Really, this might be the dumbest question I have presented on the forum. Littlejock's thread on finding a tele-zoom is the reason for this question.

Local sports photogs and wildlife photogs, those who use long lenses, all tell me to get the fastest lens I can afford.  So the question is:

Does an f/2.8 tele at f/4 take a cleaner pic than an f/4 lens at f/4?  Sure, dumb question. But honestly, most images I see from these folks are not taken at f/2.8 but at higher aperture (smaller opening, larger number) .  The pics are clean and nice...is that from the capibility of the lens?

Is the f/4 lens straining optics at f/4 and the f/2.8 lens is not? Would the f/2.8 have better optics(and larger glass) and that somehow make the recommendation of "get the fastest lens you can" valid?  Is fast glass only valid if you shoot at wide aperture?

I am really curious about this from those who do have the really fine glass on their cameras.

Thanks for any input.  I am totally at a loss as to what responses might be.   There has to be a reason for recommending the fastest glass.

    TomD'Art.

P.S.  Could it be those who recommend a fast lens are using a tele-zoom and want a lens capable of close to the same aperture at the long end without the aperture drop off of other zooms?   

Boy oh boy, I hope to get a response to this, even if limited to a few.       TomDart.

hehe - i use a f2.8 105mm... but that isnt really telephoto so i cant really comment much - i would imagine that because of the higher performance needed out of the optics of a faster lens the image you get from stopping down a fast lens to f/4 must be better.

But i could be wrong - i am also interested in seeing what people have to say who use these lenses :)

edit - and a faster lens is a godsend for action shots - if you notice my recent series they are all f2 with my canon or 2.8 with my sigma - that made for shutter speeds in the thousandths and completely motion-blur free action shots and it was overcast! ( i was using ISO 400 - which is still very acceptable in terms of noise)

Hi Tom,

IMHO the faster glass is always better quality glass than the more main-stream so-called consumer glass. In other words, yes the F2.8 lense will almost certainly take better images than a more consumer oriented F4 lense, but not for the reasons you think.

It's not really that the F2.8 isn't 'straining' to shoot at F4 but the F4 lense is, its just better quality glass, better coatings, etc etc (read more expensive) that go into the F2.8 lense. This is not necessarily always the case, but close enough.

One exception that comes to mind may be something like a stock 50mm F1.4 or F1 lense. Even though they are very fast they are also far more common (at least used to be) than your current pro or prosumer fast glass. I'm not sure if they have superior optics as well as just being fast.

Hope this helps, and as usual its just my 2c worth.

Wayne

Hi Tom No it is not a dumb question.... The faster lens at 2.8  will not be that much sharper than a very good f4, but in order to let in more light the lens has to be bigger and bigger makes them more expensive, but opens up another question in the design like flare.... One of my sharpest tele zooms  I own is the 70-200 f4 L compare the size to the 70-200F2.8, L IS and you can see that the extra size and weigh, sure it can play a part in getting good shots thankfully the 2.8 has Image stabilising and  along with faster optics will allow for better shots as they can be at higher shutter speeds.. 

Designs are improving all the time the latest f4 L in that range has now got IS with a 4 stop range making that  also a great contender.... The final points are,  that in the f4 70-200 the lens is light weight and a simple design so it can be easily hand held, and having less glass kind of makes up for the better design of the faster lens and image stabilising.. Most lens lose quality at the edges of the frame, and on a sensor with 1.5 to 1.6 crop it is also less critical than full frame sensors, and you get more reach with any tele zoom...  (without having to crop)

You can as has been suggested also overcome the lack of speed by pushing up the ISO this however will then make the lens more prone to blown out highlights... (and more dependant on how good the sensor is regarding noise)  I guess after all that, it comes to the law of diminishing returns a Sigma 2.8 300 mmm at 1500 pounds here in the UK would certainly give any of the main makers a run for its money and save you 1500 as well

