Improvising: long focal length lens

[simon_rodan]

I hope to do a portrait on 4x5 early next week and the longest lens I have is 180mm. I would ideally like to use a 300mm but I can't afford to buy one and would prefer not to have to hire one unless I have to.<p>

I discovered after a little experimenting that removing the front cell of my 180 Symmar-S (i.e. using only the rear cell) extends the focal length of the lens considerably (perhaps to around 300 though I have not measured it).<p> Does anyone have any thoughts on the viability of this 'improvisation'?

[armin_seeholzer]

Hi Simon

 

<p>

 

I have an older Symmar f1:5.6 210 mmand if I take only the back element

then I get f1:12 370mm it is green stated on mine.

Just test it on the groundglas if you get it sharp with a loupe, but

you need a bellows lengs from about 300mm.

Otherwise take it with the 180mm just with shoulders not only the head

then it should be okay with 180mm almost.

Don`t forget the different F stops if you only need the back elemnt.

The other idea is take the front element alone and check it also thies

way.In may case I still did not test it with the front element alone,

but I`m quite sure it works also with my older one.

Best you trie all versions then you know it, and let me know to!

 

<p>

 

Good luck and good light!

[andrea_milano]

unless you need to fillyour format (slides for viewing .....or

something like that), it is a lot better to crop your image and let

the lens alone (Armin is right it is the front element you should

remove.....)the lens performs as a longer lens allright but with a

tremendous loss of quality, enlarging is a better option. Most

portraits on large formats are done with shorter lenses than the small

format, for a number of reasons....