Factors to consider in buying Prime Lens


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Dec 3, 2008
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#1
Hi,

I am new to photo taking, so would like some advise on what considerations to take into when buying a prime lens.

I am currently using a D70 camera which comes with the usual Kit lens. I am considering one of the following prime lens as I would take some photos of people motion eg. dances, stage performances in dim light without the use of flashes (usually not allowed in performances).

I have asked around, and seems that there are some in the range:

1) f1.8 50mm (around S$200) (give or take S$20)
2) f1.8 85mm (around S$700)
3) f1.4 50mm (around S$700 - think so, can't remember)
4) f1.4 85mm (around S$1,800)

What are the factors I have to consider when choosing one of these lens?
I understand that there will be a price gap for different apertures, but why does the 50mm lens and the 85 mm lens differ by more than double the price for the same aperture?

What about speed of autofocus, whether the autofocus function can work on D70? Are these things I have to find out, or are they a given?

Are there any other factors affecting the quality of pics taken in these lens?

Thanks in advance.
 

zac08

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Feb 21, 2005
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#2
Size of the glass is an indication on the price...

Anyway, for your application, you should be looking at the 85mm's

You won't be in range using a 50mm....

actually, you may be even better off considering a 70-200 f2.8 due to the distance.
 

dennisc

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#3
The question should be rather, what is your budget range? If you've the moolah, just get the f1.4 or even f1.2

50mm vs 85mm differs in range and complexity construction. 85mm gives you more bokeh.

Ever wondered why a 35mm f1.4 lens cost even more? In terms of autofocus speed, you need not worry bout any of it here, it's almost instantaneous even with the D70.

Quality factors should be the flaring, softness, overexposure probs, etc, the usual. Between 1-4 choices, it all looks the same to me, can achieve almost the same results (though I've to admit, I've never use a f1.8 before, straight jumped to f1.4 and f1.2)
 

lBlOlSlSl

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#4
Personally there's nt much differences between 50mm f1.8 and f1.4 other than the bokeh maybe. Same goes for the 85mm f1.4 and f1.8. The price difference between them are almost double and only for 2/3 stop. so if you ask me, f1.8 is good enough for me. I have never tried the 85mm still sticking to my faithful 50mm f1.4.

If you are trying prime lens for the first time, I suggest you take it easy on the spending as you might need some adjusting to the framing of the pic. Its unlike taking pic with other lenses.


Hope this helps.

Cheers~
 

Dec 3, 2008
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#5
Thanks guys. That really helped narrow down the options :cool:


Anyway, for your application, you should be looking at the 85mm's

You won't be in range using a 50mm....

actually, you may be even better off considering a 70-200 f2.8 due to the distance.
The problem is that I am afraid a 85mm will be too narrow, and a 50mm too short...you just can't win them all, can you? LOL.

Yep, I'll start checking out the specs for 70-200 f2.8. The reason why I am looking at Prime lens is because I heard that the 70-200 f2.8 is no cheap.

The question should be rather, what is your budget range? If you've the moolah, just get the f1.4 or even f1.2
I got Moolah...I'll buy them all! :lovegrin:
Actually the f1.4 85mm is already way out of my range, but I am still looking at it because I want to know what I am actually missing out.

50mm vs 85mm differs in range and complexity construction. 85mm gives you more bokeh.
Sorry for a noob question...what's 'Bokeh'? From what i read from the forum, seems to mean the sharpness of the image that is within the depth of field?

If you are trying prime lens for the first time, I suggest you take it easy on the spending as you might need some adjusting to the framing of the pic. Its unlike taking pic with other lenses.
What is the main difference between using the prime lens and the usual kit lens apart from not having the zoom features? Is it to do with the 'crop factor' thinggy?

Agree with the easy spending part totally!! My main concern is whether i will find that I want a 85mm f1.8 a few months after I get a 50mm f1.8.
Which is why I want to know as much as I can about the difference between them.

Hey, really appreciate your advises, guys!

