Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Nikon dSLR

Reply
 
Thread Tools Search this Thread
Old Feb 24, 2005, 2:46 AM   #31
Junior Member
 
Join Date: Feb 2005
Posts: 25
Default

NHL wrote:
Quote:
The reason 'fast' lens are HUGE is that the max aperture is a ratio: :idea:
http://www.srphotography.co.uk/srpho...read.php?p=340

It's by design that they are larger as comparable to variable aperture zoom where this ratio varies because the lens diameter stay constant while one increase the focal lenght

Prime lenses are always sharper because they are much simpler to design (ie less elements), and also no worry about keeping this aperture ratio constant... Can you live with the inconvenience though? I have an 85mm f/1.2 as well as a 150mm f/2.8 too, but I use them in specialised situations: the 85 is mainly for portraits while the 150 is my macro :?
the tamron 28-75/2.8 and the sigma 24-70/2.8 cover about the same range yet the tamron is 67mm and the sigma 82mm. not that i am complaining but i would have assumed that their diameters be about the same. also sigma has a 28-70/2.8 and 24-60/2.8. these are 67mm and 77mm respectively.

so a tamrom 28-75 has the same glass dia as the 28-70 but the 24-60 needs more glass. obviously wide angle lenses and telephotos need more glass than "normal" lenses. for examplethe sigma20-40/2.8 lens with a 2x zoom ratio will need larger glass (82mm) than say a the Nikon 35-70/2.8 that uses 62mm glass right??

so it is not only the zoom range and fixed maximum apeture that nessiciates larger glass but also how far the zoom operates away from the "normal range". similarly a 85/1.8 lens uses 62mm while a 180/2.8 lens uses 72mm glass while a 50/1.8 lens uses only 52mm glass.

primes lenses are sharper but not only has to put up with the inconvience one also has to constantly change lenses exposing the CCD to dust. for a digital SLR i wold not venture beyond a "2 zoom". that is one reason why i prefer the 100-300/4 to the 70-200/2.8 with 1.4TC becuase adding the teleconverter means one more change. I dont think there will be that much of a difference in the light required between a F2.8 and F4 lens. if the light is not enough for F4 lens in all probability the F2.8 lens wont fare well either. (this last bit is with respect to the sigma and nikon 70-200, 80-200 and 100-300 lenses mentioned earlier).
navin advani is offline   Reply With Quote
Old Feb 24, 2005, 4:10 AM   #32
Senior Member
 
cameranserai's Avatar
 
Join Date: Jun 2004
Posts: 548
Default

Interesting though, that the 17/55 and 17/35 Nikkor lenses are so similar in weight despite the different focal length. Both use 77mm filters, the 17/55 weighs 755 grams and the 17/35 only 10 grams less. Also the 17/55 has 14 elements and the 17/35 13. I know the 17/35 is supposedly sharper, but not to the naked eye, and to all intents and purposes the 17/55 seems the more practical lens in everyday use. I certainly have got some superb portraits with it.
cameranserai is offline   Reply With Quote
Old Feb 24, 2005, 6:23 AM   #33
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

navin advani wrote:
Quote:
the tamron 28-75/2.8 and the sigma 24-70/2.8 cover about the same range yet the tamron is 67mm and the sigma 82mm. not that i am complaining but i would have assumed that their diameters be about the same. also sigma has a 28-70/2.8 and 24-60/2.8. these are 67mm and 77mm respectively.
... and I agree completly!

However you fail to notice that the larger lens is suited for a full-frame camera, check the MTF curves of the smaller lenses (including Nikon's DX) -> the more compact lens sharpness drop off earlier around the cropped sensor size: :?




