DSLR - SLR lens equivalents

[McCormack]

I shoot mainly with 28mm, 50mm, and 200mm prime lenses with my Canon A-1, and with an upcoming purchase of a DSLR I want to continue to shoot with prime lenses, but I've read that a 50mmm SLR lens is not the same as 50mm DSLR lens. What size DSLR lens will I be needing to match what a SLR 50mm is?

[gryphonslair99]

What you are talking about is crop factor. It is different than focal length. No matter what camera you put it on a 50mm is a 50mm. Focal length does not change by going to a smaller sized sensor. The characteristics of different focal length lenses are still the same.

What you do get is a crop of the view the lens projects onto the smaller sensor. Basicly you get the sweet spot in the central portion of the lens instead of the full field of view. Some people talk about it being a magnification of the lens. It is not, a magnification, it is a crop of the field of view. You should find that you can enjoy the same lenses in the same way. You may need to take a step or two back to get the same field of view, but if you are looking for a particular characteristic for a particular focal length that will not change.

[deckcadet]

Well, if you wish to stay with primes you would need approx. an 18mm-20mm lens for the 28mm replacement, a 28/30/35mm to replace the 50mm, and a 135mm to replace the 200mm.

For either of the major brands, I'd suggest really skipping the 18mm/20mm prime in favor of a good zoom- the primes are generally older designs and don't get amazing reviews, while the modern zooms are really exceptional and go wider for less money

For the 50mm replacement, you could go for an f/2.0 35mm lens, the Canon 28mm f/1.8, or the Sigma 30mm f/1.4 EX DC HSM. The 30mm lens is DC, which is the Sigma equivalent of Canon EF-S or Nikon DX- it is designed for the smaller sensor size so if you upgrade to full frame you would need to replace it with a full frame compatible lens.

If you've got deep pockets Canon has a 35mm f/1.4L which is truly exceptional.

To replace the 200mm, 135mm is the rough equivalent. Canon offers the 135mm f/2.8 SF, and the 135mm f/2.0L for much more. The L is a wonder among lenses, offering fast focusing, professional build, and extraordinary sharpness, bokeh, and color rendition... plus an extra stop of light over what you're likely used to with your 200mm, unless of course it's the 200mm f/1.8

[McCormack]

OK, thanks for the DSLR lens education, guys.

I've never really cared all that much for zoom lenses, so I'll be sticking with prime lenses, and in order to get the proper crop it looks like I'll be needing a 35mm to replace the 50mm that I use with my SLR.

Thanks again.

[Franglais]

OK, thanks for the DSLR lens education, guys.

I've never really cared all that much for zoom lenses, so I'll be sticking with prime lenses, and in order to get the proper crop it looks like I'll be needing a 35mm to replace the 50mm that I use with my SLR.

Thanks again.

The DSLR crop factor depends on the sensor size. Canon currently have three sensor sizes:

APS-C : Digital Rebel XT, XTi, 10D, 20D, 30D (correction factor = 1.6)
APS-H : ID, IDmk2, 1Dmk3 (correction factor = 1.3)
"Full frame" : 1Ds 1Dsmk2, 5D (no correction factor)

If you buy a 5D, the sensor size is the same as on your A1 so the 50mm still gives the same view. If you get a 30D then your 50mm become the equivalent of a 50x1.6=80mm.

I prefer zoom lenses over primes for most uses. Most modern zoom lenses are designed for the specific requirements of digital cameras and in my experience do as good a job or better than primes. Plus you don't have to change the lens so often so there is less risk of getting dust on the sensor. Nowadays I use my Nikon 18-200 (equivalent of a 27-300mm) for jobs that I would have done with my Hasselblad 6x6 film camera - and I get better results.

[DEvianT]

I found I thought I prefered a zoom but noticed when I used a wide zoom most of the time it's when at wide end and when using a 24-70mm zoom it was mostly at 70mm so now tend to stick on an 85mm prime instead.
D

[McCormack]

Thanks for clarifying the sensor/lens relationship Charles, and if you're getting zoom results as good or better than your Hasselblad then I owe it to myself to at least give the DSLR/zoom lens combo a chance before I dismiss zooms altogether.

Thanks for your comments D.

[deckcadet]

some SLR wide primes (normal and tele are fine) get downright ugly on digital- softness, light falloff, chromatic aberration, the works! Digital sensors can be far pickier about the angle at which light hits, so film lenses that let it hit at the wrong angle end up really doing a poor job. The new breed of lenses designed for the digital era addresses that and more.

[McCormack]

Thanks for the heads-up on the wide primes. If I go digital I want to keep it real simple, so the only prime that I would interested would be a 50mm (or it's equivalent). I'm thinking that I'd be better off with a 50mm prime that's specifically made for digital, so I'll have to do some research and see what the various camera companies have to offer in lenses for their digital cameras.

[Loupey]

Pre-digital, I only used primes as well. When I went digital, I bought 3 "L" zooms right off the bat hoping that the advances in lens design and manufacture were sufficient for me to leave primes behind to enjoy the conveniences of zooms. I must admit that these lenses provide image quality that surpasses what I was getting with my medium format equipment as well, but...

...I'm back to using primes. I hardly ever use my zooms (I don't shoot much sports). As you know, good quality primes are still sharper, lighter, faster, cheaper (usually) than even the highest priced zooms. Of course everyone uses equipment differently and for many the conveniences of zooms greatly outweight its compromises.

Having said all that and knowing that you have an appreciation for primes, I would highly recommend the Canon 28mm f/1.8 USM for your use as a "standard" lens with an APS-C fitted dSLR. Built well, sharp, fast focusing, and it's f/1.8.

[DEvianT]

I favour primes myself and on any canon DSLR the 50mm f/1.4 USM is a cracking little lens. The 85mm f/1.8 USM is also very nice. If you want to go up the range the new 85mm f/1.2 L USM II is jaw droppingly sharp. I've heard very good things about the 35mm f/1.4 L USM also though only taken a couple of shots with one so can't really comment with authority.

Where I make an exception and have zooms I really rate are the following zooms:

16-35mm f/2.8 L USM II is just amazing easily up their with primes for sharpness but also has a certain something about the image quality that's just beautiful.
24-70mm f/2.8 L USM is as sharp as a prime. In fact they test primes against it on the bench at Canon (a contact of mine stated). Certainly I use one probably more than my other lenses (I'm on 5D with no crop factor)
70-200mm f/2.8 L IS USM the image stabalizer gives 3 stops of hand holdability extra and it is as sharp as any prime. Again this is also a lens where the colour and contrast tell a story an MTF chart can't. A cracker of a lens! Also when used with 1.4x Tele II there is no significant image loss.

Back onto primes...

The 135mm f/2 L is possibly the sharpest thing I'd ever seen until the 85mm f/1.2 L II. It's a wonderful lens.