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Finally, a fresh film shot

astrophotography beginner
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#1 telesonic

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Posted 08 November 2018 - 11:59 PM

Yesterday I received the prints of my 2 rolls, and just as I had expected... there is certainly much more for me to learn about this fascinating hobby. The first roll was just spent testing focus, some fixed tripod shots, and a mix of daylight and blank frames. Not totally useless for note taking... just to figure out what works.

The second roll had a couple of shots I thought were half decent, so I'm posting this one up for a sort of starting marker.

 

This is a resized image (taken from the photo cd) from the lab, original. 

 

Trying to catch some milky way (original)
 
This is the same image with just some post processing in iphoto / gimp, that I whipped out earlier.
 
Milky way edited

 

Image Details:
Vicinity of Deneb / Sadr (I think)
Film was Fuji Xperia 400
Lens 28mm f2.8 down 1 stop?  (notes aren't too clear)
Exposure - 8 minutes
Vixen Polaris EQ mount roughly aimed at the pole by eyeball, single axis drive (self modified Orion unit)

Just set it down and let it go with no guiding or corrections.

 

 

 

When I got both rolls back, I was surprised by how light many of the frames were... almost as if overexposed or developed wrong. I don't live under a pristine dark sky, more like a mixture of urban and rural (yellow/green zone) so I suspect that I'm picking up sky glow / sky fog from the surrounding areas (local area lights and light domes) is that correct? I do notice some coma on the edges of the frame... likely from the lens, and I'm not experienced enough to pick out tracking errors or anything like that... so for now, it is what it is... a start.

 

Feedback is welcome of course,

Temp


Edited by telesonic, 08 November 2018 - 11:59 PM.

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#2 Michal1

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Posted 09 November 2018 - 03:32 AM

Hi telesonic! Good start! I reminds me my beginnings. To improve your photos, you can work on the following:

- a better film. See the newest post here https://www.cloudyni...tography/page-2 , many also have high expectations of the newly introduced Kodak Ektachrome 100.

- stop down your lens. The elongated stars in the corners of the image indeed look like being caused by lens aberrations.

- With a stopped-down lens and a slower film, you will probably have to increase the exposure time. Then you will have to put more effort to polar alignment and guiding.

 

I guess that your photos came out so bright because they are overexposed. You used a fast film and lens. Experimenting will allow you a quick start. Remember: "You have to waste film or you will waste your time".


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#3 telesonic

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Posted 09 November 2018 - 04:42 PM

Thanks Michal!

I do have some 200 speed Kodak Gold rolls that I'm going to try soon, and I'm also curious to hear how that Ektachrome works for astro shots.... but don't think there have been any results posted here yet.

 

Next time I will be using my Super Polaris mount, which has a polar alignment scope (and updated reticle) to help me get it more precise, and a better single axis drive with hand controller, so I should be able to guide with my short 80mm scope. I may have to man up and learn drift alignment too, but haven't got that far yet.

 

 

Thanks for your comments,

and that last line about wasting film or wasting time is true! I hope to get some more shots soon, and I'm not worried about using up film do do so.

 

Cheers,

T



#4 Uwe Pilz

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Posted 15 November 2018 - 09:04 AM

As long as you make the first steps in film bases astrophotography, it may be worth using b/w film. It can be processed easily at home, and you may process just a few images. YOu get negatives, of course, but their use is not uncommon in astronomy. To look what you got a simple slide projector is of use.


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#5 telesonic

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Posted 15 November 2018 - 08:13 PM

Uwe,

 

It has been on my mind to try some b&w.. and may do that to, as my girlfriend took a few years of photography at the university level. She is familiar with the process of developing it, but I may have convince her it would be a good idea... we live in a small home with not much indoor space for more things. 

 

 

Can you, or maybe anyone else that reads this suggest a good b&w film to start with? I've read mentions of Ilford +5 (I think) and one other brand. I think I've also read (maybe on here) about winding your own film into cartridges with only a small amount of film to develop instead of a full roll, is that what you are referring to?

 

Temp



#6 Uwe Pilz

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Posted 16 November 2018 - 12:22 AM

Dear Temp,

 

I make (non astronomical) b/w photography since around 1973 an may give you some hints.

 

> we live in a small home with not much indoor space for more things.

 

You don't need much. A developing tank, a bottle of developer and one of fixer and maybea funnel. I gave you links to powder chemicals, yo you don't need more space for stock bottles.

 

Every photographer recommends the film it uses for theirself, so I do.

 

If you want a classical emulsion, than I recommend APX 400 new aka Kentmere 400 aka CHM 400. It need a exposure time of around 5...10 mins under rural sky at f/2.8, SQM around 21.

If you want best quality / finest grain, take Ilford Delta 100. It takes the double time.

I don't recommend the high speed films Ilford delta 3200 and Kodak TMZ. They cannot be stored well and have a giant grain.

 

I strongly recommend the developer Atomal 49, which makes most of the speed. It is powered, so there are less problems with shipping beyond the ocean. 

 

For my rarely done astronomical work I use a mechanical camera, which does not depend on batteries. After shooting, you may open the camera in the total dark (bath room at night with lights of) and cut the exposed film strip.

 

You should sacrifice a film for practicing how to insert it in the tank. Try it first in an illuminated room to see how it works.

 

If you have more questions, please ask.


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#7 telesonic

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Posted 16 November 2018 - 09:47 AM

Uwe,

Many thanks for your reply, and detailed information.

 

Both cameras we have are mechanical, so no problems there. I will re-read over your information this evening, and will ask if needed.

