An A1 user is being dragged into the new age.

[cpritch007]

I've made the decision. I'm going digital. My wonderful, thirty year old, Canon A1 is going into retirement and I'm going to replace it (probably) with a 500D and I'd like some advice please.

The favourite lens for the A1 is an FD 85mm f1.8 which I use for 80% of my photos. My delight is informal portrait photography (snappery really) where I use slowish film and expose at f1.8 thus achieving a short depth of field which throws the background out of focus. It seems to me that this lens provides a very mild telephoto effect with regard to the subject's face which is often flattering. (This may be a figment of my imagination).

I am wondering if I can replicate the above with the Canon 500D. I have heard that digital cameras have intrinsically longer depths of fields compared with 35mm ones. Also the range of lenses available for the 500D is a bit daunting - which would allow me to operate in a similar way to my use of the 85mm FD?

I am intending to buy the 500D with the 'kit' lens, 18mm - 55mm, which I understand is about 28mm - 85mm in real money. If I use this lens at its longest,55m, I assume it will be working at f5.6 which may make it difficult to shorten the depth of field sufficiently methinks? So it looks like I'll need a non zoom equivalent to my 85mm FD?

Your advice will be gratefully received and please don't limit it to the above musings.

Colin Pritchard.

[PaulMontgomery]

I must admit, this still confuses me, but if I've understood correctly then:
A 85f/1.8 will give the same DoF on both your old and new cameras.
However, due to the cropped sensor, you will appear to be closer and that will have an impact on your framing so you'll need to stand back a bit.
The increased DoF apparent on cropped sensor cameras is due to a smaller focal length lens being used to get the same framing.

Hope that's some help...

[Sue Allen]

Why not go body only and add a Canon 50mm f1.8 - cheapest way to get roughly the equivalent of what you're used to and [from the time I had Canon] much better quality than the average Canon kit lens.

[Forseti]

Colin, a lot of what you have written is fundamentally correct. However, as in all matters concerning photography it is important that correct terminology is used otherwise a lot of confusion and misunderstanding can be introduced. A good example is the use of dpi (dots per inch - only applicable for printing) when the user really means ppi (pixels per inch).

As concerns your particular question what should be referred to is FOV (field of view) as this is where the main difference lies between the use of lens X on different type cameras. Rather than post a lengthy reply here is a very good short essay/tutorial regarding sensor sizes and thus crop factors: http://www.cambridgeincolour.com/tut...ensor-size.htm

[cpritch007]

Thank you all very much for your advice and taking the trouble to respond.

I read the tutorial that Forseti recommended and now appreciate how the size of the sensor changes the rules but am still a bit shakey on all the theory and using my new knowledge to predict the effect of various lenses on digital slr cameras.

Then I had a brianwave. I borrowed a Canon 300D with an EF S 18mm - 55mm f/3.5 - 5.6 lens. I assumed that as far as framing goes this would give the same result as if the lens were attached to the more modern Canon 500D. I got out my Canon A1 and attached my FD 85mm f/1.8. Then I set up a fluffy toy dog at about head height and pretended that I was taking a portrait of it from about 5 feet. I was hoping that the zoom lens on the 300D operating at its maximum, 55mm, would give me a very similar photo to the FD 85mm. That wasn't to be.

Firstly the view using the 85mm lens was much brighter than that provided by the 55mm lens. Am I right in thinking that this was because it was operating at f/1.8 as compared to f/5.6?

Secondly the composition was completely different. The 85mm lens gave a distinct impression of 'telephoto' in that the apparent distance from the dog to the background wall, about 8 feet, was much shorter than it appears with the naked eye. Also the wall was very clearly out of focus. This is the effect I am looking for. The EF S zoom operating at 55mm gave a view that was very similar to real life and the background wall was nothing like as fuzzy as it was with the 85mm lens.

