Chris Ross

I think you are somewhat missing the point, this lens performs acceptably behind a dome where the centre of curvature is around 80mm behind the entrance pupil. Sure the pics in the link I posted are relatively small, but they are enough to show that they produce pics a lot of people would be delighted with. It basically shows that the lens is relatively tolerant of misplacement of the centre of curvature. If you look at the size of this port, the dome section is only about 20mm high so the lens focuses right down on the port allowing you to get very close to your subject - which makes a significant difference for CFWA, the subject becomes all the more prominent in the frame and small differences in distance makes a big impact with a fisheye lens. But this of course involves a compromise, with a small deterioration in corner performance.

Thanks @adventurer for your response, I should mention that I spent some time comparing the two different extensions with the 8-15mm though it didn't help that the image scale was different in them and spent a lot of time flicking back and forth between the two images till I thought i was starting to hallucinate. So I downloaded the two images and cropped an equivalent part of each and pasted in a single image to compare them, here it is 30mm is on top: Now I may need to get my eyes checked but the difference doesn't really set the world on fire, if anything there might be a bit more micro contrast on the collar to the right of the 6 in the serial number, but really not much in it to my eyes. To be fair there may be more to be seen in the original tifs, but based on this I think I could use either one happily. It would be interesting to see a similar comparison for a rectilinear lens.

A rectilinear lens is always going to be more sensitive to this than a fisheye lens, the way they render lines is fundamentally different to a rectilinear. It actually not possible to make a rectilinear lens with a 180 deg diagonal field of view, have a look at the formula for rectilinear lenses it falls apart when you try to solve it for 180 deg. Basically the ends of a straight line need to be at infinity to be rendered rectilinearly. If you look at the infocus field for a fisheye it's a curve not a line, almost like it was designed to be used behind a dome. I have never doubted that a rectilinear needs to be close to the ideal position. Fisheyes however are another story. I don't have the maths to describe it correctly, but experience from lots of people posting about the Canon 8-15 show it's nowhere near as sensitive to dome position. I don't doubt having the centre of curvature 40 or 50mm away from the entrance pupil will have some impact, but if you are within 5-10mm you will be in pretty decent shape. Some of it seems be down to the way the image is compressed in the corners, the image scale is a lot smaller and kind of hides aberrations by shrinking them. If you want to do these investigations, then more power to you of course, but if you don't fret about your image corners too much the Nauticam port charts seem to be pretty decent.

That may well be but Nauticam for example suggests 20mm of extension to compensate. I don't think 2mm will make a lot of difference in your images, most port systems only go up in 5 or 10mm increments depending on the housing system you are working with.

Nauticam already has a port recommendation for a Canon 8-15 plus 1.4x in the port chart, they just add 20mm of extension and they have a zoom ring for that combination as well. From what I recall and various evidence of what various manufacturers offer on the internet for this lens it seems that fisheye lenses are not particularly sensitive to positioning the dome port correctly. A prime example is ikelite 8 inch compact dome which is quite a small segment of a sphere and the Centre of curvature is well behind the dome. It works and the image samples provided look quite OK at first glance. I'm not saying that you can't or shouldn't try to do better, but this port is a long way out from ideal placement and still provides quite usable images. Here is a post with examples. GET the Canon 8-15mm Fisheye Before It’s GONE! // Underwater Review &

The valves will both have an m16 thread, the only thing that might be different could be placement of the o-ring so that it contacts the seating surface correctly.

How big was it? If it's quite small it looks reminiscent of a triplefin, except for the mouth, but a large mouth triplefin seems close? https://www.inaturalist.org/taxa/338587-Ucla-xenogrammus/browse_photos

In general two strobes are not additive because you generally don't point them at the subject UW, rather have the edges of the beams overlap a little in the centre so each strobe lights mostly it's own side of the image and fills in the shadows created by the other strobe. Whether you need the extra power depends. At one extreme shooting a full frame camera with an MWL lens at the recommended f16 needs plenty of power, compared shooting the same scene with a 180° diagonal fisheye at f8 or even f5.6 on m43. Likewise shooting full frame big animals at f13 with a 16-35 in a big dome that don’t get that close is also power hungry. Macro on the other hand you can shoot at f22 with a single small strobe as you are so much closer - a single MF-2 or Inon S220 can work just fine.

