Interceptor121

That is not what he said When you are very close you have depth of field, field of curvature and other aberrations that are more prominent than when you focus away in general wider lens closer to the subject

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There are no problems with the lens bumping except it may dent the glass. In effect there is a black ring inside the wet lens so if it goes metal on metal you can just put some tape on it or small silicon spacers There are many lenses that do not offer the full zoom range on the port chart the tamron is not an exception some lenses even only work at a single focal length

thanks phil useful info I have the required extension and if I get lucky also a WACP-C to try in few days

That's right I have not used the lens with other bodies so I commented on A1+90mm as I have read many complaints The A1 computing speed and higher frame rate definitely helps a lot autofocus

Yes I have concluded I will use the m10 ball removing the screws of the metal bars or you could fit the M5 I use a lanyard for passing the rig to the boat it is more easily removed and no need for triple clamps that limit certain movements of the arms Sent from my iPhone using Tapatalk

Last week I took my macro rig to the pool https://interceptor121.com/2023/03/27/going-macro-with-sony-a1-and-90mm-macro-lens/ Surprisingly the autofocus did not hunt. I had only two shots where I was doing a movement stress test and ended up focusing on the wrong target but otherwise 100% success I do not know if the setting I adopted which were really for the worst case (focus limiter, aperture drive, etc etc) helped but I feel much more comfortable after this @Phil Rudin has repeadtely said he use the 90mm for blackwater and @Alex_Mustard used the 90mm for blackwater in Lembeh and said he was pleased with it I was skeptical due to topside use but frankly the A1 autofocus pretty much sees in the dark and the lens has beautiful rendereing wide open

Actually now that I see the comparisons the G2 is shorter so it is likely not to bump in the rear of the WACP-1 at all

The lens hitting the glass means zoom range reduced to 45mm as per chart The lens only extends 18mm so additional 5mm should do the trick but it may vignette at wide end If you have the extension ring 40mm you can check both without even the zoom gear on land Sent from my iPhone using Tapatalk

Not really There is a macro slider right there where you rig camera and lens. Inside the glass tank there is a dome port you move the macro slider until you get what you think is the best distance -> extension ring is measured Limitations: 1. Each dome has a given field of view. If the field of view of the lens is larger than the dome any solution determined is not ideal anyway 2. The target is 80 cm away from the camera this is not where you see the most severe issues. Look at my tests when you are at 30 cm situation changes as distance does play a role 3. The size of the tank is 180 cm which means it is more suited to focal length of 20mm and wider Other than that this is exactly how it should be done. Perhaps you can find a way to move the resolution targets closer for a more severe test

You don’t build things like those any other day of the week Sent from my iPhone using Tapatalk

Very nice it does have resolution charts but only at the edges? There are distance markings on the flat plane 180x80 presumably 80 deep So that would be more or less a 20mm lens to fill up the entire field of view which is not that wide I see there is another hole on the short side perhaps for flat ports or maintenance It is also interesting to see that the aspect ratio is 2.25 so clearly not for classic 3:2

Those images look quite good to me those shots are not exactly what you get a lens like this for anyway Sent from my iPhone using Tapatalk

It is visible at the edges of the frame if you look for it The key issue is that nobody tests the lens on land first so without knowing your starting point it is difficult The worst offenders are domes with large field of view but relatively small in radius which are badly affected Sent from my iPhone using Tapatalk

Visual assessment confirms the vignetting method is wrong because it is not aligned with dome port theory You don’t need quantitative method unless you want to measure how much is wrong Sent from my iPhone using Tapatalk

Do not want to post affiliate links but there are plenty of those on google lol In essence you need to adopt the slider to eliminate the need for all extensions test so it is much quicker than trying The dome part goes underwater and the rest is outiside the water The problem of this set up is that it depends on the outcome If you are looking for the longest extension for no vignetting this works amazingly well If you are trying to ascertain if the field of view is preserved or if the performance is the best this is not good unless you have wet MTF charts take all shots and then compared them with analysis software which is not what is getting done here In practical terms the approach extend as much as you can works very well for fisheye lenses with 180 degrees field of view and very bad for rectilinear lenses that do not have a very wide field of view This is one of the reason why fisheye lenses look better simply because the simple technique works for those lenses and not for others As an example I have here a lens 24-70mm that has suggested extension of 90mm with the 180mm dome however doing some quick calculations the lens only need 75mm You put your 90mm on try the lens and end up with horrible pincushion distortion and spherical aberrations so you dismiss the lens while in fact you had the wrong extension The simple technique of go until vignetting only works when the lens field of view is equal or very near to the port field of view otherwise it is flawed Then there are other situations for example your port field of view is less than your lens field of view you need to push the lens inside the port this generates barrel distortion and spherical aberration....

I would agree however in my case my affiliate links point to general photography equipment mostly lenses, USB parts accessories not to underwater parts which are in competition with wetpixels advertisers. Those items are either not sold at all by those shops and if they are they are not their prime business by any mean I would see a problem if someone was writing something that then pointed elsewhere but after all it is always the same people For example in the case of Phil Rudin he points to UWPmag but UWPmag issues are also on the front page of wetpixel so I see no issue I am struggling to see in practical terms what are the specific examples you are worried Adam. Can you elaborate with a specific case instead of generics?

I am trying to understand the optical performance of this lens as an alternative to the average Sony 28-60mm The lens has all the right characteristics it changes little in length when you zoom and is on the Nauticam port chart with range 28-45mm which is fine

That’s correct the important part is where the lens is wider than 74 degrees on the horizontal which is the zoom range between 28 and 40 mm Once you are competing with 24-70mm zoom you are in dead zone as there are plenty of sharper options In fact you may even argue that from 32mm you are getting some serious competition from rectilinear lenses The WACP is a contender to lenses in the 12-16 range where a rectilinear lens looks generally ugly at close range even topside outside this range there is plenty of other choices Sent from my iPhone using Tapatalk

Thanks Phil. Will got for two M5 one each side

The shadow will be cast by the strobe you use to take the photo lol Anyway I found the solution M5 mounting ball to replace the M5 screws that fix the handle bridge all sorted going to put two of those

This lens has a minimum working distance of 28cm and at the same time is really small The combination means that it needs an extremely large radius port to work properly Unfortunately the Nauticam 250 wide angle port has a very small angle of view of 103 degrees so there is not really anything out there that would fit this lens well A port with 16 cm radius which is what this lens needs and you would be looking at a 40cm port a bit overwhelming

The tamron 17-28mm doesn’t have particular issues of field of curvature this can be seen in the top side shots at the edges but also from the mtf charts that do not have the typical ripple to correct field of curvature The sea and sea correction lens is a field flattener it may help other lenses but this one doesn’t need it as the spherical aberration can only seen at the very extreme edges of the frame and is a consequence of the dome not the lens See the cfwa shots in water with focus on the edge no residual spherical aberration is there The lens has the classic drop on the meridional at the edges at f2.8 but it is already better than the sony at f/8 by the time you close to f/8 there is nothing to worry I believe as explained that out of coincidence the nauticam 40mm extension plus the 35.5 adapter works perfectly The suggested extension for the 230 on this lens is incorrect so I cannot comment on their chart according to my calculations the 230 needs at least 1 cm less but then the lens field of view doesn’t require it and the lens doesn’t need the extra 1cm radius either Sent from my iPhone using Tapatalk

I think it goes through all the way and is fixed. Will let you know when I get it Sent from my iPhone using Tapatalk

I had the same dilemma and for me is the M5 mounting ball to replace the screw directly