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

  
 
Svenning
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p.1 #1 · p.1 #1 · Recommended f/stop.......


http://www.ephotozine.com/article/olympus-mf1---om-four-thirds-adapter--review-7198

I have just read the article about the OLYMPUS MF1 adapter and I saw to my surprice that there was recommandations to f/stops to be used with the old OM-lenses.

Do any of you FM Forum members have any experience with Recommeneded f/stops for other brands of analoge lenses?

My own experiences has taught me that analoge lenses on modern digital cameras needs a proper aperture stop Down to about f/5.6 - or am I wrong?



Dec 17, 2014 at 09:28 AM
jcolwell
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p.1 #2 · p.1 #2 · Recommended f/stop.......


Many lenses, old and new, get the highest resolution across the frame at f/5.6 or f/8. Of course, there are often DOF and subject content considerations that would cause you to use wider or narrower aperture settings. So like most things in photography, it depends...


Dec 17, 2014 at 09:39 AM
Eric Gottesman
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p.1 #3 · p.1 #3 · Recommended f/stop.......


I've read that 1-2 stops off wide open is where a lens is usually the sharpest.



Dec 17, 2014 at 10:53 AM
mcbroomf
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p.1 #4 · p.1 #4 · Recommended f/stop.......


Some old "analog" magazine tests that were scanned by FM member Ed Sawyer some time ago... many OM. As I recall OM seem to like about F8
http://www.edsawyer.com/lenstests/

Mike




Dec 17, 2014 at 10:58 AM
galenapass
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p.1 #5 · p.1 #5 · Recommended f/stop.......


The purpose of this adapter is to convert some nice, older Oly glass to m43. The old f/8 "rule" does not apply well to m43 since the effects of diffraction begin to appear at f/5.6. In this link (from the OP), there are some listed recommended f-stops in the range of f/5.6 to f/11. There is even one that is f/8 to f/11! Even so, the effects of diffraction differ from lens to lens. For example, some lenses are so sharp that diffraction does not bring down overall image IQ until f/11. Some lenses need one stop for max sharpness, some need 3. Some are better performers up close, and not so good for distance, while others are the opposite. Image IQ is going to be a complex mix of all of these factors. So, as Jim put it above...it all depends. I would not take these recommend f-stops seriously, nor any of the replies above that suggest there is some sort of widely applicable rule. Do keep in mind that in general for m43 the effects of diffraction set in earlier than so called full frame.


Dec 17, 2014 at 11:39 AM
AhamB
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p.1 #6 · p.1 #6 · Recommended f/stop.......


Eric Gottesman wrote:
I've read that 1-2 stops off wide open is where a lens is usually the sharpest.


But it's often necessary to stop down further to get maximum sharpness in the corners (esp. with wideangle lenses), which will reduce sharpness in the center, so it's a tradeoff. As a rule of thumb I'd try not to go beyond f/11 though (for full frame and APS-C).



Dec 17, 2014 at 01:35 PM
J.D.
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p.1 #7 · p.1 #7 · Recommended f/stop.......


No offence to the OP but articles like that often confuse more than they inform. Sometimes I think some photography writers just feel the need to over analyse.

Hardly a shock to me that f/5.6 - f/11 were the most likely apertures for best lens performance but as they say in my business, "whatever it takes to get the shot". An adapter should make no difference to any of that as long as it's constructed accurately. Aside from that, I've pretty much always shot at f/8. The only exception is my 85mm f/2 which I shoot at f/5.6. Don't ask me why. I don't remember.

However, just to show there's no animosity, I'll post this for anyone who's curious. Some of the longer, slower lenses do actually vary a bit from the norm:

Olympus Lens Tests

Not by any means biblical. Just a rough guide. If that stupid link I put in doesn't work, just go down the left hand side to "Articles and Features" -> "Gary Reese Lens Tests" -> "Olympus Lens Tests".



Dec 18, 2014 at 08:50 AM
galenapass
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p.1 #8 · p.1 #8 · Recommended f/stop.......


J.D. wrote:
Hardly a shock to me that f/5.6 - f/11 were the most likely apertures for best lens performance ....


