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Astrophotography and Sketching >> Film Astrophotography

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PaulEK
professor emeritus
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Reged: 05/25/08

Loc: Wisconsin
Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: Nightfly]
      #5853938 - 05/11/13 02:39 PM

That's why I want to get back into film. I think the DSLRs are the best choice for close views of smaller DSOs, for several reasons. And really high resolution on bright Solar System objects is now best done with the even smaller sensors of dedicated astronomy video cameras. But for wide, deep views, digital cameras still don't come close to film (unless you have the tens of thousands of dollars a medium format digital back costs, and they are not really friendly for astro, as far as I can tell). I have a modded Canon T1i and an Imaging Source webcam, and I'm building a 14-inch reflector, partially to use them to their fullest. But I want to print poster sized swaths of space, and large pieces of film are the best way, and the cheapest way, to do it. I suppose I could create mosaics with the DSLR, but they just don't look the same. And I can create mosaics with film, too!

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Nightfly
Pooh-Bah


Reged: 06/20/07

Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: PaulEK]
      #5854011 - 05/11/13 03:26 PM

Sounds good Paul. Yes, mosaics with film. Now you're talking! The resolution with film is very high in wide-angle work. I believe this is in part to the optics. A normal lens in medium format is 90-105 mm. In the case of the 105, its focal length and aperture is much greater than the typical APS-C chipped cam. At f/4 is has an aperture greater than 25mm, where a 35mm lens at f/4 would only be less than 9mm. The efficiency of the sensor makes up for this in part, but not fully. Aperture is a limiting factor.

You can do the math for the 165 and 200 and beyond. Aperture and focal length provide greater resolution for a given field of view.

If one could manufacture a large format camera with long fast lenses, keeping the film flat and eliminating flexure, this would be a killer ap.

For medium to small object through telescopes, digital wins.


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PaulEK
professor emeritus
*****

Reged: 05/25/08

Loc: Wisconsin
Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: Nightfly]
      #5854038 - 05/11/13 03:47 PM

'If one could manufacture a large format camera with long fast lenses, keeping the film flat and eliminating flexure, this would be a killer ap.'

They tried that on Mount Polomar: to keep the film flat, they used huge glass plates, and they had a pretty long, fast lens, too!

I did just buy another Aero Ektar lens, so knowing I'll have more funds coming, I spent some of what I already had on a late 55mm f/4 lens. We get so few great nights for imaging here that I want something nice to use for daytime landscape shots, so I can use up a roll of film quicker.

i'd better not get too free with the cash, though: I have a 14-inch mirror on the way, and I need to build a scope around it.


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Nightfly
Pooh-Bah


Reged: 06/20/07

Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: PaulEK]
      #5854123 - 05/11/13 04:55 PM

You'll love the 55. Again, redesigned from the ground up by Pentax. It seems to be a variant of the Zeiss distagon. Critically sharp, wide open or not. A great landscape lens. I have used it for astrophotography, but due to its narrow aperture, < 10mm @ f/5.6 it takes rather long exposures to get enough light on the film. Ninety minutes does the job with E200 when shooting the Milky Way.

The 45/4 is almost as sharp and offers the widest rectilinear image in the 67 system. I find I use this one the most nowadays. Depth of field is wonderful when doing moonlit landscapes.


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Doppler
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Reged: 01/04/13

Loc: NE Georgia, USA
Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: Nightfly]
      #5854337 - 05/11/13 08:11 PM

There's a 77mm Borg on the classifieds, with a 2.5-inch focuser, perhaps it covers 6x7(?).

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PaulEK
professor emeritus
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Reged: 05/25/08

Loc: Wisconsin
Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: Doppler]
      #5854674 - 05/12/13 12:23 AM

Thanks, Doppler. I think it might cover, too, and the price is good. But it's fairly slow at f/6.6. That would work fine for digital, but would require quite long exposures for film, I expect.

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Doppler
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Reged: 01/04/13

Loc: NE Georgia, USA
Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: PaulEK]
      #5854922 - 05/12/13 07:05 AM

I think they make a f4 reducer for it, but that might be pricey.

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PaulEK
professor emeritus
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Reged: 05/25/08

Loc: Wisconsin
Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: Doppler]
      #5855146 - 05/12/13 10:18 AM

Yes, and it would also make it about comparable to the 300mm f/4 ED Pentax lens, several of which are up on eBay right now, for prices that are probably less than the total this would come to.

If there was something rare, excellent, and not too expensive up for sale right now somewhere, I'd consider finding a way to pay for it. But I suppose I can wait till I actually get the camera, too!


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Nightfly
Pooh-Bah


Reged: 06/20/07

Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: Nightfly]
      #5856229 - 05/12/13 08:01 PM

But then again, the 105 is a great lens for mosaics!!




