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Everything posted by Interceptor121

  1. The 180mm has a 11 cm radius the 230 has a 12cm radius the difference is the field of view. I see almost zero benefit using the 230 dome with this lens. Is either the 180mm for a smaller set up or the 250mm port for the most ideal set up The disbenefit of the smaller port is that you will loose the close focus as explained by @ChrisRoss you will give up on 8cm. So while the 250mm port would offer you 48cm range the 180mm will offer you 25cm focus range resulting in a more compressed depth of field. You will not gain anything from the smaller port as the camera will not focus right on it so you will only gain on weight and cost. For what concerns the macro idea again you are not going to get that close to be able to focus consider that the 180mm port is not that small definitely not a macro device but can be used for close up of a moray eel or similar
  2. As I wrote if you write to both cards and one for any reason chokes this can lock the camera looks like this is what is happening The camera will eventually write to a sector on one of the card that is problematic and start going for a wonder I recommend you consider writing only to one card if you upload your photos on a computer what is that you are protecting the potential failure of a single card vs another or the computer going lost? For photos is fairly simple keep writing on that card without ever deleting a file and keep uploading on your computer every dive or every day. The issue is only if you don't have a computer but you can connect to a sony camera in a variety of ways and back up to a tablet or other device
  3. Paul You are saying the same thing I never said you don’t need any verification but the error margin is low And am not talking about MTF etc this is simply positioning As the extension is fixed if the entrance pupil moves performance will change so it won’t work well at all focal length This is not fixable by any fixed port system With regards to refractive index that alters the visual image but again matters nothing to the positioning of the port related to the entrance pupil refractive index is not part of the formula Anyway this is going wildly off topic I have asked nauticam if they will make a zoom gear for this lens and I am still considering if this is worth it myself Sent from my iPhone using Tapatalk
  4. There are detailed simulator that even include focus breathing But focus breathing doesn’t change entrance pupil position anyway Check the optical bench on photonstophotos to have an idea what is available for most lenses Even without a model you can calculate with good precision the position of the entrance pupil either starting from angle of view and filter size or put the lens on a tripod and find the position yourself As of now the error margin I have had is less than 5mm so depending on what data you have you can reduce your error margin a lot On top not everyone has all parts to play with so having your own method is a way to save money When I asked nauticam how they make they evaluations i was told they use a macro slider which means they do this is a little tank Having to take a lens at sea to determine the correct extension would be very inefficient so the manufacturers themselves don’t do that Yet in some cases I am not totally sure of the consistency of port charts and there are cases where things don’t get the asterisk blessing and still work fine I think knowledge helps matters and knowing how things work is a good thing it makes the process efficient and you have a solution before the manufacturer makes the test which is useful to check of a lens is even worth a focus gear that you can also 3D print The idea that we should dismiss knowledge and just jump in the water slapping what we think may work may work if you have a lot of time on your hands but no doubt is inefficient and potentially inaccurate It may give someone a headache to know someone else has a grip on those concepts without even having the lens but that’s pretty much a reality We can then disagree on what is ideal for two different people but dismissing the fact one may have a method that produces results quickly seems illogical Besides even from the datapoint provided by Phil you can work out how to make a correction isn’t that a good thing? Sent from my iPhone using Tapatalk
  5. Assuming your lens is vignetting against the dome aperture and not the entire surface (plausible as the lens is fairly wide) Your 70mm extension is around 20mm too long. You can try a shorter one in a bathtub without even going to the pool and see if it is preserving or not the field of view With this system you would have saved yourself two trips to the pool There is more without this you will now go back with 60mm and conclude that works because it doesn’t vignette but that is incorrect too and your angle of view will be reduced You can keep doing the same things for any number if years you want but ultimately this is physics Even in physics you do observation but the purpose of theory and model is to reduce them to the minimum so you don’t have to go back to the drawing board every time Of course is your prerogative to use your own time as you wish as well as define your own level of quality you are satisfied For clarity once you know the lens design you need trigonometry which is year 11 in UK 10th grade in US This is not advanced science Sent from my iPhone using Tapatalk
