Piers-
Since diffraction starts limiting resolution beyond F16, you might try
F16 instead of F22 to see if there is an appreciable difference.
Also, if you have a 24mm lens, try the 24, a 2x teleconverter, and then
whatever extension you need to get into the same ballpark. From what
I've seen, the 24mm setup will give more depth of field. Why, I can't
really tell you.
Thanks, Steve Goss, Dallas Tx usa
Piers Hemy wrote:
> I don't get it either! You'll have noticed that I didn't sepcify the
> aperture on the CCTV lens - unmarked, and I wouldn't know the relevance
> either. All this shows is that it is worth experimenting.
>
> --
> Piers
>
> -----Original Message-----
> From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On Behalf
> Of Chuck Norcutt
> Sent: 22 September 2005 23:27
> To: olympus@xxxxxxxxxx
> Subject: [OM] Re: OM macro lenses?
>
> The DOF of the shorter lens pair makes a superior result but I still don't
> understand it. After looking at the amount of extension I'd have said the
> effective focal ratio of the short pair was much higher than the
> 50+extension but the exposure time is the same. I don't get it.
>
> Chuck Norcutt
>
> Piers Hemy wrote:
>
> --snip
>
>>www.hemy.me.uk/Miscellany/50+25tube.jpg was taken with a Zuiko 50/3.5
>>with 25mm extension tube at 1:1, lens at f/22.
>>
>>www.hemy.me.uk/Miscellany/Tandem20+4.jpg was taken with a Zuiko 20/3.5
>>with 150mm of bellows extension, lens at f/3.5, coupled to a 4mm CCTV
>>lens which was mounted to the Zuiko using a custom engineered adaptor.
>
>
> --snip
>
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