True you can have a smaller 'digital' lens only - then the lenses could be made more compact, and lighter since one doesn't really need as much metal to hold the smaller optical elements in place... I'm sure they don't mind saving some $ making it smaller, but would you want it though? :G


I'm thinking in term of 24x36mm, check the 1st graph - you are only using it up to ~13 with a D70:
- The best part of the lens! :idea:
NHL is offline   Reply With Quote
Old Feb 24, 2005, 1:01 PM   #34
Junior Member
 
Join Date: Feb 2005
Posts: 25
Default

i did not know the tamron is a digital only lens.
navin advani is offline   Reply With Quote
Old Feb 24, 2005, 2:24 PM   #35
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

navin advani wrote:
Quote:
i did not know the tamron is a digital only lens.
Most 'digital' lens will work on a full frame, just don't expect them to be such an outstanding of a performer at the peripherals :?

Just look at the above right chart for the 24-60 f/2.8... It's definetly sharper than the 24-70 toward the center, but drop quite steeply at the edges of the frame: This 'digital' lens would work on a full-frame too, but nowhere near the performance at the center, at least at wide open!
-> ie one needs the larger circumference!


Do you care though if all you ever use is a D70? :idea:
NHL is offline   Reply With Quote
Old Feb 25, 2005, 12:24 AM   #36
Junior Member
 
Join Date: Feb 2005
Posts: 25
Default

does this chart exist for teh tamron 28-75 XR di too?

Thereason I am doing all this research is that I expect to hold on to atleast some of my lenses even after i upgrade the camera body to a full frame DSLR (when they become affordable).

3reasons I am still sitting on the fence on teh D70

1. the issue of dust on the sensor.

2. a flip screen like my circa 2001 Canon G2 P&S so that one can "see" around corners.

3. the D70 is not yet available in India (officially) and I will have to wait till i travel to the US next to purchase it.

till then I am using the time to research lenses. The 100-300/4 seems to be the best bet for a good tele zoom. The wide zoom would either be the kit lens (18-70 3.5-4.5) or 18-50/2.8 sigma or maybe a yet unreleased (i can dream cant i)wide zoom with a range from 16-60/2.8DX/DC/Di with 82 mm glass that cost undre $800. Nikon's 17-55 DX lens uses 77mm glass but costs almost twice my budget. BTW canon's 17-40/4 full frame lens also uses 77mm glass and i notice that canon is not making DX/DC/Di lenses for the smaller sensor. i guess they dont intend to cate to the small sensor format. right?
navin advani is offline   Reply With Quote
Old Feb 25, 2005, 6:24 AM   #37
Senior Member
 
Join Date: Mar 2004
Posts: 113
Default

Nikon is really committed to the DX sized sensor. The new D2X is still a DX sized sensor and it shows an unbelievable level of details. If you dont plan to use your lenses for film photography, dont worry about getting a DX LENS.
Morris is offline   Reply With Quote
Old Feb 25, 2005, 10:39 PM   #38
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

navin advani wrote:
Quote:
does this chart exist for teh tamron 28-75 XR di too?
I don't know... but in general a 'digital' lens MTF's are only plotted to 13mm (and not 24mm) - Canon EF-S series are the 'digital' equivalent of the Nikon's DX: http://www.canon.com.hk/En/Product/P...7&tag_id=10657

-> Again you can generally tell by the size of the lens (or its diameter) - You can't cheat the law of physic/optic
NHL is offline   Reply With Quote
Old Feb 25, 2005, 10:50 PM   #39
Junior Member
 
Join Date: Feb 2005
Posts: 25
Default

does this mean that bigger is better 82mm is usually better than 77mm and 77mm better than 72mm ....?
navin advani is offline   Reply With Quote
Old Feb 26, 2005, 7:24 AM   #40
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

navin advani wrote:
Quote:
does this mean that bigger is better 82mm is usually better than 77mm and 77mm better than 72mm ....?
In general - YES, but that also means a lens is also heavier because of the larger optics and the need for more metal to keep them together (instead of plastic). Plus remember manufacturers tend to save money and compete on cost - they don't give you extra unless they have to!

However you should ask yourself if you need a full-frame... With Canon 'digital' its obvious, but like the previous poster has said with Nikon it's still a question mark... I collect Nikon film cameras so this is more important for me.
NHL is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 9:46 PM.