Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-08-2012, 07:45 AM   #61
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
QuoteOriginally posted by Deimos Quote
So if the crop factor would make the FL roughly 5.6x, how does that affect the "equivalent" aperture value to APS-C, f1.5 would be what roughly?
depends on what you want to compare, the light opening or the depth of field?

Light opening stays the same so f/2.8 on any system will be f/2.8 no matter what.
DOF is effected though, not by the aperture so much but by the size of the sensor and focal lend and focus distance so yes you can use roughly the equivbelant for that.

09-08-2012, 08:14 AM   #62
Pentaxian
Fogel70's Avatar

Join Date: Sep 2009
Location: Stockholm, Sweden
Photos: Albums
Posts: 1,737
QuoteOriginally posted by deimos Quote
so if the crop factor would make the fl roughly 5.6x, how does that affect the "equivalent" aperture value to aps-c, f1.5 would be what roughly?
f/1.5 on Q gives about the same aperture size as slowest zooms on APS-C (when comparing same FOV).

f/1.5 * 5.6/1.53 = f/5.5
09-08-2012, 08:18 AM   #63
TZH
Senior Member
TZH's Avatar

Join Date: Aug 2010
Location: Kuala Lumpur
Photos: Gallery | Albums
Posts: 118
QuoteOriginally posted by Fogel70 Quote
f/1.5 on Q gives about the same aperture size as slowest zooms on APS-C (when comparing same FOV).

f/1.5 * 5.6/1.53 = f/5.5
... f5.5 is pretty slow .... so the selling point is small and tiny ?
09-08-2012, 08:27 AM   #64
Veteran Member
eurostar's Avatar

Join Date: Dec 2006
Location: Albareto, Italy
Photos: Gallery
Posts: 813
It is called slow because it requires slow shutter time... but f1,5 "stay the same" from an exposure point of view, so it's not slow at all.

It's just regarding DOF that 1,5 "become" 5,5.

09-08-2012, 08:43 AM - 2 Likes   #65
Site Supporter
cheekygeek's Avatar

Join Date: Jul 2008
Location: Alda, Nebraska USA
Photos: Gallery | Albums
Posts: 1,245
This whole equiv. DOF discussion is going to really confuse people.
For exposure, a shutter speed is a shutter speed - no matter the sensor/film size. Likewise an aperture is an aperture - no matter the sensor/film. A f2.8 zoom is fast. A f1.8 would be faster.

To figure out how DOF is affected by sensor size go to the online DOF calculator, and assume a 100mm macro lens at f2.8 and focused at something 10" away. Choose a Canon 5d from the drop down menu and note the DOF for a full frame sensor. Next, select a Pentax k-5 and do the same. Finally, select the Pentax Q.

Same aperture, same focal length, same aperture. Wildly larger DOF with the smaller sensor
09-08-2012, 11:26 AM   #66
Veteran Member




Join Date: Aug 2009
Photos: Gallery
Posts: 1,236
QuoteOriginally posted by Docrwm Quote
I'd settle for ANY Tokina lenses being currently made in K mount.
You are right. The only Tokina on my radar is the 11-16mm f2.8...

I guess the Fisheye and 12-24mm f4 don't count as they are a mutual thing.
09-08-2012, 12:36 PM   #67
Veteran Member
Docrwm's Avatar

Join Date: Sep 2010
Location: Somewhere in the Southern US
Photos: Gallery | Albums
Posts: 11,275
QuoteOriginally posted by sjwaldron Quote
You are right. The only Tokina on my radar is the 11-16mm f2.8...

I guess the Fisheye and 12-24mm f4 don't count as they are a mutual thing.
I just want to see the old relationships revived and more access to K-mount lenses. Tokina made a killer 70-200/2.8 in K and they're hard to find now. They've made some other solid lenses too.
09-08-2012, 07:02 PM   #68
Site Supporter
cheekygeek's Avatar

Join Date: Jul 2008
Location: Alda, Nebraska USA
Photos: Gallery | Albums
Posts: 1,245
QuoteOriginally posted by Docrwm Quote
I just want to see the old relationships revived and more access to K-mount lenses. Tokina made a killer 70-200/2.8 in K and they're hard to find now. They've made some other solid lenses too.
I believe you are thinking of the Tokina AT-X 828 80-200mm f2.8.

09-08-2012, 07:04 PM   #69
Site Supporter
cheekygeek's Avatar

Join Date: Jul 2008
Location: Alda, Nebraska USA
Photos: Gallery | Albums
Posts: 1,245
QuoteOriginally posted by sjwaldron Quote
You are right. The only Tokina on my radar is the 11-16mm f2.8...

I guess the Fisheye and 12-24mm f4 don't count as they are a mutual thing.
I lusted for that lens in Pentax also, until my son-in-law got it for his Canon. He says it flares badly. I'm quite happy with my Sigma EX 10-20 mm f4-5.6.
09-08-2012, 11:29 PM   #70
Senior Member




Join Date: Mar 2012
Photos: Gallery
Posts: 165
QuoteOriginally posted by Mistral75 Quote
As for the Pentax labelled Tamron:
...
no in-lens stabilization (same as the Sony version: the stabilization group is blocked)
...
What is the point of blocking stabilization group then...looks like it means that we pay more but we get less than Tamron label users!!!

09-09-2012, 12:55 AM   #71
Pentaxian
thibs's Avatar

Join Date: Jun 2007
Location: Belgium
Photos: Albums
Posts: 5,159
QuoteOriginally posted by 123jippo Quote
What is the point of blocking stabilization group then...looks like it means that we pay more but we get less than Tamron label users!!!

