass
Offline
• • • • •
Upload & Sell: Off
p.2 #7 · p.2 #7 · Recommended f/stop.......


jcolwell wrote:
That's safe, but boring.

Besides, some of the "non specific" lenses are probably better, in at least a few important ways.


In addition, using native lenses does not somehow get one away from the issue optimal aperture settings.



Dec 31, 2014 at 09:02 PM
theSuede
Offline
• • • •
Upload & Sell: Off
p.2 #8 · p.2 #8 · Recommended f/stop.......


Why bother with that "recommendation"?

I'll gladly admit to being a measurement-type techie with way to much mathematical knowledge of lens and sensor measurements, BUT...!
-When I grab a camera to actually USE it, either for fun or profit, I honestly don't care AT ALL what the "best" setting is. Use what you need! The world isn't centered on what's optimal for your camera/lens combination. It's the other way around - your camera/lens combination should be centered around your "world" of usage!

Knowledge and some analytical thinking is needed when you see parts of your own work that you aren't satisfied with from a technical PoV. THEN you need to look at stuff like:
-"Do I need a lens that is sharper at large apertures?"
-"Do I need better low-light performance? How do I do that in this case without making DoF to short?"
-"Do I need some kind of stabilization here?"

-and so on...
Knowing what to look for, and HOW to actually analyze (which most of the time boils down to "compare"!) stuff in a productive way helps a lot. At least it saves you (can save you?) a LOT of money. Granted - I do have access to quite a lot of really good equipment, and I know quite a lot about that equipment and their alternatives. So I usually bring stuff that is "adequate" with good margins to spare...

Unfortunately that does mean - most of the time - that the piece of equipment I would need to replace to make this or that session work out better - is me...



Dec 31, 2014 at 09:15 PM
RustyBug
Offline
• • • • • • •
Upload & Sell: On
p.2 #9 · p.2 #9 · Recommended f/stop.......


Diffraction is caused by the smaller physical / optical aperture. Pixel size is just how small it segments / reassembles the effects of diffraction. While it is true that diffraction's CoC can be contained within a single pixel or extend across multiple pixels depending on pixel size, pixel density does not cause the optical projection to be diffracted. Diffraction is a property of optical projection, not pixel capture density/size.

Depending on your focal length, your physical / optical aperture size will vary. Smaller focal lengths can project diffraction a bit more readily than longer fl's at similar f-stop, due to the smaller physical/optical aperture.

Essentially, the wider open the lens is ... less diffraction occurs in the optical projection.
However, the wider open the lens is ... the more challenging it can be to get sharp corners since the distance to the corners is farther from the center @ Zones A, B, C

So, the "sweet spot" on a lens is often times between wide open to avoid diffraction and stopped down to achieve corner sharpness.

The upside to using a FF lens on a crop sensor is that the image circle is larger than needed to cover the sensor. As such, the need to stop down as far to achieve sharp corners at the farther distance of the FF corners is not required as much.

So, while the advice for stopping down to achieve sharpness into the corners on FF is not quite the same as for crop. The upside to this is that not needing to stop down as far, is that you don't induce as much optically projected diffraction. The crop factor also impacts the DOF correspondingly. As such, the conventional aspect that a lens may need to be stopped down to f/8 on FF really doesn't fully apply on crop.

What does apply is that finding the sweet spot between stopped down to getting good corners and not stopped down so much to induce diffraction. Generally speaking the smaller the crop, the less the need to stop down quite as far as on FF.



Dec 31, 2014 at 10:00 PM
pandorf
Offline
• • •
Upload & Sell: Off
p.2 #10 · p.2 #10 · Recommended f/stop.......


jcolwell wrote:
That's safe, but boring.

Besides, some of the "non specific" lenses are probably better, in at least a few important ways.


Maybe boring, but then you're not wasting time "testing" and can be out enjoying the art of making photographs.



Jan 01, 2015 at 12:04 AM
pandorf
Offline
• • •
Upload & Sell: Off
p.2 #11 · p.2 #11 · Recommended f/stop.......


galenapass wrote:
In addition, using native lenses does not somehow get one away from the issue optimal aperture settings.


Optimal is up to the one that's six inches behind the camera. Aperture is what creates the artistic look you're after. The shutter controls how much light you want in.



Jan 01, 2015 at 12:07 AM
jcolwell
Offline
• • • • • • •
Upload & Sell: On
p.2 #12 · p.2 #12 · Recommended f/stop.......


I "test" my Canon AF lenses for AF accuracy. I use my "Alt" lenses to see if I like the results. Neither is a waste of my time. YMMV.