That's a big reason I wouldn't consider them, but you've got them already so need to deal the weight. I assume you have your floats on the closest arm to the strobe. I'm not sure what you are using for floatation but ideally if you get the strobe and float near neutral on it's own and closely linked to each other it should be less prone to torquing. However if you are using a lot more than the 200-250 gr per side that is required to offset the strobes then they'll want to torque, You could transfer the rest of the buoyancy to the inner arms closer to the housing and potentially bolt some foam underneath. 10 Bar have this: https://www.divesea.shop/shop/10bar-base-tray-float-29093#attr=3681 It could work if 400 gr is not too much. The principle is that if the buoyant part is above the non buoyant part it's stable and the closer the buoyancy is to the centre of gravity the more stable it will be.

12 and 6 o'clock strobe positions is generally not recommended for a number of reasons, lighting from below by the 6 - o'clock position strobe tends to look un-natural. Plus the bottom strobe might be a lot closer to substrate and blow it out. The general recommendation tends to be put your strobes in 9 and 3 or 10 and 2 or some variation while in portrait as well. See this video at about 9:35 for the positions: https://tutorials.brentdurand.com/underwater-strobe-positioning/amp/#wide I would also add if you are getting a lot of torque like that you might have too much flotation on your arms and could benefit from less on the arms and transfer some buoyancy to the housing possibly under the base. I had this issue with my rig which had around 1.5kg in float arms and it was difficult to twist upwards. I ended up pulling the two smaller float arms and replacing them with standard ones and diving the rig a bit negative.

I once dived with a camera that was slightly positive (new configuration) and found it really magnified the tendency for the dome to want to twist upwards, was quite a pain to use on that dive. It was maybe about 100 gram buoyant at most. I'm always clipped to my camera with a lanyard.

I have seen insects on land that can depart between pre and main flash, they are mostly small flies, very fast to react, I would think water would slow most things down enough for most subjects. The time between pre and main flash is generally pretty small. Having said that With a bit of thought and practice I would think you should be able to get manual to work for you first time.

Basic Rules - READ this before you Post Please make sure you have familiarised yourself with and understand the guidelines for posting in the Classifieds section. The Waterpixels Classifieds Forum is a space for members within the Waterpixels community to trade items. Consequently, we currently require that new members make a minimum of 3 posts in any of the other forums before gaining posting privileges in the Classifieds section. You must always provide pricing for the item/s to be sold. Please be aware that topics and posts cannot be edited or deleted. In the event of a sale, indicate this by adding "SOLD" as reply to the topic. Likewise, any adjustments, such as price reductions, should be made by adding to the original topic rather than creating a new one. Share your buyer or seller experiences in the feedback thread for the community's benefit. Waterpixels cannot accept responsibility for any forum activity. If you decide to proceed with a transaction, you do so at your own risk! If you are uncertain about the legitimacy of a transaction, reach out to us. The admin team have tools which might be able to help identify potential fraud but buyers must make their own assessment. For Industry/Commercial members: Kindly reach out to us through the contact form to assess the appropriateness of your proposed post. This determination will be made on a case-by-case basis. While this section is not intended for commercial product advertisements, we acknowledge that Industry members may have pre-owned equipment available, potentially of interest to the Waterpixels community. Posts deemed by the admin team to violate any of the aforementioned rules may be edited or removed at their discretion.

It's basically a matter of policy that classifieds are not able to be edited. This is to avoid issues where hypothetically someone edits the original post to try to influence a dispute. Similarly classifieds posts can't be deleted. The standard approach is to make changes to the offer with a reply to the post, this preserves a record of the offer and any changes made to prices etc. Similarly as items are sold a reply can be used to note this.

The website linked has some nice shots, though I should note that I looked at his wide angle shots and checked the EXIF data and it shows "flash not fired"for all that I looked at - the macro shots however all show flash fired. So all of the wide shots are natural light and they do look very well balanced . The AOIs would be a great solution for macro where you need a lot less power compared to wide angle as the strobes are so close to the subject. I am thinking they might struggle a bit for wide angle.

Shooting m43 is less demanding you are not closing your aperture down so much compared to full frame. Certainly reef scenes take the most power, but the YS-D2 has enough for m43. Diving in the tropics also involves thinking about transport, The YS-D2 is near half the weight and is almost neutral UW, if you are using the AOI housing then you likely won't need any buoyancy arms, but you'll probably be wanting them with the HF-1 strobes. On the dual strobes, while you can have them different and make it work and even if you want to have uneven lighting it's less thought to go from even light both sides to unbalanced, to me it's conceptually easier to have two identical strobes as my starting point.