Bang went my decision to follow Sue Allen's advice and buy a 50mm f/1.8 with a 500D body as I was not getting the telephoto effect and very short depth of field I was hoping for. On the other hand maybe Sue Allen's 50mm lens opened up to f/1.8 would have given a similar effect to my 85mm one at f/1.8 ???

May I impose on you for a little more advice. What lens do I need to buy to go with the Canon 500D that will give me a very similar photograph to one I would take with my 85mm lens attached to Canon A1? I am thinking of portrait work at a distance of about 6 feet. In particular I am interested in throwing even fairly close background, say 15 feet from the camera, out of focus and I also want to achieve an apparent shortening of distances/depths (telephoto effect?).

Colin Pritchard.

[Sue Allen]

You're right that an f1.8 lens will be much brighter to look through. The kit lens operating at 55mm and f5.6 is'nt going to throw the background OOF in the same way as your current lens set to maximum aperture. Put an f1.8 - or better still an f1.4 - on the 300D and open the aperture wide and you should see the difference. Reading about it is fine but the only real test of what's right for you is trying out the options. If possible [with a couple of exceptions] I'd always go body only and add a better lens if you can afford it - loads of second hand lenses out there.

[Forseti]

Take a look at this online DOF (depth of field) calculator: http://www.dofmaster.com/dofjs.html

From the drop-down lists you can put in any camera you want (35mm film plus digital SLR's) as well as apertures, focal lengths, f stops and subject distance. Have a play and use the same aperture settings and distance settings etc for both the A1 (35mm film which is equivalent to a full-frame digital SLR) and the 1.6x crop cameras such as the 500D. I think that comparing the depths of field, especially the near and far limits will go a long way to answering a lot of your questions.

As concerns 'brightness' in the viewfinder: yes of course an f/1.8 will be brighter than an f/3.5 - remember when looking through the viewfinder the camera is always showing you the view at maximum aperture. It is only when the shutter button is depressed that the lens closes down for the setting chosen by the user when in aperture priority or to an aperture the camera thinks suitable when in full auto. This is the main reason why most cameras have a depth of field preview button.

Brightness to some extent is also a feature of the camera. By way of example, the viewfinder on my 7D is much brighter when compared to the 40D - both 1.6x crop cameras and with the same lens fitted to both.

[cpritch007]

Thank you once again Sue Allen and Forseti.

I visited the dofmaster site and tried out various lenses and as a result am inclined towards a 85mm f/1.8 lens to go with the body but I will make the decision in a camera shop when I can experience the therory live. In the meantime I've ordered a 500D body just in time to avoid the VAT increase. The person I borrowed the 300D from has ageed to lend me the 18-55mm lens until I've sorted our which lens(es) I'm going to buy. I live in the sticks and plan to take a trip to London in mid January when I've had time to become familiar with the operaton of my new camera. I may be able to pick up a second hand lens in one of the big camera shops in London.

Thank you alll again for taking the time to help me.

Colin Pritchard

[Sue Allen]

By co-incidence I bought an 85mm f1.8 off ebay a couple of days ago - Nikkor rather than Canon - and have been trying it out today. Certainly gives the OOF you want and I think even with the crop factor it's a great lens for portrait type shots.

[flake]

Hi Sue, nice to see you again!

Being a Canon user you are truly spoiled for prime lenses, and I think you should consider the 50mm f/1.4 which is significantly better than the f/1.8 version, and nothing like as expensive as the eye watering f/1.2 L.

The viewfinder is brighter on your film camera because of the crop factor as well as the larger aperture, so it will still be 1.6x brighter than a lens with the equivalent aperture on the 500D

You might want to consider buying a second user Canon 5D which seem to fetch about £750 body only on Ebay but it is a full frame camera, so the switch over should be more painless. It's a very nice camera, perhaps something of a classic for the future. Alternatively there's the 40D which you should pick up for about £450 second user, although it's still crop frame it feels much more like a grown up camera than the 500D.

Just to confuse things!