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  1. Glass (lens?) and mirror (telescope?)...but light still gets through to the film. Is it not the same light? I know it's not "pure" light from the star due to the atmosphere and other things that filter it, but some of the original photons make their way to the film.
  2. I've been reading about the process of capturing an image on film at the atomic level. I'm hoping someone here has a good background in chemistry and/or physics so they can help me understand more about it. This may belong in the general discussion forum, but part of my question is specific to deep sky objects (or any stars). The best source I can find is this article: Chemistry of Photography Briefly, the article explains that when light of sufficient energy hits a silver halide molecule (e.g. AgBr) it causes the ions to split and releases an electron from the bromide ion, leaving Ag+ + Br + e-. From there, the free electron combines with the silver ion to form a neutral silver atom, which ultimately leads to the latent image. Here is where I can't find a clear answer to my first question. Based on various other sources, it sounds like the light (photon) energy that breaks apart AgBr and ejects an electron is partially absorbed by the bromine atom (in the form of potential energy?) and partially absorbed by the electron (in the form of kinetic energy?). So, is it accurate to say that the photon's energy is (partially) "captured" by the electron and then later by the silver atom that attracts the electron? Or is the energy in that electron lost again when it combines with the silver ion? The big question: Does film actually contain stardust? Star matter is released by conversion to energy (photons) that end up hitting the film. If that energy is not released at some stage in the chemical process, then it would follow that negatives literally capture pieces of stars.
  3. Thanks, Dennis. Have you ever used Ilford PAN F Plus 50? If I understand what I've read it sounds like FP4 is just a faster version of PAN F.
  4. This makes a lot of sense. When seeing is average, then a short exposure time could eliminate "blur" caused by turbulence, but the distortion is still there. The image would appear to have better focus but would not necessarily look perfect. So the only way to avoid blur from turbulence is either fast film and a fast shutter when seeing is average-good, or slow film with a slow shutter on a night with perfect seeing...and even then there will be some distortions in the image. Is that correct?
  5. What about Rollei ATP 1.1? I've read that it is very comparable to Kodak Tech Pan, but if it too should be exposed at 6-12 ISO then it may be too slow to freeze even minimal effects of seeing. How does FP4 compare to Delta 100? That has been my most used film. I must admit that I know nothing about developing film. When I first got into photography I ruined a few rolls I tried to develop and gave up, so I pay the photo shop to develop for me. I'm willing to learn again if it means I can get better results with a different film and/or developer. The shop may not even be able to develop Rollei ATP, if I end up using it. I know they don't sell it. Your hat trick method is similar to an idea I had. Based on my results with a simple large black card it seems like my "shutter speed" is too slow for ISO 100 film, although it may work for 50 or 25. Anyway, I thought about building a guillotine with a similar black card and a slit through it. After doing some research I found out that was one of the original shutter designs before they were built into cameras. My carpentry skills are, well, they don't exist so I haven't tried that yet. Repeatability aside, it sounds like the hand held version of that worked well for you. I'd like to give it a try. About how wide was the slit in your card?
  6. Maybe I don't fully understand how active optics works, but to me that sounds like anything faster than 1/30s - 1/20s is good enough to "freeze" turbulence. I know I'll need to wait for the best possible seeing. I just want to make sure I'm not expecting more than is possible without breaking the laws of physics. For example, some websites report that you can get a sharp image of the moon at 2000mm with exposures as slow as 1/2s. Maybe...if you're next to the Keck Observatory. So, what's the limit with great seeing at sea level? If 1/30s is too slow, then any film slower than ISO 100 is probably out of the question. The expense of film is not a problem, yet. If I had access to a good DSLR, then I would definitely try it just to help me tweak everything under my control. So far the cost of all the film processing does not add up to more than the price of a good DSLR or even the cost of renting one for a month. I've made a lot of improvements and have some very well focused images, just none good enough to make a big enlargement. It feels like I'm very close to reaching my goal. Focusing is not a problem (I think). To verify this I should get some really fast film to test it. I have a focusing aid with a 20X loupe. Unless it is not properly calibrated, then my focus should be fine.
