[EarlVonTapia]

A neat article was posted on PetaPixel today.

How-To: Picking a Great Lens for Milky Way Photography

It goes really in depth in a way I hadn't read before.

What was most interesting to me is the chart about 2/3rds of the way down that gives an Astro rating to each lens.

http://petapixel.com/assets/uploads/2014/01/milkyway6.jpg

Looks like it's a 24mm f1.4 on a Full Frame.

Just going by what would be the closest equivalent of that on APS-C for Pentax, is that the SamBoRokiVivinon 16mm f2?

[jimr-pdx]

Good stuff, and the shutter-speed demo is a very clear explanation of star trails.
I liked my Sigma 15/2.8 fisheye, but I didn't use it often. I now have the Samyang&c 8mm fisheye, hoping to use it more in the dry season.

[Kendigitize]

Thanks for posting this! I was in the middle of setting up everything for shots of the stars tonight and this confirms most of the settings I have arrived at thru trial & error. I use my 18-55 kit lens because it's all I have in the 18-24 range and 15sec is about the exp. I use at f3.5. I have tried the DA35 2.4, but never been very happy with the results. My best results come from my fa50 1.4 with a 10sec exp, but the field of view is cut in half and I tend to miss most of the meteors I see at night. I had planned on picking up a 24mm sigma specificly for astro photography, and now this confirms it.
I'm going to try out the Q with 01 lens tonight too and see what results I get.

FYI: Here are the links to stargazing info I use to determine the best times and nights for viewing:
Stargazing Information | StarDate Online
American Meteor Society

This photo was taken with the 50mm during the last major shower:

[Kendigitize]

SamBoRokiVivinon 16mm f2

Just got this, LMAO

[Na Horuk]

Thanks for sharing that link. I have the Samyang 14mm f2.8 and it great for astrophotography because you can use a very long exposure. But it has some problems.
Because it is 14mm, the stars are very tiny. 16mm might be a more convenient range.
The other problem is QC. I returned my first copy of the 14mm. The second one is better, but still suffers some lens decentering. This becomes apparent especially with stars, because stars on the left side of the photo are not nice points, but are slightly blurred.

Samyang also makes a 24mm f1.4 lens btw. And the Pentax astrotracer GPS thingy can allow even the use of a relatively slow lens, even without a fancy tripod

[EarlVonTapia]

Hmm, I might be wrong about this, but based on the information provided in the advanced spreadsheet that was linked to in the article, my understanding is that the best lens for Astroscaping in full frame OR APS-C is the Samyang 24mm f1.4.

https://docs.google.com/spreadsheet/ccc?key=0AomVJ2lbrwb1dDRGeHJOaVZfYnlFR2Z...=sharing#gid=2

[mattb123]

My favorites are the DA 15/4 and Rokinon 8mm/3.5
Neither are all that fast but they get the job done and are nice and wide for trying to catch meteors.
I have also used a A 50/1.7 which works well but is too long IMO.

DA 15


Rokinon 8mm

[Cannikin]

Hmm, I might be wrong about this, but based on the information provided in the advanced spreadsheet that was linked to in the article, my understanding is that the best lens for Astroscaping in full frame OR APS-C is the Samyang 24mm f1.4.

The problem is, 24mm on APS-C is not particularly wide, and for Milky Way shots you want as wide as you can get without sacrificing too much aperture (especially if you want a landscape in the foreground). If you ever get the chance to go to a really dark location, like the mountains on a clear night, you can see that the main band of the Milky Way spans across almost the entire sky. 24mm on APS-C only gets you a small portion.

[interested_observer]

Does anyone know or have a link to the maximum "tracking" times for the O-GPS1? When it first came out, Pentax had a website that had some sample images along with some sample times for a range of focal lengths. I believe that the longest was something like 5 minutes for the widest angle and 30 seconds or so for the 300mm. I have gone looking for it and it appears to have been swept up in Ricoh's rebranding of all the Pentax websites.

At 5 minutes of exposure time, that would amplify the "astrophoto" ratings of the wider lenses.

[VisualDarkness]

My Sigma 20/1.8 is really good then!