eric_. Posted August 14, 2003 Share Posted August 14, 2003 I am sorry, I should have added this question to my previous one. But here goes: I am about to get my first DSLR: the D60. I'd like to know if it makes sense to get the Canon 180/3.5 macro (or the Sigma equivalent) with the 1.6 crop factor of the D60? The DOF will be very small already at 180 mm, especially at wider apertures (use of flash to improve?), so is it better to get the 100mm instead (yielding an effective focal length of 160)? I will be shooting butterflies, other insects and small flowers. Thanks. Link to comment Share on other sites More sharing options...
gerry_szarek Posted August 14, 2003 Share Posted August 14, 2003 The 180 will give you more working distance, for the butterflies and other insects. GS Link to comment Share on other sites More sharing options...
eric_. Posted August 14, 2003 Author Share Posted August 14, 2003 Gerry, I realise that of course. But due to the crop factor of the D60 the effective focal length is already long in case of the 100mm. The 180mm will even turn in an effective 290mm....yielding a DOF of nanometers...:-) Link to comment Share on other sites More sharing options...
emaxxman Posted August 14, 2003 Share Posted August 14, 2003 I don't think your assessment about DOF is correct. DOF is a function of focal length, focus distance, and aperture setting. The 1.6 crop factor is not actually increasing your focal length of your lens. Let's look at an example. Suppose you have two prints of the same slide. The first is an 8x12. The second is a 16x24. Both are full frame prints. Since they are both from the same slide, they both have the same DOF. Now what the 1.6 digital crop factor is actually doing is similar to cutting an 8x12 section out of the middle of the 16x24 print. You now have 2 8x12 prints. However, the "cropped" print looks like it was taken with a longer lens. It wasn't though. Also, the DOF is also the same in both prints. Link to comment Share on other sites More sharing options...
eric_. Posted August 14, 2003 Author Share Posted August 14, 2003 Thanks Thang, that is an eye opener! Link to comment Share on other sites More sharing options...
the the Posted August 14, 2003 Share Posted August 14, 2003 Thang is right, Eric. The crop factor will not bring you closer to the subject, it will just make the subject fill more of the frame than it would with a 35mm film camera. Link to comment Share on other sites More sharing options...
johnlund Posted August 14, 2003 Share Posted August 14, 2003 Eric, you might find photo.net's <a href="http://www.photo.net/learn/optics/dofdigital/">Digital DOF article</a> interesting. Link to comment Share on other sites More sharing options...
eric_. Posted August 14, 2003 Author Share Posted August 14, 2003 Thanks John. I must admit that I should have searched better before asking this question... Link to comment Share on other sites More sharing options...
brent_mcdade Posted August 14, 2003 Share Posted August 14, 2003 Eric - Don't feel bad - I had wondered the same thing. Link to comment Share on other sites More sharing options...
alex_p._schorsch Posted August 16, 2003 Share Posted August 16, 2003 I think that the 100 macro would be excelent for your proposed use. The 180mm is a big lens and must be much heavier. Buy a 25mm tube which can come in handy. I am having a lot of fun with the 400 f/5.6 for birds and animals along with the 100mm for insects. Have fun. Link to comment Share on other sites More sharing options...
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