Yep and Sigma does so too now.
Maybe they got support problems with customer enabling both at the same time and running into troubles.
09-09-2012, 11:37 AM   #72
Pentaxian
Mistral75's Avatar

Join Date: Feb 2009
Location: Paris
Posts: 2,777
QuoteOriginally posted by Mistral75 Quote
I presume it does. Living open the possibility for some future 24x36 lenses (telephoto lenses, in particular) to have shake reduction as well.

Have you guys also seen the HD in the name "HD Pentax-D FA645 Macro 90mm f/2.8 ED AW SR"?

Could this point out a new generation of 645 lenses designed for highly pixelized 645 sensors?

Could this mean that the 645D II or 645Dn or whatever its name is would have more than the rumoured 50 Mpixels, knowing that some Teledyne Dalsa 645 sensors have as much as 80 Mpixels?
QuoteOriginally posted by Asahiflex Quote
I read on the Dutch Pentaxian forum that HD could mean "Hypersonic Drive". A new type of ring motor (Pentax has patents in this regard) could be used in that lens...
In-lens stabilization is confirmed. HD is a new coating name that replaces smc ().

Source : Digicam Info ?????????????????????? - ????info
09-09-2012, 11:41 AM   #73
Veteran Member
Docrwm's Avatar

Join Date: Sep 2010
Location: Somewhere in the Southern US
Photos: Gallery | Albums
Posts: 11,275
QuoteOriginally posted by Mistral75 Quote
In-lens stabilization is confirmed. HD is a new coating name that replaces smc ().

Source : Digicam Info ?????????????????????? - ????info
Google Translate results in this for the above link:

Summary and additional information about the new product for Pentax

From readers, we have to provide additional information about the new products to be announced in the near future Pentax. The following is a summary of the information so far.
  • K-5 II: AF unit-3EV SAFOX X corresponding to F2.8 brightness and low, the LCD monitor air gapless.
  • Low-pass-less version of K-5 II: K-5 IIs.
  • Order 20 colors are available grip + body 5 colors, color 97: PENTAX Q10.
  • Built-in mechanical shutter: Q for K-mount lens adapter.
  • (Through F2.8) ,15-45mm F2.8 telephoto zoom for Q: PENTAX-06 TELEPHOTO ZOOM.
  • high magnification zoom for K mount: 18-270mmF3.5-6.3 ED SDM smc PENTAX-DA.
  • Super telephoto lens for K mount: 560mmF5.6 ED AW HD PENTAX-DA. The newly developed HD coating, drip-proof dustproof.
  • Macro lens for 645: 90mmF2.8 ED AW SR HD PENTAX-D FA645 MACRO. HD coating of newly developed Aero Bright coating, image stabilization (SR).

It is the information from people you trust. As rumored Apparently, K-5 IIs looks like a low-pass-less version of K-5 II.

In addition, the Pentax seems to have developed a new HD coating alternative to SMC, with 90mm macro for the 645, the beginning of the name has been changed to HD lens from SMC and DA560mm.

In the future, whether it will become a "HD Pentax" from "SMC Pentax" familiar. In addition, it is noted in the lens image stabilization is also being adopted in the 90mm macro.
09-09-2012, 05:00 PM   #74
Site Supporter
Biro's Avatar

Join Date: Jan 2009
Posts: 1,159
Hey, I have the Pentax DA 18-250. And, despite the technical compromises inherent in the lens design, it is a surprisingly good lens in the real world. It remains in demand to this day. Yes, there is some distortion at the extremes but those who have never used this lens would be shocked at how good it is from 28 to 200mm. The newer 18-270 is reportedly every bit as good and even a bit better. In fact, if memory serves correctly, the Tamron 18-270 won all kinds of awards when it was first released. If the Pentax version of the 18-270 has WR and the ring focusing motor, I'm sure it would be a home run. Of course, that's unlikely.
09-09-2012, 05:15 PM   #75
Veteran Member
Docrwm's Avatar

Join Date: Sep 2010
Location: Somewhere in the Southern US
Photos: Gallery | Albums
Posts: 11,275
QuoteOriginally posted by Biro Quote
Hey, I have the Pentax DA 18-250. And, despite the technical compromises inherent in the lens design, it is a surprisingly good lens in the real world. It remains in demand to this day. Yes, there is some distortion at the extremes but those who have never used this lens would be shocked at how good it is from 28 to 200mm. The newer 18-270 is reportedly every bit as good and even a bit better. In fact, if memory serves correctly, the Tamron 18-270 won all kinds of awards when it was first released. If the Pentax version of the 18-270 has WR and the ring focusing motor, I'm sure it would be a home run. Of course, that's unlikely.
I own the 18-250 in the Tamron flavor and like it very much. I agree with you about its pluses and minuses but for what it is, a superzoom so you don't have to change lenses when you are traveling, it is an excellent lens.
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!
90mm, macro, pentax news, pentax rumors
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Macro benefits? dedicated Macro VS Telephoto/Macro choices Tricktech Pentax SLR Lens Discussion 11 07-01-2012 11:17 AM
100mm f2.8 Macro - Fa or DFA? stormtech Pentax SLR Lens Discussion 21 03-14-2011 02:44 AM
Pentax DFA 100mm f/2.8 Macro vs Sigma 105mm f/2.8 EX DG vs Tamron AF 90mm f/2.8 Di SP dyusem Pentax SLR Lens Discussion 2 02-13-2010 08:11 PM
Voigtländer Apo-Lanthar 90mm f3.5 SL Close Focus vs Tokina AT-X 90mm f2.5 1:2 macro Patriot Pentax SLR Lens Discussion 4 06-02-2009 08:15 PM
Macro handling questions: Tamron 90mm SP and Pentax DFA 100mm troyz Pentax SLR Lens Discussion 3 02-22-2009 01:17 PM



All times are GMT -7. The time now is 02:13 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