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Sigma 105mm f/2.8 Macro DG OS HSM:optimum aperture


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#1 martino papesso

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Posted 24 October 2016 - 03:54 PM

Please, 

Which F is the best for the Sigma 105 (on nikon D 800)?

Lens: Sigma 105mm f/2.8 Macro DG OS HSM

Many thanks.

Martino Papesso

Italy


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#2 JoJu

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Posted 24 October 2016 - 04:42 PM

I have the Nikon Micro 105/2.8 and I try to avoid apertures closer than f/8. "Then there's not enough DoF!". Yes, right, it never is enough DoF and from f/11 the DoF is paid with lower resolution. But there's a cure against that: Have a look at Helicon Focus stack.

 

See also http://www.heliconso.../helicon-focus/ in case you haven't heard about that possibility. Downsides: Not possible for moving (also breathing) creatures or in windy situations outside.


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#3 martino papesso

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Posted 24 October 2016 - 04:58 PM

Does exist test for to know with is the best aperture for Sigma 105 at minimun distance of focus (about 32 cm ) and at another distance?

 

Many thanks.



#4 JoJu

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Posted 24 October 2016 - 05:14 PM

I'm not aware of such a test, but the internet is a big thing. You might research on dedicated macro-websites. As a rule of thumb, 2-3 f-stops from wide open is the optimum aperture of every lens. The higher the cameras MP, the sooner sharpness and/or resolutuon will decrease after a certain aperture.

 

Maybe a good read: https://www.lensrent...op-down-a-lens/

 

quick summary from that article: "The general rule that lenses get much sharper stopped down two stops from wide open is generally true."



#5 Brightcolours

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Posted 24 October 2016 - 07:47 PM

Does exist test for to know with is the best aperture for Sigma 105 at minimun distance of focus (about 32 cm ) and at another distance?

 

Many thanks.

There is no such thing is "best aperture, really, as JoJu points out.

 

For shallow DOF, wide open usually is best. For best contrast, closing down usually is a good idea. For most DOF, you need to stop down a lot, and for best sharpness, f5.6 usually is the best idea (for medium close up to infinity).

 

When you go close, the effective f-stop diminishes. 

See for instance this thread:

http://www.cambridge.../thread1358.htm

Your Nikon D800 will actually show a close approximation of the effective aperture (try it yourself.. set for instance f4 at medium distance, then focus on something very close up and you will see that the camera shows a different f-value than you originally set).

 

What is the best aperture to use totally depends on what you are trying to achieve for a certain shot. 



#6 JoJu

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Posted 24 October 2016 - 08:50 PM

There's maybe no such thing in the weird cosmos of BC. If you're able to read German (no offense meant, I just didn't find it in another Wikipedia language) you can check for "Förderliche Blende", "Beugungsunschärfe" or also Kritische Blende which simply means the aperture number Martino is looking for, and leads to maximum resolution. I know, you're addicted to DoF, but this is not necessarily leading to best resolution or good pictures  :P

 

And the effective f-stop diminuishes because the diameter of the front lens remains, but the focal length changes - it gets longer, meaning the f-number gets higher. The focal length is calculated at infinity, as you for sure know two days longer than God. oldno23x25.gif



#7 popo

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Posted 24 October 2016 - 09:30 PM

FoCal Pro seems to be able to do this. I never played with it that much beyond AFMA so haven't tried this feature myself. I believe it can use arbitrary targets so you could go different distances.

 

https://www.reikan.c...ture-sharpness/


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#8 JoJu

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Posted 24 October 2016 - 10:15 PM

AFMA??? Oh sorry, just read the full sentence now. Yes, FoCal Pro can try to find out the best aperture and print a nice graph. But this is "the best aperture at any costs, preferrably in the center of the image, no matter how much the corners blurr". It looks nice, but honestly I didn't see much of a difference. You meant this here?

i-HVzvJtQ-M.png

 

 

I just didn't see that much of a difference between wide open, the best and the worst aperture...

 

i-ZVhQKdj-L.png

 

i-DQQxSwS-L.png

 

 

i-k5dpnXL-L.png



#9 dave's clichés

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Posted 25 October 2016 - 06:47 AM

 The problem with the sharpest apertures is how the effective aperture changes with the distance:

 

 I used to have the Sigma 105mm macro non OS version shooting on the Pentax K3. (sold,can't give figures)

 

But looking at the Nikor AF 55mm F2.8 macro,  aperture changes with distance are:

 

Infinity...F2.8       0.35 mts...F3.5      0.27 mts....F4    0.24 mts... F4.5     0.23 mts ...F5    at 1:1...F5.5.  nearly minus 2 stops.

 

And for the Sigma 150mm EX F2.8 non OS version.