Milky Way: Three Panel Mosaic by Nightfly Photography, on Flickr


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PaulEK
professor emeritus
*****

Reged: 05/25/08

Loc: Wisconsin
Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: Nightfly]
      #5856462 - 05/12/13 10:24 PM

Very nice, Jim!

I noticed a couple of things at the link that raised some questions: First, you said this was done on Fujicolor 100 negative film; can you say something about it? How is it different (better?) than, say Provia 400x? Also, what scanner are you using? And, last, now that I have a 55 and 200, would you think a 105 would be good, for either daylight or astro?

I'm probalby not going to run out of questions very soon, but I won't ask for all of the answers from you.


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Nightfly
Pooh-Bah


Reged: 06/20/07

Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: PaulEK]
      #5856877 - 05/13/13 06:28 AM

Hello again Paul. Yea, it was a lazy post. But since you asked. Film. Fujicolor 100 (Superia) is no longer available but I have freezer stock to last a bit. I generally do only a few special runs per year with this film. It is superb in performance yielding high quality images. As a negative film it has the advantage of greater tonality over transparency films and also suffers less halation which gives tiny pinpoint star images. Notice how very delicate details are preserved on the film.

The film is scanned on an Epson V600, stitched and post processed in Photoshop.

The 105 yields a larger field of view and a flat field at f/4.8 allowing wider field mosaics such as this one.

A slightly larger version of the above mosaic can be found here:

https://dl.dropboxusercontent.com/u/59003880/MW003-2_stitch_1280_pix.jpg

This type of work requires very long exposures on the same night. The image above started at the south horizon first and worked my framing up as the night progressed. The three hour of exposure was constantly monitored for aircraft and bright satellites. This is not easy work and I doubt many, if any, will duplicate it. Perfect polar alignment allows the 60 minute exposures at high declinations without field rotation.

I enjoy the challenge and its rewards. The image itself is the ultimate reward and sharing it is a pleasure.

The setup can be viewed here:

http://www.flickr.com/photos/12598495@N08/sets/72157626760790621/detail/

I believe this may spark more questions Paul.


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PaulEK
professor emeritus
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Reged: 05/25/08

Loc: Wisconsin
Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: Nightfly]
      #5857177 - 05/13/13 10:39 AM

The location of your observatory shows that you sure do have very dark skies. I'm not that lucky, but will just have to see how it goes. It's going to be a while, but I'm fairly confident that I'll have a permanent place to mount the G-11 in the next year or so. I'm really looking forward to being able to simply slide open a roof, push a few buttons, and start observing/imaging!

I'll probably have more questions later, but right now, I have to go ship that camera I had up on eBay, to China.


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Doppler
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Reged: 01/04/13

Loc: NE Georgia, USA
Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: PaulEK]
      #5857464 - 05/13/13 01:01 PM

Quote:

The three hour of exposure was constantly monitored for aircraft




Now tell the truth Jim, when was the last time you saw an airplane up there in the middle of nowhere? I couldn't resist, living just 60 miles from the Atlanta International.....


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Nightfly
Pooh-Bah


Reged: 06/20/07

Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: Doppler]
      #5858010 - 05/13/13 05:22 PM

Many would suggest there would be few aircraft, but my view to the south looks over the Atlantic and every aircraft going over the pond to Europe passes my way. Sunday nights are the most quiet and I can let my guard down a bit.

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PaulEK
professor emeritus
*****

Reged: 05/25/08

Loc: Wisconsin
Re: 165 f/2.8 OR 200 f/4 for Pentax 6x7? new [Re: Nightfly]
      #5859060 - 05/14/13 01:26 AM

I am very close to the flyway between Minneapolis and Chicago. When I lived in New Mexico, even when I'd drive hours to get between two wilderness areas, high altitude aircraft buzzed by like insects. I think most were military.

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Iksobarg
member


Reged: 02/19/14

SMC 200 f/4 definitely! new [Re: Nightfly]
      #6402177 - 02/28/14 03:18 PM

The Pentax SMC 67 200/F4 ($125)arrived two days ago along with a 72mm IDAS P2 filter($300) and the iOptron V2Skytracker($500). I'm chomping at the bit as my wife has now taken them for wrapping as my bday is still a week away. After much research and careful spending I'm looking forward to the this first "tracking" wade into AP. I'm expecting teething pains but thankful for backup of my AP for Beginners book and the good people of this and other forums for help.

Edited by Iksobarg (02/28/14 03:23 PM)


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Nebhunter
Carpal Tunnel


Reged: 10/04/03

Loc: Frostbite Falls
Re: SMC 200 f/4 definitely! new [Re: Iksobarg]
      #6408241 - 03/03/14 08:39 PM

Enjoy, take your time, and awaiting results. If you need any E200 film for the Pentax let me know.

Igor


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