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Any advantages shooting astrophotgraphy with film over digital?

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#51 Alen K

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Posted 24 June 2018 - 08:36 AM

Praise the emulsion and pass the film canister. :D



#52 Shakedown St.

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Posted 24 June 2018 - 05:45 PM

Here's a few shots I took with color slide film on an 8" Schmidt Newt (F/4) - a wonderful imaging scope btw.
These are all single 30 minute shots, except M45 which was a 45 minute exposure.

Hey, would you happen to remember what size film these were taken on? They came out really good.

Edited by Shakedown St., 24 June 2018 - 10:03 PM.


#53 Michael Covington

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Posted 24 June 2018 - 07:36 PM

By the way, someone said you have to take "hours and hours of exposures" with digital.  No, you don't.  Some people do, and it does pick up more faint detail, but you'd be surprised what you can get with, say, a stack of five 3-minute exposures.   Much more than a 15- or 30-minute exposure on film.



#54 Shakedown St.

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Posted 24 June 2018 - 10:06 PM

By the way, someone said you have to take "hours and hours of exposures" with digital. No, you don't. Some people do, and it does pick up more faint detail, but you'd be surprised what you can get with, say, a stack of five 3-minute exposures. Much more than a 15- or 30-minute exposure on film.


Mainly I've been using Kodack Portra 200/400 and Ektar. Would you happen to know any specific color film that would be better for astrophotography with a low failure rate.

Edited by Shakedown St., 24 June 2018 - 10:06 PM.

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#55 Michael Covington

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Posted 24 June 2018 - 10:48 PM

Mainly I've been using Kodack Portra 200/400 and Ektar. Would you happen to know any specific color film that would be better for astrophotography with a low failure rate.

Given that Ektachrome is not yet out, I think Ektar is the winner, at least for H-alpha response.  But switch to Ektachrome 100 when it comes out.

And compare digital to it side-by-side.  You'll be surprised!



#56 ClownFish

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Posted 25 June 2018 - 02:03 AM

Hey, would you happen to remember what size film these were taken on? They came out really good.

I used 35mm film, both Fuji Provira 400F which was awesome for faint blue sensitivity, and Kodak Ektachrome E200 which excelled at Ha response.

 

10399352_19631392857_2351_n.jpg

Fuji Provia 400F, 45 minutes, hand guided

 

 

10399352_19632077857_37_n (1).jpg

Fuji Provia 400F, 30 minutes, hand guided

 

 

1923811_19632632857_1589_n (1).jpg

(Kopdak E200, 45 minutes, hand guided)


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#57 Todd N

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Posted 25 June 2018 - 06:01 AM

Mainly I've been using Kodack Portra 200/400 and Ektar. Would you happen to know any specific color film that would be better for astrophotography with a low failure rate.

I tried Fuji Superia 800 many years ago and it as fairly good with good red response.



#58 SandyHouTex

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Posted 25 June 2018 - 08:44 AM

I used 35mm film, both Fuji Provira 400F which was awesome for faint blue sensitivity, and Kodak Ektachrome E200 which excelled at Ha response.

 

attachicon.gif 10399352_19631392857_2351_n.jpg

Fuji Provia 400F, 45 minutes, hand guided

 

 

attachicon.gif 10399352_19632077857_37_n (1).jpg

Fuji Provia 400F, 30 minutes, hand guided

 

 

attachicon.gif 1923811_19632632857_1589_n (1).jpg

(Kopdak E200, 45 minutes, hand guided)

Very nice!



#59 Shakedown St.

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Posted 26 June 2018 - 06:02 AM

Thanks! 45 minute exposure that is impressive, I'm learning how to overcome reciprocity failure right now.

#60 ClownFish

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Posted 26 June 2018 - 06:25 AM

Thanks! 45 minute exposure that is impressive, I'm learning how to overcome reciprocity failure right now.

 

I will tell you, there's a huge difference between a 45 minute autoguided exposure and a 45 minute hand-guided one!

