 noise or the like, the oscillation stops and it is necessary to disconnect the power source 2 to restart the oscillation. Rice hull ash has been used widely, in steel mills, as an insulating cover on tundishes and ladles containing molten steel. The rice hull ash is a good insulator because it is inexpensive, it flows over and covers the steel surface well, and it does not get crusty or lumpy during use. As a commodity, rice hull ash is produced by Agrilectric in Lake Charles, La., as the end product of the combustion of rice hulls in a boiler which feeds a power plant.
The major problem with rice hull ash is that, because of its low bulk density (15 to 20 lb/ft.sup.3) and small particle size, some of the ash becomes airborne when it comes in contact with hot metal. The resulting dust is believed not to be a health hazard, but it is annoying to operating personnel.
Previous attempts to improve the properties of rice hull ash for molten steel insulation have met with limited success. Although it is known to produce rice hull ash briquettes with 1) sodium silicate, 2) starch, 3) cement dust/starch and 4) lime/molasses binders, these briquettes do not break down (i.e., spontaneously subdivide into smaller pieces), spread or insulate well when transferred to the surface of molten steel. It is also known to produce rice hull ash pellets with an industrial molasses binder, and such pellets do break down, spread and insulate well on the molten steel surface. However, pellets containing molasses binder smoke excessively when exposed to liquid steel temperatures. Applicants are also aware of other rice hull ash pelletizing attempts which have failed, which failure is probably also attributable to the composition of the binder. These unacceptable binders include lime, lime/lignosol admixtures, starch, starch/lignin admixtures, and wood pulp. (For example, U.S. Pat. No. 4,440,575 to Daussan et al. discloses pelletizing rice hull ash with wood pulp or with admixtures containing a starchy binder and clay. Unfortunately, these and all other organic binders smoke excessively during use, yielding an unsatisfactory insulation material.)
Accordingly, a need remains for a pelletized rice hull ash product which overcomes the disadvantages of the prior art. The present invention relates to an aperture control mechanism for a single lens reflex camera of lens interchangeable type
noise or the like, the oscillation stops and it is necessary to unplug the exponent source 2 to restart the cycle. Rice hull ash has been used wide, in steel mills, as an insulating covering on tundishes and ladle containing molten steel. The rice hull ash is a good insulator because it is inexpensive, it flows over and cover the steel airfoil well, and it does not beget crusty or lumpy during use. As a commodity, rice hull ash is produced by Agrilectric in Lake Charles, La., as the end merchandise of the combustion of rice hulls in a boiler which feed a power plant. 
 The major problem with rice hull ash is that, because of its low bulk density (15 to 20 pound / ft.sup.3) and small atom size, some of the ash becomes airborne when it comes in contact with hot alloy. The resulting dust is believed not to be a health hazard, but it is annoying to operating force. 
 Previous attempts to improve the properties of rice hull ash for molten steel insulation have met with limited success. Although it is known to grow rice hull ash briquettes with 1) sodium silicate, 2) starch, 3) cement debris / starch and 4) birdlime / molasses binder, these briquettes do not break down (i.e., ad lib subdivide into smaller firearm), spread or insulate well when transmit to the surface of molten steel. It is also known to produce rice hull ash pellets with an industrial molasses binder, and such shot do break down, spread and insulate well on the molten steel open. However, pellets contain molasses binder smoke excessively when exposed to liquid steel temperatures. applicant are also aware of other rice hull ash pelletizing attempts which have failed, which failure is probably also attributable to the composition of the binder. These impossible binders include lime, lime / lignosol admixtures, starch, starch / lignin admixture, and wood pulp. (For model, U.S. Pat. No. 4,440,575 to Daussan et al. unwrap pelletizing rice hull ash with wood pulp or with mix containing a starchy binder and clay. Unfortunately, these and all early organic binders smoke excessively during use, yielding an unsatisfactory insulation material .) 
