Click to See Complete Forum and Search --> : Aperture and Focal Length

01-17-2006, 09:10 PM
I have a Digital Rebel 300D with a 28-90mm lens.

I was experimenting with the aperture and i was able to measure the maximum focal length to be around 6-7 inches when the aperture is set to 32 @90mm.

Is that a decent size for a focal length? Can I increase the focal length by getting a better lens?

01-17-2006, 09:51 PM
Some photos i took while testing

f22.6 @ 28mm
f29.3 @ 34mm

Big Up Ya
01-20-2006, 06:06 AM
Your focal length IS 28-90mm. Back in the day...a lense was the length of it's focal length (determined by the distance from the front element to the film plane). It's only modern lense design that has changed things.

If you want a longer focal length you need to buy either a longer lfocal length lense or a teleconverter. If you do go down the teleconverter path, generally don't go larger than a 1.4x convertor otherwise image quallity can suffer.

Be aware also that for some thuings longer doesn't help any. Like portraits, anything longer than a 135mm reasonably close tends to start to compress facial features. Sometimes it's just better to get in closer. If you want to get closer to smaller objects either spend a decent amount on a dedicated macro lense, OR you can go very cheap and buy a close up filter. Baring in mind the latter is limited in quallity but still resonably good. THey come on varying diopters and can be used to some degree on top of one and other.

If you want a longer lense, you can save a heap by going with a non marque lense such as Sigma, Tamron etc but do realise that the lense is THE most important part of a camera. Get the best you can afford.

Big Up Ya
01-20-2006, 06:11 AM
Reading your post again, I think what your getting confused with its the clsoest focusing distance. You need to go macro or close up filter. If you do go the filter route stick with the bigger names. Cokin, Hoya, Schneider. No need to buy different sizes for different lenses either, just buy step up or step down rings.

01-20-2006, 06:23 AM
I just got a 60mm f/2.8 Micro (http://www.nikonusa.com/template.php?cat=1&grp=5&productNr=1987) for my D70. Super crisp portraits and good macro capabilities... I used it for this product detail shot of a cigar.


01-21-2006, 09:22 AM
I have a set of macro 'tubes' that will attach between the camera body and lens making the camera focus very closely, depending on the focal length of the lens you can get within a millimetre of your subject and focus.

They're not as good as a real macro lens but they are cheap and I'm not into macro photography enough to justify buying a macro lens. I've been happy with the results. This was taken with a canon 85mm with macro tubes attached.


01-21-2006, 06:52 PM
One of my largest problems was that i could never get crisp portraits, the faces always looked blurred and flat (usually inside an office which seems amply lit).

Admedia, i'll look at that lens. I'm fairly sure it will work with my canon.

01-21-2006, 08:04 PM
Admedia, i'll look at that lens. I'm fairly sure it will work with my canon.
Yea, I am sure you can get something similar from cannon or a different brand.