Questions about 1.4x extender... not sure i understand :(

[will_akandou]

<p>1) I will acquire soon 2x40D or a 50D for wedding photography.<br>

I made my choice for almost all prime lenses (i want only prime lenses with good aperture to go from 35mm to 135mm)<br>

But due to his 1.6 crop factor, it gets a bit complicated because i miss a 105mm Full Frame equivalent.<br>

To get on those APS-C bodies a 105mm, i need to find a 65mm lense (or 70mm) and it doesn't exists (the 600m does, but only 2.8).</p>

<p>So i thought about buying a 1.4 extender and use it when i need a 105mm, with my 50mm, because (tell if if i'm wrong...all that crop and extender stuff mixed up make me confused) the 50mm is actually a (aprox) 85mm on my futur bodies. So if i understand well, adding an extender on my 40D or 50D + 50mm will give me this:<br>

50mm x1.6= 80mm the real lenght of the lens of the 40D * 1.4 (extender) will give me 112mm on the 40D is that right?<br>

And knowing the 50mm is f/1.4 i will have 1.4*1.4= 1.96 so a 112mm f/2 is that right?</p>

<p>Same thing to get a 200mm with the same extender. I will uwse the 85mm f/1.8 i'll buy.<br>

So i'll get 85*1.6(crop)=136mm > 136*1.4 = 190mm is that right?<br>

And for the aperture i'll have a 190mm f/2.52 is that right?</p>

<p>That's a bit complicated all that :/</p>

<p>2) What are the stuff i'll lose with an extender except the stops? Will i lose the HSM ou USM of my lenses? will i lose something special?</p>

<p>3) The name of those extender are Canon EF (without the S like EF-S) are they reserved only to full frame or can i use them with APS-C bodies?</p>

<p>Thanks :)</p>

<p> </p>

[will_akandou]

<p>4) will the image quality go down from the original lens when it comes with the extender?</p>

[conraderb]

<p>michael - what are you using now? I'm a huge primes fan but not so much that I buy an extender to make one.<br>

all extenders degrade image quality and you lose a stop.<br>

if you are really married to the 105mm focal length, get a 5D and a 100mm 2.0.</p>

<p>or get the 70-200 - at 70, it is really close to 105mm equivalent (112 really). or the 24-70 or the 24-105.</p>

<p>kor the 60mm macro :-)</p>

<p>but really - I think that if you are doing this seriously, the 70-200 2.8 IS is something that you will want in your bag eventually.</p>

<p>you do not lose HSM or USM with an extender IIRC.</p>

<p>I don't think that exnteders work on any EF-S lenses.</p>

<p>check the extender reviews at the-digital-picture.com. good luck.</p>

<p>cheers. conrad</p>

[jon rennie]

<p>The first thing that jumped out at me is your widest lens is a 35mm on a crop body for wedding photography!?  I have no idea how you can shoot a wedding without anything wider.<br>

All functionality on lenses will stay the same but the quality will also drop.<br>

EF work for both crop and FF.  EF-S only works on crop.</p>

[rainer_t]

<p>1) Forget about using the 1.4x TC with the 50mm or the 85mm prime. (See my comment in your other thread).</p>

<p>2) USM/HSM will continue to work. If (when you use a TC) AF is fast and reliable as it used to be is a different question.</p>

<p>3) Converters can be mounted on all EOS bodies, but onto the converter only EF lenses can be mounted. (EF-S lenses will not mount.)</p>

[matthew_newton]

<p>Image quality will go down some. I use a 1.5x teleconverter with a 50mm f/1.4 lens on my film body (Olympus OM-1). The results are okay wide open, but not great, acceptable. For good results I have to stop down to around f/4-f/5.6, where as without the teleconverter I can get good results simply stopping down to f/2.8.</p>

<p>35mm also seems really narrow for a crop body, I wouldn't want to have anything less then 28mm on a film body, let alone something that is only the equivelent of about a 50mm lens. Look for a 20mm lens for your 40d or 50d and you should have the wide end covered acceptably, but you may still want something wider.<br>

Since it looks like you want to go all prime you may need to accept the fact that you aren't going to have all of the focal lengths covered. I think the best coverage for you would be a 20/2.8, 35/2, 50/1.4 and an 85/1.8. If I had only 3 lenses I would go with the 20/2.8, 35/2 and 50/1.4. If you really feel a burning desire to cover a lot of focal length, then your best bet is a zoom or zooms with maybe a prime or two in there. A 17-55/2.8 or something similar with a 50/1.4 and a 85/1.8 could be your best bet. If you need reach I would also look at a 70-200/4 IS or 70-200/2.8 IS.</p>

[will_akandou]

<p>ok i think i will give up the converters if it downs the quality :( that was just the only way i found to have a 105mm giving more light than using a 70-200mm f/2.8 on a crop body</p>