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Medium Format Camera for Astrophotography? Pentax 6x7?

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#1 mfoose

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Posted 23 June 2015 - 05:51 PM

I have fallen in love with film and astronomy so I figured, why not combine them?! I currently own a Canon F1 35mm camera and it is great, but I only own one lens a standard 50mm f1.4. I was looking for a new lens, but before I pulled the trigger I wanted to reassess my goals for astrophotography. After doing so, I concluded that I wanted to use my camera for primarily wide field long exposure shots. After doing more research it dawned on me that a medium format camera with a goto GEM would be best for this. So, rather than investing in a new lens for my 35mm camera I have decided to buy into a whole new MF camera system.

 

So I began to research what cameras are available and which would best fit my needs. First, I was set on buying a Hasselblad. This is because I love the shots they made during the Gemini and Apollo missions and I always thought it would be cool to use. However, I quickly discovered they are way out of my price range. So I began to dig deeper. Eventually this led me to a Mamiya RB67. I have been pretty set on buying one, but then I began to read posts in this forum. Many members here who have success in MF astrophotography have a Pentax 6x7.

 

My question is why a Pentax 6x7? The one thing that turned me away from them is that they are battery dependent and I don't want to be out shooting and have my batteries die mid exposure. But so many people have used them and they almost have a cult following for MF astrophotographers. 

 

I am just hoping to be able to either have peace about my decision on a Mamiya RB67 or to be convinced to buy a Pentax 6x7. I just want to sure before I invest in a camera system.

 

Clear Skies,

 

Michael



#2 Michal1

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Posted 24 June 2015 - 06:27 PM

I chose Pentax 6x7 because I liked the images people had taken with it. It is relatively cheap, it holds the film flat well, a variety of good lenses are available, there are a lot of users who can help you, etc. Batteries are not necessary if you build a battery eliminator. It is easy.

http://www.cloudynig...-1#entry1539368

I don't know how about RB67, but Danilo Pivato had a great success with Mamiya RZ67, search the forum.

Let us know your progress and don't hestate to ask if you have any questions.



#3 mfoose

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Posted 24 June 2015 - 07:18 PM

Seeing that there is a way around a battery for the Pentax 67 definitely helps!

 

I also appreciate your opinion! I have noticed in comparing the two that the Pentax appears to have better lenses than the Mamiya. Some have said that they may be some of the top MF lens around.  

 

The one feature I love on the Mamiya RB67 is the rotating back. The Pentax doesn't appear to be able to be mounted vertically on a dovetail or a piggyback. Have you had any issue with this? Or is this a feature that I should not be focusing on? I do plan to use this camera for more than just astrophotography, but I am focusing on the astrophotography pros and cons for buying it.
 



#4 Nightfly

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Posted 24 June 2015 - 08:33 PM

I switched to the Pentax 67 in 2007 after years of 35mm work.  The step up in size gives a very high quality image.  I would recommend the Pentax 67 for astrophotography, but only if you can acquire the proper films.

For B&W work you can do very well with Fuji Acros 100.  Color work will require some legacy emulsions, such as Kodak E200 or Fuji's Provia 400F or 400X.  Harder to find is Superia 100 (Not Reala 100) or Centuria 400.

 

I generally do not recommend anyone to enter into film astrophotography because of the lack of proper emulsions and the skill set required to pull it off to a satisfactory level.  If you have mastered wide-field 35mm work already, then you may be prepared to go medium format.  

 

I have mentored some people in the past and in my experience many have gotten in over their head and quit after putting much equipment and effort into it.  I do not want to discourage you, but ask anyone on this forum that shoots medium format and they will tell you it is often daunting.  

 

Good luck in you efforts.  



#5 mfoose

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Posted 25 June 2015 - 07:44 AM

Thank you for your advice and your warning. I am not going into MF just for astrophotography, so if I cannot get satisfactory results I will not be devastated. I love doing film astrophotography just for the experience. I love going out on a clear night when everyone else is in bed and pointing my camera in the heavens. Results are just icing on the cake.

 

I was planning on using Fuji Acros 100 as I began. I have access to a darkroom where I can develop B&W film for free. After I became comfortable with B&W I would integrate color. From reading some earlier forum posts I saw that color film suitable for astro is all but dead. I have seen Fuji Provia 400F recommended elsewhere too. I think Fuji still makes Provia 100F. Would this work as a good color film? Or should I just try to find some of the legacy emulsions you mentioned above? 

 

The differences in film still go over my head. What makes some film good for astro and other film bad for it?



#6 Joe F Gafford

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Posted 25 June 2015 - 12:08 PM

  I used an RZ 67. It has a separate manual shutter release jack on the lens barrels. The 110mm F/2.8 is a good lens for that. See the "Sagittarius Star Cloud" string for one example. 

