s70 F stop limitation

[tekstyle]

hey guys. however much i love my s70, one thing that pisses me off is the F stop limit. at certain settings, i would only be able to get down to a F3.5 and no bigger. is there a hack or anything that will allow me to set F stop, shutter, ISO, etc.. all independently? I want to get it down to about F2.0 as I wish. thanks

[mfunnell]

The maximum apeture represents the maximum size of the hole that lets light into your camera. As a physical constraint, nothing much can be done about it short of using a drill which is likely to have, um, side effects:shock: I don't think there are any compact cameras with lenses faster than f2, with f2.8 being the widest I recall. What are you trying to achieve? If it's shallow depth-of-field then you really need a larger sensor camera (whether film or digital), as sensor size alters apparent DOF and such cameras are also supported by better availability of fast lenses.

...Mike

[tekstyle]

i just notice that sometimes the lowest i can get the F stop is 3.5. but at other times, i can get it down to 2.8 the lowest i believe. i just want some way to hack it so i can have the full range of my Fstop at any given setting whether it is the camera setting or the environment. i am not asking to make it go lower than the camera can physically go. i know that is impossible, but it seems as though the software is some how holding back those extra F's when i want it.

[Obor]

Your minimum f you can achieve will increase (apper. will decrease) as you use your zoom. It's still a physical constraint and there is no hack other than the above mentioned drill :-) . That is why on the front of your lens it probably says 1:2.8-3.5 which gives you the f values at each end of the lens (wide and telephoto) If you want to achieve a f/2.8 at full zoom you would need a big lens (ie. on compacts - panasonic FZ20 has f/2.8 over the whole zoom range.)

[tekstyle]

ah, i see. thanks for your clarification. i did not know that zoom would affect the F, but now i do. learning something new everyday :)

[DavidW]

Most zoom lenses are variable aperture zooms - as you zoom in, the maximum aperture available decreases. There are such things as constant aperture zooms, which have the same maximum aperture across the focal length range. However, constant aperture lenses are bulkier and heavier because they need larger elements - and as a consequence, they're much more expensive.


Canon do produce some EF and EF-S mount constant aperture zooms for DSLRs, but they're amongst the more expensive lenses. I've got three f/2.8 constant aperture zooms in my bag (EF 16-35mm f/2.8L, EF 24-70mm f/2.8L, EF 70-200mm f/2.8L IS), which, together, cost around £3200 in the UK.

Cheaper EF and EF-S mount lenses are variable aperture. For example, the "kit lens" is EF-S 18-55mm f/3.5-5.6.



David