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Hypering film with light in the telescope!

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#1 Giorgos

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Posted 22 October 2020 - 04:24 AM

Hi everybody!

I read an old S&T article about hypering film with a stopped down electronic flash in a darkroom. I have an idea about something simlper and why not as much as effective: just a flat box or even a uniformly lighted white wall or piece of cardboard. Aim the telescope or tehlephoto lens with film camera attached to the flatbox and take a measure. Shoot a 4-5 stops underexposed. Recock the shutter (the camera has to be able for double exposures of course!) and take your astrophoto with your hypered film! Has anybody tried something similar?


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#2 Todd N

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Posted 22 October 2020 - 06:28 AM

Hi Giorgos,

Yes. I had done a lot of indoor preflashing tests last year and earlier this year with promising results. The weather didn't cooperate for most of this year so, wasn't able to get out in the field. I devised a simple light box with a 12"x12" opaque white plastic sheet from Rock Hard Plastics I bought off Amazon as a diffuser, a 10"x10"x12" shipping box and the back side of a disassembled Lite-Bright as a light source. I initially bought the Lite-Brite toy to see if I could use it to test films spectral response with it's illuminated colored pegs but that didn't work. With this setup I preflashed film in SLR camera with lens stopped down to f/5.6 for best even illumination and directly on top of the light box. I found stopping the lens down further didn't produce a better preflash. The correct exposure of coarse depends on each film and the light box arrangement. The best from my testing by far is Ilford HP5. TriX worked but less so and required a longer exposure. There was some worthwhile benefit to new Fuji Acros also. I'll upload some test images but I don't have it organized at the moment.

 

Despite what the literature may document I found a heavier preflash far more beneficial, around one stop using a Stouffer step wedge; Sources usually recommend a preflash that just barely registers a density increase from base. Too heavy a preflash doesn't improve performance and reduces dynamic range and blunts the highlights which nevertheless may be useful for certain objects with bright cores and fainter outlying areas. Preflashing isn't quite a substitute for H2 hypering for films that will respond to that treatment. I also tested post flashing which has a benefit but much less so. Applying both a pre and post flash to the same frame didn't improve performance and reduced dynamic range; Not recommended.

 

Regards,

 

Todd


Edited by Todd N, 22 October 2020 - 06:37 AM.

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#3 Todd N

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Posted 22 October 2020 - 09:15 AM

One needs to go through a testing process to see what would be the correct preflash exposure based on the variables of one's setup and film type. As I stated, the camera lens should be stopped down to provide the most even illumination. It didn't seemed to matter much at all if the camera was up close to the light box or a few inches away. I basically rest the camera/lens face down on the light box usually with the lens hood on. SLR needs to have multiple exposure function on same frame. Take preflash, adjust aperture if one wishes to use a faster f-ratio or remove lens to attach camera to scope. Light box is made from a simple shipping box, plastic sheet as a diffuser and the disassembled back of a Lite-Brite as a light source which uses LEDs and simply powered by three AAA batteries.

 

Rock Hard Plastics - 12" x 12" White Acrylic Sheet Lucite Plexiglass

 

Light Box:

https://www.flickr.c...eposted-public/

https://www.flickr.c...eposted-public/


Edited by Todd N, 22 October 2020 - 09:52 AM.

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#4 Todd N

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Posted 22 October 2020 - 10:13 AM

Ilford HP5 ISO 400

https://www.flickr.c...eposted-public/

 

Ilford HP5 ISO 800

https://www.flickr.c...eposted-public/

 

Fuji Across 100 II

https://www.flickr.c...eposted-public/

 

Tri-X

https://www.flickr.c...eposted-public/

 

I've tested these and many other films developed to various ISOs but these seem to perform the best especially Ilford HP5. Tmax 100 and 400 didn't seem to benefit much or at all. I will probably retest Tmax 400 again.  ISO 100 films in general had a lesser response benefit. ISO 400 films performed the best. ISO3200 didn't perform as well.  Ilford Delta 100 had a good response but under low light testing was almost as grainy as HP5 @ISO400 but less sensitivity of coarse.

 

Also, preflashing H2 hypered film(Fomapan 400)  didn't work well together, low contrast. So, I wouldn't try it with Techpan if one has some on hand.

 

Todd



#5 Giorgos

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Posted 25 October 2020 - 02:42 AM

WoW! Your work is at least IMPRESSIVE Todd! Thank you! Another question: have you tried hypered Fomapan for astrophotograph? any pictures? I would also like to see the H2 hypering setup if you wish!



#6 Todd N

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Posted 25 October 2020 - 04:21 AM

WoW! Your work is at least IMPRESSIVE Todd! Thank you! Another question: have you tried hypered Fomapan for astrophotograph? any pictures? I would also like to see the H2 hypering setup if you wish!

