F Stops & mm's at DVinfo.net

Brendan Marnell · January 26th, 2006, 05:57 PM

Please tell me (a)how the final set of pictures on your FOV Comparison might have been different if you had chosen different f/stops to those you chose and (b)what is meant by f/4 full wide and f/5.6 medium and (c) what the mm measurements for 16:9 & 4:3 refer to?

Sigma EF 70mm - 300mm with Canon EF Adapter and 1.6x Extender
320mm f/4 full wide
16:9 = 2,496mm / 4:3 = 3,072mm

480mm f/5.6 medium
16:9 = 3,744mm / 4:3 = 4,608mm

Top row: Sigma 70mm-300mm at 200mm w/ 1.6x Extender in 16:9 and 4:3
Bottom: Sigma 70mm-300mm at full tele w/ 1.6x Extender in 16:9 and 4:3

Geoff Voorhees · January 27th, 2006, 08:03 AM

I'm not sure what FOV Comparison you are referring to, but I believe to answer b):

f/4 is your f stop when the zoom is all of the way wide and f/5.6 is the f stop at halfway zoomed.

That would be my guess, anyway, but I've been wrong before.

Chris Hurd · January 27th, 2006, 08:07 AM

The reference is to my XL2 FOV page at http://www.dvinfo.net/canonxl2/articles/article10.php

I simply used the maximum aperture available at each f/stop (that is, each end of the zoom range at full wide or full tele). That was the method. The mm measurements for 16:9 & 4:3 refer to their 35mm still photo lens equivalents for those particular fields of view.

Brendan Marnell · January 27th, 2006, 01:51 PM

Thank you for the info which I'll be absorbing slowly as usual.

I'm sitting in front of my Sigma DL Zoom 75-300mm 1:4-5.6, made in Japan bought 10 years ago which I've only used for long-shot stills (on Digital Rebel now). Is this a similar lens to what you were able to use on your XL2 (simply because XL2 accommodates interchangeable lens)? Or does the XL2, being a camcorder, require a different sort of lens? Could the XL-H1 use my Sigma 75-300?

I'm beginning to think that there should be a separate thread entitled: Implications of XL2 FOV Comparison. It would have deep significance for me at any rate if (a) the comparative detail revealed would also apply if, say, the tractor was a moving object, and (b) the results obtained with your XL2 could be equalled by the XL-H1.

Chris Hurd · January 27th, 2006, 05:43 PM

Could the XL H1 use your Sigma 75-300? If that lens has an EOS mount, then yes you can, providing you also obtain the Canon XL to EF adapter (about $450). The lens may provide a suitable image for SD but I don't think it's up to scratch for HD. Also I noticed a significant amount of chromatic abberation with that Sigma lens at the long end.

Brendan Marnell · January 27th, 2006, 06:30 PM

Thank you kindly, Chris

January 26th, 2006, 05:57 PM	#1
Brendan Marnell Major Player Join Date: Dec 2004 Location: Dublin, Ireland Posts: 938	F Stops & mm's Please tell me (a)how the final set of pictures on your FOV Comparison might have been different if you had chosen different f/stops to those you chose and (b)what is meant by f/4 full wide and f/5.6 medium and (c) what the mm measurements for 16:9 & 4:3 refer to? Sigma EF 70mm - 300mm with Canon EF Adapter and 1.6x Extender 320mm f/4 full wide 16:9 = 2,496mm / 4:3 = 3,072mm 480mm f/5.6 medium 16:9 = 3,744mm / 4:3 = 4,608mm Top row: Sigma 70mm-300mm at 200mm w/ 1.6x Extender in 16:9 and 4:3 Bottom: Sigma 70mm-300mm at full tele w/ 1.6x Extender in 16:9 and 4:3

January 27th, 2006, 08:07 AM	#3
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	The reference is to my XL2 FOV page at http://www.dvinfo.net/canonxl2/articles/article10.php I simply used the maximum aperture available at each f/stop (that is, each end of the zoom range at full wide or full tele). That was the method. The mm measurements for 16:9 & 4:3 refer to their 35mm still photo lens equivalents for those particular fields of view. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

January 27th, 2006, 01:51 PM	#4
Brendan Marnell Major Player Join Date: Dec 2004 Location: Dublin, Ireland Posts: 938	Thank you for the info which I'll be absorbing slowly as usual. I'm sitting in front of my Sigma DL Zoom 75-300mm 1:4-5.6, made in Japan bought 10 years ago which I've only used for long-shot stills (on Digital Rebel now). Is this a similar lens to what you were able to use on your XL2 (simply because XL2 accommodates interchangeable lens)? Or does the XL2, being a camcorder, require a different sort of lens? Could the XL-H1 use my Sigma 75-300? I'm beginning to think that there should be a separate thread entitled: Implications of XL2 FOV Comparison. It would have deep significance for me at any rate if (a) the comparative detail revealed would also apply if, say, the tractor was a moving object, and (b) the results obtained with your XL2 could be equalled by the XL-H1. Last edited by Brendan Marnell; January 27th, 2006 at 05:28 PM.

January 27th, 2006, 05:43 PM	#5
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	Could the XL H1 use your Sigma 75-300? If that lens has an EOS mount, then yes you can, providing you also obtain the Canon XL to EF adapter (about $450). The lens may provide a suitable image for SD but I don't think it's up to scratch for HD. Also I noticed a significant amount of chromatic abberation with that Sigma lens at the long end. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

January 27th, 2006, 08:03 AM	#2
Geoff Voorhees New Boot Join Date: Dec 2004 Location: United States Posts: 18	I'm not sure what FOV Comparison you are referring to, but I believe to answer b): f/4 is your f stop when the zoom is all of the way wide and f/5.6 is the f stop at halfway zoomed. That would be my guess, anyway, but I've been wrong before.

January 27th, 2006, 06:30 PM	#6
Brendan Marnell Major Player Join Date: Dec 2004 Location: Dublin, Ireland Posts: 938	Thank you kindly, Chris