It's a very powerful strobe, typically with m43 you shoot at f8 for wide angle. For full frame on the same shot probably f13-16 range depending on your setup, you just don't need as much flash power. It will certainly work, but it's quite a heavy strobe and a lighter cheaper strobe will get the job done.

You can generally get two different strobes to work though they will need to have different settings if they differ greatly in power like the YS-D2 and HF-1. In TTL they will both have the same duration which means the HF-1 will be quite a bit brighter than the YS-D2 and you'll be trying to use compensation on them to balance the lighting. Generally it's simpler if the two flashes are the same, less to think about and murphy requires that the you'll have the high power strobe on the side of the camera where you want less light. On the choice of strobe the HF-1 is probably overkill for a m43 camera.

If you are shooting super macro having the flash on manual should work well without much need of adjustment. Your distance to the subject is more or less constant so the flash power will remain constant. I found on my camera with exposure mode manual using an olympus flash in the hotshoe that I could assign flash exposure compensation to a dial (OM-1 Mk1) with the flash turned on and it would allow me to vary it. BUT - it only actually worked to change flash exposure in TTL it had no impact if the flash was in manual, be it RC manual or regular manual. Presumably OM thinks if you are in manual you want fixed flash output By the way if you are using RC this sends out flash control signals prior to the main flash in manual mode if you are varying manual power from the camera, this is how it varies the flash power from the camera. I'm not sure what you are doing with TTL, it should only have a single pre-flash and be effectively instantaneous, though RC mode TTL might be a little slower perhaps?, I've never really used RC mode much. I also don't have your trigger and it may slow things up a little and behave differently to a regular flash. I assume you have already disabled red-eye reduction as it will cause significant delay. Looking through what I can see on my camera, you can do two things. First go to full manual and change flash exposure on the flash. Second use TTL and see if you can find out why it is slow - with an olympus flash in the hotshoe I can't detect any lag or detect a pre-flash. To use full manual set the flash power before you move in to your subject on a part of the reef at the high magnification you want to use. Then approach and frame up your subject. If you are the same distance then you should be very close on exposure as long as the flash is positioned such that it is not shaded by parts of the reef. If the subject is slightly over exposed stop down a touch more. I find I rarely adjust flash power if I'm shooting the same size subjects. On your settings - I tend to shoot f10-11 most of the time as it means I'm not fiddling with flash power too much and I generally want the depth of field. The only reason to try high speed sync to get beyond 1/250 is to get your background water darker. If you use HSS then you start to significantly lose flash power.

Anything specific you struggle with on the OM-1? It will have a little less depth of field in comparison with the m43 sensor in the OM-1 and you do need to place it well.

If you choose to upgrade to the OM-1, I would seriously look at options other than AOI. Your other option would be to search around and see if you can find an adapter to use your Olympus ports on a new system. Their housings are quite cheap but their dome ports are relatively expensive. For example their 4"glass dome is $899 while Isotta sell their 4.5"glass dome for $682.

The cable I suspect is not the weak point- rather it's where the coiled lanyard attaches through those two plastic mouldings. The plastic clip can also be an issue - I can say from experience they are quite difficult to unclip as the little cutout the wire clip seats in catches on your D-ring and needs two hands to unclip - at least one of which you want to be using to hold your rig. This can be a lot of fun when you are bobbing around trying to stay by the boat and unclip to pass up your rig. Combining one of these: lanyard with the lanyard most dive shops seem to sell to replace the coiled plastic would be much sturdier I think. Adding a quality bolt snap instead of the plastic clip would complete the ideal lanyard I think.

It's called a circular fisheye adapter for a reason, it produces a circular fisheye image, just like a Canon/Nikon 8-15mm at 8mm will on a full frame camera. It's should be about a full 180° field all around Zooming is perfectly fine I wouldn't expect any image degredation apart from the fact the lens aperture decreases a little as you zoom. When you zoom in until it just stops the vignette you should have something like the field of view of a 180° diagonal fishete like an 8-15mm at 15mm on full frame.

just a FYI, you can use your current N120 ports on an Isotta housing by changing the lug ring in most cases, it also has 3 M16 and one M24 port to use you current vacuum valve and other accessories in. You can purchase an adapter ring to use your Nauticam viewfinder. You may need to buy two ball adapters for their housing handles. The housing is slightly smaller, weighs 1kg less approx and close to $2K cheaper at backscatter. Seems like it might be worth checking out.

Yes I think best to talk to Balazs, he should be able to tell you how the system is supposed to behave. If you follow what I laid out above it will tell you the system is doing if you want to pursue it. Let us know what the end result is please.