Go Back   Steve's Digicams Forums > Digicam Help > Add-On Lenses

Reply
 
Thread Tools Search this Thread
Old Nov 7, 2004, 9:36 PM   #1
Senior Member
 
pianoplayer88key's Avatar
 
Join Date: Jan 2004
Posts: 405
Default

I was wondering - what's a good way to figure out required focal length (in 35mm terms) for a particular subject coverage at a given distance? For example, for a head to below-belt shot of an average 6' man, for example Randy Johnson, Barry Bonds, Curt Shilling, Trevor Hoffman, Khalil Greene, etc, with my camera's focal length set at 58mm (10x optical zoom, 380mm 35mm equiv focal length) how far away would my subject need to be for that coverage? (For example let's say the subject I'm photographing is, at max, 30" wide by 40" high).

Or, besides that 380mm focal length example, if I know how far away the subject is, how do I figure out what focal length I need to get the same coverage area as above?
For example (and btw I would need a good teleconverter in this case for my S1) let's say the subject is 1,320 feet away - what would my focal length need to be?

Also, for a teleconverter, how long can my focal length be and maintain an F/8.0 or wider aperture, for a lens whose width is equal to the width of the Canon S1 IS with the LCD screen flipped out? Also how long of a focal length to maintain an F/3.2 aperture for when I'm not zoomed in (on the teleconverter) quite as far? Also I would like as little vignetting as possible - some darkening of corners is OK, but no quiero blackness on the top/bottom/sides, por favor.

Some time ago I had been considering getting a Crystalvue 8x teleconv for my S1, but have been having second thoughts. Is this a viable option?

I should mention that budget right now is a major factor, but I am willing to wait a while till I either have more money (which at this point is absolutely required for me to buy a major camera accessory), prices come down, and/or something better comes out for a good price. I would prefer (depending on financial situation) not to wait more than about a year or so. If I end up getting a different camera, I at least want something that (when turned off) is a comparable size, has a larger sensor (either a 36x27mm sensor, or if a small sensor to keep the camera compact, good noise reduction to enable use of ISO 3200 without much if any loss of image detail or much noticeable noise (comparable to a current P&S at ISO 50)), more megapixels (at least 5), less noise at high ISO's (good results at ISO 400 or 800), wider aperture overall (F/1.x or 0.x), longer zoom (> 800mm focal length), better overall image quality, shorter shutter lag including focus and in low light, and a comparable price to what I paid for the S1 ($500 brand new). Would something possibly be available meeting those requirements sometime within the next year or two?
pianoplayer88key is offline   Reply With Quote
Sponsored Links
Old Nov 11, 2004, 9:20 PM   #2
Senior Member
 
pianoplayer88key's Avatar
 
Join Date: Jan 2004
Posts: 405
Default

Let me see if I can condense this.

Ok, so let's say I know the approximate size of the largest dimension of my subject. We'll use 48" as an example.
I want to know how far (for that size subject) a certain lens (usually in 35mm terms) will reach, for example a 760mm lens. I found one site that helped me get started figuring out a few things, but how do I figure out other parts of the equation? It won't let me put in focal length or field of view, for example, as an option. I would like to know if there's a way to calculate those?

Also, what lens can I get for my S1 IS that costs no more than 1/3 the cost of the camera that's decent quality, has an aperture of, say, 6" for example (or 8" maybe), can zoom in and out (by telescoping preferably so that when I'm not zoomed in as far the lens is smaller), and has a maximum actual (not 35mm) focal length of about 6 to 7 feet? I also want it to be able to focus on objects as close as 5 feet from the lens at full zoom.

What lenses are out there, or are there any good websites that talk about making your own lenses?
pianoplayer88key is offline   Reply With Quote
Old Nov 13, 2004, 10:13 AM   #3
PvB
Senior Member
 
PvB's Avatar
 
Join Date: Nov 2004
Posts: 208
Default

Have a look at www.ckcpower.com. There you can find the CrystalVue LX and the CrystalVue 8x32 Sharpshooter.

Have a look at this thread as well: Extreme telephoto with canon s1. It's on the first page of the list (Canon forum). Read dinoddc's 2nd post there. The post says that the sharpshooter will vignette too much with the S1, whilest the LX may do better. I myself can't comment on that, because I have no experience with either lens.

I hope you find what you're looking for.
PvB is offline   Reply With Quote
Old Nov 13, 2004, 8:28 PM   #4
Senior Member
 
pianoplayer88key's Avatar
 
Join Date: Jan 2004
Posts: 405
Default

I'm willing to accept vignetting when my camera is at wideangle. I would prefer that at full tele on-cam the most vignetting is corner vignetting.
pianoplayer88key 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 6:51 AM.