Making everyone happy with Scarlet Lenses

[Radoslav Karapetkov]

The HV20 / HV30's from Canon are essentially fixed lens "out of the box" cameras but it is possible to remove the lens and mount other lenses via an after market 35mm adapter (if you feel the need to).

You don't remove the lens, you attach the 35mm adapter in front of it.

[chuck colburn]

You don't remove the lens, you attach the 35mm adapter in front of it.

Yes, that's correct. An aux. optical group which attaches to the front of an imaging lens fixed or otherwise is sometimes referd to as an afocal lens. They can be positive or negative in focale length. They most often are single or doublet in construction but can be more complex particularly if negative in focale length.

This is similar to what we use on our night vision goggles.

http://www.nightoptics.com/pc/NO-NA-...ocal+Lens.html

Here's another use for an afocal optical device.

http://www.stargazing.net/david/Niko...lcoupling.html

[millrick]

Why won't you let them sell you a cheap camera? WHY?!:ranting2:

Sounds like the old "Cheap / Good / Fast" conundrum.
"They" want all three.
:whistling:

[Davide B.]

Nice post Chris, people just can't seem to understand that 18mm is 18mm. Point number 2 is the critical thing - if your lens creates a circle big enough to cover the sensor then you can use it as long as you can get the sensor at the correct distance from the lens to focus the image.

So if you shoot with the same camera i.e. RED with its s35/APS-C (APS-C is the designation for the sensor size on cameras like the REBEL XT, EOS40D, etc. and is almost identical to the RED) no matter if you take a lens designed for a tiny sensor or large 4x5 film, (as long as you can position it so if focuses) if it is an 85mm it will look the same on the RED i.e a moderate telephoto.

Yes an 18mm is an 18mm. And if you put a regular Canon EF 18mm or an EF-S 18mm lens on an APS-C type body you'll get the same field of view.

I think you're misinterpreting Point 2 by Chris. The point of the rear element extending backward is to make it possible to fit a small wide angle lens on an slr. Wide angle lenses are huge in SLRS versus rangefinder cameras because of the long flange focal length of SLRS. Rangefinder wide angle lenses can sit mostly inside the camera because there is no mirror that flips up that would hit them. Because an SLR wide angle lens is constrained to be far away from the film plane they are designed to be retrofocus, i.e. they are like reverse telephoto lenses.

This design helps eliminate fall-off and vignetting but it also makes for very large lenses. To allow for smaller wide angle lenses Canon designed EF-S to move the rear element closer to the film plane like rangefinder cameras. The point is NOT to get the same field of view with the same focal length as on 35mm. The EF-S 18-55 still gives the field of view of 29-88mm (according to the Canon website, link below). The point is to allow for a small wide angle lens. Yes, being closer to the film plane improves clarity on the wide angle side of EF-S zooms most tests find, but it doesn't give you 35mm field of view.

Don't believe me? Check out the Canon press release on EF-S lenses. Reducing size and weight is their explanation for using the EF-S design. Don't you think it'd be strange for them to leave out a feature as amazing as eliminating the crop factor on aps-c sized cameras?

http://www.canon-europe.com/for_home...-5.6/index.asp

[Alsone]

You don't remove the lens, you attach the 35mm adapter in front of it.

I stand corrected.

[Radoslav Karapetkov]

I stand corrected.

I am glad to hear that.

Lol. :)

[Chris Newman]

I am glad to hear that.

Lol. :)

Yeah, we don't hear that very often from anybody around here.

[Alsone]

Yeah, we don't hear that very often from anybody around here.

I don't have a problem admitting if I've got something wrong. There's no ego from me, just a genuine desire to take part in the discussion. :)

[Radoslav Karapetkov]

Yeah, we don't hear that very often from anybody around here.

You can always count on me :)

Cheers.