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Some decent questions

PostPosted: Sat May 30, 2020 2:44 pm
by NN637261711496057836UL
Hey guys,
I have a photophase back and I need a filter to cut IR (like TG1)
I would like to use it with a 47XL @ 120° (shifted) and because its expensive, I prefer to have only one filter for all lenses

There are 3 places to put the filter
If I put it on the front ofthe center filter (86mm) I have to find a 122mm filter (because of 120° angle) and the 86 to 122 ring.
If I put behind the lens, It can be less large but may introduce optical aberrations and it must be coated. and not easy to fix it.
If I put it in the front of the spring back, I need a 128x128mm² or 5x5in² size filter but it must be coated. SO,
1) What is the best way?
2) does the TG1 filter exist in that sizes?
3) if not, what is the Schott equivalent of the TG1? BG38? KG3? ??
4) are phase one filter coated?

Thanks in advance

Re: Some decent questions

PostPosted: Tue Jun 09, 2020 7:35 am
by Ulf
Hi

The filter it self is a BG39 and it is coated.
It is an unusual size so it might be a special order.
The best option is often to place the filter infront of the lens.