  6. Trial and error with no information basis is called guessing Having precise information about lens design and making calculations that need to be optimised is called modelling What Phil is doing is closer to the first description what I am suggesting is closer to the second Food for thought Sent from my iPhone using Tapatalk
  7. They are both distorted you can see the bent line of the pool
  8. Images do not look good at all I think your extension is way too long the 230 port has a field of view of 140 degrees while the lens has 94 degree using vignetting as a criteria is not going to help Here is where numbers and calculations work better than trial and error
  9. There 230 port has a radius of 12cm vs 11cm of the 180 not a worthy upgrade Am talking about the 250 port that has a radius of 16cm The lens will focus in any dome but will waste space 8cm as per your calculation so the useful range will be 33-8=24 cm You can still use it for sure in the past people would use diopters when the lens was not focussing at all Am not rejecting the lens just yet am just saying that due to the shape it has some limitations To be fair most sony lenses have the same or worse behaviour it is difficult to find lenses that focus very close I will be curious to see if this lens makes it to the nauticam port chart what they recommend although I am not always aligned to their views Sent from my iPhone using Tapatalk
  10. I am not sure I agree that there are trade offs when if comes to range There are essentially three cases when you look at lens plus dome combination. 1. the lens focuses on the dome you have the maximum magnification and loose nothing in terms of range -> ideal scenario 2. The lens focuses inside the dome what you loose is magnification i.e. things will look smaller. The focus range will remain indentical 3x dome radius but you can't get as close as you would like things will look smaller. This case can be forced when the lens is so large that it does not fit inside a dome. 3. The lens can only focus outside the dome you will loose both magnification and focus range because it will take away from the 3x dome -> worst possible case to be avoided when possible With regards to the Panasonic 8mm fisheye the lens is 67mm front to focal plane and the pupil entrance is 12mm from the front 67-12=55mm Working distance is 100mm it follow that 100-55=45mm is the minimum dome radius that the lens can take. Nauticam acrylic 4.33 is 55mm you are loosing one cm for magnification purposes. If this matters something to you then go for the ZenDP100 but you will only gain 5mm as there are no domes of 9cm. Or you can use a 3.5" wide angle port that is not a dome but the lens will somehow focus although loose field of view. This will give you that 1cm if that mattered a lot to you. The Sigma with the 140mm dome is near to case 1 above so ideal scenario. With the 230mm dome goes in case 2. If yuou used the sigma with the 4.33" acrylic it would fall in case 3 above. If you look long and hard enough in each port chart there will be some lenses that are better than other in terms of working inside a dome. The 20-70mm does not look a great candidate for a small dome it will fit in the 180mm dome in terms of field of view but will loose some range as per case 3 above. The other consideration for this lens is that it extends a lot 4cm in fact it is unclear what happens to the entrance pupil of the lens but this is another variable to take into account compared to lens that shift less If and when a lens patent is made available I will have another look to the construction to see how the zooming affects things For sure the focal range is interesting and will deserve further consideration if someone makes a zoom gear for it
  11. The lighting is the same two strobes at the same power the distance is very much the same too one guy is bigger than the girl identical strobe position. One is mid water in the deeper end of the pool the other is on the bottom on the shallow end of the pool. with the female diver the light travels until it bounces on the wall, with the male diver to an extent it bounces on the bottom and then goes through A real demonstration that there is more than strobe positions and camera settings that make the image The second image is in focus the focus point is where it needs to be. Looking at the 50 megapixel images you can clearly see it is in focus However when you scale down to 2048 wide the image of the male diver looks sharper and this for me is simply due to the lens The canon 8-15mm with kenko 1.4 HDX in a dome at the same field of view produces more contrast than the Sony 28-60mm with WWL-1 I did not shoot systematically the first combination to compare as I was looking more for a solution in between the fisheye and the WWL-1 field of view however at the interesecting point it looks like the Canon 8-15mm even with a teleconverter is better Separately I have assessed the issue is the actual lens the Sony 28-60mm is very weak across the edges it is not always obvious but if you focus the camera on a point away from the center the image looks blurry even if technically is in focus From a color rendering perspective instead I would say the Sony looks better vs the canon with kenko but not better compared to the pure canon. the tc is obviously taking away something from the lens