 

Joe



#7 mfoose

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Posted 25 June 2015 - 12:56 PM

Beautiful Joe! How did you do with the "T" setting for long exposures? I have been reading that you either need to turn the lens back to 1 second or slight move the shutter cocking lever to end the exposure. What about the Mamiya lenses? I know the RZ uses an electronic leaf shutter in their lenses, but how good was the quality?



#8 Joe F Gafford

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Posted 26 June 2015 - 01:09 AM

  There are 2 shutter releases, one in the front below the bellows and the other on the lens barrel for the dual release. The one on the lens has a T switch. The T switch holds open the shutter iris at the selected F-stop and flips open the shutter. You had to slide the T shutter to normal to close the shutter on the camera. The power is to open the shutter only and the shutter release cable cable put in either place to trip open the shutter. No holding to the shutter release as the switch does the closing. On my old original model RZ-67, it mattered not the shutter speed. The newer model, the Pro II, may have different instructions for the T setting. The Pro II is made so you can use a CCD back and it talks to the back as well as the lens.

  The old version of the 110 mm lens was made for film at the F/2.8 setting. I had to stop it down to F/5.6 for CCD work. There is the usual vignetting at the full 6x7 format at the full open on the old lens, slight coma in the corners. The newer version of the lenses may have improved over the F/5.6 limit for CCD work. I even made an adapter for that to fit my CCD. I had an old thread on how to make an adapter for the RZ, but I cannot find it after they reformatted this site. My camera, accessories, spot level meter, 50 and 110 mm lenses and adapter was stolen 2 years ago. I missed that camera and that left my Orion mosaic unfinished. 

  I priced the pro backs for this camera and found the cost is as much as an SUV!  The Pro backs may not do long exposures. This camera was made for studio use and landscapes. Even the special dew zapper I made for the lens was taken in the burglary.  

 

  Taken in July 1988 at the site near Kenosha Pass, CO at night awaiting the clouds to clear. My old film setup with this camera.

I_07_16_88002_web.jpg

 

  Taken in February, 2009. The 110 mm lens with the CCD setup. Notice the changes to the mount and imaging board over that time? And I had to rubber band the preview lever to get the selected F/ stop?

P2163405_web.jpg

 

Joe



#9 Glen A W

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Posted 26 June 2015 - 01:17 PM

I wouldn't be nervous about trying film.  It's very organic and more an art than science.  I got a lot more enjoyment out of it than I ever have with digital.  I started doing B&W in my closet darkroom and then did E-6 slides in the kitchen.

 

The trouble is that even in the heyday, films which had the right response were pretty few.  And, you generally could not buy them at WalMart.  So far as I know, films like ScotchChrome are long long gone.

 

Films which don't have the right sensitivity for what you are shooting are basically like shooting at a greatly reduced speed.  In fact, they may never show the object you are going for.  When I was shooting it, Scotch 400 was the best, by far, for the reds seen in images of nebulae.  So, there is some frustration there.

 

I do not know if you are aware but years ago people went to all sorts of extremes to get better sensitivity, including gas treatments and dry ice cooling.  And, they would try all sorts of tricks in processing, as well as dodging and burning.  That's mostly forgotten art, now.

 

I would keep an eye out on used prices for your equipment so you don't get burned if the bottom falls out of pro 120 equipment like it did with 35mm!

 

Glen



#10 Glen A W

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Posted 26 June 2015 - 01:21 PM

PS - The advantage to shooting film is that your images look "real."  Digital images are fantastic but they can't match the natural appearance of good film shots.

 

Glen



#11 mfoose

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Posted 26 June 2015 - 02:37 PM

After thinking about everything I have decided to buy a DSLR. I love film and I find it more enjoyable than digital, but as some of you have pointed out there isn't much a future in film. It is becoming harder to find and expensive to develop. I could get my own darkroom, but I feel like I would be delaying the inevitable.

 

My plan now is to purchase a decent DSLR for astro and use it for everyday life too. I am leaning heavily towards a Nikon D5300 and a Rokinon 14mm f/2.8 lens for it. I want to start off wide field, make my own mechanical barn door tracker to get decent result for around 20 minutes and slowly upgrade lenses. Hopefully in 5 years or so I can upgrade to a full frame DSLR and a GEM. I will still shoot 35mm film from time to time, but a majority of it will be digital.

 

Thanks for all of your input and advice! 

 

Michael



#12 Glen A W

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Posted 26 June 2015 - 07:17 PM

You are making a good choice.

 

I love film and want to shoot it again for AP.  I have been saying that for years, and have not done it yet.  The last film I shot for AP was in 2003!

 

I still have all the equipment, but film and chemicals would set me back as much as a star party trip or two.  I still hope to be able to afford it before film is all gone.

 

Film is a wonderful medium, so you might want to do it with your 35mm and film which can be mailed off.  Then you can scan the negatives or slides.  Medium format is amazing but a 35mm can give great results.  Using the equipment you have will let you experiment with little investment.