 

 

Thanks again,

Temp



#8 NWAAstronomer

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Posted 16 November 2018 - 10:29 AM

The raw image looks to me like reciprocity failure: https://en.wikipedia...y_(photography)

 

From that wikipedia article: Astrophotography

Reciprocity failure is an important effect in the field of film-based astrophotography. Deep-sky objects such as galaxies and nebulae are often so faint that they are not visible to the un-aided eye. To make matters worse, many objects' spectra do not line up with the film emulsion's sensitivity curves. Many of these targets are small and require long focal lengths, which can push the focal ratio far above f/5. Combined, these parameters make these targets extremely difficult to capture with film; exposures from 30 minutes to well over an hour are typical. As a typical example, capturing an image of the Andromeda Galaxy at f/4 will take about 30 minutes; to get the same density at f/8 would require an exposure of about 200 minutes.

When a telescope is tracking an object, every minute is difficult; therefore, reciprocity failure is one of the biggest motivations for astronomers to switch to digital imaging. Electronic image sensors have their own limitation at long exposure time and low illuminance levels, not usually referred to as reciprocity failure, namely noise from dark current, but this effect can be controlled by cooling the sensor.



#9 Alen K

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Posted 16 November 2018 - 08:10 PM

The qouted passage from Wikipedia does nothing to explain what reciprocity failure is or how it affects exposures. But there is an explanation in the article.

PS. Reciprocity failure not only leads to needing increased exposure time, it can also result in color shifts because the different layers of the emulsion of color film often (usually) have different failure "rates" (the exponent Uwe mentions below).

Edited by Alen K, 17 November 2018 - 10:59 AM.

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#10 Uwe Pilz

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Posted 17 November 2018 - 12:48 AM

For Delta 100, the reciprocal exponent is around p=1.5.

 

You have to calculate

 

F = f ^ p

 

Here is f the factor of the exposure time you think you need, and F the factor you real need.

 

Example: You need 5 minutes at f/2.8 but want to use f/4. This is a factor of f=2, you think you need 5 minutes * f = 10 minutes.

In reality, you need F=2^1.5 =2.8. That means you need 2.8*5 mins=14 mins.


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#11 telesonic

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Posted 17 November 2018 - 05:35 PM

Here is another one from the same roll, 5 minutes exposure.

First is the original (washed out by the lighting from town) and the second one I worked on today.

 

This image is aimed in the direction of Cassiopeia - (it's a little up and on the right of center)

 

T

 

Cass area
 
 
Cass area edited

 

 


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#12 Michal1

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Posted 17 November 2018 - 05:35 PM

Can you, or maybe anyone else that reads this suggest a good b&w film to start with? I've read mentions of Ilford +5 (I think) and one other brand.

 

Not every B&W film is suitable for astrophotography as some of them have severe reciprocity failure. For example, once I bought a cheap Fomapan 100 and 60 min shots showed just a tiny bit more than unaided eye.

 

I have seen some nice astro images taken on Kodak Tri-X 400:

http://nightflyphoto...ax-400-for.html

http://nightflyphoto...-milky-way.html

 

If you can find any, get Fuji Acros 100. It has been discontinued recently but you can still find some in offer at ebay.  It produces beautiful images and the reciprocity failure is extremely low. You can find many notes on it if you search this forum. Some examples:

https://www.flickr.c...157626901237517

https://www.flickr.c...157632706581150

https://www.cloudyni...a-few-bw-shots/

 

As for the Ilford films, when I went through their data sheets a few years ago, the stated that they suffer from substantial reciprocity failure.


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#13 Michal1

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Posted 17 November 2018 - 05:48 PM

Here is another one from the same roll, 5 minutes exposure.

It seems to me that when you do the software adjustments, you manipulate with jpeg images. This increases noise. The best way is to scan your films into a tiff with 16 bits per channel and then keep using this format for editing. The conversion to jpg or png is the final step. If your scanner can't make 16-bit scans, use whatever bit depth you can but use the highest pixel resolution. Then you can reduce the noise by downsizing the images.


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#14 telesonic

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Posted 17 November 2018 - 06:26 PM

It seems to me that when you do the software adjustments, you manipulate with jpeg images. This increases noise.

Yes, definitely. I had the developer put these on photo CD, since I don't have a film scanner yet... I'm still looking into those. Luckily, this shop does return your negatives to you so that is good - but the bad deal is that the resolution of the files on the CD are pretty low, so isn't much for me to work with yet.

 

Temp



#15 Alen K

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Posted 18 November 2018 - 12:25 PM

Yes, definitely. I had the developer put these on photo CD, since I don't have a film scanner yet... I'm still looking into those. Luckily, this shop does return your negatives to you so that is good - but the bad deal is that the resolution of the files on the CD are pretty low, so isn't much for me to work with yet.

How low is low? I routinely scanned my color slide photos at 11 Megapixels, which was sufficient to resolve the film grain in 200 speed Elite Chrome 200 / E200. But even 6 Megapixels should be useable.

#16 telesonic

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Posted 18 November 2018 - 02:12 PM

Alen,

 

Images on this disc are all 1471x980, and range from 900kb to 1.4mb per file... which is quite a bit less than the other roll I'd posted here."First 35mm"

That one that I had walmart develop are 3072x2048 and anywhere from 3 to 4.5mb per image... but I've no clue what those numbers translate into Megapixels, or if they even do.   Just figured that out thanks to the 'ole google.

 

 

The shop I'm using now does process quite a bit of film, and other specialty work.... so maybe I just need to notate high-res scan on the package next time? 

 

edited to fix.

Temp


Edited by telesonic, 18 November 2018 - 02:19 PM.


#17 TxStars

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Posted 22 November 2018 - 12:35 AM

The 3072x2048 images are slightly over 6.2 Megapixels *scanned  (h x w = MP)..

There is much debate on actual digital equivalent res.. *ymmv

File size will usually vary due to color depth of the subject.

Yes have you images scanned at the highest res then can do them at.


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