I have never heard of the manufacturers using different glass or coatings between different lens of the same range even though the maximum aperture is different. They have certainly missed a huge marketing ploy if they do and that seems very unlikely.  The glass and coatings on say  Canon 70-200 F4 L lens which Danny has mentioned and the glass and coatings used for the 70-200 F2.8 L lens are the same as far as I know. The difference in price comes from the difficulty of manufacturing the larger diameter lens to the same quality as a smaller diameter lens. 
Danny has also made a very valid point about weight. It is slightly off topic, but if I were a sports photographer who had to carry it round all day getting action shots I would be taking the 70-200 F4 and not the F2.8.  Many professionals actually do, and vouch the quality is indistinguishable between the two, the only difference is with one your arms and shoulders are going to ache, with the other not so much.

To get back on topic no lens is going to work as well at the extremes of its range as it does at the median. So yes if you need to shoot F4 get a F2.8 and stop it down and you will get a better image marginally. The difference is not going to be noticed by most photographers though as modern lens are very good at what they do in general. The difference as I understand it would be caused by reflections within the tube of the lens so lessening the contrast of the image. With the larger barrel of the larger aperture lens you would have more tolerance when stopping it down a stop.  However I think the main reasons are ones Danny has touched on. Brighter viewfinder image & quicker focus, most shots are not going to be made at the largest apertures on these lenses in my experience. It is much more likely you are going to be stopping down to F8 or thereabouts to get the dof you need and at mid apertures the difference in the lens is going to be indistinguishable for ones of the same quality. 

As a side note to this, the quality will also fall off if you start using a lens at the smallest aperture. This is caused by refraction of the light around the leaves of the aperture opening.  Hence when I shoot a landscape shot I rarely stop it down beyond F22 even though my lens would go much smaller.  This effect is particularly noticeable on compact cameras where F8 is smaller than a pin hole !

In the previous thread mentioned I suggested a F2.8 lens simply because a 2x converter could be used to obtain 400mm. So in that instance to go for the F2.8 lens gives you great versatility. You would have a great lens operating in the 70-200 range on its own, but is is large enough to add a the converter and still give very acceptable results at 400mm. If you add teleconverters to smaller aperture lens you will slow the focus down and eventually it will not work at all beyond F5.6 on most cameras, and yes I do know there are dodges around that if it is only just on the limits and you have a good camera. For wildlife shots you are most likely going to need the 400mm or even a bit more. 

As mentioned above no lens will perform as well at the extremes of its range as it will in the middle, they are all a compromise in one way or another. You can eliminate one of the factors though, and go for a prime lens and this will be optimised for its length of course and won't have to compromise to work acceptably over a whole range of focal lengths. The same will apply however with regards to apertures as applies to the zoom lens.

Perhaps when someone suggests to you to always get the fastest lens you can, you could ask if they carry it around all day? Ask a press photographer at a golf tournament. I reckon a few of the wiser ones will be carrying the F4 not the F2.8 and for one reason only - the weight ! 

and photography thus evolves into an endurance sport...

Sorry  Onslow, dont buy that!....

quote: Perhaps when someone suggests to you to always get the fastest lens you can, you could ask if they carry it around all day? Ask a press photographer at a golf tournament. I reckon a few of the wiser ones will be carrying the F4 not the F2.8 and for one reason only - the weight !

Well thats fair enough Jim. 
But no point in saying you don't buy it unless you give your reasons.

Please explain what advantage the F2.8 lens has, and contribute to the thread in a constructive way to answer Tom's question.

Sorry Onslow.... I am answering your reply!!

What is the weight diff actually?

30 and a half ounces if we go by the Canon versions which Danny was referring to.

To put that in perspective that is more than the total weight of my camera body a Canon 30D and more than the weight of a Canon 5D.

Yeah or The f/4 is about half the weight of the 2.8 (700g vs 1350g  there is a different coating Richard. on the f4  It has a calcium flourite lens element (the 2.8 does not...has UD instead).

