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Old Jun 7, 2006, 3:17 PM   #1
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About ready to order -- but, I have a couple more questions before I do involving lenses.

Does that 1.5 equivalence factor apply with these cameras? In other words, would the kit 18-55 translate to approximately a 27-82 equivalent for the old K1000 35mm?

I'm used to an Olympus C720 UZ, which gives me, supposedly, a 40-320 mm equivalent zoom lens.

Itwould be nice for a lens to "keep on the camera". Kind of a "home lens" if you will. I saw a discussion on that earlier on this forum -- the "what lens do you keep on your camera" discussion.

I have that 70-280 screw mount that I can use for the big, far-away zooms. On the other hand, changing lenses isn't necessarily something I want to do a lot of out "in the field" (read, "the Rocky Mountains", etc).

So I'm wondering if I should order a "body only" and a more flexible lens than the 18-55. I could order a body only and, say, the 28-300. That'd make my threaded lens obsolete, I guess. If that 1.5 factor works out, it'd be like using a 42-450 in the old days? Or no?

The other thing that concerns me about that lens is the narrow range of aperture. 3.5-5.6? I am probably showing my ignorance here a bit, but my Olympus C720 went to 7.1, and I didn't think THAT was small enough for good depth of field in a "Big" shot. That 28-300 goes up to F6.3. Better.

Do you think I should skip the kit lens and go for one that's more flexible but just not as wide-angle on the wide end? I guess it wouldn't be any different than my 40 mm equivalent on my Olumpus.

-P
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Old Jun 7, 2006, 3:52 PM   #2
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A certain amount of what you are asking is subjective. But in answer to a couple of things:

The 1.5 equivalence does apply so you are right about the kit lens being more like 27-82.

It isn't that big of a deal to change lenses when "out in the field" - I've done it hiking quite often. If you go that route, make sure you buy a hand blower and be careful how you change lenses. I've only had one problem with dust (while snowshoeing and a big gust of wind came up unexpectedly. I almost dropped the lens and did drop the lens cap). Of course, that also means that you'd be carrying extra weight.

A zoom lens that says its "f4-5.6" or some such (depends on the lens) means that it can't maintain f4 throughout it's whole zoom range, and normally at it's longest (say 200 in Sigma 70-200 lens I happened to look at) the wide open would be f5.6. It can close down a whole lot more than that, so f3.5-5.6 isn't the total range of the lens.

What type of lens you want to leave on your camera will depend on what you like to take. I'm lousy at wide angle shots - I just don't think that way, so keeping a 50-200 on my camera works well for me. It might be horrible for someone else who does lots of architecture etc.
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Old Jun 7, 2006, 4:12 PM   #3
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I was reading the Tamron 28-300 has been rated relatively low. On the other hand, a 50-200 means my widest angle is a 75mm equivalent -- pretty wide. That's a pentax lens, right?

Then there's that whole flaring deal... my Olympus did it badly any time there was a sharp line demarking a dark/light area. These tamrons are just slr interchangable lenses and don't have the coating on the rear element, from what I gather.

I really like the idea of the 28-300 range for $140 though.

I doubt my old vivitar screw-mount has a rear element coating, either ;-)

Just hunting around for the best compromise "walkabout" lens for this camera. I don't think 18-55 will cut it for me.

Dang. Decisions.


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Old Jun 7, 2006, 4:47 PM   #4
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The 28-300mm, like all really big zoom ranges, is not a great lens BUT, on a DSLR it will produce better images than your Olympus p&s camera does, and give you a 42mm (almost as wide as the Oly) to 450mm equivalent.

As for aperture, do not confuse maximum aperture with minimum. The Tamron has a maximum aperture of 6.3 at the long end, this will not give very much depth of field, but it stops down to about f32 (I don't know the specs on this particular lens). Remember that on your Olympus the actual focal length of the lens was probably from about 6mm to 48mm, any aperture smaller than f7-8 would be so small as to cause diffraction and lose image quality, the much longer actual focal length of the 28-300mm means that it has a physically much larger aperture and would not suffer from diffraction issues until f22-32 at least.

