Question about zoom lens design specific to DA* 50-135

Loren E · 05-01-2011, 11:36 PM

So the DA* 16-50 and 60-250 both have telescoping zooms, making them considerably more compact when at their shortest FL than when at their longest. Of course the 50-135 has a fixed size that does not change when zooming. My question: had this lens been designed with a telescoping zoom would it too be far smaller for travel when at it's most compact, or in other words, does this lens have the potential to be much smaller? I realize that many people like it's non telescoping design for durability/sturdiness, but I am curious what makes Pentax not standardize this across their DA* zooms....any insight?

Thanks -LE

dgaies · 05-03-2011, 06:31 AM

I don't know nearly enough about lens design to answer this question properly. However, I don't think the 50-135/2.8 would have been much smaller even if it had not been an internal zoom lens. I wish the DA*60-250 had an internal zoom as well, but I have a feeling that would have made for a considerably longer lens. As it stands, the 60-250 isn't that much taller than the 50-135 when at it's smallest for storage.

Hopefully someone with more insight into lens design can chime in with a more specific answer

05-01-2011, 11:36 PM	#1
Loren E Senior Member Join Date: Oct 2010 Location: Washington and California Posts: 274	*Question about zoom lens design specific to DA 50-135** So the DA* 16-50 and 60-250 both have telescoping zooms, making them considerably more compact when at their shortest FL than when at their longest. Of course the 50-135 has a fixed size that does not change when zooming. My question: had this lens been designed with a telescoping zoom would it too be far smaller for travel when at it's most compact, or in other words, does this lens have the potential to be much smaller? I realize that many people like it's non telescoping design for durability/sturdiness, but I am curious what makes Pentax not standardize this across their DA* zooms....any insight? Thanks -LE

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
theoretical lens design question	tibbitts	Pentax SLR Lens Discussion	10	04-17-2011 02:17 PM
FA Limited lens series won the 2010 Good Design Long Life Design Award	Patriot	Pentax SLR Lens Discussion	26	11-29-2010 06:16 AM
specific question about kit lens II vs. DA 16-45mm	causey	Pentax SLR Lens Discussion	4	11-03-2009 11:05 AM
Sears 35-135 3.5to4.5 Zoom Mcro / A Lens	jjbuzard	Pentax SLR Lens Discussion	2	08-21-2009 02:00 PM
Question: Super Takumar zoom 135-200, does it exist?	Rense	Pentax SLR Lens Discussion	8	05-04-2009 02:02 PM

05-03-2011, 06:31 AM	#2
dgaies Veteran Member Join Date: Oct 2009 Location: Maryland / Washington DC Posts: 3,917	I don't know nearly enough about lens design to answer this question properly. However, I don't think the 50-135/2.8 would have been much smaller even if it had not been an internal zoom lens. I wish the DA*60-250 had an internal zoom as well, but I have a feeling that would have made for a considerably longer lens. As it stands, the 60-250 isn't that much taller than the 50-135 when at it's smallest for storage. Hopefully someone with more insight into lens design can chime in with a more specific answer