Thanks Danny I did not know the coating is different. 

Presumably an improvement to reduce flare and reflection ?  

Yeah the larger lens means they had to improve that I had assumed as well

Onslow, yer ever held a 70-200 2.8 ?....no big deal!
Whats the weight of the 100-400 Dan? 

1380g Jim

ok...thanks Dan... the weight isnt the issue then?
Lets think about this...
5D with the EF 500 weighs...11lbs..very handholdable!
Where 's the problem in weight?

I would think weight problems may very well depend on the hands carrying the camera and lens.  This would be an individual choice.   Too much extra weight would bother me at bit, with little cartiledge left in my left wrist...so, there are personal choices to make.

Richard, as you mentioned limits on acceptable aperture, I rarely shoot at wide open and even more rarely stopped beyond  f/18.  Generally, my tele shots are in the f/8 range or there abouts and all works well.

Tom.

Sorted then Onslow

Not for me I would love the 2.8 IS version as it is much the same weight as the 100-400 esp for the in flight shots where f4 is pushing it ... I would say that the f4 is very sharp and would be better for Sports photography when it's lighter weight and shorter length would be great for crowded places where we dont have the room we get out in the field..

Out in the field you can take a break once in a while....: )

Oh come on Dan... the 2.8 isnt THAT longer!

Well all that all got well off topic didn't it talking about the weight of specific lenses and Tom's got a Nikon anyway :D

The original posted question and the main body of my contribution was about lenses in general not about specific makes.  

Like Tom I would be interested if there are any specific optical reasons why someone should buy the fastest lens that is available when what they want to shoot is covered by a lens that is perhaps a stop slower, given that the quality of both optics is the same ie. lens coating and glass?

I gave my opinion based on what knowledge I have - always happy to hear of any other opinions though.

Thaks Richard.

Quote: Like Tom I would be interested if there are any specific optical reasons why someone should buy the fastest lens that is available when what they want to shoot is covered by a lens that is perhaps a stop slower, given that the quality of both optics is the same ie. lens coating and glass?

That really is the subject.  I see little specific optical reasons, mostly user opinion and that is fine and good...but who compares the lenses?  Apparently some have and use the "ligher to carry" but "slower lens" and find that to do the job just fine.   

I asked the question simply because "fastest lens" is the general recommendation with little reason exactly why!   A local man who teaches digital photography and does fine work told me once the f/4 would do just fine in almost all instances. He saw my lens and was pleased with it.  He was also the only one not to immediately recommend the fastest lens right off the bat.   It all comes down to results.  

We hear hearsay and perhaps repeated "urban legends" or pride of ownership of the most costly lens...who knows but all that is off subject as to terchnical reasons "why".   Even scholars repeat the mistakes of those they use for resources...

(If my f/4 does the job just fine, why should I spend three times as much for another lens when I cannot afford it in the first place? That would be false economy and money spent which could possibly be spent on another prime.)

Thanks for the comments.          Tom.

edit - and a faster lens is a godsend for action shots - if you notice my recent series they are all f2 with my canon or 2.8 with my sigma - that made for shutter speeds in the thousandths and completely motion-blur free action shots and it was overcast! ( i was using ISO 400 - which is still very acceptable in terms of noise)

Inshaala nailed it on the head.

You'll see sports photographers on the sidelines at football games with masive lenses with wide apertures because when all the way open they will have faster shutterspeeds to stop any and all action. And when the sun gets lower they'll need that fast shutter for shooting subjects in the shade. THEN when the sun goes down and they have to shoot in the supplied artificial light... You get the idea. It is for speed and speed alone.

The same thing is reccommended for those who shoot events like weddings to minimize motion blur in low-light situations - but with the advent of IS, OS, or VR systems (as well as faster ISO speeds - keep in mind this advice has been consistant from the 70's when a blazing fast ISO was 160!) this is less needed.

Any differences between 2.8 lenses and 4/5.6 lenses will be pretty much unnoticeable when care is taken for the quality of the shot - shoot the shot well and no one will know what was used.