Cheers.
 

billycadiz

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Oct 3, 2008
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#6
bokeh is the japs term for blur..;)
sorry to hijack this thread but its the same topic..
Mr.zac, does the 70-200f2.8 have the similar bokeh of that 50f1.4?:dunno:
 

geraldkhoo

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Jun 15, 2007
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#7
The number of aperture blades does affect the shape of the bokeh. The AF-D 50mm f/1.4 has 7 blades, and the new AF-S 50mm f/1.4 has 9 blades. The more blades means that it is able to form a nicer circle, which means that the shape of the bokeh on the AF-S 50mm f/1.4 would be nicer than the AF-D 50mm f/1.4. The AF-D 50mm f/1.4 sometimes gives you a bokeh that is polygonal, depending on what aperture you are using.

Both 85mm f/1.4 and f/1.8 have 9 blades to the aperture, which means that the bokeh for both lenses are very nice. At almost every f-stop, the bokehs still come out rounded, but for the 85mm f/1.8D lens, there are certain f-stops where it is not rounded, but can see the polygonal shape from the aperture blades.

As a general rule of thumb, a lens is at its sharpest when it is about 2-stops down in the aperture. Between f/1.8 and f/1.4 may be 2/3 stops, but the f/1.4 is still sharper at a lower aperture than the f/1.8. Price wise, the f/1.4 lens is about 3 times that of the f/1.8 lens, but it not only owes to the glass, but also the build of the lens. Lens tests have shown that in most aspects, the f/1.4 lens is better than the f/1.8 lens for both the 50mm and 85mm lens.
 

zac08

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Feb 21, 2005
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#8
Thanks guys. That really helped narrow down the options :cool:

The problem is that I am afraid a 85mm will be too narrow, and a 50mm too short...you just can't win them all, can you? LOL.

Yep, I'll start checking out the specs for 70-200 f2.8. The reason why I am looking at Prime lens is because I heard that the 70-200 f2.8 is no cheap.

I got Moolah...I'll buy them all! :lovegrin:
Actually the f1.4 85mm is already way out of my range, but I am still looking at it because I want to know what I am actually missing out.

Sorry for a noob question...what's 'Bokeh'? From what i read from the forum, seems to mean the sharpness of the image that is within the depth of field?

What is the main difference between using the prime lens and the usual kit lens apart from not having the zoom features? Is it to do with the 'crop factor' thinggy?

Agree with the easy spending part totally!! My main concern is whether i will find that I want a 85mm f1.8 a few months after I get a 50mm f1.8.
Which is why I want to know as much as I can about the difference between them.

Hey, really appreciate your advises, guys!

Cheers.

Simple exercise. Do you have a zoom lens currently? Say a 18-70 or better still a kit lens from D80, etc... 18-135 type.

If so, try setting the zoom to 50mm and then you do a series of shots on subjects which you deem would be the distance from the seat to the stage. Thereafter, you try again using 85mm zoom.

This will show you which focal length you would want to consider.

Yes, a 70-200 is not cheap and will cost approz 2.5k. But if you are looking at this focal length, do consider the Tamron or Sigma versions, which would cost about less than 2k, no updated prices for these 2 yet.

A prime lens has a fixed focal length and to frame a picture, you may need to move back and forth. And this is not possible if you are sitting in the seats during a concert or performance.

As for wanting after getting.... well, my dear Fren, it's called the BBB virus... you'll never stop. :bsmilie:
 

zac08

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Feb 21, 2005
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#9
bokeh is the japs term for blur..;)
sorry to hijack this thread but its the same topic..
Mr.zac, does the 70-200f2.8 have the similar bokeh of that 50f1.4?:dunno:

Bokeh will depend on distance of subject to camera, distance of subject to BG and aperture used. So they will not be the same at the same distances....
 

nakedtoes

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Jan 12, 2004
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#10
I m thinking of this.. i use my 18-200 vr2 to play around.. to comapre the range of a fixed 30mm and a zoom 18-50mm

I set at 30mm and to get to the 18mm range i need to walk 3 steps back.. to get to the 50mm range i took 3 steps forward.. zoom with my legs... i think a fixed prime is a much better choice.. i loves my 30mm f1.4 and my legs:bsmilie:
 

zac08

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Feb 21, 2005
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#11
I m thinking of this.. i use my 18-200 vr2 to play around.. to comapre the range of a fixed 30mm and a zoom 18-50mm

I set at 30mm and to get to the 18mm range i need to walk 3 steps back.. to get to the 50mm range i took 3 steps forward.. zoom with my legs... i think a fixed prime is a much better choice.. i loves my 30mm f1.4 and my legs:bsmilie:
But note that the perspective of the subject to the BG will change.