 

Glen



#13 Michal1

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Posted 29 June 2015 - 11:59 AM

Michael, once you have a setup for a digital camera, you can also try a 35mm film camera. There is still a choice of good films in the 35mm format and I guess they will still being developed for a long time. I'm probably biased, but I expect nicer images from film. Definitely worth trying. And in my experience, shooting "from time to time" is too little. In my case, it means that I see the photos one year after the shooting. Then the learning process gets too slow. It is better to be "cruel" to the film, make a lot of test shots and waste it. 

 

Nightfly, what is your opinion on Ektar 100? The image you took on it looks well.

https://www.flickr.c...ador/3829654187

Its red sensitivity is not as good as that of E200 but it is still fair.



#14 Nightfly

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Posted 01 July 2015 - 04:38 PM

 

Nightfly, what is your opinion on Ektar 100? The image you took on it looks well.

https://www.flickr.c...ador/3829654187

Its red sensitivity is not as good as that of E200 but it is still fair.

 

 

Hi Michal,

 

I have not gotten a chance to try Ektar again.  I was hoping someone else might try and do it :-)

 

But seriously, I would try it but I am going with what works.  I got lots of tried and true films and a limited number of nights to shoot with.  But now you got me thinking.......

 

I did try Portra 160 and 400.  They were not very good at all for astro.  I was anxious to try Fuji 106NS as I think it might be a good film judging from its spec sheet.  It looked to be close to Superia 100 in response and reciprocity.  

 

So there are films to still test and with possible candidates for a good film.  Ektar might be fabulous with bright star clouds and bright nebulae.



#15 Michal1

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Posted 01 July 2015 - 05:24 PM

Nightfly, lets make a public agreement. It might help to speed things up. I will try Ektar this summer and you 160NS, OK? A few shots on the stars and the rest as we like.



#16 SMigol

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Posted 03 July 2015 - 02:16 AM

I've got some Ektar in the fridge that I can use in a few weeks.  What exposure lengths should be tried?

 

I'll be shooting Acros and some E200 in 13 nights at the Golden State Star Party. 



#17 Nightfly

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Posted 03 July 2015 - 05:29 AM

Nightfly, lets make a public agreement. It might help to speed things up. I will try Ektar this summer and you 160NS, OK? A few shots on the stars and the rest as we like.

 

I cirrently own a roll of 160S which is suppose to be the same as 160NS.  It's a 220 roll I will be exposing in August.  I'll shoot a few  frames for astro test.



#18 Nightfly

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Posted 03 July 2015 - 05:31 AM

I've got some Ektar in the fridge that I can use in a few weeks.  What exposure lengths should be tried?

 

I'll be shooting Acros and some E200 in 13 nights at the Golden State Star Party. 

 

I would try 30 minutes or more @ f/4.  Being negative film, you can't overexpose it unless you LP is bad.  

 

Have fun at the star party!  Looking forward to your results!



#19 Michal1

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Posted 03 July 2015 - 06:16 AM

I cirrently own a roll of 160S which is suppose to be the same as 160NS.  It's a 220 roll I will be exposing in August.  I'll shoot a few  frames for astro test.

 

What is that 160S? I don't see it in the offer of the local shops. Is it still in production? Is it available in the 120 format?



#20 Nightfly

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Posted 03 July 2015 - 04:35 PM

 

I cirrently own a roll of 160S which is suppose to be the same as 160NS.  It's a 220 roll I will be exposing in August.  I'll shoot a few  frames for astro test.

 

What is that 160S? I don't see it in the offer of the local shops. Is it still in production? Is it available in the 120 format?

 

 

160S in no longer manufactured, but now offered as 160NS.  It is available in Japan as an export and is sometimes offered in small quantities in the USA.

 

Comparisons of 160S - 160NS - Superia 100

 

 

http://www.fujifilm....s_datasheet.pdf

 

http://www.fujifilm....s_datasheet.pdf

 

https://www.fujifilm...in/AF3-007E.pdf

 

 

I don't expect it to perform as well as CN100, but it's worth a try.

 

 

Kodak Ektar looks to be the best.  On paper at least.

 

http://www.kodak.com...e4046/e4046.pdf



#21 Michal1

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Posted 05 July 2015 - 08:59 AM

Interesting comparison, thanks Nightfly. The only difference between 160S and 160NS I can note are a little different characteristic curves. The 656 nm sensitivity of 160N is a little worse than that of Superia 100, but its characteristic curve looks better between 10^-2.5 and 10^-2 lxs. I will test it! SMigol and Nightfly, be sure to test your films!



#22 Michal1

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Posted 08 July 2015 - 04:51 PM

 I will test it!

The film 160NS is bought!



#23 SMigol

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Posted 10 July 2015 - 06:06 PM

I looked in the fridge and I have a roll of 160S.  I also have 2 rolls of Ektar.  I'll run them side by side on a setup to see what comes out next week.

 

Exposures I'll test will be 30 to 60 minutes at F4 to F5.6, depending on lens setup.

 

May only have 3 nights of clear skies - there's a 50% chance of rain on Saturday.

 

Will see what happens.

 

Stephen




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