Achieving focus with a modded 450d and lens

[Stuf1978]

I've bought a cheap canon 450d with the intentions of doing a self mod for astro and removing the LP2 filter. I intend to image widefield targets with a variety of lenses:

Canon ef 50mm f1.8

Canon 24-70mm F4L

Canon 70-300 f4-5.6L 

What I'm concerned about is achieving focus manually using live view. Is this still going to be possible? I understand I'm going to lose auto focus but the camera will only be used for astro so I'm not bothered about that. However, I've read conflicting reports online that I'll not be able to focus to infinity with the modded 450d and lens combo. 

Has anybody had an issues manually focusing a lens on a modded 450d?

Thanks

Stu

[michael8554]

Focus with LiveView after modding is always correct, with proviso's:

Attached to a Scope - no problem if there's enough range on the scope's focuser.

Attached to a Canon lense - the lens will Autofocus slightly in front of the sensor after modding , giving out of focus images, particularly if the lens is wide open.

LiveView is of course showing the image, so you can correctly manually focus IF there's enough focus range on the lens.

Before modding, if the lens is on it's end stop at infinity focus, then after modding it probably won't have enough range, particularly if wide open (small depth of focus).

That's the theory, in practise you may be lucky !

Michael

[Stuf1978]

Brilliant thank you, I guess it's just a case of trying it. If i can't achieve focus I guess I can always get the sensor shimmed to retain auto focus and therefore the ability to manually focus correctly. 

[Merlin66]

I have a fully modded (both internal filters removed) Canon 1000D and found I needed to fit a clear clip in filter to achieve focus with the camera lenses.

Obviously OK with the telescope.

 

[Stuf1978]

Hmmm may just send it off to cheap astrophotography services and get it modded with the shim then I know I'll have no issues. 

[Alien 13]

Most modern camera lenses with AF are designed to go to infinity and beyond for video use so that the motors dont hit a solid end stop.

Alan

[michael8554]

29 minutes ago, Alien 13 said:

Most modern camera lenses with AF are designed to go to infinity and beyond for video use so that the motors dont hit a solid end stop.

Alan

That's useful info, is that any lens sold with a video-capable camera.? 

Michael 

[Stuf1978]

33 minutes ago, Alien 13 said:

Most modern camera lenses with AF are designed to go to infinity and beyond for video use so that the motors dont hit a solid end stop.

Alan

So in theory I should be fine 👍

[carastro]

I never had any problems getting focus with my modded 450D, but I did have a baader filer glass put in in instead of the removed filter.  I believe you can also use plain glass.

Carole 

[Stuf1978]

Thanks everyone, I'll remove the filter and if I struggle to get focus ill just send it off to get the sensor re-shimmed 👍

[StevePM]

On 23/07/2019 at 08:39, Stuf1978 said:

Hmmm may just send it off to cheap astrophotography services and get it modded with the shim then I know I'll have no issues. 

I’ve just done the self mod and opted to leave the LP1 in place with no replacement for the LP2. The mod appears to have worked functionally but I have issues with focus. 
I also have the 70-300mm L and tried to focus this last night. It appears to move through the point of best focus (so I don’t think I have an infinity issue) but the best focus is still pretty fuzzy compared to my unmodded body. 
I’ve ordered a CLS CCD clip in filter to see whether that sorts / improves it. Other than that I guess getting the shims checked or adjusted will be my option. I could go with the Baader replacement glass but I don’t want to throw more money at it if that’s still going to leave me out of focus...

 

Any thoughts?

[Stuf1978]

13 hours ago, StevePM said:

I’ve just done the self mod and opted to leave the LP1 in place with no replacement for the LP2. The mod appears to have worked functionally but I have issues with focus. 
I also have the 70-300mm L and tried to focus this last night. It appears to move through the point of best focus (so I don’t think I have an infinity issue) but the best focus is still pretty fuzzy compared to my unmodded body. 
I’ve ordered a CLS CCD clip in filter to see whether that sorts / improves it. Other than that I guess getting the shims checked or adjusted will be my option. I could go with the Baader replacement glass but I don’t want to throw more money at it if that’s still going to leave me out of focus...

 

Any thoughts?

Seems odd, I did the self mod as you're describing and I haven't had any focusing issues. Must admit though I've given up using the 70-300L for astro as it shows significant coma especially at 300mm which is a poor show for such a pricey lens. 

[StevePM]

23 hours ago, Stuf1978 said:

Seems odd, I did the self mod as you're describing and I haven't had any focusing issues. Must admit though I've given up using the 70-300L for astro as it shows significant coma especially at 300mm which is a poor show for such a pricey lens. 

It’s all ok - have dived back into the guts of the camera and removed the 0.2mm shims from under the sensor to move it forward in compensation for the loss of glass. 
Fiddly as hell but had the desired effect...

[Stuf1978]

On 03/07/2020 at 23:01, StevePM said:

It’s all ok - have dived back into the guts of the camera and removed the 0.2mm shims from under the sensor to move it forward in compensation for the loss of glass. 
Fiddly as hell but had the desired effect...

Good to hear it 👍