Hope that helps-
-Lew ;-)

I agree on the need for speed in certain situations, a valid point.  Much, it appears, depends on the type of photography one is apt to be doing.

Quite right Lew... and even more so if you have to have the lens wide open you are not going to get the sharpest images in any case.. So yes Tom your f4 will certainly do the job for you, and the only time it is worth considering the extra expense of the 2.8 etc is if you are going to earn a living, or it is important to be able to get a shot in the widest possible conditions..

ya never see a f4 macro or a 2.8 600mm

The f4 macro - not usually outside of medium or large format - and then it's usually 5.6-9.
The dream of a 600 f2.8 - good luck holding it still ;-)

:b_lipssealed:

Nuther one bites the dust!...see yah!...gone gone gone!!!!!!!!
Ya know where to find me...if ya wanna!...and no,  dont mean Pg!

Just figured I wasn't gonna respond to that since it was only for argumentative purposes.
And I'm not here to argue.

:glare: :huh:  Nuff said.       Thanks for the good info overall.      Tom.

Thank you so much for this subject I think I will do this weekend the same pic to flamingo with my older Sigma 70-200 F4-5.6 and the last 70-200 F2.8 Apo EX DG macro. and check the diference. I´m sure will be some and you can comment better..you know many more about that.. Than you so uch for this thread is very useful to me. 
Thank you very much Tom, Danny, Onslow and all the people write here..

Littlejock, I am very glad you have your new lens. Yes, a lens like this is more weight to handle and that does take becoming used to.   I look forward to you photos.  Please keep in your thought, your shots with the new lens will be better with more experience.   That is how it was with my f/4.   At first, I was unsure and as more shots were taken, the lens proved its real value.  The lens had not changed but I had learned how better to use the capabilities.

I am grateful for being any help here. There are many on 'rosity who know much more than I.  I am very happy such kind people reach out and share with all of us who need advice from those with more experience.

Peace to You and Happy Photography!        Tom.

thanks Tom for a lively forum, quite entertaining actually. I am wondering if someone can explain this to me in plain english as I am looking at getting a Zoom lens modified to fit my Canon A95 Powershot.
I want to be able to capture the far side of the motor racing track, wildlife and other things in the distance and people and animals in motion etc. So I was wondering how this all would relate to my sitution if at all.

Sure you will need to check that the 37mm filter size is small enough that the adapter doesn't block the AF-assist beam/self-timer lamp or the red-eye reduction lamp, and you will lose a at least 1 fstop perhaps more.... I  doubt that you will get that great a result due to these limitations.. So check the specs carefully for the adapters you will buy...

Thanks Danob,  I forgot to mention that I already have an adaptor for the macro lens that is designed for the camera so I know that fits, I just dont want to be overwhelmed with numbers and specs that I dont understand. Any suggestions as to what I sort of lens/specs I should look for are greatly appreciated. (or directions to other forums that may help.) Jenny

Well Jenny these adapters will fit on the front threads of the existing lens or slip over them... They will be designed to make the best of what is going to be less than ideal in terms of lens design, but as I am sure you have found with the wide angle adapter, can give surprisingly good results, and offer those who do not own an SLR one way to be able to get shots not possible...  You can look on the internet... My own view is to go for the official Canon ones.. But I have heard quite good things about this companies products and they appear to be good value for money : http://www.lensmateonline.com/newsite/A95A80.html

Attached Link: http://www.marietta.edu/~mcshaffd/macro/telephoto.html

50mm is considered 1:1 or close to 1x in photo use. 100mm is twice that and would give a 2x or two times larger(or "closer") view.    I don't know how far it is to the other side of the track you want to shoot but keep magnification in mind.  It takes a huge lens in mm terms to give a lot of real magnification.   And as Danny said, that generally means a drop in f stop, more light needed to get the job done.

The link might help in some general terms but is not directly applicable to the adapter you may have in mind.          TomDart.