  12. To provide some context Shot1 is Canon 8-15mm with 1.4 TC focal length 21mm Shot 2 is Sony 28-60mm with WWL-1 focal length 28mm equivalent fisheye 20mm The first shot is an adapted lens with a teleconverter this should make it harder to focus, the second is with a native lens with a wet lens. Both are f/11 1/125 ISO 100 As photo the diver in image two looks better she is a small built young diver overall this is better framed and the pool wall behind acts as a reflector In the first photo a bulkier male instructor teaching a student, the background is messy as there are others there but when I took the shot I did not have in mind a comparison and the pool was much busier I do not have a neat shot like the other What I am asking is how the diver looks, not feedback on composition or lighting purely the lens although there are some differences between the images they are minor when it comes to the main subject
  13. Most Sony OEM wide angle and zoom lenses focus at 28cm, only a few at 25cm and only the 24-70 at 21cm A shorter lens may require a larger dome as otherwise the focus area covered is smaller Considering the compression the dome brings to focus every cm you loose is important. While having a larger dome than necessary simply shifts the focus futher back (I do not prefer this arrangement but some people do) a smaller dome cuts the available focus range of the lens Each cm you take off take 3x virtual distance plus any space the lens does not focus between the dome and the focal plane. In this example 15cm would have a useful range of 45cm while 11cm will have a useful range of 11x3=33 - 4=27 cm I would also add 20mm is not that narrow and field of curvature will have a higher impact on the reduced focus range this needs to be assessed. The determinant factor of the ideal dome size is the difference between the working distance and the distance of the entrance pupil from the focal plane. A shorter lens will have a smaller distance between the entrance pupil and the focal plane resulting in a larger ideal dome If you put the sigma 15mm inside a dome smaller than the 140mm you gain nothing in fact you loose focus range and performance. The lens won't focus right on the 100mm dome anyway. Zen does not support this port lens combination and I think they know the score with that specific lens. The Canon 8-15mm instead will focus right on top of the ZenDp100 if you are looking for extreme close up that is of interest.
  14. There is a level of naivety in underwater photography gear to be frank An Ambassador is in general term someone who promotes a brand. By definition this person is able to tell you how to best use the equipment but not well placed to compare it to similar equipment made by someone else that performs same or similar function An independent reviewer is someone who is not on the payroll or receives any compensation for reviewing the gear and just says what they think, they may still have a bias Ultimately the brands should send gear to independent reviewers to try however with underwater gear this is quite difficult to do because there are camera and lenses involved and nobody is supplying those as a combined ambassador for top and underwater is rare (they still exist there is one guy who is panasonic ambassador and ikelite) Reviewers performed by those who sell the equipment may or not be supportive depending on the competitive landscape. Underwater photography is a small industry so you don't have many situations where you have a mega retailer that can call the shots. Backscatter to an extent comes the closest but yet they are not going to shoot on products they sell otherwise they would not have them in stock I have a small personal story on this to tell you that being objective is not always a good thing Years ago I started writing my blog focussed only on the items I use and the ports and accessories around it, in some cases there are small reviews and I compare across brands. Years ago I supported the pre-release review of a piece of equipment and I gave some feedback that was duly taken into account and transformed into product improvements. Some time later I got sent a whole housing and system to test for a camera I was evaluating and my conclusion was it is not a good idea to invest in this camera for the video use case despite the underwater gear is very well designed because of some less obvious camera issues that I found out during the test. Since this very blunt review I did not get anymore any piece of equipment to test and the communication has been very scarce Note in this case it was not the UW gear it was the camera showing limits that were not apparent topside but I simply said what I thought which was the housing and system is well done but frankly this camera is not something you should consider due to certain issues. The end result is that that housing will not sell if you don't buy the camera and this is a circle....
