[Digitalis]

there doesn’t seem to be an obvious amount of coma present.

No, there really isn't much coma to speak of when stopped down though I will point out that accurate focusing is critical to achieve this, the use of a bahtinov mask is essential. The high vignetting @ f/2.4 on the DFA21 is more problematic for night sky imaging particularly when image stacking is involved. Vignetting is mostly gone by f/5.6~f/8



Pentax K-1 D-FA21mm f/2.4 T=1m Un-stacked un-sharpened 100% crops from upper right corner of starfield image.

---

Last edited by Digitalis; 05-03-2022 at 05:03 PM. Reason: replaced sample image for comparison.

[acoufap]

K-1 | FF mode | DFA21Ltd + DA TC1.4x | 29.4mm | f/3.5


K-1 | FF mode | DFA21Ltd + DA TC1.4x | 29.4mm | f/4

[LennyBloke]

[acoufap]

x-post


K-1 | 29.4mm | ISO100 | f/11 | 1/80s

[Digitalis]

Pentax K-1 D-FA21mm f/2.4 ASPH Limited @ f/11 ISO 100 1/125th


Pentax K-1 D-FA21mm f/2.4 ASPH Limited @ f/16 ISO 400 1/125th

[acoufap]

x-post





Both K-1 | FF mode | DFA21Ltd | f/5.6

[Digitalis]

Pentax K1II SMCP-HD D-FA21mm f/2.4 ED ASPH Limited @ f/2.4


Pentax K1II - DFA21mm f/2.4 @ f/2.4


Pentax K1 II DFA21mm f/2.4 @ f/11 - [SATOBI DCU 5 - tonally tweaked]

[Trissa]

May I ask, in the western or eastern part of the Baltic Sea? It looks similar to places where I have been.

Sorry for the late answer: The western part of the Baltic Sea, near Travemuende (or Luebeck).

[acoufap]

Sorry for the late answer: The western part of the Baltic Sea, near Travemuende (or Luebeck).

Don't worry, no problem. A very long time I lived in Kiel. So not far from Travemünde/Lübeck. Also have been where you made this Bodensee harbour photorgraph, guess it's Lindau, isn't it?

[Trissa]

Don't worry, no problem. A very long time I lived in Kiel. So not far from Travemünde/Lübeck. Also have been where you made this Bodensee harbour photorgraph, guess it's Lindau, isn't it?

It is. Same location, just 5 minutes earlier


and one of my favorites with the K3-III and the new 21mm

[acoufap]

This thread is dedicated to the DFA21Ltd. So I think we should explore it further ...

"Oh no, an integrated hood" came to my mind when I saw it and read the specs. And now it's my first such lens - and I really enjoy it.

I have to check how much the built-in hood would restrict filter usage I thought. My M10 filter system doesn't work. Okay, I could DIY something to attach it. But when I tested the coverage of the hood openings it was clear, that it's not that easy and especially rectangle GNDs would be far from the front glass element. Some people say that such filters are obsolete today, since the cameras have such great dynamic range and there are other techniques like HDR to get along. I'll not discuss these things here and go directly to the usage of screw-in filters.

Until now, I didn't own 67mm screw-in filters. Since I want to be able to use a PLC and 10stop filter I ordered these and on top a clear filter for situations where flying sand and/or salt water could be a problem. To prevent from strong IQ degradation I decided to go for very good ones. Read and viewed some internet reviews in addition to my experiences with filters from Hoya and 10stops from Haida until now. The Haida 10stops shows more color shift than I thought.

I read good things about the B&W Master series and similar for the Breakthrough X4. The latter ones were significantly more expensive so I decided to go for the B&W's Master series - no fault!

With PLCs you have to be very careful when working at 21mm @ FF to get no uniformity problems in blue sky, I know. Did some simple tests mainly at different apertures, mainly to see how it works concerning vignetting when stacking the filters and I always was curious if I'd see significant color shift. My results:

• I can stack 2 of the slim B&W Master series filters without any problems - nice!
• When I stack a third filter, I get dark corners
• And with the 10stop color shift seems to be really absent or shows to be marginal - cool

In total I have really no reason to complain.

A test image taken with 2 slim B&W filters:


K-1 | FF mode | DFA21Ltd | B&W Master PLC | B&W Master 10stop | ISO400 | f/16 | 15s

One last thing: since the lens hood has two open areas down to the filter thread, it is very easy to turn the ring of the PLC filter - much easier than if you use a hood with one small window!

Hope this info is helpful.

[acoufap]

K-1 | FF mode | 21mm

[RobA_Oz]

This thread is dedicated to the DFA21Ltd. So I think we should explore it further ...

"Oh no, an integrated hood" came to my mind when I saw it and read the specs. And now it's my first such lens - and I really enjoy it.

I have to check how much the built-in hood would restrict filter usage I thought. My M10 filter system doesn't work. Okay, I could DIY something to attach it. But when I tested the coverage of the hood openings it was clear, that it's not that easy and especially rectangle GNDs would be far from the front glass element. Some people say that such filters are obsolete today, since the cameras have such great dynamic range and there are other techniques like HDR to get along. I'll not discuss these things here and go directly to the usage of screw-in filters.

Until now, I didn't own 67mm screw-in filters. Since I want to be able to use a PLC and 10stop filter I ordered these and on top a clear filter for situations where flying sand and/or salt water could be a problem. To prevent from strong IQ degradation I decided to go for very good ones. Read and viewed some internet reviews in addition to my experiences with filters from Hoya and 10stops from Haida until now. The Haida 10stops shows more color shift than I thought.

I read good things about the B&W Master series and similar for the Breakthrough X4. The latter ones were significantly more expensive so I decided to go for the B&W's Master series - no fault!

With PLCs you have to be very careful when working at 21mm @ FF to get no uniformity problems in blue sky, I know. Did some simple tests mainly at different apertures, mainly to see how it works concerning vignetting when stacking the filters and I always was curious if I'd see significant color shift. My results:

• I can stack 2 of the slim B&W Master series filters without any problems - nice!
• When I stack a third filter, I get dark corners
• And with the 10stop color shift seems to be really absent or shows to be marginal - cool

In total I have really no reason to complain.

A test image taken with 2 slim B&W filters:


K-1 | FF mode | DFA21Ltd | B&W Master PLC | B&W Master 10stop | ISO400 | f/16 | 15s

One last thing: since the lens hood has two open areas down to the filter thread, it is very easy to turn the ring of the PLC filter - much easier than if you use a hood with one small window!

Hope this info is helpful.

Very helpful, thank you.

I’d been similarly considering the use of filters on my copy of the D FA21, so it’s good to know that the B&W brand has lived up to expectations, here.

[acoufap]

Very helpful, thank you.

I’d been similarly considering the use of filters on my copy of the D FA21, so it’s good to know that the B&W brand has lived up to expectations, here.

Your feedback is very wellcome! I mostly do such tests to get familiar with new equipment and to determine restrictions and opportunities. People like you show me that it's worth to put some effort in describing my findings in the Pentax Forums - thank you very much!

[ChatMechant]

Some interesting flare on this one: