Chris Ross

Thanks for weighing in Alex, the AF behavior described certainly sounds like a camera/lens with some sort of problem or settings issue to me. The OP mentions a fish near in focus doesn't snap to focus but instead starts hunting. I'm thinking the MFO probably shouldn't be expected to help with an issue like this.

Don't really agree with the TC comment, it is proposed to put a 1.4x on a 50mm lens to get a 70mm lens , yes there's more water compared to the bare 50mm but it's less water than framing the same way with a 100mm macro and lots of people use them. With crop factor that's like a 112 mm lens on a full frame camera.

The MFO is designed to counteract the abberations caused by refraction of light through the flat port glass. These aberrations get progressively stronger as you go from centre of field to the corners. The camera in question here, the R7 is APS-C so much of the corners are cropped out of the frame compared to a full frame sensor camera. This means the sharpness benefits will be a little less. The aberration are worse with shorter focal length lenses like a 50-60mm lens on full frame and this is where the biggest benefits would be expected. In the past the aberrations with a 100mm range macro lens were accepted as there wasn't really an alternative and they were relatively small. I agree a 100% corner crop pasted side by side with and without the MFO would be of interest. I think it is worth checking if the camera/lens combination also hunts on land , try shooting something in similar light levels, you could check the ambient exposure on your next dive to know the sort of light level you might need. It would also be worth asking if others have experienced hunting as bad as you describe with the RF 100mm. Also check what AF points others use, do use a single centre point or an array of some type. I would also suggest trying to find someone else with an RF100 you could try and/or an R7 body to compare how they perform compared to your gear. Also confirm you have the limit switch set for the full range. of focus.

Don't believe it is , a lot of compacts used to have accessory converters to increase the focal length that went on front - the only option as the lens was not detachable. Interchangeable lens cameras generally use a tele-converter between lens and body, probably because it a cheaper solution with smaller optics compared to a full diameter optic attached to the front of the lens. So one could probably be designed, but the market would be quite small I expect, mainly barbecue conventional 1.4x and 2x converters do such a good job at a reasonable price point.

That's exactly why you have the variation - buoyancy is equal the the weight of the water displaced by the monitor, the bigger it is physically the more buoyant, if you have more air space inside it is more buoyant.

Wet lenses generally allow you to focus closer not to increase the focal length. I think this has been asked before and the only option was a Canon 50mm f1.8 prime lens as far as what would fit in the housing goes. You might be able to add a Kenko 1.4x to the 50mm f1.8. I found a review of the 18-45 that said it was 77mm long at max extension The 50mm f1.8 is 46mm long and extends to 60mm long and the Kenko is about 20mm thick so it might just fit and the lens would just hit the port glass at minimum focus. Min focus would be about 200mm from port. You would be stuck at this focal length and just be shooting fish portraits the whole dive. Any wet diopter works by allowing the lens to focus closer, it doesn't give more reach, the KRL-05S is no different to any other diopter.

If that is the extent of the length change of the lens, behind any sort of dome I can't see that being a big issue, The sharpness might deteriorate a small amount, but there's no shortage of lens that zoom like this. In any case the usual situation as I understand it is that the manufacturer will test the lens at its widest which is where positioning is most important. Even internal zoom lens may move the entrance pupil around a bit.

Something like this should work: https://www.jaycar.com.au/m3-x-6-3mm-tapped-nylon-spacers-pack-of-25/p/HP0920 If the screws are M3 x 10 the spacers would be at most 7 or 8mm long to have enough thread showing through to screw into the housing. If the spacer is threaded it would make it captive to the board, possibly making installation easier.

Agree that there is no harm trying out existing domes you may have, however it also places the lens further from your subject, reducing available working distance and magnification, which is why I think the 4" macro port is favoured. It depends on what your targets are if this will present a problem or not.

I would suggest matching your UW lenses to what you might want to shoot UW. UW shooting is different in that the goal is to get close to minimize the amount of water between you and your subject. Not all good lenses translate well into UW shooting - the main requirement is close focusing and even then it pays to choose lenses that are proven UW performers. A lot depends on what you shoot and in in what conditions. Clean tropical waters are somewhat different to shooting in temperate waters where there may be lower visibility and more particulate matter to deal with. In the tropics for WA I like my adapted Canon 8-15 for wide angle work and it works nicely for CFWA as well. In temperate waters the narrower fields of something like a 20-24 lens are a little easier to deal with and you can swap between things like fish schools and larger single fish, big nudis and other critters which are physically large enough to shoot with a mid range zoom. The Tamron 17-50 I don't know I've heard of anyone using UW, the min focus at the long end seems a bit too long to work well UW. The 20-70 on the other hand has been used by a few people on the forum and is reported to work well. The 6 and 8" seafrogs domes might be a little small and not have ideal extensions to work with lenses in the 16-17mm range and corner performance may suffer. This becomes less critical at narrower angles of view and 20-24 lenses will not have the same penalty. Fisheye lenses are different and work quite well in smaller dome sizes. Personally I would try using what you have now for a while and see what you find you are missing out on in experience. Again though this might vary depending on where you are diving and the subjects you find you like.

This is the standard way items shipped from overseas are handled. Any business can only collect tax on items sold in country or in this case the EU, they collect this and pay to the government. They can't collect any tax or import duties charged when the item is imported into another country as they are not setup to do this and many jurisdictions will only allow collection at import. That is charged prior to the item being imported being released. If you click on the ? next to Shipping, this pops up. There is also a footnote next to the price which refers to a similar note on that page: If I was to buy one and import into Australia, the importer would collect 10% GST on the items value including shipping costs. Depending on the item they could also collect customs duties and also their handling fee. You would need to inquire with the importer about how much they would charge.

That 8-15 gear is for Sony either alone or with a 1.4x, it's reversible to do both services. Probably need to make it longer to use with a 2x.

You really need to read the fine print, used to be that a lot of policies specifically exclude water damage for cameras for example, including specialist camera gear insurance. Regular travel insurance includes riders limiting the maximum value for individual items in particular categories, so you end up needing to list items and it can get very expensive very quickly. For example you might have $10,000 cover for valuables but are limited to a maximum value for any one item of $1500 as an example.

It's really not a great deal different to changing a port except on a smaller scale, treat the o-rings the same way. As mentioned Isotta use a threaded ring to retain the viewfinder. The two holes they suggest using a small allen key in each one to get more leverage if required. If you have circlip pliers that's ideal, but the two small keys should be enough. It doesn't need to be super tight, just snug as the water pressure will hold the viewfinder in.

I believe that is what the EP is saying: moving 4 aperture clicks on a camera requires adjusting 4 strobe clicks if both of them are 1/2 EV each