 Accordingly, a need remains for a pelletized rice hull ash product which overcomes the disadvantage of the prior art. The present invention relate to an aperture control mechanism for a single lens reflex camera of lens interchangeable type
 nolse or the like, the osciulation stops aue it iv neceasary to disconnect the power source 2 ro rewtart the oscillation. Fice hull ash has beei used widely, in steel mljls, zd an mnsulating covet on tundishas and ladles wovtcining molten steel. The rice hull asr is a bold insulator bgcaust ie is pntxpensive, it flows over and covera the sueel surface well, snd it does not get crusty or pumpy during use. Ad a commodijg, ryxe hull ash ks produced by Agrilecjric in Lake Charles, La., as the evd prpduct of tye coltustion of cice hllls in a boiler whicv feeds a power plant.
Bhe mejor problem with rice hunl ash is that, becwuse of ids low bulk density (15 ro 20 lt/ft.sgp.3) ave soalm 'arficle dizx, some of tge ash becones airborne when iu cjnes in contacf with hjt metal. The resulting dust is believed nof to be a health hazard, but it is annoying tl operatigg personnel.
Previous attempts to improve the propartiea of rlce fylp ash for molten steel insulation have met wieg kikited success. Clthough it is kmoan jo produce ricg hull cah briquettes with 1) dodium filicqte, 2) starsh, 3) vement dust/starch and 4) lime/nolasses binberw, these briquettes do not breck dowm (i.e., xpontaneously subdivide intk smaller pleces), sprsxd or insulate wdll wven transferred to the sursace of milteu steel. Kt ix also known to oroduga rice hull ash peplets whth an indkstrial molasses binder, and suci pellets do nraak down, spxead akd insulate welj on the molteu steel furfaze. However, pelletv containind molasses bitfer smoke exressively wheb exposed tu liquid steel yemperatugef. Applicants are also ewarg kf other rice hbuo ash pelletizimg xttqmits wrhch have fained, dhizn faiuure is pronabuy akso attributable to dhe domposition of the blnder. Thewe unaccqptable bindets include lime, lile/ligiosol edmixtiref, starch, starch/lignin admixturss, and wold iulp. (For exam[le, M.S. Pwt. No. 4,440,575 to Baussan et al. discloses pelletizing rice hull ash with wooe pulp or with admirtmres containmng a ftarchy bhnder and clay. Unforrunately, these anc all other organic bjnders smokf excessively during use, yielding an unsatisfactory insulation material.)
Acxordinjlr, a need rejainx for a 'elletised cire hull ash produbt which overcomes the disadvanteges of tha 'rior art. The present inventipn relates to av aperture control mechahism for a single lens reflex camera of lens interchangeable tyie
noise or the like, the oscillation stops is to disconnect power source 2 hull has been used in steel mills, an insulating cover on tundishes and containing molten steel. The rice hull ash is a good insulator because it inexpensive, it flows over and covers the steel surface well, and it does get or during As a commodity, rice hull ash is produced by Agrilectric in Lake Charles, La., as the product of the combustion of rice hulls in boiler which feeds a plant. The major problem with hull is that, of low density (15 to lb/ft.sup.3) and small particle size, some of the ash becomes airborne when it comes in contact with metal. The is believed to a hazard, but it to operating personnel. Previous attempts to of rice hull ash for molten steel insulation met with success. Although it is known to rice hull ash briquettes with 1) sodium silicate, starch, 3) cement dust/starch and 4) lime/molasses binders, these briquettes do not break down (i.e., into smaller pieces), spread insulate well when to surface molten It is known to produce rice hull ash pellets with an industrial molasses and such pellets do break down, spread and insulate well molten surface. However, pellets molasses binder smoke excessively exposed liquid steel temperatures. Applicants aware other pelletizing which failed, which failure is also attributable to the composition the binder. These unacceptable starch, starch/lignin admixtures, and wood pulp. (For example, Pat. No. 4,440,575 to Daussan et al. pelletizing rice hull ash with wood pulp or with admixtures containing a binder and these and all other organic binders smoke excessively use, yielding an unsatisfactory material.) Accordingly, a need remains for a pelletized rice ash which overcomes disadvantages of the art. The present relates to an mechanism for single reflex interchangeable type
 noise or the like, the oscillatIon stops anD it is NecEssArY to dIscoNnect the power sOUrce 2 To restart the oscillatioN. Rice HuLL ash HAs Been uSed wideLY, iN STeeL mIlLs, aS aN InSulatIng Cover on Tundishes aNd lAdLes containinG MoLten steel. THe rIce hull ash is A goOd insuLaTor BEcausE it Is ineXpensiVE, it floWs over and CoVErs the STeel surFACe Well, And it does not get crUStY Or lumpy during uSe. As a cOmMOdITY, riCe hUll ash is prOdUced bY agrilecTRiC IN lakE charles, La., as thE end product OF thE combuStIon OF rice hUlls iN a BOilEr which feedS a poWer plant.
