I now have 3 canon lenses–what should I do w/the Tamrons?

[lokisbong]

lokisbong please don’t be offended by this question but are you sure it isn’t dust on the sensor?

not that i’m in sleeping‘s knowledge group but dust on the external lens elements is one thing. dust inside is pretty rare.

Not offended. I can see it when I look through the lens with it not on the camera so I am pretty sure it’s not on the sensor. I have looked at the sensor and don’t see anything on it and it doesn’t affect my other lenses at all. I know it’s a rare thing but this lens was on the camera when a strong gust of wind caught a lawn chair and blew it into my tripod knocking the whole shebang lens first into the sand and I am pretty sure that’s when the dirt started showing up in my pictures.edited to add The autofocus has been twitchy ever since too.

[sleeping]

It’s probably in the rear part of the lens if it’s showing up in photos – the closer any dust/damage is to the sensor, the worse it is. It might be worth checking to see if the rear element group unscrews easily (assuming you can reach it safely), you might be able to get it out if it does.

[ravnostic]

Taking my tip from Orionid, I’ve started the Darlot Project. I quickly determined using my Tamrons as parts isn’t necessary nor even the most optimal way to go.

My t-mount adapter mount for the camera to telescope happens to have the same diameter around it’s widest point as the Darlot lens mount point–2-3/8″ (roughly). And there is a PVC pipe fitting from Home Depot that has that dimension as an interior diameter (it matches the exterior diameter of a 2″ interior pipe) and 3 inch length–just about perfect. I’ve ordered the adapter ring (so I don’t trash mine) separately for $12 on Amazon, but I had enough to get the configuration right (or what I think is right.) Thus, the first pictures with the Darlot as my prime lens to my canon (1879 meets 2005, technologically speaking):

No exciting photos; just a test run. It seems to result in very soft photos; I haven’t coaxed anything more crisp. This may be due to the PVC being white (where the hell is my matte black paint, anyway?), or just a property of the lens.

There is definitely some distortion; I should make up a lined posterboard and take a shot to determine that I suppose. I’m able to focus as near as 2-3 feet, and to ‘infinity’ using the original mechanical slide wheel. No aperture setting, of course, it’s f/2 all the way (or is it? The optics are clear at 3 inches from the body mount–does that count against the f/stop?). Shutter, of course, the alternative adjustment.

Suggestions as I go along? I’ll get this finished within a week or two–lots of work in the next couple’a, so I won’t have much time for this.

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[Curious]

interesting adaptation and shots.

[sleeping]

It’s actually not easy to determine the correct aperture of a lens by measuring the physical object – you need to know the location of the rear optical node (so you can measure the focal length) and the entrance pupil (so you can measure the aperture). I think the easiest way to approximate it is to compare exposures with a known lens.

You might be able to get sharper photos by installing an aperture, it’s effectively wide open as-is. Think Waterhouse stop: http://en.wikipedia.org/wiki/Waterhouse_stop

[ravnostic]

Some Darlots have that feature, sleeping, but not this particular one. I know as the ‘raw’ lens goes, it’s f/2, but attached upon the PVC, being further away from the sensor, I’m just not able to do the maths for that, as I don’t know from what point to measure–the sensor? The camera body orifice (effectively the ‘diameter opening’ point)? Currently I have the telescope mount inner ring, which is 1/25 in diameter, attached–that could be considered the aperture?)

These things I do not know. Nor, honestly, will they make a difference to me once everything’s put together. I’ll learn proper exposures as I field test it. Needed are a ring around the exterior of the coupling wide enough that I can screw the flange to the coupler, and a few set-screws to attach the coupler to the t-mount. And the new t-mount, of course, dedicated to the cause. Right now I just hold it together with my hands.

[sleeping]

Some Darlots have that feature, sleeping, but not this particular one.

I meant to fabricate one – it would depend on the optics, but there’s a decent chance something like that would work if you put it right behind the lens instead of in the middle somewhere.

[ravnostic]

Some Darlots have that feature, sleeping, but not this particular one.

I meant to fabricate one – it would depend on the optics, but there’s a decent chance something like that would work if you put it right behind the lens instead of in the middle somewhere.

1.25″, in above post, not 1/25th.

I wouldn’t even know where to begin in fabricating a shutter without making it much more complicated to put together (I’m all for easy and cheap, it’s written on the bathroom stall, too). Perhaps Orionid can chime in with an idea (he got me finally going on the project, after all…).

[orionid]

If you fashion waterhouse stops, you can use non-standard apertures, as well.

ETA: http://www.flickr.com/groups/homemadelens/discuss/72157623873502868/

[ravnostic]

If you fashion waterhouse stops, you can use non-standard apertures, as well.

ETA: http://www.flickr.com/groups/homemadelens/discuss/72157623873502868/

Brilliant! Hadn’t thought of that. I’ll need a slit cut into the coupler, some thin sheets of firm plastic, and perhaps some black felt to ‘lock’ out unwanted light coming in through the stops. I’ll add this to the projects to do list! I’m looking forward to the different stop configurations–CMIIW, but isn’t that technique used in bokeh photography to acheive interesting patterns?

[orionid]

I haven’t done it yet, but it’s definitely in the to-do pile, along with even less standard apertures like thatching, or some others from the fellow linked above: http://www.flickr.com/photos/johnnyoptic/4640374356/ and http://www.flickr.com/photos/johnnyoptic/4104137957/

[ravnostic]

For waterhouse stops, I’ve decided to work with cookie press die. They’re about the right size, or I can affix them to something that is. Only $15 bucks at amazon; they’re aluminum which I can paint, and the ‘odder’ shapes I can just keep for making cookies (though some of those might be fun, too.)

I’m lacking in a couple things still; I need a way to attach the darlot to the coupler without damaging the darlot. The waterhouse stops I’ll need to work on once I have the plates in, about a week. I may have the rest figured out, by then. I hope.

[orionid]

Ooooh, neat idea.

[Zero_Exponent]

Ooooh, neat idea.

Ya, what he said, very creative solution!
I like that first pic of Blerticus. The soft focus works well there.

[ravnostic]

Well damn! I had no idea I’d get my cookie press today! I figured next week, at the earliest. So instead, I picked up an additional OT shift–which now I DON’T want to work as I’d rather work on completing the Darlot Project!

But…look at all the interesting shapes I’ll have to work with… 😀

[Author]

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