  7. TeaDwarf, thanks for the response. So anything slower than 1/100s will almost certainly be blurred by the atmosphere, even on a "perfect" night, or is that 5-10ms range for a typical night with average seeing? I've taken LOTS of images, dozens of rolls in fact, and still struggle to find the perfect shot. I'll keep trying though. It's just getting frustrating because I think I've nailed down almost everything I can control, but a tack sharp image still eludes me, so I'm looking for new ideas.
  8. rfdesigner, Yes, I realize most of the images on the web are stacked. There are some that are single frames, and in my opinion, look even better. Whatever your preference, there is no arguing that some of the best single frame shots are definitely tack sharp. Here are a couple examples: waxing gibbous and quarter moon (first image). Admittedly the waxing gibbous image was at 1/400s with ISO 800, so it's possible the effects of seeing were eliminated due to the short exposure time, but other than the camera his setup is the same as mine. The quarter moon gives me a little more hope for my goal because that guy used ISO 100 with only a 1/20s exposure time. Both used digital cameras, but I seriously doubt there is a difference between sharpness on film compared to digital, even at 21 megapixels (gibbous moon), and certainly not at 8 megapixels (quarter moon) when stacking is not part of the equation. It may be possible that I have not completely eliminated vibrations. Even with mirror lock up the shutter itself has to move, so it must create some vibration. I tried the hat trick with ISO 100 and 400 film, and the results were overexposed by several stops. That may be the final step to a perfectly steady shot, but it will only work with very slow film. What I'd like to know is if seeing, even on the best nights, has a significant impact on image clarity when exposure time is longer than 1/500s or 1/250s. Looking at that quarter moon image taken at 1/20s it would appear that seeing does not cause big problems...or that guy lives on top of a mountain. I e-mailed him to see if he can provide more details; waiting for a response.
  9. I start out using polaris, too, since I'm already on it from polar alignment. So as long as I can find the star there is no problem with jumping from 26mm to 4mm? I may give that mask a try. My attempt to make my own Bahtinov mask was a disaster. This one looks much easier to cut
  10. Thanks, roundycat. My problem is that I'd like to use the slowest film possible, maybe even ISO 25 tech pan. That means my exposure time needs to be longer. So far mostly working with ISO 100 my best exposures have been around 1/60s with a Celestron C8 SCT, 2000mm, f/10. My thought was to work on things like collimation and eliminating vibrations until I get a tack sharp image, and then try slower films. However, I still can't seem to achieve critical focus on film, and I'm wondering if seeing is the problem. Should I try ISO 400 or 800 just to see if a much faster shutter speed eliminates atmospheric disturbances? Is it a pipe dream to think I can get a tack sharp image using really slow film and therefore exposures longer than 1/60s?
  11. I bought a 1970's Celestron C8 SCT on eBay, and it only came with a 26mm eyepiece. This was not a problem for me at first because my only intended use for the C8 is astrophotography. Then I realized that precise collimation is critical for astrophotography. I think I'm collimating very well with the 26mm eyepiece, but it's difficult to make the final adjustments when a slightly defocused star is so small in the field of view. Most guides suggest starting at low power and working up to higher power eyepieces in steps. Others say to go straight for a 400-500X eyepiece. Is there any benefit to going from 26mm to 20mm to 15mm to 9mm to 4mm rather than straight from 26mm to 4mm? Also, would a less expensive house brand, such as this OPT 4mm be sufficient for collimation?
  12. I finally realized that I've been concentrating on the wrong variable in my attempts to photograph the moon. While the speed of the moon moving across the sky (and my film) is a factor, it is trumped by seeing. While it may be possible to "freeze" the moon at exposures as long as 1/8s, the atmosphere still causes distortions that blur the image. So, assuming seeing is good or even great what is the minimum shutter speed required to eliminate most of the effects of atmospheric disturbances? Stacking is clearly the ideal way to handle this problem, but I am working with film so I need the best single frame, tack sharp image possible.
  13. Here is the response I got from Kodak. They may have discontinued some types of film like Tech Pan, but they certainly did not stop making all film several years ago.
  14. StarryEyes, any luck? I would imagine you are correct. To think they stopped producing film "several years ago" but have yet to run out doesn't make sense. Most companies don't overproduce enough to have a stockpile that will meet demand for many years. Maybe the film industry is different though.
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