  15. I also want to add sometimes lens construction does not help If you have two lenses with the same field of view and working distance but one is much smaller than the other typically the smaller lens will require a larger dome of the larger lens A typical example although fisheye is the sigma 15mm vs the canon 8-15mm both have a working distance of 15cm from the focal plane but the sigma is a shorter lens which means it will require a larger dome than the canon Having small lenses is not always a good thing for domes what matters is how far the minimum focus point is from the entrance pupil of the lens As lens designs are not always published there can be challenges but you can locate it yourself with good approximation using some formulas or putting the lens on a tripod and find the no parallax point as panorama photographers do
  16. For rectilinear lenses radius of curvature is important If you place the right radius the lens has 3x the radius working distance from the dome surface this is an ideal scenario Consider that due to the working distance of the lens you are already at 25cm this is not that close already Generally the best lenses are those that focus at even shorter distance however most Sony focus pretty far like 28cm As the dome compresses the image increasing the depth of field is ideal to have the largest focus range possible so that the lens can still focus Once you get to that minimum size making it bigger will not actually yield benefit but only push you further away I work out all my lenses extensions and radius based on that formula and it works very well for me Unfortunately very few rectilinear lenses focus closer than 25cm and sometimes if the lens is small the radius goes up which for some people is counterintuitive Sent from my iPhone using Tapatalk
  17. The radius of the dome starts at the entrance pupil of the lens not at the sensor while the working distance starts at the sensor focal plane rounding for easier illustration Working distance=25 Lens length =10 Flange=2 Pupil distance =2 25-10-2+2=15 Ideal radius so that the lens can focus on the dome surface If you make it shorter it will focus further away so some focus range will be wasted Sent from my iPhone using Tapatalk
  18. I have now tested the 28-60mm with WWL-1 in the pool I can confirm the issue at the edges is due to the 28-60mm lens In this example I focus on the writing on the slate at f/8 and even so the writing is soft. Clearly the lens has issues on the sides full stop When you stop down to f/11 the lens is as good as it can be in the edges but overall pretty mediocre I think the 28-60mm lens is OK for 4K video but there are better options for photos and this regardless of WACP-C WACP-1 etc being used
  19. There is extensive material on this In essence a camera has only one ram buffer and one bus so it will write to two cards at the same time The slower card will throttle the channel and if it errors lock up the camera. It does use more battery and produces more heat how much difficult to say
  20. Bill this camcorder that I know well is a 1" sensor like a Sony RX100 we are not in the same league
  21. It is not out of focus the focus point is exactly where it needs to be the images are at 2048 wide but yet it is possible to compare Sent from my iPhone using Tapatalk
  22. Those two images are taken with different optics on the same A1 body at similar settings f/11 ISO 100 Which one looks best in your view? There are some little framing differences the second is a cleaner shot as there is nothing behind but just focus on the diver
  23. Sd cards have physical issues i.e. they fall apart. But they are reliable The files of the A7R cameras are huge and Sony doesn’t exactly excel in bus management so you may think you are protected against card failure while you are actually stressing the camera to write twice on the same bus. Sent from my iPhone using Tapatalk
  24. When did one of your card fail individually the last time? Sent from my iPhone using Tapatalk
  25. That’s not for underwater but exactly for land photo. Writing to two cards slows down the time to have the camera available Considering that in 30+ years I have not had a single card fail my approach is to have one card for photos and one for video Failure of a camera is possible failure of a card (provided you follow guidelines) extremely rare so not worth doing things that put the camera under pressure In addition doing back up requires matching cards (several discussions with technical teams of card producers on that) Most people back up on a cheaper slower card and eventually lock up the camera Sent from my iPhone using Tapatalk
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