DA* 11-18mm f/2.8 is to have a defog option for astrophotography?

**FozzFoster** · 09-10-2018, 08:25 AM

Originally posted by Mistral75

Ricoh Imaging know and they write '2019'.

That's when it's available. I'd be surprised if they don't mention it at Photokina though..

JPT · 09-12-2018, 07:33 AM - **1 Like**

A thought occurred to me about the delay on this lens. I wonder whether when this lens resurfaces it will still be a KAF3 one or whether they will make it KAF4.

Pentax is talking up the benefit of KAF4 for the DFA* 50mm - "Electromagnetic diaphragm-control mechanism,* for flawless, high-precision exposure control during movie recording"

It's a little strange then that Pentax is not using it for the DA* 11-18mm. One possible, and entirely speculative, explanation for the delay is that they decided it should meet the new start standard, and incorporate KAF4.

**FozzFoster** · 09-12-2018, 11:26 AM

Originally posted by JPT

A thought occurred to me about the delay on this lens.

Interesting perspective JPT, I had chalked up the delay to all the earthquakes in the Asia areas.

I hope you're right, and that the flawless exposure control will be implemented!

**Yoda boy** · 10-10-2018, 05:05 PM

Originally posted by Greg1956

Interesting photo, why is the AF/MF on the lens body??

I thought that was on the camera body, change in direction? or wrong labeling? or something to keep the world occupied?

From the magical land of Australia
Greg

Some Pentax lenses have a MF/AF switch on them in addition to the one on the Pentax camera body. I believe that the switch on the lens is an override of the one on the camera body. If you move the lens switch, that takes preference over the body's position switch. This information is included in some of the lens instruction manuals. If you wish to switch from manual from Auto ( or vice versa ), you only have to use the lens switch. You can leave the switch on the camera body in the usual position.

Last edited by Yoda boy; 10-10-2018 at 05:07 PM. Reason: added info

**Pål Jensen** · 10-11-2018, 08:13 AM

No. It is a zoom/focus lock.

**Larrymc** · 10-11-2018, 09:08 AM

Originally posted by Pål Jensen

No. It is a zoom/focus lock.

@Fogel70 answered that in post #7, it is in fact an auto/manual focus switch.

**Pål Jensen** · 10-11-2018, 09:56 AM

The picture of shows that it is labeled lock (clamp). It probably has an AF/MF switch as well....

Last edited by Pål Jensen; 10-11-2018 at 11:25 AM.

Mistral75 · 10-11-2018, 12:05 PM - **1 Like**

Originally posted by Greg1956

Interesting photo, why is the AF/MF on the lens body??

I thought that was on the camera body, change in direction? or wrong labeling? or something to keep the world occupied?

From the magical land of Australia
Greg

All DA★ and D FA★ lenses, as well as some other lenses (e.g. D FA 150-450mm f/4.5-5.6), have an AF/MF switch. It's in particular useful for trap focus.

This one has a focus clamp in addition to the AF/MF switch.

Dr_who · 10-23-2018, 09:20 AM - **1 Like**

Originally posted by jimr-pdx

Telescopes with secondary mirrors exposed to the elements i.e. Newtonian) do use such heating to reduce condensation. One can wire up some resistors, buy pre-made devices or use small hair-dryer type blowers to occasionally reduce the temperature differential as the cold air hits the secondary and chills it. The catadioptric design has the second mirror enclosed but heaters are still helpful, I understand.

edit - kendrickastro.com also makes heaters for the primary mirror; I'd never felt a need for that myself.

I'd say they are even more popular with telescopes like refractors, as a simple dew shield isn't always enough to prevent dew. Comes down to climate and where you live and image I suppose and how humid it is.

---------- Post added 10-23-18 at 10:23 AM ----------

You would hope that no matter which lens, if they add a defog option, that they make the lens to have low coma and astigmatism

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09-10-2018, 08:25 AM	#61
FozzFoster Custom User Title Join Date: Jan 2016 Location: Alberta Photos: Albums Posts: 6,806 Original Poster	Originally posted by Mistral75 Ricoh Imaging know and they write '2019'. That's when it's available. I'd be surprised if they don't mention it at Photokina though..

