Jump to content


Photo
- - - - -

fisheye and crop factor


  • Please log in to reply
8 replies to this topic

#1 nataq

nataq

    Sea Nettle

  • Member
  • Pip
  • 12 posts
  • Location:Austria

Posted 06 August 2005 - 04:58 AM

Hi,
I have several questions concerning the use of fisheyes for over/underwater photography. I am using a 300d in a sea&sea housing.

1. can you generally do reasonable over/unders with a crop factor of 1.6x?
2. does somebody have an example to show the effects one can expect?
3. has someone tried the zenitar MC2.8, 16mm fisheye (I found just one post of someone having problems with it when focussing?

I´d love to read your answers.

Tanks so far,
Wolfgang

#2 Alex_Mustard

Alex_Mustard

    The Doctor

  • Super Mod
  • 8366 posts
  • Gender:Male
  • Location:La Maddalena

Posted 06 August 2005 - 07:44 AM

It works fine, Wolfgang.

I have shot many split levels with a 16mm fisheye on my Nikon cropped sensor DSLR. I prefer a wider lens - but in good conditions the 16mm is very suitable.

One tip is to shoot verticals rather than horizontals.

Alex

Alexander Mustard - www.amustard.com - www.magic-filters.com
Nikon D4 (Subal housing). Olympus EPL-5 (waiting for housing).


#3 Jolly

Jolly

    Lightning Kraut

  • Member
  • PipPipPipPip
  • 835 posts
  • Location:Germany

Posted 06 August 2005 - 07:58 AM

the 15mm lens is fine for split shots. Basically you want a lens with short focal length in order to have some depth of field for getting the under and topside part in focus. 15mm is not bad at all. The smaller field of view on a cropped DSLR does not reduce the depth of field that much (just a little bit due to the smaller circle of confusions but the physical focal length is unchanged).
I haven't done much split level shots since switching to digital, just a sample with just 97° field of view (less than the 15mm):
Posted Image

but yes, I would prefer wider too if it would be possible with my camera :lol:

Julian
| Canon 5D I+II / Sealux CC5-GD I+II custom converted | 2x Ikelite DS-125 | ULCS |

#4 nataq

nataq

    Sea Nettle

  • Member
  • Pip
  • 12 posts
  • Location:Austria

Posted 07 August 2005 - 12:43 AM

Thank you two very much for your tips. Especially the idea of shooting verticals. I am going to use a tripod, to have better control in the beginning.

Alex, your picture (over/under Nr.1) look like you used a polarizing filter, but I guess that is just good work in photoshop, right?

How do you guys deal with the waterdrops on the domeport? I have tried to use an apple in freshwater, but it didn´t work that good.

Thanks again,

Wolfgang

#5 Alex_Mustard

Alex_Mustard

    The Doctor

  • Super Mod
  • 8366 posts
  • Gender:Male
  • Location:La Maddalena

Posted 07 August 2005 - 02:20 AM

Is this the one you mean, Wolfgang? Its one of my favourites.

Posted Image

This picture was taken on slide and the slide looks just like this. The exposure is even above and below because of shooting decisions I made. I chose to shoot when the sun was high so there was as much light as possible underwater. I also chose to take this shot over bright white sand (for the same reason). I also shot with the sun coming from slightly behind me (even sitting here in the UK I know that to get the sun at the right angle I took this shot at about 11:30am on Seven Mile beach on Grand Cayman). And finally the best way to stop droplets on the port is to never get the port wet in the first place. I walked into the water to take this shot and kept the port dry until I dipped the camera to take the shot - so there were no droplets.

Alex

To make a general point not directed at you (!), many new photographers make the mistake of thinking that good images must have had special kit or loads of photoshopping. And I think this leads to a lot of people not learning proper technique - never believing that the pros images look great straight from the camera.

Alexander Mustard - www.amustard.com - www.magic-filters.com
Nikon D4 (Subal housing). Olympus EPL-5 (waiting for housing).


#6 motionsync

motionsync

    Tiger Shark

  • Member
  • PipPipPipPip
  • 631 posts
  • Location:Greece & Sweden Lambis Stratoudakis
  • Interests:UW photography with available light<br />Freediving

Posted 07 August 2005 - 06:28 AM

Alex what are you saying is that the exposure is even
above and below because of the time the angle decisions that you have made?
Then u say to shoot verticals rather than horizontals.

Is it becauce the camera is more "under & over" and becauce off this exposuse and focus will be more acurate ??
Lambis Stratoudakis - http://www.lambisstratoudakis.com

#7 Alex_Mustard

Alex_Mustard

    The Doctor

  • Super Mod
  • 8366 posts
  • Gender:Male
  • Location:La Maddalena

Posted 07 August 2005 - 08:26 AM

Verticals tend to work better with less wide lenses (like a 15 or 16mm fisheye) because it gives you more space to control the meniscus of the water and also enables you to get more above and more below (as you say).

Split levels are more difficult in open/deep water as there is more of a difference between the above and below parts of the image. This difference gets greater as you get away from the middle of the day.

Alex

Alexander Mustard - www.amustard.com - www.magic-filters.com
Nikon D4 (Subal housing). Olympus EPL-5 (waiting for housing).


#8 motionsync

motionsync

    Tiger Shark

  • Member
  • PipPipPipPip
  • 631 posts
  • Location:Greece &amp; Sweden Lambis Stratoudakis
  • Interests:UW photography with available light<br />Freediving

Posted 07 August 2005 - 08:43 AM

Thanks Alex for the great tip!!!!!
Split levels is really not easy but like you say if you lan it correct dont put the dome in the water wait for the light etc.. the results will be better.

Thanks!!
Lambis Stratoudakis - http://www.lambisstratoudakis.com

#9 Lionfish43

Lionfish43

    Great White

  • Member
  • PipPipPipPip
  • 910 posts
  • Location:Dover, NH USA

Posted 07 August 2005 - 09:13 AM

Alex,
Ever consider developing a split/half ND filter for rear filter holders along the lines of your new av light filter.
Larry Oberlander My Webpage
Nikon D200, Aquatica AD200