Hibster. Posted September 5, 2007 Share Posted September 5, 2007 I will ignore GTD until this evening "However, I am now tempted to buy a doubler instead of thousands on a new big lens...ideas on a postcard" Would need to be a big postcard. A shorter lens and a TC won't give you the kwality of a longer lens (in general) and probably won't be as fast i.e. won't have such a big max (numerically small) apperture so it won't be as good in lower light levels I've been considering getting a 2nd hand manual focus long lens (prolly 400mm) as they are much cheaper and often with motorsport you can get away with pre-focussing on the track before the cars come along The general rule would always be the more you spend the better the lens although you won't necessarily get better images just because you've shelled out £££ Myles will be along later with even wiser words as he owns more lenses than I own pants Supercheese R250 Caterham pictures here 😬 Link to comment Share on other sites More sharing options...
JamesZ Posted September 5, 2007 Share Posted September 5, 2007 Boring bit warning... why does the aperture affect the reveal of sensor dust? Boring explanation warning... Having had dust on my sensor (20d) and cleaned it off (nerve racking the first time but now a little less worried), it definitely does. Apparently there's a layer of (presumably) glass in front of the sensor, so it's this that the dust actually sits on. So, as there's some distance between sensor and dust, changing the aperture is enough to change the appearance quite dramatically. James Edited by - james xflow on 5 Sep 2007 17:06:28 Link to comment Share on other sites More sharing options...
Myles Posted September 5, 2007 Share Posted September 5, 2007 Boring bit warning... why does the aperture affect the reveal of sensor dust? If the dust is against the sensor then it's on the 'focal plane' of the sensor and focussing/aperture DOF etc aint gonna make any difference. Surely a wide open aperture reduces the chance of lens dust confusing the issue? Another explanation is that a smaller aperture is more akin to a point light-source and so there is more shadow... That makes more sense to me than DOF explanations. 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester Racing 7s Equipe™ 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
WindyMiller Posted September 6, 2007 Share Posted September 6, 2007 Boonie to stop this happening again you can prevent dust ingress along the sliding/rotating zoom with a liberal coating of axle grease. Only to be applied after the washing and airing cupboard. You can also greatly reduce the chance of dust getting in during lens changing if you carry out this operation in space. Hope this helps Windy Red and Black 1.8K Link to comment Share on other sites More sharing options...
Boonie Hound Posted September 6, 2007 Author Share Posted September 6, 2007 Much appreciated - just travelling to NASA with your camera to try that out. Are you still on for tonight? Myles - any suggestions about douberling? Link to comment Share on other sites More sharing options...
GTD Posted September 6, 2007 Share Posted September 6, 2007 MIght help? Doucherling They tried to make me go to Gatwick, I said No, No No Link to comment Share on other sites More sharing options...
Mrs GTD Posted September 6, 2007 Share Posted September 6, 2007 Lady of Leisure again Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now