The aperture numbers are actually the ratio between lens focal length and effective aperture size. Therefore a 50mm lens with a 25mm effective aperture would be an f2 lens since 50/25=2. Your Olympus probably gives a similar angle of view at 8mm so f2 would mean a 4mm aperture, f8 would be a 1mm aperture, very small. If this camera went to f16 it would produce a tiny 0.5mm aperture which is effectively a big pinhole and problems start to result (but DOF would be enormous).

Hope this doesn't confuse, your best bet is to get two good zooms, such as the Pentax DA 18-55mm and the DA 50-200mm and do some swapping. My "walk around" lens is a Sigma 24-135mm, equivalent to 36-205mm, a nice range for most general photography.

Good luck choosing, LBA (lens buying addiction) is one of the most common disorders among DSLR owners.

Ira
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Old Jun 7, 2006, 5:17 PM   #5
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Ok, that actually helps. I have to keep reminding myself that yes, one reason you want a DSLR is the flexibility of being ABLE to change lenses -- a lot of the attraction for me is the ability to override automatic focus/exposure if you want to. Which most of the time, I won't.... but sometimes myOlympus c720 frustrated the heck out of me as I tried to trick it into doing what I wanted it to do for a certain shot. Not the least of which was to get it focused on what I wanted it to focus on, AND give me the exposure I wanted on top of that.

Which means, Phil, go ahead and buy the body only + the Tamron28-300. It's not like you can't get an 18mm lens later if you want, and if you really need super awesome results for your 36"x48" prints (ok, so I'm joshing here :lol: ) then you can get a super-awesome telephoto.

But I'm probably going to be happier with theDL withthe28-300 as an all around lens than I was with the Oly, and it'll probably be worth the extra $50 (to me) over the kit lens. I'll have an extremely flexible camera right off the bat, and I won't be backing myself into a corner because it's a DSLR.And I can succumb to lens buying addiciton as time goes on.

And I understand that may be sooner than I think :G

(ok, I've played with the funny icons... I feel better now)
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Old Jun 7, 2006, 5:59 PM   #6
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Hi philmon

One other thing to consider with the 28-300 is the extra weight that you will be carrying around all the time. Beleave me it gets very tiresome lugging a lense that size all day.

Just my 2 cents

BK
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Old Jun 7, 2006, 9:19 PM   #7
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Hmmm... it is almost twice the weight of the kit lens at 14.8 oz -- pushing 1 lb. The kit lens is 7.9 oz.

So I'd be carrying an extra 6.9 oz around. Which, now that I look at that number -- really doesn't sound so bad for the extra range. The lightweight backpacker in me disagrees, but heknows he'sin a futile argument with the shutterbug in me. :G

Thing is, I'd likely be carrying the telephoto around in addition to a smaller lens anyway just "because".

Better go check on my Rationalization® perscription. :-)


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Old Jun 7, 2006, 10:07 PM   #8
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Alright, that's it.

I just weighed my 75-260 Lens.

It's 2.5 lbs.

My 55mm lens is about 12 oz.

I think a 14.8 oz lens is a nice compromise :-)
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Old Jun 8, 2006, 8:30 AM   #9
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Quote:
Does that 1.5 equivalence factor apply with these cameras? In other words, would the kit 18-55 translate to approximately a 27-82
I was under the impression thatPentax smc DA lenses were designed especially for digital slr's, so the 1.5 equivalence factor did not apply to these lenses. In other words the kit 18-55mm smc DA lens acts likea true 18-55mm lens.

Can someone comment on this please ....

Thanks,

Rick




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Old Jun 8, 2006, 9:16 AM   #10
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Was wondering that myself - I have the 2 kit lenses - 18-55 and 50-200.



Are these really 27-82.5 and 75-300??
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