Another Crazy Project.

[Don Hoey]

Originally Posted by Peter Waites

This is absolutely fascinating stuff Don. Please keep the instalments coming when you find time.

Another to keep you happy Peter.

Aquiring the subject.

This was a bit of a problem when I came up with the MkI. As magnification increases above 1:1 this becomes an ever greater problem due to the ever lessening depth of field.

Option one was to put a spike on a mount to bayonet on the front of the bellows, but that idea was discarded as unless sthe subject distance was within the coarse focus movement of the bellows sliding plate it could still take time to aquire the subject.

Next up I found what looked like a good optical solution. Back in the 1980's I bought a 'lens scope converter' from Jessops. Quite a handy bit of kit before the age of decent small bins. Simply attatch to a lens and you can use it as a monocular. So in use, a 50mm camera lens becomes a x5 monocular, 100mm lens x10 and so on. Sounds impressive, but in reality the exit pupil is only about 2.5mm so the image is quite dim unless used with lenses with an aperture greater than f2.8 or in bright conditions. Image quality also does not compare with any half decent bins or scope. But anyway I dug mine out and even at the least bellows extension magnification was too high. However cranking the bellows out and using good light on the subject, magnification was really impressive.

Mmmmmmmmmmmmmmmmm ...... Probably quite obvious to some, but it took me a day to think about it before I had my eureka moment.

How about using a spotting scope optic. OK it would not be an erect image ( upside down ) but never the less worth a go. Quick toilet roll and black tape job and it worked. The image was far brighter than the lenscope. So next up I made a proper bayonet mount for the bellows and it worked brilliantly. For general use we had a 20x-45x zoom that Stevie got as a freebe when she got her scope. So I nicked that. With that mounted and set to 20x and the bellows at minimum extension I found the subject would be dead on when the bellows was at full back extension using a 75mm lens. As the reversed 50, 28 and 24 have only a few mm between them in terms of lens to subject distance, problem well and truely solved. Use that with a reversed lens and you have a seriously good bench magnifier. All very good and a major advance on the dim lenscope, but using a 20x widefield scope eyepiece, or for more magnification, a 38x widefield, gives a huge exit pupil and so a really bright image.

If Dave Smith was about I am sure he could try out an astro telescope eyepiece with a diagonal, on a long lens, as that would give an erect image.

NO Andy, I am not going down that route for this before you suggest it as a further spend.

Some pics attatched.
I am not a photoshop buff so I was unable to give a circular aperture to the frame edges to give a view similar to that you would actually see looking through it, as all birders would recognise, but the magnifications are accurate. Oh, and to be true to form I should have turned all pics through 180 degrees so please excuse that.

Don

[Peter Waites]

I'm actually gonna have to print this lot and sit down with it one rainy afternoon. So much in there to absorb it's like a masterclass in kit building. Lots of the references you make and take for granted need work on my part to take in but it does prompt further study.
In a way it reminds me of the days of my youth when I spent more time fettling (ie bodging) the old motor bikes than riding 'em - so apart form coins what will you actually manage to paralyze long enough to shoot Don?

[Don Hoey]

Originally Posted by Peter Waites

.................In a way it reminds me of the days of my youth when I spent more time fettling (ie bodging) the old motor bikes than riding 'em - so apart form coins what will you actually manage to paralyze long enough to shoot Don?

Peter,

I guess I just really enjoy bodging too.

I got into photography in the 1960's when kit as a proportion of salary was considerably more expensive than now, and as a lowly airman in the RAF cash was seriously limited, so through lots of trial and error and through that I learnt a lot of photographic basics. There is a thread on the forum where Christine and Rob as the main contributors were posting shots of insects in flight. Well to use that as an example, my first attempt was in the 70's and I was handholding a reversed 50mm and chasing hoverflys. ........ No money to spend on proper kit but willing to have a go at anything and learn from it. Some things like reversing lenses I discovered by accident and as viewed by knowledgeable folk I would probably have been seen as reinventing the wheel.

In photography I see things that people spend a fortune on, and almost by implication it is access to large funds that is required to do that particular thing. Just like you and your motorbikes, your knowledge allowed you to get great enjoyment from doing things that others would struggle with due to their lack of mechanical knowledge. So with me I like the challenge of doing things for as little as possible. This particular exercise is a bit of an oddball, as I am probably the only forum member with access to a workshop to make things, however in most cases tests on bits and pieces have been done with cardboard, wood, black tape, in fact anything to hand, before I have done a workshop job on it. For interested parties its all about ideas and then when it comes to kit probably quite a bit can be cheaply bought on e-bay or at boot sales or camera fairs.


What am I going to take with this lot ???? Well the whole thing was fired up by finding dead bugs in the garden earlier in the year. There do not seem to be any around at the moment and I am not into killing or disressing anything just for a pic, so I will keep my eye open for a suitable subject.

You mention " Lots of the references you make and take for granted need work on my part to take in but it does prompt further study. " Well that is down to 45 years worth of playing around in quite a few areas of photography so I would hope some of it has stuck . When posting in threads like this I cannot anticipate the knowledge or lack of it, by any interested parties, so can only rely on the posts prompting questions. If I know the answer then I am happy to help. If I don't I will say so. I pride myself in not handing out duff info as that always comes back to bite.

Nobody was born with the knowledge, and whatever they have, was gained through others, and personal experience. There will always be someone more knowledgeable than you, and someone less so. So any questions you have do not be afraid to ask.

Now we have digital cameras, so can experiment for little cost, and have forums like WPF to share our experience and pass on some knowledge, we are all gainers.

Don

[petrochemist]

One thought that might help with aligning your subjects.

If you get hold on a cheap laser (I've seen them for a couple of quid at boot sales) & can engineer a mount for it to replace your camera on the bellows (it will have to be properly centralised/parallel but with a lathe that shouldn't be a broblem) you should get a nice red dot shining at the centre of the field of view.

Align subject, mount camera in place of laser & you just have to focus.

[Don Hoey]

Originally Posted by petrochemist

.......If you get hold on a cheap laser

The spotting scope attatchment works well but that is good thinking as an alternative method Mike. As you say, easy enough to make an adaptor to mount on the bellows.

Never having used a laser pointer I am wondering about the size of the projected dot. Any ideas??

Don

[petrochemist]

I hadn't thought of that - With the lens removed the bright portion of the dot would be of the order of 1mm diameter.
I guess with the lens in place it could get rather dispersed, but should be small enough to be usable if the lens is near focus.