Why f2.8 lenses referred to as of better nature than f1.4 lenses ?

[richard_sentry]

I have seen reference, in postings to this board, to the smooth

quality or nature of 2.8 lenses, particularly in comparison to 1.4

lenses. Is there a physical factor that I am not aware of that would

bring this about. I know that the 2.8 lens (all AIS) that I do have

are excellent, particularly in the portrait range they are superb, but

I do not quite see or know why a 1.4 or 1.8 lens would be lesser in

quality, by virtue of its speed, alone. Excluding � or perhaps

including � the ED characteristic of some of the classic 2.8 lenses.

This is relevant and significant to my son in the choices of the new

AF lenses for Nikon pro digital cameras as my son is evolving from my

older manual focus lenses. I am all ears. Thanks.

[_________2]

i can't comment about differing results (images quality) in using

f1.4 as opposed to slower lenses but i can comment about the process.

what i mean is that i often find it easier to manually focus a 2.8

lens than a much faster one - the exception being an AIS85/1.4 which

is the lens i focus with most easily. this is likely a function of the

camera's viewfinder which might lend itself to better focussing with

a "slower" lens. i use 3 SLR cameras: F100 and F3 about equally, and

an F801 occasionally. i definitely find it easier to focus the f2.8 -

f4 lenses with the F3 and F801. i don't recall it mattering too

much with the F100.

 

if it is true that i can manually focus better with an f2.8 lens then

it might follow that i'd get a better resulting image. i can't

honestly claim this to be so in real world examples.

 

if memory serves, David Ruether had written a piece or a post on

this some time ago. i'm sure you'd find his opinion worthwhile.

[richard_sentry]

So far I have found David Ruether lens references at:

http://www.ferrario.com/ruether/slemn.html

and I am still searching for a specific article re F2.8 versus F1.4. Thanks, I will continue.

[_________2]

richard, try this - http://www.nikonlinks.com/ruether/posts_html/85mm%20z.html

 

it answers your question to a "T", AND DR uses the example of the

85mm 1.4 vs. the 1.8.

 

out of the dozen SLR lenses i use (4 are autofocus)

only the 105M AFD and the old 2-touch 80-200 are 2.8's

and while they focus in AF reasonably well

neither is built for rapid AF focussing.

[todd peach seattle, washi]

I think perhaps you're mixing together a couple generalizations and coming up with a 'blanket rule' that does not hold together.

<p>

Here's a few generalizations:<br>

<ul>

<li>Fast lenses (f/1.4) have harsh 'bokeh', or out of focus images. Generally true of Nikon's fast 50mm's.

<li>Small lenses (slow, fewer elements) with decent multi-coating are often superior at flare control than faster large lenses.

<li>Fast lenses used wide open often have unsharp corners due to field curvature or residual uncorrected aberrations.

<li>If you don't intend to use a fast lens wide open or one stop down on a regular basis, save your money.

</ul>

<p>

Does that mean the 28/1.4 or 85/1.4 AFD are crap? Not according to the reports that I have read. Both get stellar reviews from people who use them in real-world situations. The 28 actually delivers sharp corners wide open. The 85/1.4 has very smooth bokeh.

<p>

Does it mean that a 50mm f/1.4 AFD might give harshly rendered backgrounds when used as a portrait lens on a DSLR? Perhaps.

<p>

I understand that your question was trying to get to the nature or trend of these differences, but when it comes down to buying decisions, you still need to 'compare and contrast' 2-3 specific lenses and ask how they will meet your needs. A big board like this one will often shake out people who have used (or continue to use) the 2-3 lenses you're interested in and can render opinions on them.

<p>

If your son is going to do journalism or event photography with his DSLR, I predict he'll want at least one f/1.4 or f/1.8 lens.

[ilkka_nissila]

In principle, it is more difficult to design a f/1.4 lens than a f/2.8 one, simply because the better and simpler optical designs cannot be implemented for the fast aperture lenses. However, manufacturers put a lot more effort (which means more $$$) into the fast lenses and hence they are usually just as good. This is wrt. primes. The f/2.8 and faster primes basically are considerably better than the f/2.8 zooms near the f/2.8 aperture. My experience is based on 35-70, 20-35 and 80-200 f/2.8 AF Nikkor zooms, and maybe 15 primes.

[Brian1664876441]

In comparing F2.8 "normal" lenses to my 50mm F1.4 Lenses, The 55mm F2.8 Micro-Nikkor and 60mm F2.8 AF Micro-Nikkor are probably the sharpest lenses that I own. The floating element design allows for its use across the distance range. The micro-Nikkors have always been known for sharpness. The 45mm F2.8 GN-Nikkor is good, but does not stand-out compared to the faster lenses. It is true that the faster lenses have "harsher Bokeh". The out-of-focus highlights tend to appear as "platelets", which tends to be a bit distracting. But how often do you shoot wide-open outdoors? I believe that this is due to overcorrection for spherical aberration. As you stop-down past F4 the effect is not as noticeable.

[richard_sentry]

Thank you, these are wonderful responses.

 

Regarding:

http://www.nikonlinks.com/ruether/posts_html/85mm%20z.html

 

I have taken a look and I am lead to a separate and important posting. This will be placed tomorrow.

 

Regarding :

 

--- It is true that the faster lenses have "harsher Bokeh". The out-of-focus highlights tend to appear as "platelets",

 

Fast lenses (f/1.4) have harsh 'bokeh', or out of focus images. Generally true of Nikon's fast 50mm's. ---

 

These are also very important points in that he will need at least one good mid range portrait lens.

 

I still have not seen a specific flat out statement re the value of f2.8 types, but the surmising of the responses is effective.

 

My conclusion at this point, and particularly in light of:

 

--- If your son is going to do journalism or event photography with his DSLR, I predict he'll want at least one f/1.4 or f/1.8 lens. ---

 

That he should have a more dedicated portrait short or mid telephoto that is limited to an open F2.8 � as the bokeh factor is super important.

 

And that he should also have a f1.4 or even a MF F1.2 for event photography, as he will definitely be doing more of that also.

 

Also that the references to some lens trouble in the corners would be minimized with the D1 and its perspective of view not including the input from the outer edges of the lens.

 

This is wonderful and a real help to him, thanks.

 

Also - Are there any linkable images which would demonstrate the "platelets" like bokeh of the 50mm F1.4 or 50 mm F1,8 ?

[steve_levine]

Stopped down a few stops,the sharpness will be the same.What isnt the same is the brighter viewfinder image,a fact often over looked by the tyro.Many people own fast glass ,and never shoot it wide open!

[pontus_gustavsson]

A faster lens needs a large front lens, and large lenses are rarely perfect. That's the main reason why slower lenses are sharper at full aperture IMO. But stopped down they should be equal, and sometimes the faster lens is better because it costs more. Cost and quality often go hand in hand as you know.

 

Regarding the post about ease of focusing, I feel my 35/1.4 is easier to focus quickly than my other lenses, because the viewfinder is bright and the object you're focusing on sort of "pops" into focus because of the short depth of field. So I focus much faster with a 35/1,4 set to f/2.8 than with a 35/2.8 wide open.

 

Regards,

[pontus_gustavsson]

I once had a 55/1.2, but got rid of it quickly. It wasn't sharp, the bokeh was terrible and I never managed to get the closest eye in perfect focus... At f/5.6 it was fine though.

[Brian1664876441]

This is an old formula lens, the Nikkor 5.8cm F1.4 that was replaced by the 50mm F1.4. It will give you an idea of the background. This shot is close-up and wide-open.<div></div>

[Brian1664876441]

And for a Comparison, The 10.5cm F2.5.<div></div>