Jan 01, 2015 at 12:09 AM
galenapass
Offline
• • • • •
Upload & Sell: Off
p.2 #13 · p.2 #13 · Recommended f/stop.......


pandorf wrote:
Optimal is up to the one that's six inches behind the camera. Aperture is what creates the artistic look you're after. The shutter controls how much light you want in.


OK - well...that is all obviously true (to some extent) but did I say anything contrary to this? These are all factors that would be in play regardless of whether one is using alt or native lenses. I am not sure what you point is?



Jan 01, 2015 at 02:23 AM
galenapass
Offline
• • • • •
Upload & Sell: Off
p.2 #14 · p.2 #14 · Recommended f/stop.......


pandorf wrote:
Maybe boring, but then you're not wasting time "testing" and can be out enjoying the art of making photographs.


I disagree. I don't think testing is a waste of time. What testing does do - IMO - is simply makes me more informed about my equipment so that I can achieve the look I am going after. I like to understand the strengths and weaknesses of the tools that I am using.



Jan 01, 2015 at 02:37 AM
RustyBug
Offline
• • • • • • •
Upload & Sell: On
p.2 #15 · p.2 #15 · Recommended f/stop.......


galenapass wrote
I like to understand the strengths and weaknesses of the tools that I am using.


+1

Whenever I get a new lens ... particularly the alts ... I "torture test" my glass.

MFD wide open is not where many shots are ever taken, but it can reveal things.

Shooting directly / obliquely into the light to check its flare handling.

Of course a series of test shots stepping through @ f-stop intervals will reveal where your diffraction starts to kick in and where it becomes objectionable. Case in point, my 24L TS-E (not alt to some, just stuck in my memory) testing revealed that f/11 in soft light is where it starts to barely show up @ pixel peeping. f/13 it is showing up in slight lowering of contrast ... f/16 and beyond I really don't want to go there unless for some odd reason it is paramount.

Same can be said for essentially any / all attributes of concern.

If I know that my torture testing ... whatever I may concoct / conduct ... that I won't use shows me the "limits" of the lens, then that all else will be better than that.

On the other side of things from finding my "limits" is finding my "sweet spot". In the cast of my 24L TS-E, I know that WO is just a touch softer than if I stop down from WO @ 3.5 to 5.6 or 8. 5.6 is probably the "sweet spot" because there is no real gain in sharpness doing from 5.6 to 8 ( a bit more dof of course), particularly if using a tilt function ... AND ... 5.6 is one stop FARTHER (vs. f/8) away from f/11 where my diffraction starts to reveal.

So, my sweet spot is sandwiched between sharpness and diffraction. Rinse & repeat for other glass. Some are already sharp @ WO and really don't need much stopping down (i.e. the advice of 2 stops from WO). Kinda depends on how the mfr designed the lens. Subject distance can make a diff also. Portrait lenses and macro lenses can be optimized for diff subject distances. Some glass makes better infinity distance, others make better street distance.

With so many attributes in play, testing is a good thing for those who are attentive to it. Some folks, just grab glass and go with whatever is, is. Nothing wrong there either, but if you are inclined to want to know ... I can relate. I'll shoot with anything and nothing will really prevent me from using any camera / glass, but it is nice to know how they differ, so you can work to their strengths ... or sometimes exploit their weaknesses.

Granted, the "pixel peeping" doesn't make a lens good / bad ... but, imo ... learning where it's strengths and limits are, affords one a confidence in their chosen tools.

As to the Oly's ... they tend to have very even sharpness across the frame, where Nikon's or others have a stronger central sharpness in Zone A at the expense of Zone C. For Oly's their issue of concern can be the vignetting that accompanies them, regarding how far you might want to stop down.

On a crop body, though the advice needed for stopping down on FF will be different as you are only capturing a more centralized portion of the image circle projection. I shoot my Oly's on FF, so I chose them for their even sharpness across the frame. Some Voigts and Nikons can tend to have sharper centers (optical compromises). If I were shooting crop, I may not be as interested in the Oly's for their overall more even frame sharpness.

The nuance of alts is a study unto itself. Optics are almost always some form of a trade-off / compromise. Diff mfr's approach those differently. So, depending on one's taste / needs ... there is a bevy of different glass to choose from ... which is not necessarily the same thing as one lens being better than another (unless you qualify "better" @ what).

HTH






Jan 01, 2015 at 11:12 AM
1      
2
       end




FM Forums | Leica & Alternative Gear | Join Upload & Sell

1      
2
       end
    
 

You are not logged in. Login or Register

Username       Or Reset password



This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.