Why is that not a shock when diffraction lowers image quality at ~ 5.6 and onwards for both 4/3 and m4/3? Why would the optimal performance for lenses tested on full frame be the same for a smaller format? This makes no sense.

Folks, this adapter is used to attach FF lenses to 4/3. So applying the usual f/8 rule, or tests done on ff camera is NOT VALID. Diffraction starts to effect image IQ at 5.6 on the smaller sensors. If anything the "rule" should be f/4 to 5.6 for optimal performance. Images at f/11 should be quite soft on a smaller sensor.

See this photozone review for an example:

http://www.photozone.de/olympus--four-thirds-lens-tests/509-leica25f14?start=1



Dec 18, 2014 at 11:45 AM
J.D.
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p.1 #9 · p.1 #9 · Recommended f/stop.......


Well, assuming the adapter is any good, you're still trying to focus light rays the same way at the same distance. Why should sensor size make any difference? I have tried this with my old Zuikos on my E-M1 (using the Olympus MF-2 adapter) and although I haven't used a test chart, it's difficult to see a lot in it.

I will say though that my old 300mm f/4.5, which used to be a stellar performer on film, is not a practical option for M43. There's just too much CA.



Dec 18, 2014 at 06:40 PM
galenapass
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p.1 #10 · p.1 #10 · Recommended f/stop.......


J.D. wrote:
Well, assuming the adapter is any good, you're still trying to focus light rays the same way at the same distance. Why should sensor size make any difference? I have tried this with my old Zuikos on my E-M1 (using the Olympus MF-2 adapter) and although I haven't used a test chart, it's difficult to see a lot in it.

I will say though that my old 300mm f/4.5, which used to be a stellar performer on film, is not a practical option for M43. There's just too much CA.


Scroll down for a brief explanation:

http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm



Dec 18, 2014 at 07:03 PM
Steve Spencer
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p.1 #11 · p.1 #11 · Recommended f/stop.......


J.D. wrote:
Well, assuming the adapter is any good, you're still trying to focus light rays the same way at the same distance. Why should sensor size make any difference? I have tried this with my old Zuikos on my E-M1 (using the Olympus MF-2 adapter) and although I haven't used a test chart, it's difficult to see a lot in it.

I will say though that my old 300mm f/4.5, which used to be a stellar performer on film, is not a practical option for M43. There's just too much CA.


It is not sensor size per se, but pixel density that causes diffraction. That said, in current cameras smaller sensor have a lot greater pixel density than full frame cameras. Even a full frame 36 mp sensor does not have nearly as dense pixels as a 16mp APSC sensor and certainly not as dense as a 16mp m4/3rds sensor, so diffraction will set in a lot sooner at for smaller sensor because of the higher pixel density.



Dec 18, 2014 at 07:08 PM
J.D.
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p.1 #12 · p.1 #12 · Recommended f/stop.......


I guessed that was probably something to do with it but for me it defies logic.

Just as I would have thought that an M43 sensor, being half the size of a 36MP "full frame" sensor should have similar sized light sites.

As I say, I haven't noticed it myself but I've never cared much about diffraction.



Dec 18, 2014 at 07:12 PM
Steve Spencer
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p.1 #13 · p.1 #13 · Recommended f/stop.......


J.D. wrote:
I guessed that was probably something to do with it but for me it defies logic.

Just as I would have thought that an M43 sensor, being half the size of a 36MP "full frame" sensor should have similar sized light sites.

As I say, I haven't noticed it myself but I've never cared much about diffraction.


But a m4/3rds sensor isn't half the size of a full-frame sensor, it is about a quarter the size. Remember we are talking about area when we are talking about the size of a sensor. A full frame sensor is 36mm by 24mm or 864 square mm. A m4/3rds sensor is 17.3mm by 13mm or 225 square mm, so only about a quarter the size.

It is the same if you think about plots of land. A square mile is 640 acres, a square half mile is only 160 acres (or a quarter of a square mile).

The reason it isn't exactly a quarter is because a full frame sensor is 3 X 2 and the m4/3rds is of course 4 X 3 in shape. I hope that makes sense and makes it clear why jamming 16mp in a m 4/3rds sensor is going to mean the pixels are a lot more tightly packed, than 36 mp in a FF sensor.



