Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-12-2012, 08:39 AM   #1
Site Supporter




Join Date: Jan 2008
Location: Connecticut, USA
Posts: 813
Help me understand this new 560mm lens

The purpose of this thread is really to educate me (and hopefully others). I donít know much about lens design.

I have been intrigued by the 560mm lens ever since they announced it long ago. I think itís important for Pentax to have a lens above 300mm in order to help their credibility and provide an upgrade path for budding photogs looking for long lenses.

When the first prototype was shown, the first striking thing was how long and narrow it was. I was thinking that this design allowed less glass to be used in an effort to keep the cost down. The same was the reasoning as to why it was an f5.6 versus 4.0 or 4.5, so that it could be a little more affordable. People also speculated that the unusually long length could be somewhat mitigated by the fact that it would be either collapseable or separated entirely for easy transport.

Now, we have been presented with a 20Ē lens thatís not collapsible, and is $7000. As many people have mentioned, the Sigma 500 f4.5 is $5000. That lens is only 2/3 as long. That seems like a huge advantage to me. Why does the Pentax have to be so long? I donít do wildlife shooting so maybe I donít understand something. Is the 20Ē length less of an issue than I would think it would be?

I have been doing some reading on it, and the only thing I can think of is that the long design allows less lens elements and this means that the IQ should be better than lenses that are fatter and shorter? I guess that must be the case, right? So, when this lens is released and tested and if it trounces the others in IQ, then I guess it will all make sense then?

09-12-2012, 08:48 AM   #2
Ole
Administrator
Ole's Avatar

Join Date: Sep 2006
Location: Copenhagen, Denmark
Photos: Gallery | Albums
Posts: 3,785
I think you're right. Shorter lenses need more lens elements which could detract from image quality. Only tests will show if there is a real advantage in practice to the Pentax design which has just 6 elements (the Sigma has 11 elements).

Then one would also expect that fewer (and smaller) elements would mean that the lens is less expensive to manufacture. In other words, there should be room for Pentax to bring the price down from the current level.
09-12-2012, 09:01 AM   #3
Junior Member
topher's Avatar

Join Date: Aug 2009
Location: Central Pennsylvania
Posts: 31
I think Pentax lens pricing is so screwed up that it is difficult to make any sense out of it.........
09-12-2012, 09:08 AM   #4
Site Supporter




Join Date: Jan 2008
Location: Connecticut, USA
Posts: 813
Original Poster
In doing some other reading, I understand that Pentax got out of the telescope market a few years ago. This lens looks similar to the Pentax 125 SDP telescope. Maybe some manager figured out they could just use the same design and slap together a camera lens, just to say they have a lens over 300mm.

09-12-2012, 10:05 AM   #5
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
QuoteOriginally posted by jake14mw Quote
Now, we have been presented with a 20Ē lens thatís not collapsible, and is $7000. As many people have mentioned, the Sigma 500 f4.5 is $5000. That lens is only 2/3 as long. That seems like a huge advantage to me. Why does the Pentax have to be so long? I donít do wildlife shooting so maybe I donít understand something. Is the 20Ē length less of an issue than I would think it would be?
Because of the lens design.
Pentax uses a simpler telescope design which should yield in larger but cheaper lens, it's indeed large but if it's cheap?
09-12-2012, 11:04 AM   #6
Veteran Member
snappychappy's Avatar

Join Date: Jun 2010
Location: Leeds
Posts: 1,636
It's a lens that appeals to such a low minority of people, why bother.!!!! Where is the equivalent to the respectable Sigma 100-300 F4.
09-12-2012, 11:09 AM   #7
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
QuoteOriginally posted by snappychappy Quote
Where is the equivalent to the respectable Sigma 100-300 F4.
Pentax DA*60-250 f/4
09-12-2012, 11:23 AM - 1 Like   #8
Pentaxian




Join Date: Oct 2006
Location: Chicago suburb, IL, USA
Posts: 1,535
Personally, I use my long teles for close ups of birds and wildlife. One of the advantages of camera lens design over that of a telescope has always been an attempt to offer a shorter Minimum Focusing Distance. A pretty typical modern 500mm camera lens will focus to @ 13 feet. The DA 560 has a MFD at over 18 ft. It obviously is optimized for long shots, and not suitable for my use regardless of price. In my case, a 300 f2.8 with a good 1.7x TC offers 510mm f4.8 with a MFD of 6-8 ft and is smaller, lighter, and less expensive(!) as bonuses.

Pentax already had a stellar 300 f2.8 in the FA* -- IMO, they should have reworked this design with more modern glass and dual focusing systems, allowing switching between SDM and screw drive for practical TC use. It probably would have been nearly as expensive, but a much more versatile and useful lens, despite retaining their FL ceiling at 300mm (which is just a matter of consumer perception).