Yes. I posted a few results some time ago and they are on my Flickr page:

 

Orion Nebula/C8 SCT @f/6.5, 20min. exp.

https://www.flickr.c...57626254918562/

 

Orion Nebula, C8 @f/10, H-alpha, 10min. exp.

https://www.flickr.c...57626254918562/

 

Orion Wide-field

https://www.flickr.c...57697664120191/

 

These are not good shots but were more so tests from suburbia with plenty of light pollution. Out of all the testing I have done Fomapan 400 had the best response to H2 hypering along with extended red sensitivity. It's not like Techpan but it does attain a significant response to H2 treatment. It is very grainy and not a great choice for wide-field but I still intend to pursue it.

 

I don't have a picture of my hyper setup. It's a Lumicon large hypering chamber, vacuum oil pump, heated by a Best Value Vac hot plate that is temp regulated. I wrap a towel around it and is covered by a large styrofoam cooler. For B&W, I use pure H2 and use nitrogen for purging the chamber and soaking. I'll try to later post an image of the rig.

 

Todd


Edited by Todd N, 25 October 2020 - 04:22 AM.

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#7 Giorgos

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Posted 25 October 2020 - 05:30 AM

Nice results! The film is cheap and easy to find here. It would be interesting to try flashing it for comparison with the H2 hypered. Flashing is far easier and practical as a method. Which developer do you use?


Edited by Giorgos, 25 October 2020 - 05:31 AM.


#8 Todd N

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Posted 25 October 2020 - 05:50 AM

Nice results! The film is cheap and easy to find here. It would be interesting to try flashing it for comparison with the H2 hypered. Flashing is far easier and practical as a method. Which developer do you use?

I have tested both but I'm missing and think I forgot to take a control shot from stock film for comparison. I did the preflash image and the H2 hypered image to compare and the H2 performs way noticeably better but, preflashing does work to some degree. Most of my testing in the past was with Kodak HC-110 but I'm now using more often Ilford Microphen. I don't plan on buying HC-110 anymore since it has been reformulated and it's shelf life is uncertain as far as I know.


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#9 Jerry Lodriguss

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Posted 31 October 2020 - 08:48 PM

Wow guys, I feel like I have fallen into a black hole and been transported back in time to 40 years ago!

I did all this stuff too back in the day!

I even tested preflashing and hypering to increase sensitivity for short exposure sports like pro football in the Superdome when it first opened.

This thread is great!

Are they still making Techpan?

Just be sure you get your sprocket holes lined up the same when you preflash!

Jerry

Edited by Jerry Lodriguss, 31 October 2020 - 08:49 PM.

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#10 TxStars

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Posted 01 November 2020 - 01:21 PM

"Are they still making Techpan?"

 

I wish, but sadly no,  The last production was 2004 ...



#11 Marty0750

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Posted 01 November 2020 - 09:09 PM

Can someone tell me what the luminous intensity of the light box screen should be and a typical  exposure rate to preflash, say the 400 asa film?



#12 Jerry Lodriguss

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Posted 02 November 2020 - 12:59 PM

Are you all plotting dLogE curves with a densitometer?

 

Jerry



#13 Todd N

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Posted 02 November 2020 - 07:19 PM

Are you all plotting dLogE curves with a densitometer?

 

Jerry

I'm not. I thought of dabbling in sensitometry for rainy days but haven't yet. I don't think it would have worthwhile value in evaluating films for astrophotography. Indoor testing with a dim light source is simpler.

 

Todd



#14 Giorgos

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Posted 04 November 2020 - 03:17 AM

There is also treatment of film with light AFTER exposing it. It is called "latensification" and it is not done with a brief flash light but with a dim light of long duration (like a very dim dark green safelight). It is also an interesting technique to try... The problem is that you have to stay in a dark room for a loooonngg time with the film. Tip: buy a radio!



#15 Giorgos

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Posted 04 November 2020 - 03:49 AM

Can someone tell me what the luminous intensity of the light box screen should be and a typical  exposure rate to preflash, say the 400 asa film?

There isn't an easy answer to this... You have to experiment. Different film brands may act differently. BTW nice that yellow telescope of yours!


Edited by Giorgos, 04 November 2020 - 03:51 AM.


#16 Tony Pilato

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Posted 28 November 2020 - 03:01 PM

Jerry,

 

They stopped making kodak tech pan aroound July 2006. I still have a roll in freezer of the previous campaign 05/06. Still have some forming gas. 100% film C/11 at F/6.5 and F/10.

 

Good to see another old APML'er. Thanks for all your help long, long ago....

 

Tony Pilato 

www.darkstarimages.com 



#17 Helge F.

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Posted 02 December 2020 - 10:15 AM

 

I even tested preflashing and hypering to increase sensitivity for short exposure sports like pro football in the Superdome when it first opened.

Would you mind sharing the results and thoughts?

 

I read an article from some of the last serious Kodak funded research in astrophotography in the 90s (I lost the link of course), that traditional moisture removing H2 hypering was actually not good for HIRF. It made the emulsion shrink, putting enormous force on the halide crystals. Basically severely handicapping them for fast exposures.

Only soaking in H2, and no vacuum or excessive purging of moisture should be the ticket. 

 

I’d be very interested in seeing photos from you experiments.


Edited by Helge F., 02 December 2020 - 10:17 AM.



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