 

Infinity...F2.8      3.0 mts.   F3.5         0.8 mts...F3.8    0.58 mts...F4      0.5 mts...F4.5   at 1:1 .. F5.6....minus 2 stops.

 

 So finding which aperture is the sharpest will vary according to the distance. resolution tests would have to be done at a range of distances at all apertures, not something I will pursue!

 

 In practice when not "focus stacking"  we compromise to have a visually pleasing depth of field, often F11, which is way beyond the lens's  optimum sharpness which is commonly F4.5-5.6.



#10 dave's clichés

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Posted 25 October 2016 - 06:56 AM

This fly is taken with the Nikor 55mm F2.8 micro at F11  D7100, very small depth of field, I tried F16 for more DOF but sharpness suffered.

 

 

 

https://www.flickr.c.../[email protected]/

Attached Files



#11 JoJu

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Posted 25 October 2016 - 09:39 AM

... but sharpness suffered.

The fly also doesn't look too healthy  ^_^



#12 martino papesso

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Posted 22 June 2017 - 09:31 AM

Is available sharpness curves for these lens : Sigma 105mm f/2.8 Macro DG OS HSM mounted on nikon full frame?



#13 martino papesso

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Posted 22 June 2017 - 09:34 AM

I have the Nikon Micro 105/2.8 and I try to avoid apertures closer than f/8. "Then there's not enough DoF!". Yes, right, it never is enough DoF and from f/11 the DoF is paid with lower resolution. But there's a cure against that: Have a look at Helicon Focus stack.

 

See also http://www.heliconso.../helicon-focus/ in case you haven't heard about that possibility. Downsides: Not possible for moving (also breathing) creatures or in windy situations outside.

When you use helicon focus for your shots Which aperture do you use with your nikon 105/F 2,8 ? 



#14 JoJu

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Posted 22 June 2017 - 09:44 AM

Is available sharpness curves for these lens : Sigma 105mm f/2.8 Macro DG OS HSM mounted on nikon full frame?

 

Not as curve, but you are in Photozone.de and there is a lens test: http://www.opticalli...15028ff?start=1

 

Apparently f/5.6 is - as usual when a lens aperture is two stops closed - the aperture with the highest resolution (not the same as best sharpness, depending on definition of "sharpness")



#15 JoJu

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Posted 22 June 2017 - 09:46 AM

When you use helicon focus for your shots Which aperture do you use with your nikon 105/F 2,8 ? 

 As I said, never beyond f/8. Mostly I use f/5.6. f/2.8 could lead to harsh transition between bokeh and sharpness.


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#16 martino papesso

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Posted 22 June 2017 - 10:20 AM

Not as curve, but you are in Photozone.de and there is a lens test: http://www.opticalli...15028ff?start=1

 

 

NOT 150 but 105 ( Sigma 105mm f/2.8 Macro DG OS HSM mounted on nikon full frame )



#17 JoJu

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Posted 22 June 2017 - 10:32 AM

Sorry, confused numbers. However, it's just the same, and it doesn't matter if this lens is mounted on Nikon, Pentax, Sony, Canon, whatever - 2 stops down on most lenses gives the best resolution. If you doubt that, you can check all PZ tests to show me something else.  :D


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#18 Brightcolours

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Posted 22 June 2017 - 10:37 AM

Sorry, confused numbers. However, it's just the same, and it doesn't matter if this lens is mounted on Nikon, Pentax, Sony, Canon, whatever - 2 stops down on most lenses gives the best resolution. If you doubt that, you can check all PZ tests to show me something else.  :D

And that is at MTF testing distances. At closer distances (read: higher magnification), you will find that diffraction softening will worsen, so you can get at a point where closing down 2 stops from wide open will get you softer results.



#19 JoJu

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Posted 22 June 2017 - 10:57 AM

Eben with dedicated macro lenses? I thought-  but never looked into it - macros are abd choice for landscape photography becasue they are less good at ∞?



#20 Brightcolours

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Posted 22 June 2017 - 11:18 AM

Eben with dedicated macro lenses? I thought-  but never looked into it - macros are abd choice for landscape photography becasue they are less good at ∞?

Before IF lenses, macro lenses had the bellows effect. The further you push the lens out (the bigger the magnification), the more impact diffraction will have. With IF lenses, things are a tad less predictable. But your Nikon body will tell you that things indeed still change the closer you get (the higher the magnification) with modern Nikon F-mount lenses (you see the max. aperture number available go down). With Canon for instance, things are not that obvious (the Canon does not adjust the max. available f-stop setting). But of course, the exact same thing happens.

 

Some macro lenses are less good at infinity, others are just great at infinity also. It depends on the designer. Some non-macro lenses can do great with extension tubes or bellows too, and some others suck when you focus closer.






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