Scott

09-12-2012, 11:30 AM   #9
Site Supporter
LaurenOE's Avatar

Join Date: Sep 2009
Location: San Francisco Bay Area
Photos: Albums
Posts: 3,463
Obviously there are technical reasons for the design of the 560.

What I am about to say is hearsay/opinion.

I think the price of the 560 is tied to the fact that the engineer who designed it, was trounced by the Hoya folks, so he started his own Telescope company.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/187065-da560mm-borg.html

Mr. Nakagawa, may or may not be a Pentax employee again.

To make the 560, Pentax might have to be paying a premium for the glass (or to Mr. Nakagawa) that goes into the 560. That is - Hoya - glass.

So the fact the Mr. Nakagawa was shafted by Hoya, and then he and Pentax need to buy their optical glass from Hoya for the 560, well do you see where this can lead?

So before any glass can be made into lenses, they need sand.

And in the case of the sand needed for the 560 glass, someone is telling someone to "Go pack some sand" if you know what I mean.

And with that, WE get a $7000 lens that should be thousands less.

Sounds like politics as usual.
09-12-2012, 11:32 AM   #10
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
Here is your dream lens... maybe?
https://www.pentaxforums.com/forums/pentax-news-rumors/82894-da-400mm-f4-coming.html
09-12-2012, 11:34 AM   #11
Site Supporter
Stone G.'s Avatar

Join Date: Jun 2010
Location: North Zealand, Denmark
Photos: Gallery | Albums
Posts: 1,511
QuoteOriginally posted by jake14mw Quote
In doing some other reading, I understand that Pentax got out of the telescope market a few years ago. This lens looks similar to the Pentax 125 SDP telescope. Maybe some manager figured out they could just use the same design and slap together a camera lens, just to say they have a lens over 300mm.
Indeed, to me this also looks like a small refractor. Compare for example with this one - an f/5.4 system with an FL of 545mm and a tube lenght around 20" - from TeleVue

Tele Vue Optics: Tele Vue NP-101


Now, the TeleVue APO refractor (Optical tube assembly only) costs around USD 4,000 in the US. To that, add auto focus motor, aperture blades & aperture coupling etc. and you would have a very similar photographic lens at a street price of ???? k$.

TeleVue is more or less the king of high quality, small APO refracors. So, I am really curious to see some test images taken with the Pentax 560mm
09-12-2012, 12:18 PM   #12
Pentaxian
Just1MoreDave's Avatar

Join Date: Feb 2007
Location: Aurora, CO
Photos: Gallery | Albums
Posts: 4,817
This new 560mm lens really makes my Tamron AD2 55BB look good. OK, I give up a few things but at 1/100th the price, I am comfortable with that.
09-13-2012, 03:26 PM   #13
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,314
It will be interesting to see the final product.

clearly a relatively long lens with few elements, will by all accounts have much higher light transmission than a shorter, true telephoto, (note here that a true telephoto is a lens where the overall length is significantly shorter than the physical length)

this lens should also have the ability to have distortions properly corrected with more complex lens designs etc. it won;t be lighter as the 112 mm front element takes care of all weight and size considerations.

I just hope that it delivers performance, and for me, that means close focus of less than 2.5 meters (my adaptall 2 200-500/5.6 does this now) and greatly improved sharpness over the lenses I use now at 500mm
09-13-2012, 03:55 PM   #14
Pentaxian
littledrawe's Avatar

Join Date: Jan 2010
Location: Red Rock
Photos: Gallery | Albums
Posts: 2,434
if this lens follows relatively the same pricing plan as the K-30 camera bodies what will the price of it be 3 months after it is available for purchase??
09-13-2012, 04:26 PM   #15
Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: Liverpool, NY
Photos: Gallery
Posts: 12,309
QuoteOriginally posted by littledrawe Quote
if this lens follows relatively the same pricing plan as the K-30 camera bodies what will the price of it be 3 months after it is available for purchase??
Lenses don't follow the same pricing as cameras. They tend to go up in price over time.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
560mm, design, iq, k-mount, length, lens, lenses, pentax, pentax lens, people, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Official Pentax DA 560mm f/5.6 lens images leaked... JohnBee Pentax News and Rumors 103 12-10-2012 12:43 PM
Pentax 560mm ? ElJamoquio Pentax News and Rumors 928 09-30-2012 08:07 AM
PentaxForums CP+ video w/K-01 and 560mm Adam Pentax K-01 12 02-15-2012 11:37 PM
help me understand the sub-18mm lens landscape rpriedhorsky Pentax SLR Lens Discussion 17 02-01-2009 12:33 PM
wanting to understand- lens distortion and 1.5 crop factor slip Pentax DSLR Discussion 10 03-29-2007 06:59 PM



All times are GMT -7. The time now is 11:01 AM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top