dfperrault

I plan to shoot a video of a violinist dancing while playing in an outdoor non performance setting. Please comment on the following items 1. Violin contact audio transducer connected to small recorder hidden on musician Zoom H5 or the more compact F1 or F2 2. Sync Audio and Video - Is is sufficient to do one handcap in the camera so it is picked up on the audio and video in order to sync. - Are there better ways to create a reference to sync audio and video. 3. Slo Mo Would the video be awkward if I did some slo mo video but had the audio at normal speed.

Thank you. I know of Jack. But this was a different guy. I will contact the camera club.

Does anyone now the name/contact info of the person who claims to own (ed) the largest f/1 lens collection in the world? He lives in Brookline, MA. The collection was on ebay last year. moderator note - this thread is moved to Casual Photo Conversations as likely more members might notice it and assist the OP.

Can the typical camera sensor cleaning swabs be used to clean 35mm slides, when used with a cleaning solution like pec? Or is the foam too course and could it potentially scratch the emulsion? I have seen these for sale at $40/1000 on alibaba.

Sorry, I have not explained my goals in enough deals. I started off posting a color correction question based on a target. There are two levels of adjustment I need to do 1. Color correction for ambient conditions (this is not that difficult) 2. Color/Exposure restoration of the target print to match a published museum quality version Each of the 100 target images have been collected from different sources, storage conditions, different print dates etc. over the past 150 years. The target Images need to be individually corrected to match the higher quality version. Sure, I can do this by eye for the 100 prints. 25-50hrs of work. Just curious of there are some computational solutions that are less subjective.

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If I want to mathematically match the colors/exposure of a target image (image to be corrected) to a reference image, could I do this by calculating the difference or ratio of the two images in PS, and scale the target image to match the reference image. I would have to make sure they are physically scaled to the same size /alignment. Would it be better to do each color channel independently in RGB of CMYK? Method 1 - Differential Error Layer 1 - Reference Image Layer 2 - Target Image Layer 3 = (Target - Reference) / Reference Layer 4 = Target / (layer 3 +1) Method 2 - Ratio Layer 1 - Reference Image Layer 2 - Target Image Layer 3 = Target / Reference Layer 4 = Layer 2 / Layer 3 If this method works, then I could do this in Matlab, and have all the 100 images processed in a minute or so. But I suspect it is not that easy. BTW, I just realized what Q&D means

They calibration target is in every image so I thought I would try to use it. If there were all photographed at the same time / conditions, I can apply the correction for one target to all. so it is not that difficult. This would eliminate the ambient effects so I can focus on color matching to high quality text books Images. Also what is "Q&D"

Is this data in this article sufficient or would your measured values be more accurate. What are you rates? https://www.imaging.org/site/PDFS/Papers/2002/PICS-0-267/7122.pdf Do I fine tune the need to manually create a calibration file or try to fine tune the RBG slider to match the image target vales to the reference values. or do I need to do a Curve fit and change gamma settings within photoshop?

Thanks for the swatch link. I would like (not need) the colors to be adjusted to how they appear when they were created. Which is more difficult than how they appear when they were documented. Since they are wood block prints from the 1800's. I have a book that has these prints with beautiful colors. I will try your swatch out, as a rough guide to correct the source and camera. I have to give more thought to doing it by eye vs the numbers.

After I correct for the camera and source, is it worth while trying to create a compensation matrix from manually selected points across the color space from a higher quality reference image to restore faded colors, etc.? Or is color restoration by eye the easiest approach?

Yes I agree, I would like a good starting point by eliminating the camera/illumination effects. This will likely turn into a color restoration project. I have a book with excellent color version of these prints. So I will manually adjust them to match. I wish I had the bandwidth to play around with machine learning image processing.

Rodney, Thank you. I wrote haiku for all one hundred prints in the series, that I am trying to publish.

Attached is an image of an art print that has a color patch to left. Is it possible to do color correction with all of the color patches in Photoshop or another program? The problem is the color values of the original color patches are unknown. I am under the impression that a color checker software with a known calibrated target is required eg. Xrite. I figured the best I can do is set the white balance and white and dark levels. I have 100 of these files to adjust. I suspect the corrections may all be the same if they were photographed at the same time and lighting conditons.. I have a book that has high quality images of the same prints, so I can visually adjust each one by one. I plan to publish these photos in a book. The other idea I had is that I have access to a color corrected file of the same print different edition. I could write a program in Matlab to look at the color difference between the two prints and create a normalization file to match the colors of the two prints. The color corrected file version copyrighted so I can't use it directly. Getting the two files aligned and registered will take a lot of work and might required some machine learning algorithm to do it successfully. It might be best to do it my eye.

I need to measure a laser generated grid 0.25mm width (4lp/mm) at 5 meters w/ 75% Contrast. Does anyone think that I would not be able to resolve that with a canon 135mm f/2.0 L, or the 200mm f/ 2.8L II lens at f/2.8? The MTF for both at 10LP/mm, 1.0 /1.5meters is 90% across the full field.

Are there any compact lenses for a 4k camera that are 1/2-1in in diameter?

My iphone 6 has really saved me. I have had about 8 kidney surgeries over the past few years and have not been able lift my DLSRs and L series lenses for many years now even after numerous PT visits. I really enjoy the Moment 18 and 58mm lenses, the bokeh is nice for a phone. I have been doing alot of ICM color photography w/ the slow shutter ap of flowers, and merging with old photos of cemetery statues taken in IR in my 5DMkII IR converted camera. I am in the process of selling many of my lenses to survive after my hours were cut 50%. I am still lucky to have a job and healthcare, and a camera I can lift. Hopefully in a year I will be able to lift, work full time, and travel again and buy back a few lenses. but my iPhone will still be part of my creative workflow.

I decided to support a used book store by buying a used copy on Amazon. I have read many of his other books, they are all excellent. River at the Center of the World is one of my favorites.

Whenever I see a linear periodic structure like this in an optical system, I immediate think interference fringes. I suspect that it is caused by interference of refections of the out of focus rays between the filter and the lens elements. Try a higher quality filter with more coating layers that will have a lower value of %R. Other people have been commenting on this being a good example extended to a more general comment that all filters have a negative impact on image quality. Which is not a valid. There are many ways in which filters can potentially impact and not impact image quality and it is highly dependent on the lens, filter design, illumination conditions and the observer.

Eigen engineering sells iPhones and Android phones that have the IR filter removed for IR photography, as well as a wide range of filters, Near Infrared (NIR) and Fluorescence Imaging Smartphone Developer info@eigenimaging.com

Ludmilla. thanks for you reply. IR stands for infrared. The part of the optical spectrum beyond red outside of what the human eye can see. Here is a more detailed explanation w/ examples of Infrared Photography. what-is-infrared-photography. I found that my roommates galaxy phone is sensitive the the IR light from a remote control. I will try to put the red long pass filter in front to see if it will work.

I am looking to convert a smart phone to shoot infrared photos. I apologize of I have missed any previous postings on this topic. I was surprised not to find this topic come up when I did a search Questions/Options 1. Do Samsung Galaxy phones have and IR Blocking Filter? - I don't own one so I can't check with a remote control LED - If not, then I should be able to mount an IR long pass filter in front of the lens 2. Iphone X clone - Requires that I take it apart to remove the IR blocking filter mounted to the lens assy 3. iPhone 6 or above Is the IR cut off filter deposited on the sensor itself, of on a window in front of the sensor that could be removed by a lab? 4. Other options I have not consider.

I decided not so pursue this.

ok, I was hoping it was snapped together. Ok, you must have a newer model, I have a connector. thanks.