If people want to "be at one with the Cosmos) in their astrophotography -  hand guiding will do it.

 

I used to tell folks who wanted to know what it was like, and I would say "go to your kitchen, bend over the sink, and look up into your faucet.  Now stay there for 45 minutes".


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#61 SandyHouTex

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Posted 26 June 2018 - 08:50 AM

I will tell you, there's a huge difference between a 45 minute autoguided exposure and a 45 minute hand-guided one!

If people want to "be at one with the Cosmos) in their astrophotography -  hand guiding will do it.

 

I used to tell folks who wanted to know what it was like, and I would say "go to your kitchen, bend over the sink, and look up into your faucet.  Now stay there for 45 minutes"

Yep.  Those were the days.



#62 Shakedown St.

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Posted 26 June 2018 - 09:16 AM

Learned something incredible today regarding the world of film. There is no difference between a film exposure and digital exposure. A fifteen minute exposure is a fifteen minute exposure, the difference being that you have to overexpose to compensate for the chemical reciprocity of your film.

So a fifteen minute film exposure done properly will bring out just as much detail as a fifteen minute digital exposure, if you compensate for reciprocity correctly. That may well mean that in order to capture a fifteen minute exposure, you need to overexpose for another forty minutes to protect your negative. Some black and white films do not require you to do this, and are no less time consuming than a DSLR.

#63 Michael Covington

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Posted 26 June 2018 - 10:16 AM

Learned something incredible today regarding the world of film. There is no difference between a film exposure and digital exposure. A fifteen minute exposure is a fifteen minute exposure, the difference being that you have to overexpose to compensate for the chemical reciprocity of your film.

So a fifteen minute film exposure done properly will bring out just as much detail as a fifteen minute digital exposure, if you compensate for reciprocity correctly. That may well mean that in order to capture a fifteen minute exposure, you need to overexpose for another forty minutes to protect your negative. Some black and white films do not require you to do this, and are no less time consuming than a DSLR.

That is a weird way to describe it.  Film requires much more exposure time than digital sensors to collect the same amount of light, because of reciprocity failure.  Some films have less reciprocity failure than others, but all have quite a bit of it.  See the section on reciprocity failure in any of several books on film astrophotography or photographic theory, with particular attention to the Schwarzschild formula.  I have never tested a film with p > 0.9.  


Edited by MCovington, 26 June 2018 - 10:30 AM.


#64 ClownFish

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Posted 26 June 2018 - 10:48 AM

"That may well mean that in order to capture a fifteen minute exposure, you need to overexpose for another forty minutes to protect your negative."

 

That's a contradiction. 

 

As Covington says, film does require a lot more exposure to gain as much detail as digital.  The way to think of reciprocity failure is forgetfulness.  Film forgets what it saw, and needs to see it over and over again to remember it. 



#65 Michael Covington

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Posted 26 June 2018 - 11:12 AM

Here is how it all works.  Film and digital sensors both rely on photoelectrons -- electrons that are displaced by the energy of incoming light.  In a digital sensor, the photoelectrons are stored in tiny capacitors that have (over the time period involved) virtually no leakage.  Then they are read out and delivered to the computer.

In film, the photoelectrons cause a latent chemical change in the silver iodide crystal.  But this change is not permanent.  Given time, the electrons find their way back to where they started.  Also, to some extent the same latent chemical change proceeds without the photoelectrons, causing fog.

 

Particularly of interest to us is the fact that the fewer electrons, the less stable the chemical effect -- if you have only a few photoelectrons, they nearly all leak away.  This is called low-intensity reciprocity failure (LIRF).  It is why 1 second at one light level is not equivalent to 1000 seconds at 1/1000 of that light level.  In the latter case, reciprocity failure is severe.

I did a lot of actual measurement of reciprocity failure back in the 1990s, and when digital sensors became good enough, I switched to digital.  I still do film photography in the daytime as an art form, but I can't see that it has any advantages for astrophotography.