09-12-2018, 07:33 AM - 1 Like	#62
JPT Pentaxian Join Date: Jan 2012 Location: Tokyo Photos: Gallery Posts: 2,821	A thought occurred to me about the delay on this lens. I wonder whether when this lens resurfaces it will still be a KAF3 one or whether they will make it KAF4. Pentax is talking up the benefit of KAF4 for the DFA* 50mm - "Electromagnetic diaphragm-control mechanism,* for flawless, high-precision exposure control during movie recording" It's a little strange then that Pentax is not using it for the DA* 11-18mm. One possible, and entirely speculative, explanation for the delay is that they decided it should meet the new start standard, and incorporate KAF4.

09-12-2018, 11:26 AM	#63
FozzFoster Custom User Title Join Date: Jan 2016 Location: Alberta Photos: Albums Posts: 6,806 Original Poster	Originally posted by JPT A thought occurred to me about the delay on this lens. Interesting perspective JPT, I had chalked up the delay to all the earthquakes in the Asia areas. I hope you're right, and that the flawless exposure control will be implemented!

10-10-2018, 05:05 PM	#64
Yoda boy Site Supporter Join Date: May 2015 Location: Central Ontario Photos: Gallery \| Albums Posts: 144	Originally posted by Greg1956 Interesting photo, why is the AF/MF on the lens body?? I thought that was on the camera body, change in direction? or wrong labeling? or something to keep the world occupied? From the magical land of Australia Greg Some Pentax lenses have a MF/AF switch on them in addition to the one on the Pentax camera body. I believe that the switch on the lens is an override of the one on the camera body. If you move the lens switch, that takes preference over the body's position switch. This information is included in some of the lens instruction manuals. If you wish to switch from manual from Auto ( or vice versa ), you only have to use the lens switch. You can leave the switch on the camera body in the usual position. Last edited by Yoda boy; 10-10-2018 at 05:07 PM. Reason: added info

10-11-2018, 08:13 AM	#65
Pål Jensen Site Supporter Join Date: Dec 2007 Location: Norway Photos: Albums Posts: 4,371	No. It is a zoom/focus lock.

10-11-2018, 09:08 AM	#66
Larrymc Site Supporter Join Date: Jun 2014 Location: Mississippi, USA Posts: 5,251	Originally posted by Pål Jensen No. It is a zoom/focus lock. @Fogel70 answered that in post #7, it is in fact an auto/manual focus switch.

10-11-2018, 09:56 AM	#67
Pål Jensen Site Supporter Join Date: Dec 2007 Location: Norway Photos: Albums Posts: 4,371	The picture of shows that it is labeled lock (clamp). It probably has an AF/MF switch as well.... Last edited by Pål Jensen; 10-11-2018 at 11:25 AM.

10-11-2018, 12:05 PM - 1 Like	#68
Mistral75 Pentaxian Join Date: Feb 2009 Location: Paris, France Posts: 7,527	Originally posted by Greg1956 Interesting photo, why is the AF/MF on the lens body?? I thought that was on the camera body, change in direction? or wrong labeling? or something to keep the world occupied? From the magical land of Australia Greg All DA★ and D FA★ lenses, as well as some other lenses (e.g. D FA 150-450mm f/4.5-5.6), have an AF/MF switch. It's in particular useful for trap focus. This one has a focus clamp in addition to the AF/MF switch.

10-23-2018, 09:20 AM - 1 Like	#69
Dr_who Veteran Member Join Date: Jun 2009 Location: Edmonton, Alberta, Canada Photos: Gallery \| Albums Posts: 777	Originally posted by jimr-pdx Telescopes with secondary mirrors exposed to the elements i.e. Newtonian) do use such heating to reduce condensation. One can wire up some resistors, buy pre-made devices or use small hair-dryer type blowers to occasionally reduce the temperature differential as the cold air hits the secondary and chills it. The catadioptric design has the second mirror enclosed but heaters are still helpful, I understand. edit - kendrickastro.com also makes heaters for the primary mirror; I'd never felt a need for that myself. I'd say they are even more popular with telescopes like refractors, as a simple dew shield isn't always enough to prevent dew. Comes down to climate and where you live and image I suppose and how humid it is. ---------- Post added 10-23-18 at 10:23 AM ---------- You would hope that no matter which lens, if they add a defog option, that they make the lens to have low coma and astigmatism