Also a wider angled lens will lengthen the features while a narrow one will compress the features... be careful with this when doing portraits.
 

aryanto

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Feb 16, 2005
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#12
before you buy think for a while what kind of photoshoot are you aiming to do with the prime lense.
for event you need to know your distance & subject, that should determine your focal length, buying incorrect one means waste all your money.
 

Dec 3, 2008
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#13
As a general rule of thumb, a lens is at its sharpest when it is about 2-stops down in the aperture.
Does that mean that if I get a f1.8 lens, and to get sharp images I will typically set it at, say f2.8 instead of setting it to the widest while I am taking the photos?

Both 85mm f/1.4 and f/1.8 have 9 blades to the aperture, which means that the bokeh for both lenses are very nice. At almost every f-stop, the bokehs still come out rounded, but for the 85mm f/1.8D lens, there are certain f-stops where it is not rounded, but can see the polygonal shape from the aperture blades.
Sorry for being noob...but I think I am not sure what 'rounded' and 'polygonal' bokehs mean (considering I just learnt the word 'bokeh' now). At what 'angle' (for a lack of better word) can I tell whether a part of the picture being rounded or polygonal? Or is it something I can see if I enlarge the photos?


If so, try setting the zoom to 50mm and then you do a series of shots on subjects which you deem would be the distance from the seat to the stage. Thereafter, you try again using 85mm zoom.
I set at 30mm and to get to the 18mm range i need to walk 3 steps back.. to get to the 50mm range i took 3 steps forward.. zoom with my legs... i think a fixed prime is a much better choice.. i loves my 30mm f1.4 and my legs
Good ideas,Thanks! I will try them out with the zoom lens first. The crop factor should be the same, I believe?

before you buy think for a while what kind of photoshoot are you aiming to do with the prime lense.
for event you need to know your distance & subject, that should determine your focal length, buying incorrect one means waste all your money.
I am actually thinking of very dim light conditions, eg. performance at stages or something like the street performances you have just behind the Esplanade. Distance probably ranging from 3m to, say, 30m. Focusing on one or two members of the performance rather than the whole stage (but of course with sufficient background). And of course, being totally new, I would also like to a have a lens which I can 'walk on the streets' with for taking photos under normal lighting.

~~Hmm am I making much sense here? :embrass:
 

zac08

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Feb 21, 2005
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#14
Does that mean that if I get a f1.8 lens, and to get sharp images I will typically set it at, say f2.8 instead of setting it to the widest while I am taking the photos?

Sorry for being noob...but I think I am not sure what 'rounded' and 'polygonal' bokehs mean (considering I just learnt the word 'bokeh' now). At what 'angle' (for a lack of better word) can I tell whether a part of the picture being rounded or polygonal? Or is it something I can see if I enlarge the photos?

Good ideas,Thanks! I will try them out with the zoom lens first. The crop factor should be the same, I believe?

I am actually thinking of very dim light conditions, eg. performance at stages or something like the street performances you have just behind the Esplanade. Distance probably ranging from 3m to, say, 30m. Focusing on one or two members of the performance rather than the whole stage (but of course with sufficient background). And of course, being totally new, I would also like to a have a lens which I can 'walk on the streets' with for taking photos under normal lighting.

~~Hmm am I making much sense here? :embrass:
Yes...

with a f1.8 lens, you'll get optimum results at f2.8 to f4.

Let me see if I can find an example...



This is rounded bokeh, I used the lens wide open. This will also occur on the better lenses which has more blades to round off the aperture opening.



This has polygonal bokeh, which happens when I stop down the lens on my 50mm f1.8 to about f2.8. There are less blades present and as such when the aperture is reduced, there are obvious angles instead of a round opening.

You can look at your lens and try to close them to see this effect.