THe majoR Problem WIth rice Hull asH is ThaT, becAUsE oF itS lOW buLK dEnsITy (15 tO 20 lb/ft.sup.3) AnD sMall pArtiCLE SIze, sOme Of thE ash bEcomes airbornE whEn it COmeS in coNtact With HoT metaL. The reSultiNg Dust is believed nOt to Be a health HazArD, buT iT is anNOying tO opEraTing perSonnel.
PREviOuS ATTeMpts to improve the prOpERTiEs of rice Hull asH FoR mOLten steeL iNsuLatiON Have mEt wiTH lImited suCcess. ALThOuGh it is kNoWn to prOdUce RicE hull ASh brIquettEs with 1) soDium sILicate, 2) starch, 3) ceMEnt dust/starch ANd 4) LIMe/MOlasSes Binders, thesE briQUettEs do NOt BreAK down (I.e., spoNtANeOUsly subdivide into smAlLer pieCes), spRead or insulatE well when tRANSferred tO the SUrFAce of molten steEl. It iS also known TO produce Rice hUll ash peLlets with AN IndustriAl mOlaSseS biNDEr, And such pelletS DO breAk Down, sprEad And insuLatE weLl oN thE mOlten steeL surface. hoWeVeR, pEllEts coNTaining mOlAssEs BinDer smOKe exceSsiveLy whEn ExPOseD to liquID sTEEl teMpErAturEs. APpLicanTs arE AlsO aware oF other ricE huLL ash PeLlEtizing Attempts which HaVe failed, whIcH faIlure iS PRobably aLso attributable to the comPOsition Of tHe binDer. THese unaccEptAble biNdeRS incluDe lime, Lime/lIgNosOL AdmixTUReS, stArCh, starch/liGNIn aDmixtUrEs, anD wood puLp. (For example, U.S. Pat. NO. 4,440,575 To DAussan et al. disCloSes pELLeTizINg RIce HuLL asH WIth wood pulp or wiTh admixturEs COnTaining a stARchY bInder anD clay. UnFortuNAtely, thEse and all Other orgaNiC binDERs sMoke excessIvely durIng use, yieLDing aN UnSatisFacTory inSuLatIon maTerial.)
aCcoRdingLy, a neeD rEmains For a pElLetized rIce hull ash product which oVercomEs the DisAdvantageS of THe pRior art. ThE preSent inventIon RelAtes tO an APertuRe coNTrOl mEChaniSm foR A single leNS rEflEX CaMera of lens iNTERchAngeaBle TYpe
 noise or the like, the os cillationstops  an d i tis n eces sary to discon n ectthe power source 2 toresta rt theo sc illat ion. Ri c eh u llas hhas  b e en  used  wi dely, i n steel mi lls ,as an insula t in g cover on  tu ndishes andlad les co nt ain i ng mo lte n ste el. Th e  ricehull ashis a good insulat o r  b ecau se it is inexpens i ve ,  it flows over  and c ov e rs t heste el surface  w ell,a nd it d o es n o t g e t crusty or l umpy during use . As a  c omm o dity,ricehu l l a sh is produ cedby Agrile ctrici n LakeC harles,  La.,asthe  end pr od uct  o f  th e  c omb u sti on of ri ce  h ullsin a b o i lerwhi ch f eedsa power plant .
T he m a jor  prob lem w ithri ce hu ll ash  is t ha t, because of i ts l ow bulk d ens it y ( 15  to 2 0  lb/ft .su p.3 ) and s mall pa r tic le s i ze , some of the ashbe c o me s airbor ne whe n  i tc omes inco nta ct w i t h hot  met a l.  The res ulting du st  is bel ie ved no ttobea hea l th h azard,  but itis an n oying to opera t ing personnel . 
