DA 35mm macro stationary element

Jonathan Mac · 12-20-2011, 03:19 AM

I just noticed something weird. Unlike every other (non internal focusing) lens that I own, the DA 35mm macro ltd has a stationary rear element that does not move with the other optics when focus is changed. I'm intrigued.

Why is this? Is it because it's a macro lens? Does this bring any benefits to the optical design?

**Lowell Goudge** · 12-20-2011, 05:16 AM

This is a Fixed Rear Element design like the old K28/2. The fixed rear element is part of the focusing design which results in a reduction in focal length when focusing in close, this is a benefit to a macro to keep it small, but it means that the working distance would be shorter for any magnification ration than a true 35mm. You can test the lens to see the reduction in focal length as you get close

12-20-2011, 03:19 AM	#1
Jonathan Mac Pentaxian Join Date: Apr 2009 Location: Madrid, Spain Posts: 10,897	DA 35mm macro stationary element I just noticed something weird. Unlike every other (non internal focusing) lens that I own, the DA 35mm macro ltd has a stationary rear element that does not move with the other optics when focus is changed. I'm intrigued. Why is this? Is it because it's a macro lens? Does this bring any benefits to the optical design?

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12-20-2011, 05:16 AM	#2
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	This is a Fixed Rear Element design like the old K28/2. The fixed rear element is part of the focusing design which results in a reduction in focal length when focusing in close, this is a benefit to a macro to keep it small, but it means that the working distance would be shorter for any magnification ration than a true 35mm. You can test the lens to see the reduction in focal length as you get close