At 3m, you can get away with even a 24mm. At 30m, you'd want a long lens to get up close say 180 - 200mm or so...
 

Dec 3, 2008
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#15
Ahhhhh...okok. Thanks for the illustration.
Can tell that the light 'dots' have a round or polygonal shape. ;)
Are the 'light dots' in the background the only thing that gets affected, or are other aspects of the photo different as well?
 

aryanto

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Feb 16, 2005
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#16
I am actually thinking of very dim light conditions, eg. performance at stages or something like the street performances you have just behind the Esplanade. Distance probably ranging from 3m to, say, 30m. Focusing on one or two members of the performance rather than the whole stage (but of course with sufficient background). And of course, being totally new, I would also like to a have a lens which I can 'walk on the streets' with for taking photos under normal lighting.

~~Hmm am I making much sense here? :embrass:
So you are aiming to get more like a fast lense (low apperture lense) rather than a prime lense but you choose prime lense because you think it is cheaper (which is true).
The highest you want to go is F2.8 for ambient light, at night.

If you are using a prime lense, what you capture at 3m (close up) is different totally from what you capture from 30m (landscape of crowd, stage with performer as miniatures). I hope you understand that.

You have to trade-off the zoom power with leg zoom (walk closer / further).
I think it is best if you rent or borrow before you buy to get a hang of the lense first and see if that is suitable for you.
 

Dec 3, 2008
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#17
So you are aiming to get more like a fast lense (low apperture lense) rather than a prime lense but you choose prime lense because you think it is cheaper (which is true).
The highest you want to go is F2.8 for ambient light, at night.
Precisely. I can't afford a F2.8 Zoom lens.
Though it will be a nice thing to look forward to own.

I think it is best if you rent or borrow before you buy to get a hang of the lense first and see if that is suitable for you.
Are there people who actually rents out lens? How much should I expect the rental to be?

Yes...

with a f1.8 lens, you'll get optimum results at f2.8 to f4.

Let me see if I can find an example...
BTW, the expression of the cat in Zac's first photo is so cute, can't help but to keep looking at it and smile. :bsmilie:
 

aryanto

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#18
Precisely. I can't afford a F2.8 Zoom lens.
really?

hm.. 25mm f2.8 zuiko (olympus pancake) roughly $360 but I bought second hand at $250. This is now my default "lense cap" when it goes in the bag.
Or get a faster lense Sigma 30mm F1.4 (4/3 mount). Roughly $600 but I bought second hand at $500.

You can get E510 or E520 (in-body image Stabilisation) if E-3 is too expensive.
Buy second hand too to lower the price.

I bought E-3 body only a year ago because I really want it. LOL.
With that 2 lense and olympus 2x crop, 100% viewfinder, or tilt-livefiew LCD, I am free to roam at night. :lovegrin:
 

zac08

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Feb 21, 2005
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#19
really?

hm.. 25mm f2.8 zuiko (olympus pancake) roughly $360 but I bought second hand at $250. This is now my default "lense cap" when it goes in the bag.
Or get a faster lense Sigma 30mm F1.4 (4/3 mount). Roughly $600 but I bought second hand at $500.

You can get E510 or E520 (in-body image Stabilisation) if E-3 is too expensive.
Buy second hand too to lower the price.

I bought E-3 body only a year ago because I really want it. LOL.
With that 2 lense and olympus 2x crop, 100% viewfinder, or tilt-livefiew LCD, I am free to roam at night. :lovegrin:
Zoom.. not prime.

a 50mm f1.8 prime is only $180... but a 24-70 f2.8 zoom is more than 2.6k :sweat:
 

aryanto

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#20
Zoom.. not prime.

a 50mm f1.8 prime is only $180... but a 24-70 f2.8 zoom is more than 2.6k :sweat:
Thread starter talking about prime lense bro. ;)

If you want to compare specs look for SHG (super high grade) F2 zoom lenses from Oly. Fast lense, but drain $$$ from wallet very fast too. Plus not immediately available, must order from shops cos too ex normally they do not keep in stock. :sweat:

Prime lense is always cheaper because the design is simpler and they use less glass in the first place. There is less mechanism (only to allow AF) and not having to deal with "zooming".
 

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