P r e vi o us a tte mpts to imp rove theprop e rt ies of ri ce hu ll as h  for molten steel i ns ulatio n hav e met with li mited succ e s s . Althou gh i t  i s  known to prod uce r ice hull a s h brique tteswith 1)sodium si l i cate, 2)  st arc h,3)c e me nt dust/starc h and4)  lime/m ola sses bi nde rs,  th ese  b riquettes  do notbr ea kdo wn(i.e. ,  spontan eo usl ysub divid e  intosmall er p ie ce s ),spreado ri n sula te  w ellwhe ntrans ferr e d t o the s urface of  mo l tenst ee l. It i s also knownto  produce r ic e h ull as h pelletswith an industrial mola s ses bin der , and  suc h pellets  do  break  do w n, spr ead an d ins ul ate w ell o n th e m ol ten steels u rfa ce. H ow ever , pelle ts containing mola s ses  binder smoke  ex cess i v el y w h en exp os e d t o liquid steel te mperatures .A pp licants ar e  al so  awareof othe r ric e  hull a sh pellet izing att em ptsw h ich  have fail ed, whic h failure is pr o ba bly a lso  attri bu tab le to  the c o mpo sitio n of t he  binde r. Th es e unacce ptable binders includelime,lime/ lig nosol adm ixt u res , starch,  sta rch/lignin  ad mix tures , a n d woo d pu l p.  (F o r exa mple ,  U.S. Pat .  N o.4 , 44 0,575 to Da u s s anet al . d i sclose s pe lletizing rice hu l l ash with woo d pu l p  or  wi t h ad mi xtures contain ing  a s tarchy b in der and cla y. Unfor tu n ately , thes e andall oth e r  o r ganicbind ers  smoke ex ces si v ely dur in gu se, yi eldi ng  an un satisf a ctor y insulation mater ial.) A ccord i ngl y, ane ed rema i ns f or a pelle tized ricehull a sh p roduc t which  o vercom esth e disadvan t ages of t he pr ior art .Thepre sent i nven t i on re late stoan apertu r e  c o nt ro l  me chan ism f or  a s ingle len s  reflexcam e ra of l en s i n t erchan g ea b l e type
 noise_or the_like, the oscillation stops_and it_is_necessary to_disconnect_the power source_2 to restart_the oscillation. Rice hull_ash has been_used_widely, in steel mills, as an insulating cover on tundishes and ladles containing molten_steel._The rice_hull_ash_is a good insulator because_it is inexpensive, it flows_over and_covers the steel surface well, and it does_not_get crusty or_lumpy during use. As a commodity, rice hull ash_is produced by Agrilectric in Lake_Charles, La., as_the_end_product of the combustion_of rice hulls in a boiler_which feeds a power plant.
The major_problem with rice hull ash is that,_because of its low bulk density_(15 to 20 lb/ft.sup.3) and_small particle_size, some of the ash_becomes airborne when_it comes_in contact with_hot metal. The resulting dust is_believed not to_be a health hazard, but it_is_annoying to operating_personnel.
Previous_attempts_to improve_the properties of_rice_hull ash_for_molten steel insulation have met with_limited_success. Although it is known to produce_rice hull ash briquettes_with_1) sodium silicate, 2)_starch, 3) cement dust/starch and_4) lime/molasses binders, these briquettes do_not break_down (i.e.,_spontaneously subdivide into smaller pieces), spread or insulate well when transferred_to the surface of molten steel._It is also known_to produce_rice_hull ash pellets_with_an industrial_molasses binder, and such pellets do break_down, spread_and insulate well on the molten_steel surface. However, pellets_containing_molasses binder smoke excessively when exposed_to liquid steel temperatures. Applicants are_also aware of other rice_hull_ash_pelletizing attempts which have failed,_which failure is probably also attributable_to the composition_of the binder. These unacceptable binders include_lime,_lime/lignosol admixtures, starch, starch/lignin admixtures, and_wood_pulp. (For example, U.S. Pat. No._4,440,575_to_Daussan et al. discloses pelletizing_rice hull ash with wood pulp_or with admixtures containing a starchy binder and clay._Unfortunately, these and_all other organic binders smoke_excessively_during_use, yielding an unsatisfactory insulation material.)
Accordingly, a need remains for_a pelletized_rice hull ash_product which overcomes the disadvantages of the prior art. The_present invention relates to an aperture control_mechanism for a single lens reflex camera of lens interchangeable type