Full spectrum modification

[zumka]

Hi guys,
I got my hands-on old Canon T5i and are planning to modify it. I know this topic has been covered many times, but I just have a few quick questions to get more clarity on the subject of full spectrum modification. I’m intending to use a modified camera with LP filter and Tamaron SP 150-600 lens in manual mode for deep space photography. Now to the questions.
I would like to avoid purchasing expensive Astronomik MC Clear Glass. Considering that I’m using clip-in light pollution filter, can I just remove both low pass filters and leave the censor open?
Will this setup affect my focusing?
Thank you

[RyanJones]

Hi Daniel,

Simple answers, yes you can and yes it will. You’ll actually be surprised how much it changes the focal point. You’re going to get a whole heap of “ you can’t use it for daytime photography and your auto focus won’t work “ comments but by the sound of it you’re intending on using it as a dedicated astro camera anyway so I’ll skip past that. When choosing a filter, make sure it’s a CCD filter as they have a a tighter U/V cut and this will stop you getting as much bloating in your stars. If you are intending on doing this mod your self, all I can say is that it will test your dexterity. Certainly doable but those ribbon cables are pretty set in their ways and are not the easiest to get back in. Don’t let this put you off though. You’ll feel great once you’ve achieved it :)
Good luck and have fun :)

Cheers

Ryan

[rustigsmed]

this ^^^

[Merlin66]

I have and use a Canon 1000D with both internal filters removed (for spectroscopy)
The mod doesn’t allow standard camera lenses to come to focus....
You have two options:
Re-set the position of the sensor within the body to compensate or
Fit a clip in filter to compensate - I use an Astronomik clear glass clip in version.
This second option allows you to manually focus lenses but the autofocus doesn’t work - this needs option one.

[zumka]

Thank you for your replies:

Clip-in Light Pollution CCD Filter, what would you recommend? I currently use Optolong L-Pro with my other Nikon D750 Camera.


Merlin66 Astronomik clear glass will cost me more than camera :)

Does anyone know where I can find clear/easy instructions on how to reset the position of the sensor within the body to compensate for missing filter?

[bojan]

Daniel,

Sensor will not be left open - you will still have glass cover over the chip.
BTW, if you intend to use the camera for AP only, auto-focusing won't be needed because you will focus via live view anyway.

And I recommend you to remove the focus screen as well, you will be able to see fainter objects through camera eyepiece easier.. sometimes this is easier than goto.

[zumka]

Thanks Bojan, so you recommending not to worry about resetting the position of the sensor since I'm going to focus via live view screen. Do you have the instruction on how to remove the focus screen in T5i

[Merlin66]

Daniel,
You originally said:
"""

I’m intending to use a modified camera with LP filter and Tamaron SP 150-600 lens
""
You may find difficulty focusing a camera lens with the FULL full mod.
I couldn't focus my EF lenses manual or otherwise without adding the clip in filter.
Replacing the removed filters with a Baader or similar filter would work.

[zumka]

I should probably be more clearer. Camera and lens will be used for AP only, so focusing will be done via the live view.

[Merlin66]

Daniel,
Any camera lens will have difficulty with infinity focus on the modded camera, whether terrestrial imaging or AP.
Obviously doesn’t matter with a telescope combo where you can focus independently of the camera body depth.

[bojan]

That is true, Ken is right - it may be difficult to focus with commercial lens.
Sometimes it is possible to modify lens as well, to compensate for lack of filter and move the focus plane further (there will be stops inside the lens that need to be moved or removed).
Or, use different lens, fixed focus primes are usually better for AP than zooms.
see here:
http://www.iceinspace.com.au/forum/showthread.php?t=51866&highlight=canon+200mm


Another possible way is to remove the shims between sensor and mirror box.
And adding flat glass as suggested by others.


Another point - if you are using glass lens with full spectrum modified camera, you will definitely need UV-IR cut filter to avoid bloated stars. See here, post #25
http://www.iceinspace.com.au/forum/showthread.php?t=153419&highlight=rocolax+filter


Better option is to use mirror lens (catadioptric) if you do not have filter.


Have a look here (https://www.google.com/search?client=firefox-b-d&sxsrf=ALeKk03zLFv5J97_c3rP0uDGl_O3G 0oqmA%3A1586157704185&ei=iNiKXtjvCpzfz7sPnay8-AY&q=T5i+focus+screen+remove&oq=T5i+focus+screen+remove&gs_lcp=CgZwc3ktYWIQAzoECAAQR0oKCBcS BjEyLTExN0oICBgSBDEyLTVQwB9YgENgqUx oAnACeACAAaoBiAH2A5IBAzAuM5gBAKABAa oBB2d3cy13aXo&sclient=psy-ab&ved=0ahUKEwjY04_0odPoAhWc73MBHR0WD2 8Q4dUDCAs&uact=5) for focus screen removal.

[zumka]

Do you know who sells clip-in filter like Astronomik MC Clear Glass?

[zumka]

Are you referring to this sort of filter https://www.astronomik.com/en/clip-filter-system.html ?

Will this setup work with commercial lenses like Tamron or do I still need to replace the removed filter as well to be able to focus ?

[bojan]

Try it... some lenses have enough spare movement to accommodate slight variations of focal distance, especially older ones.

[JA]

Hi Zumka,

Some lenses have hard infinity stops, some, usually modern autofocus (also even some older MF ones)lenses do not. A lens without a hard infinity stop may have sufficient travel beyond the usual infinity point, to allow the lens to be manually focused with filters removed, remembering that with filters removed the new focal plane would be slightly further forward (towards the lens).

There is no guarantee of success. It would depend on the original filter thickness, refractive index and how much post infinity mark lens travel is available.

Best
JA

[Merlin66]

None of my Canon EF lenses worked without the clip in filter......

[zumka]

My Tamaron SP 150-600 is a Nikon lens I'm going to use Canon converter

[Merlin66]

Daniel,
I’d say the adaptor is designed to replicate the EF lens back focus distance, you could find the same infinity focus issue.....sorry.

[zumka]

As bojan said, I can always give it a try. Worst case scenario I'll add Astronomik MC Clear Glass replacement filter later.

BTW Who in Australia sells these replacement filters ?

[Merlin66]

Daniel,
Sorry don’t know....I bought my clip in filter in Europe.