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02-08-2012, 12:40 PM   #151
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QuoteOriginally posted by Vylen Quote
If this lens is WR with a DC motor, I would love to get my hands on it. Although I dont know what I would do with it
Exactly my thoughts.. but I know what I'd do with it! I love the DC AF motor in the 18-135.. silent and fast, WR can't be that expensive to add in to a lens, look how cheap the kit 18-55 & 50-200 WR's are...
I'd love to see this be a "DA 550mm or 560mm f5.6 WR" lens with a DC motor (probably looking at what a 67-77mm filter thread?).

02-08-2012, 12:54 PM   #152
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300 f/4 is 77mm. It's going to be bigger if there's a front filter at all.
02-08-2012, 02:13 PM   #153
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QuoteOriginally posted by ElJamoquio Quote
300 f/4 is 77mm. It's going to be bigger if there's a front filter at all.
probably a drop in filter. I can't think of a modern lens this big that doesn't use drop ins at the back. a front filter with a close to 100mm filet size would be prohibitively expensive particularly for a lens targeted to sell for a lower price (less of a big issue if you are buying a 13000 euro for the built to order sony G 500 f4.0
02-08-2012, 02:47 PM   #154
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QuoteOriginally posted by eddie1960 Quote
probably a drop in filter. I can't think of a modern lens this big that doesn't use drop ins at the back. a front filter with a close to 100mm filet size would be prohibitively expensive particularly for a lens targeted to sell for a lower price (less of a big issue if you are buying a 13000 euro for the built to order sony G 500 f4.0
Yup, earlier in this thread I mentioned that I thought the rear knurling was for the drop in filter that appears to be pictured behind the knurling. Some big lenses have both though. I think the Sigma 300 f/2.8 has a 112mm front filter in addition to the rear 46mm? So our 560 f5.6 could be slightly smaller but not a whole bunch smaller; definitely in the range of 100mm.

02-08-2012, 03:00 PM   #155
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QuoteOriginally posted by ElJamoquio Quote
I think the Sigma 300 f/2.8 has a 112mm front filter in addition to the rear 46mm?
Unless that is brand new to their newest refresh of the lens, no it does not have a front filter.
02-08-2012, 03:46 PM   #156
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The diameter of the front lens of a 560mm f/5.6 lens is necessarily bigger than or at least equal to 100mm.
02-08-2012, 04:31 PM   #157
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QuoteOriginally posted by Chex Quote
Exactly my thoughts.. but I know what I'd do with it! I love the DC AF motor in the 18-135.. silent and fast, WR can't be that expensive to add in to a lens, look how cheap the kit 18-55 & 50-200 WR's are...
I'd love to see this be a "DA 550mm or 560mm f5.6 WR" lens with a DC motor (probably looking at what a 67-77mm filter thread?).
According to this:
SMC Pentax-DA 560mm F5.6 Reviews - DA Prime Lenses - Pentax Lens Reviews & Lens Database

the lens is screwdriven, has Quick-Shift, and it doesn't state whether it is WR or not ... most likely NOT.

Can someone tell me: that large "tube extension" protruding at the front of the lens: is it the hood itself? Because, it sure looks like a very long lens overall.

Now, some of you here mention about an insertable filter ... what does it do to the IQ of a lens and why would need to insert a filter at all?
I know that some larger lenses do have this feature, but I really never understood why this would be a required thing.

Cheers.

JP
02-08-2012, 04:49 PM   #158
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QuoteOriginally posted by jpzk Quote
the lens is screwdriven,
Hmm wonder what the switch is for then if not to turn the motor on /off?

02-08-2012, 04:51 PM   #159
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> This lens is designed for the APS-C sensor format.

I wonder where this came from? Has Pentax stated that somewhere?
02-08-2012, 04:54 PM   #160
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QuoteOriginally posted by jpzk Quote
Now, some of you here mention about an insertable filter ... what does it do to the IQ of a lens and why would need to insert a filter at all?
I know that some larger lenses do have this feature, but I really never understood why this would be a required thing.
Good lens design takes into account the extra piece of glass that is the rear filter, which among other things will affect focusing. Most lenses with this feature are shipped with a clear glass to be in place all the times when a filter is not used.
02-08-2012, 04:57 PM   #161
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QuoteOriginally posted by crewl1 Quote
Hmm wonder what the switch is for then if not to turn the motor on /off?
Looks like it could just be the AF/MF switch ???

I am just really guessing here.

JP
02-08-2012, 05:01 PM   #162
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QuoteOriginally posted by demp10 Quote
Good lens design takes into account the extra piece of glass that is the rear filter, which among other things will affect focusing. Most lenses with this feature are shipped with a clear glass to be in place all the times when a filter is not used.
Thanks for the reply, demp.

So, pretty much all larger "super" telephoto lenses would have this feature?

I am not into optics/physics, but how would this affect focusing?
The only think I remember reading about this was, a while back, a member of this forum acuired a FA*400/2.8 ... he had a tough time at first with the focusing until he was pointed to this specific "piece of glass" (the rear filter) that had to be inserted, which he did. Of course, he had good results with the lens afterward.

I still don't undertsand the concept though.

JP
02-08-2012, 05:02 PM   #163
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QuoteOriginally posted by audiobomber Quote
> This lens is designed for the APS-C sensor format.

I wonder where this came from? Has Pentax stated that somewhere?
I have no idea where this is coming from ... I just saw the link and pointed it out.

JP
02-08-2012, 05:03 PM   #164
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QuoteOriginally posted by Chex Quote
Exactly my thoughts.. but I know what I'd do with it! I love the DC AF motor in the 18-135.. silent and fast, WR can't be that expensive to add in to a lens, look how cheap the kit 18-55 & 50-200 WR's are...
I'd love to see this be a "DA 550mm or 560mm f5.6 WR" lens with a DC motor (probably looking at what a 67-77mm filter thread?).
Seems like there is no WR on that lens ...

JP
02-08-2012, 05:18 PM   #165
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" The current time and date in Japan is 9:17 AM
Thursday, February 09, 2012"

I guess we will know more shortly!
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