Dec 18, 2014 at 07:26 PM
millsart
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p.1 #14 · p.1 #14 · Recommended f/stop.......


I use whatever f-stop suits the image I'm trying to capture. That might mean I want to isolate the subject, or it might mean I really care about across the frame sharpness.

I might be shooting a moving subject and need to maintain a certain shutter speed etc.

I mean what are you going to do if your trying to shoot your kid running around in low light, not shoot wide open because f5.6 yields the best overall IQ ?

I mean geez, we use lenses to make photographs.

Might as well just stick our glass onto an optical bench if all we care about is measurebating theoretical maximums



Dec 18, 2014 at 08:32 PM
J.D.
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p.1 #15 · p.1 #15 · Recommended f/stop.......


I agree Millsy. Like I said earlier; 'as they say in my business, "whatever it takes to get the shot"'.

I once copped flak for shooting my Canon 300mm f/2.8 at f/20. Someone told me that if I was going to do that I didn't deserve to own such a lens...

Edited on Dec 18, 2014 at 08:46 PM · View previous versions



Dec 18, 2014 at 08:45 PM
galenapass
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p.1 #16 · p.1 #16 · Recommended f/stop.......


Which gets back to the original point made above by Jim...ideal f-stop? It all depends.


Dec 18, 2014 at 08:45 PM
philip_pj
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p.1 #17 · p.1 #17 · Recommended f/stop.......


Too bad the discussion got confounded by format diffs. It is a fascinating topic, for instance how many know the fast 35/1.4 lenses they covet get really bad at f5.6 due to extreme curvature? The smaller aperture only buys you some dof to help disguise the mess. The industry is realizing modern cameras need lenses designed for cross-frame performance not just the center donut. Hence ZM 35/1.4, FE55, both Otuses, ART, RX1.


Dec 18, 2014 at 08:46 PM
J.D.
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p.1 #18 · p.1 #18 · Recommended f/stop.......


philip_pj wrote:
Too bad the discussion got confounded by format diffs.


At least it didn't turn into a full frame vs crop flame war.

Now back to our scheduled programming!

[RUNS]




Dec 18, 2014 at 11:47 PM
Svenning
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p.1 #19 · p.1 #19 · Recommended f/stop.......


Thank you bringing attention to the term "Diffraction".

Here is a link to an explanation to the term:
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

I will start to test my old analoge lenses and find out at what aperture "Diffraction" starts to set in?





Dec 21, 2014 at 02:48 AM
philip_pj
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p.1 #20 · p.1 #20 · Recommended f/stop.......


Every kind of factor comes into the answer to this simple request, Svenning, and testing is a fine idea. People making huge prints and looking for highest IQ will tell you f8 is as small as you can go. But, effectively, it depends on your aims, your repro size, and your need for depth of field.

Many more images are lost to inadequate dof than to diffraction. If you stick with f8 and end up with slightly sharper data in the zone of reasonable dof but lose this quality from not using f11, clearly that is not optimal.

Lenses vary widely. Taking 50mm recent releases, two high end 55mm lenses, Sony's FE55 and Zeiss's Otus 55/1.4; both these decline in IQ from f8 to f11 right across the frame. By contrast, Nikon's 58/1.4 loses a little centre IQ but picks up significantly from f8 to f11. As this lens is very deficient in corner definition, the user may want to take this trade-off. And at f11 the Sony lens is still far better in the corners at f11 than the Nikon despite its f11 IQ being worse than its f8.

The general 'rule' is that best overall IQ occurs at two stops down from wide open, but this is very often very wrong. That Sony FE55 is best at f5.6, 3.3 stops down from wide open. Zeiss's 55mm Otus is best at f4, 3 full stops down.

Then preferences we all have come into it. I shoot a lot of images with focus at the middle to edge of the frame, so I use lenses with strong outer frames at relatively wide apertures, for the low light shooting I do demands that from me. Huge numbers of lenses are really only good in the center of the image, typically described as 'portrait lenses'. Myself I find this problematic, dull and boring. Leica have made an art form of producing lenses that are stunning in the 'magic donut' centre but don't even think of using them for landscapes! So you see - it all depends.



Dec 21, 2014 at 10:25 PM
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