Question about 580 zoom/diffuser with crop body

4130 · 29th of November 2008 (Sat)

I have an XSi with a 580exii and the 18-55 kit lens. I'm unsure whether to use the built-in diffuser panel with the 18mm end of my lens or not.

I considered that the 580 head zooms down to 24mm coverage, but wasn't sure whether this accounted for my 1.6x crop body, making my 1.6x18mm into 29mm full-frame length.

When I'm using the 18mm end of my lens, do I need to be using the diffuser panel? Does the flash know I'm using a crop body?

Any help would be appreciated.

Wilt · 29th of November 2008 (Sat)

The 580EXII has the ability to know when a 24mm FL is mounted on APS-C vs. 24mm mounted on FF body. The 24mm zoom head position (without supplemental lens) ordinarily is for a 84 degree FOV with FF, so it will sufficiently cover your 18mm WA setting when used on APS-C, as that is only a 74 degree FOV (same as 28mm on FF/135 format). You only need to use the supplemental flash lens if using the Canon 10-22mm lens in the 10mm-14mm part of its range.

Curtis N · 29th of November 2008 (Sat)

No diffuser panel needed with that lens on that body. It will cover 24mm focal length on a full frame camera, which is equivalent to a 15mm lens on yours.

4130 · 29th of November 2008 (Sat)

Thanks very much guys! I hate pulling that thing out when borrowing other people's lenses.

29th of November 2008 (Sat)	#1
4130 Member Join Date: Oct 2008 Posts: 94 IMAGE EDITING OK	Question about 580 zoom/diffuser with crop body I have an XSi with a 580exii and the 18-55 kit lens. I'm unsure whether to use the built-in diffuser panel with the 18mm end of my lens or not. I considered that the 580 head zooms down to 24mm coverage, but wasn't sure whether this accounted for my 1.6x crop body, making my 1.6x18mm into 29mm full-frame length. When I'm using the 18mm end of my lens, do I need to be using the diffuser panel? Does the flash know I'm using a crop body? Any help would be appreciated. __________________ Looking for a carbon tripod and head capable of supporting a 5D body and 35 mm L

29th of November 2008 (Sat)	#2
Wilt Cream of the Crop Join Date: Aug 2005 Location: California Posts: 30,885 IMAGE EDITING OK	Re: Question about 580 zoom/diffuser with crop body The 580EXII has the ability to know when a 24mm FL is mounted on APS-C vs. 24mm mounted on FF body. The 24mm zoom head position (without supplemental lens) ordinarily is for a 84 degree FOV with FF, so it will sufficiently cover your 18mm WA setting when used on APS-C, as that is only a 74 degree FOV (same as 28mm on FF/135 format). You only need to use the supplemental flash lens if using the Canon 10-22mm lens in the 10mm-14mm part of its range. __________________ Canon dSLR system, Olympus OM 35mm system, Bronica ETRSi 645 system, Horseman LS 4x5 system, Metz flashes, Dynalite studio lighting, and too many accessories to mention Keep POTN alive and well with member support http://photography-on-the.net/forum/donate.php

29th of November 2008 (Sat)	#3
Curtis N Master Flasher Join Date: Apr 2005 Location: Northern Illinois, US Posts: 18,988	Re: Question about 580 zoom/diffuser with crop body No diffuser panel needed with that lens on that body. It will cover 24mm focal length on a full frame camera, which is equivalent to a 15mm lens on yours. __________________ "If you're not having fun, your pictures will reflect that." - Joe McNally Chicago area POTN events Flash Photography 101 \| The EOS Flash Bible \| Techniques for Better On-Camera Flash \| How to Use Flash Outdoors \| Excel-based DOF Calculator

29th of November 2008 (Sat)	#4
4130 Member Join Date: Oct 2008 Posts: 94 IMAGE EDITING OK	Re: Question about 580 zoom/diffuser with crop body Thanks very much guys! I hate pulling that thing out when borrowing other people's lenses. __________________ Looking for a carbon tripod and head capable of supporting a 5D body and 35 mm L

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