Fast lens or slow?

Doug · 11-21-2003

Elsewhere, Peter was talking about selling a Skopar and getting an Ultron, so I raised the question of lens speed and its ups and downs. Time to give the issue its own thread, I guess.

I posted: "On the one hand, a fast lens can be stopped down if you don't need the speed immediately, and wouold seem flexible in offering those wide apertures. But they're big and expensive, and the speed doesn't help focusing as it does in an SLR. Only real need is for low-light and if you want short DOF.

"A modest aperture lens may be very compact, light, sharp, and modest cost. Easy to carry... But it cannot crank open to wide apertures in case of need.

"I've been following the slow-lens Skopar/Heliar path but I hear the siren song of the Ultrons and Noktons!"

And Peter replied: "I have pondered upon this question ever since I am bitten by rangefinder photography. I would think a fast lens would be useful for low light or indoor photography and I bought the Ultron for the latter reason. But IMHO a rangefinder would be better served by a wide angle lens with a moderate aperture of f 2.8 as it is easier to focus, sharper and lighter in construction due to lack of heavy lens elements. All these would also means a lower cost. If not for the need to take indoor photography (as I am doing a photo essay on nurses in Singapore) I would be very happy to use modest aperture lenses and if I want to do low light photography I would use a tripod or a very fast film like Delta 3200."

So... if you use a fast lens for those indoor lowlight shots, does the limited DOF become a problem? I'd like to pop the subject out of the background at will, but having only a centimeter or two of DOF can make things difficult too! So maybe the speed isn't all that useful?

Here's an indoor shot of the type I've been concentrating on this past year. A cobbler shop / shoe repair. Quite dim inside... Shot with CLE and Voigtlander 25mm f/4 wide open, maybe 1/30 sec, handheld, with Fuji 1600 at EI 1000. Plenty of grain, but then the film was outdated too. Really shallow DOF wouldn't be so good in this shot, d'you think?

Or am I just trying to justify budget-saving slow lenses? :-)

SolaresLarrave · 11-22-2003

Doug,
At one point, I would have advocated for fast lenses, but with rangefinders, even slow lenses act kind of fast, thanks to the steadyness you can have while holding the camera, and the lack of mirror flap.

As for me, I'm nuts for fast lenses... only to a point. In a way, I'm with Peter in this matter, because, if as he says, a lens has a maximum aperture of f2.8, you don't need to shoot ISO 1600 to get a good exposure indoors. Now, if you're talking about indoor shooting of a windowless room... not even the famous miracle Canon f0.95 would do it for you!

In other words, the speed helps, but it's not as key as, say, it can be when shooting an SLR. In fact, most of the rangefinder long lenses are slow, by RF standards, with maximum apertures of f2.8 and f3.5. Is this a problem? Not really, because the RF voids the issue with slow lenses (which is the needed slow shutterspeed and risk of blurry photos) by not having mirror flap.

Let's see which way this conversation takes...

lars · 11-23-2003

I've been quite satisfied with my CV35/2.5C lens. As Solares mentioned, you can use slower shutter speeds with a rangefinder so 2.5 is actually quite useful with most indoor lighting situations. One of the reasons I bought a rangefinder is because of its small size and light weight. A fast but larger and heavier lens will remove that advantage.

...lars

Doug · 11-23-2003

Do you think RF users are more likely to actually shoot wide open, using the available speed, than SLR users?

With an SLR I'm conscious of the wide-open aperture as a focus aid, but virtually never actually shoot wide-open. A stop of so down gives me that extra bit of DOF to cover focus errors. With an RF camera, focus accuracy is not dependent on the wide aperture, so somehow I'm more likely to actually make use if it for shooting. Weird thinking? :-)

Doug · 11-23-2003

Ah, and to finish/clarify that thought... If f/2.8 is generally sufficient for the photo, yet f/2 is wanted for an SLR in the interests of focus accuracy, that reason for lens speed isn't valid for an RF, so an f/2.8 lens would be adequate if you're willing to run it wide open... :-)

lars · 11-23-2003

Quote:

Originally posted by Doug
Ah, and to finish/clarify that thought... If f/2.8 is generally sufficient for the photo, yet f/2 is wanted for an SLR in the interests of focus accuracy, that reason for lens speed isn't valid for an RF, so an f/2.8 lens would be adequate if you're willing to run it wide open... :-)

My desire for a fast lens isn't any different whether it's a RF or an SLR except that with the RF, lens size/weight also factors into the equation. In both types of cameras, 2.8 is my comfort zone. I wouldn't want anything slower for a prime lens but often times, necessity and budget end up dictating my choice anyway.

...lars

pshinkaw · 12-01-2003

Many f2.0 lenses give higher resolution when stopped down to f2.8 than do f2.8 lenses wide open. However, if you are shooting between f5.6 to f11, it probably doesn't matter which one you are using.

-Paul

back alley · 12-01-2003

shooting with a mamiya 6, my lenses are slow, but i have not found this to be a hardship at all.
of course i prefer fast film most of the time anyway and quite like shallow dof.
without the mirror slap of an slr i find i can shoot at slower speeds if necessary and still come away with sharp shots.

when i shot with canon eos i loved the 80 to 200 2.8, very sharp and the 2.8 never really held me back.
just my 2 cents...

joe

Peter · 12-06-2003

I took this picture with Voigtlander Color Skopar 35mm. Setting was 1/8 sec, f2.5 and handheld.

I deleted the image since its posted below. Just trying to save space

JT

back alley · 12-06-2003

maybe this will be easier to view.

back alley · 12-06-2003

btw peter - great shot!

joe

Peter · 12-06-2003

Quote:

Originally posted by backalley photo
maybe this will be easier to view.

Thanks Joe for shrinking the photo and your generous compliment. I tried to shrink the already downgraded negative scan with Photoshop but with no success. How did you do it so that I could share more of my photos with the rest in future. When I took this photo, it was a hasty affair as the fisherman rowed his Sampan away after I pressed the shutter release. My friend with me at that time missed the shot as he was still fumbling with his tripod.

back alley · 12-06-2003

http://www.irfanview.com/

go here & download viewer.
it lets you resize photos very quickly.

joe

Peter · 12-06-2003

Quote:

Originally posted by backalley photo
http://www.irfanview.com/

go here & download viewer.
it lets you resize photos very quickly.

joe

Thanks Joe, got the program and it works! I think RF have the advantage of working in really slow shutter speed, which really made fast lens a nice to have piece of equipment if the subjects do not move very fast.