Jenny, did I miss something? You said "zoom lens modified" to fit your camera. I am not familiar with the Camera, btw.   Are you getting a new lens or planning to use an add on such as a dipoter that goes on the front of your camera lens?   Humm...       Tom.

Ummm, sorry Tom. No oddities except my grasp on termonology. blush I am after a lens that brings objects closer and/or captures motion such as sports better. Which terminology should I use?? What is the difference?

Your camera has a built-in lens.  I thought you were going for a modified lens to replace the current one...not a direction to go considering price and that did not make sense.  There are add on telephoto converter lenses available.  Remember what Danny said about the converter possibly blocking some key functions of the camers simply by size and being in the way. For macro photography, there are "diopter" lenses which go on the front of the original lens like a camera lens filter.  I think you are familiar with that from what you said.

A slr (single lens reflex camera) or other camera that uses removable lenses is one thing. Another lens is attached instead of the one being used on the camera. With a built-in lens, you need a converter of some sort, like the diopters used for macro shots.  

One telephoto converter is the TC-DC52A teleconverter, by Canon. This extends the zoom by 1.75 times.  For instance, if the normal lens is at 100mm, the converter sees it like 175mm, yes, a closer view by about 1 1/2x more.    A company named raynox also sells telephoto converters for camera with built-in lens.    

Don't expect the world to come really, really close this way.  It will be closer but not like using binoculars or a telescope, not nearly that.   If 100mm like 2x normal, then 175mm is like 3 1/2x normal.   Whew, now I am confused myself...hope this helps a little in terminology.   

Long day, still trying to recover from Christmas in the jewelry biz...see ya later.  I have to get to zzzzzzzzzzzland.       Tom.

Jenny, had to check the cat food before going to sleep..and had one thought. These teleconverters simply change the focal length of the lens.  For instance, if shooting at  40 mm , with the 1.75 converter the view is like that of a 70mm lens, etc.  (40mm x 1.75).   Focal length determines the wider angle or closer view, i.e.  20mm for wide angle to perhaps 200mm for telephoto. Remember, 50mm is about normal view with the eye. Others who have used teleconverters might tune in and give some real life advice or you might want to start a thread to ask about that for more answers.

I suggest if you can possibly find a dealer with one in stock, slip it on the camera and take a look first. See what you are getting and snap a few shots.  Finding a stocking dealer will be the problem.   now, to zzzzzzzzzzland.        Tom.      

Purr away Tom. I will start up a link to another thread when I get home from work, hopefully now I can avoid the above confusion. sorry to hijack your thread Tom, it was accidental. Sweet dreams. thanks Danob as well. Both have been a great help. jenny

I feel more "introduced" than hijacked.  I am purring, with two kitties at least next to me.  They always sleep there and are warm.   Good wishes on the new thread.      Tom.

Night Tom. Give the kitties a nice cheek rub for me. jen

*One telephoto converter is the TC-DC52A teleconverter, by Canon. This extends the zoom by 1.75 times.  For instance, if the normal lens is at 100mm, the converter sees it like 175mm, yes, a closer view by about 1 1/2x more. 

Tom I think you may have hit on the answer for me! This IS the lens for my little camera, I missed it because it is not available in Australia!!! (naturally) By entering it into the search field at the Canon website I found it!!!! Yaaaaay! I could Kiss you for this! ah darn it I will!

KISS, KISS KISS, KISSKISS, KISSKISS, KISSKISS, KISSKISS, KISS

blush Sorry folks but I have been searching for ages and got carried away. Now I have to find out how much it will cost me, see if I can get it into Australia and see if I can hint at it for Mothers' day from my lovely, darling hubby. sigh seriously, thanks for all your help, most of it is still beyond my comprehension but I am slowly learning. Thanks Tom for the use of your wonderful thread, I return it to you with great joy and hope you find your answers to the not so dumb question soon. 
Bye for now from a very happy Jenny.