all you pro's ................help

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kingmully

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Joined 2006
#1
Hi all
i lookong for a triplets lens or anything i can get hold of fron the uk. the thin is i wonder if a digital camera lens could be used as a projection lens?

for example if it is a 210mm focal length for a digital camera would it actually work? would it projected an image?

i have a 9 inch lcd and a fresenal of 320 or 210 mm.

all u pro out there fill me in all this please. cheers
 
#5
thanks for that is there another lens on that site that you can recomend for me? what focal length would i need for a 9 inch lcd then?

i be grateful if you can, i was just about to send the order but decided to see if you replied and thank god you did.
 
#8
If you want the maximum lighting efficiency and to make your box small, I recommend you to use 228 mm (9") FL projection lens and 228 mm (9") FL second fresnel lens. The FL of the first fresnel lens depends on the angle of your light bulb reflector, but I think FL around 220 mm will be OK.
 
#11
The 265 mm lens will work fine. Only the projection box will be several centimeter longer than using 220 mm FL lens. You need a 265 mm FL second fresnel lens to match this 265 mm projection lens. The FL of the first fresnel is not decided by the focus lens of your projection lens, but by the emission angle of your light source.
 
#12
Hi, here is something that works instead of a triplet lens: I am a photographer and had several inexpensive closeup filters of various dia lying around, I combined two of these lenses back to back to create a very nice projection lens also you can vary the lenses to create a larger or smaller projection!
The close up filters are available from photography stores for about Rs 150 ( About $4) for a set of 4 focal lengths. As these are for photography lens quality is good, buy two sets of slightly different dia helps to lock them in together.
My projection is over 90 inches across with a 150 w MHI bulb, I used a 8" car roof LCd TFT screen.
Check out Mr Cruise on my wall.I need to Make a screen as the wall is pale yellow as of now thats way the yellow cast will post more results soon.
 

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#13
Thank You, close up filters are a great idea!
How long is the adapter tube when you are using the filters as a projection lens?
I would love more details.
Which diopter filters are you using for your projection? What diameter?

If you could post pictures of your projection lens setup that would be great.

Thanks a lot!

Tgreenwood
 
#14
re Lens

Hope you find this useful, The lenses are together, but back to back- the screw in threads facing outside -there is no tube , but I made a focusing system from corrugated plastic sheet rectangular boxes that slide inside one another snugly.I will post pictures tonight if this seems difficult to understand. the dia that I used was 62mm and 57mm both filters were of +2 magnification.
 
#15
The focal length of a multiple lens projection lens changes with changes in the distance between between the individual lenses (did that make sense?). I guess what I want to know is, How much distance is between the lenses approximately? That will give me an idea of the projection focal length you are working with.

Is there any reason for the filters to be back to back, or were they just easier to mount that way?

Thanks,
Tgreenwood
 
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