Two cautions:

(1) A typical deep-sky picture of mine is a stack of 30 1-minute exposures.  But that is to reduce noise, not to accumulate light.  A *single* 1-minute exposure looks very similar, though grainier.  I spend half an hour on a deep-sky object because it's easy to do so.  I don't need that much time just to get minimum exposure, as I would with film.

(2) Newer DSLRs and digital astrocameras are *much* better than those of 15 or 20 years ago.  Don't be misled by the poor performance of early models.


Edited by MCovington, 26 June 2018 - 11:17 AM.

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#66 Shakedown St.

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Posted 27 June 2018 - 12:18 AM

I was very confused about this at first, but it helped me understand by seperating reciprocity failure from exposure. Short exposure on film and digital are the same, and if film did not suffer from that phenomenon long exposures would be identical too. Thinking in digital perfect terms, a one hour film exposure may actually give you the results of a 30 minute exposure because of this.

#67 ClownFish

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Posted 27 June 2018 - 12:20 AM

Also reciprocity failure, and the actual chemical makeup of the film, also mean that different colors are effected differently.  That is, longer exposures will shift the overall tone to the green or red.  Each color response is different. 



#68 ClownFish

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Posted 27 June 2018 - 12:42 AM

I wish we had Kodak Tech Pan still.  It was extremely fine grained, and very sensitive to Ha.  While it was very slow film, it could be hypered to reduce the effect of Reciprocity.  Hyping film was the procedure to remove oxygen from the emulsion, the main catalyst for reciprocity failure. This was done by "soaking" the film in a pressure container of hydrogen gas (mixed with inert nitrogen for safety) while baking it!  After this procedure, the film was perfect for recording faint Ha targets - and gave amazing results.   


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#69 AnakChan

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Posted 27 June 2018 - 02:06 AM

I wish we had Kodak Tech Pan still.  It was extremely fine grained, and very sensitive to Ha.  While it was very slow film, it could be hypered to reduce the effect of Reciprocity.  Hyping film was the procedure to remove oxygen from the emulsion, the main catalyst for reciprocity failure. This was done by "soaking" the film in a pressure container of hydrogen gas (mixed with inert nitrogen for safety) while baking it!  After this procedure, the film was perfect for recording faint Ha targets - and gave amazing results.   

I still have 1 or 2 rolls of TP2415 in my freezer. Dunno if it's any good...prob expired 15 yrs back?



#70 ClownFish

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Posted 27 June 2018 - 04:17 AM

:)   Send a roll to me and I'll test it!



#71 hfjacinto

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Posted 27 June 2018 - 02:10 PM

Looking at the pictures posted, digital is better, not to say you can't do good with film, but digital is more sensitive, doesn't have reciprocity failure, can be used with narrowband and can be combined to reduce noise. I also shoot from 17 miles west of NYC, in 3 minutes my image was all white with film.

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#72 hfjacinto

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Posted 27 June 2018 - 02:11 PM

Not to mention narrowband.

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#73 hfjacinto

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Posted 27 June 2018 - 02:19 PM

Here is an example of a 5 minute exposure, this is pure raw, black point is not set. No flats, bias or darks applied.

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#74 OldWally

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Posted 11 August 2018 - 11:36 AM

The same is valid for me. I started photography in general and astronomical photography in particular in the 70th. Most photography was B/W at this time, and many people printed for their self, as I did and still do.

 

For me, a real photograph comes from a b/w negative and becomes manifest at a sheet of printing paper.

 

I don't perform astronomical photographing very much. But If I do I use b/w film.  I have no intention competing with other photographer, but take rather some kind of souvenir pictures.

 

To give an example: The transit of Mercury last year:

150509Merkurtransit5.jpg

Beautiful and sharp as a tack...


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#75 Michael Covington

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Posted 11 August 2018 - 07:37 PM

There are multiple reports that, as of a few days ago, Ektachrome Elite 100 in 135-36 rolls is in the hands of beta-testers.




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